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NATIONAL CLIMATE SCIENCE CONFERENCE 2-3 JULY 2015
ABSTRACTS
DIVECHA CENTRE FOR CLIMATE CHANGE
INDIAN INSTITUTE OF SCIENCE
BANGALORE
Late Pleistocene to Holocene variations in East Asian Monsoon
using foraminifera proxy from IODP site U1429A
Abhijith, U.V1*, Raj K. Singh1
1 School of Earth, Ocean and Climate Sciences, Indian Institute of Technology
Bhubaneswar, Odisha, India – 751002
*Corresponding author email: [email protected]
Asian monsoon comprising of South Asian monsoon and East Asian monsoon has been
subjected to detailed study because of its influence on a large population, economy and also
due to scientific relevance. IODP, Expedition 346 on the site U1429 of East China sea whose
surface water conditions are determined by Yangtze river discharge showed a high
sedimentation rate of 762m/my with an excellent preservation of calcareous nanofossils,
foraminiferas,ostracods, pteropods, diatoms, and radiolarians indicating the potential of site.
In our study, we analysed two core samples from IODP Hole U1429A to reconstruct late
Pleistocene to Holocene Asian monsoon. We have analyzedplanktic foraminifera to get
mixed layer thickness, thermo cline depth and benthic foraminifera to understand deep sea
environment and productivity changes. We also calculated benthic foraminifera species
diversity to understand glacial inter glacial changes and clay percentage to know the detrital
influx. The preliminary data show high productivity when precipitation is high and low
productivity during the period of low precipitation. The mixed layer thickness and thermo
cline depth also shows variations with varying monsoon intensity. This work shows the
potential of the site for high resolution centennial-millennial scale of study of Asian monsoon
and factors influencing monsoonal behaviour.
Key Words: Foraminifera, Planktic, Benthic, Asian Monsoon, East China Sea
Influence of Indian monsoon on Carbon dioxide Source and Sink
Mechanism
Abhilash Kumar Paswan1*,Yogesh K. Tiwari2
1Indian Institute of Science Education and Research Kolkata 2Indian Institute of Tropical Meteorology, Pune
Atmospheric CO2 has become the largest contributor among all anthropogenic greenhouse
gases to warming the global climate. It is increasing globally at the rate of 2 ppm per year,
mainly as a consequence of fossil fuel combustion and human activities. In addition to the
trends, atmospheric CO2 also exhibits year-to-year strong seasonal Cycles. It also
demonstrates intra-seasonal and interannualvariabilities. In the present study, atmospheric
CO2 records from two monitoring sites over South Asia, Cape Rama(CRI;73.9 E,15.1 N),
India and Mt. Waliguan (MWC;100.89 E,36.28 N), China during the year 2000-2010 has
been chosen to understand CO2 variabilities during Indian summer monsoon and winter
monsoon months. The sites in this study are chosen in such a way that one site (CRI) has
seasonal reversal wind pattern and located in monsoon zone whereas other site (MWC) has
minimal influence of summer monsoon. This study reveals that during southwest monsoon
(JJAS) CO2 concentration over MWC is negatively correlated with CRI. But for all the other
months, correlation is positive. Both observations and model simulations agrees well. It also
reveals that during Southwest Monsoon the site MWC act as a CO2 sink region. However, if
we see the atmospheric stability over study region CRI changes neutral to slightly unstable
during SW monsoon while MWC remains in neutral condition during this period. Further
analysis will be reflected during presentation.
Impact of ISRO vegetation on EKF based Land-Data
Assimilation System for NCUM at NCMRWF
Abhishek Lodh1*,Unnikrishnan C.K1, John P George1 and E. N. Rajagopal1
1National Centre for Medium Range Weather Forecasting (NCMRWF)
Earth System Science Organisation, Ministry of Earth Sciences
A-50, Sector-62, NOIDA- 201 309, India
Phone:0120-2419409
It is important to provide accurate soil moisture initial conditions to the atmospheric models
used for Numerical Weather Prediction (NWP). An Extended Kalman Filter (EKF) based
Land Data Assimilation System (LDAS) has been implemented recently for soil moisture
analysis replacing the ASCAT nudging scheme in the NCMRWF Unified Model (NCUM)
used for global NWP. This EKF based LDAS adapted from Met Office; UK uses soil wetness
observations from satellite - ASCAT (Advanced Scatterometer instrument) as well as the
atmospheric tendencies of temperature and humidity at surface. It uses JULES (Joint UK
Land Environment Simulator) land surface model to create the perturbations for the EKF
based LDAS. The EKF based LDAS creates six hourly soil moisture analyses, which is used
to initialize the soil moisture (at 10, 25, 65 and 200 cm levels) in NCUM. The JULES model
uses the IGBP surface vegetation fractions, which is based on 1992-93 observations. As there
are significant changes in land use/land cover over Indian region in the last three decades, a
new land use/land cover dataset has been prepared jointly by NRSC/ISRO and NCMRWF
using satellite observations (AWiFS). This new land use/land cover dataset has been used in
JULES instead of the IGBP dataset in the EKF based LDAS. Preliminary results of our
investigation show positive impact of using NRSC/ISRO dataset on the soil moisture
analysis, particularly over Central and Southern India region. The details will be presented at
the conference.
Studying Indian Monsoon, Land Atmosphere Interactions Using
Land Use/Land-Cover Change Sensitivity Experiments
Abhishek Lodh1*
Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, HauzKhas, New
Delhi-110016
* Current Affiliation
National Centre for Medium Range Weather Forecasting (NCMRWF)
Earth System Science Organisation, Ministry of Earth Sciences
A-50, Sector-62, NOIDA- 201 309, India
Phone:0120-2419409
The land atmosphere interactions, the feedbacks between soil moisture and precipitation and
the role of vegetation via different land surface modules and LuLc changes has been assessed
in Indian monsoon regime using BATS and CLM land surface module coupled regional
climate model RegCM4.0 over the Cordex South Asia domain and smaller South Asia.
Calculating the variance distribution and empirical orthogonal functions of the model
precipitation and soil moisture variable captures the variability of the monsoon system. The
variance distribution of model precipitation and soil moisture is same, satisfying necessary if
not sufficient condition indicating, strong coupling between soil moisture and precipitation
within the model. The Eof pattern is also able to capture the dominant spatial patterns of ISM.
We also investigate the sensitivity of different land-use and land-cover changes caused by
impact of deforestation and afforestation on the Indian summer monsoon (ISM) precipitation
and circulation patterns, under realistic NNRP-2 boundary forcings. Overall we perform five-
afforestation sensitivity and four deforestation sensitivity experiments. In the afforestation
sensitivity experiment, RegCM4.0 model vegetation/land-use types over have been modified
to deciduous broadleaf vegetation, evergreen, forest/field mosaic, irrigated crop and short
grass types along the spatial domain of the critically affected wasteland districts of India.
Interestingly, simulations suggest that wasteland conversion with afforestation over north-
western regions of Indian subcontinent has weakened the Indian summer monsoon over
various regions. Over Central India there is decrease in JJAS precipitation. Similarly, it is
also found that extended desertification in northwest India, significantly affects the Indian
monsoon at local and large scales. In an effort to study the role of central India and north-
western region of India for Indian summer monsoon, we have performed two hypothetical
lake sensitivity experiments. Additionally experiments are also performed to study the impact
of deglaciation of Himalayan glaciers, on the regional climate for adaptation and mitigation.
Application of Remote Sensing and Gis in the Analysis of Lulc
Change Study of Jharkhali Island Sundarbans, West Bengal
Aditya Shreshtkar1*, SukhaRanjan Samadder1
1Ism Dhanbad,
Population explosion in the Sundarban regions have cost drastic change in land use/ land
cover patterns. The study area, Jharkhali (W.B), is an island in the Sundarban and it
comprises of fragile Biosphere reserve area and proposed Ramsar site. In this study, Landsat
images, acquired in 1990 and 2010, were subjected to maximum likelihood supervised
classification and then image differencing, DNDVI and overlay operation techniques were
used to analyse the change. The time-series analysis have shown massive conversion of forest
land into agricultural lands and settlements. Land consumption rate of the area has also been
analysed which signifies the increasing trend of built-up land. The Namkhana reserved forest
has suffered serious deforestation. Also, increment in aquaculture farms in later year reflects
changing economic practices.
Keywords: Sundarban, Remote Sensing, GIS, Landuse change.
Cirrus clouds in changing climate: Long-term Lidar observations
from a tropical Indian station
Amit Kumar Pandit1, 2, Harish Gadhavi1, M. Venkat Ratnam1, K. Raghunath1 and A.
Jayaraman1
1National Atmospheric Research Laboratory, Gadanki-517 112 A. P., India
2Department of Physics, Sri Venkateshwara University, Tirupati-517502, A.P., India
In the present era of climate change, distribution of the ingredients pre-requisite (low
temperature, water vapour and ice-nuclei) for the formation of cirrus clouds in tropics is
changing. Consequently, this change is expected to alter the spatial distribution, micro and
macrophysical properties of tropical cirrus clouds. Using the longest duration (from year
1998-2013) cirrus cloud observations obtained from a ground-based Lidar situated at a
tropical south-Indian station: Gadanki (13.45˚N, 79.18˚E and 375 m amsl), we investigated
the changes in the properties (viz. altitude, temperature, geometrical and optical thickness) of
cirrus clouds. We present trend analyses which reveal a statistically significant upward shift
in the altitude of cirrus clouds at a rate higher than that predicted by recent climate model
simulations. Only sub-visible type of cirrus clouds (having optical thickness less than 0.03)
which are known to cause warming and dehydration in the atmosphere exhibited this upward
shift while the other two types (thin and thick) of cirrus cloud did not. Also, the fraction of
sub-visible cirrus clouds in the atmosphere is found to be increasing in the last sixteen years.
These changes would significantly impact the temperature and water vapour budget in the
upper-troposphere and lower-stratosphere (UTLS) region.
Surface and Sub-Surface Temperature Trends In the North
Indian Ocean and Role of Oceanic Processes
Anandbabu Amere1, 2*,Anant Parekh1, Fousiya T.S1, G.Bharathi2, C.Gnanaseelan1 and
J.S.Chowdary1
1Indian Institute of Tropical Meteorology, Pune-411008;
2Department of Meteorology and Oceanography, Andhra University, Visakhapatnam
North Indian Ocean sea surface temperature (SST) trends known to have strong impact on the
climate over the Asia Pacific region.Many studies have reported increasing trend in SST over
the Indian Ocean. This is the first study exploring the concurrent surface and sub-surface
temperature trends in the North Indian Ocean using observations from Array for Real time
Geostrophic Oceanography (ARGO) as well as multiple ocean models outputs [Ocean
reanalysis (ORA), Simple Ocean Data Assimilation (SODA), Global Ocean Data
Assimilation (GODAS)] for the recent two decades (1990 to 2012). The study revealed that
there is increasing trend in SST and decreasing trend in subsurface temperature during
previous decade (1990 to 2001). Whereas no such trend in SST is evident in the recent
decade (2002 to 2012). On the other hand increasing trend in subsurface temperature is found
in the recent decade. These results are consistent in both observations and reanalysis data
sets. Detailed analysis revealed that the upper ocean vertical gradient in density display
negative (positive) trend during the second (first) decade leading to weak (strong ) buoyancy.
This supports more vertical mixing, which is also supported by the vertical velocity trend in
the recent decade. In addition to that, the horizontal advection of heat flux also has positive
trend in subsurface. Thus vertical processes and horizontal advection of heat flux seem to
play significant role in the observed sub-surface warming trend in the recent decade.
Multi-model based assessment of trends and variability in
terrestrial carbon uptake in India
Ananya S Rao1*, Govindaswamy Bala1
1Divecha Centre for Climate Change & Centre for Atmospheric and Oceanic Sciences,
Indian Institute of Science, Bangalore 560012, India
Indian terrestrial ecosystem exhibits large temporal and spatial variability in carbon sources
and sinks due to its monsoon based climate system; diverse land use and land cover
distribution and cultural practices. In this study, a multi-model based assessment is made to
study the trends and variability in the land carbon uptake for India over the 20th century.
Data from nine models which are a part of a recent land surface model intercomparison
project called TRENDY is used for the study. These models are driven with common forcing
data over the period of 1901–2010. Model output variables assessed include: gross primary
production (GPP), heterotrophic respiration (Rh), autotrophic respiration (Ra) and net
primary production (NPP). The net ecosystem exchange (NEE) for the Indian region was
calculated as a difference of NPP and Rh and it was found that the region behaves as a sink
for carbon with an estimated increase in uptake over the century by -0.6 TgC/year per year.
NPP for India also shows an increasing trend of 2.03% per decade from 1901-2010. Seasonal
variation in the multimodel mean NPP is maximum during the southwest monsoon period
(JJA) followed by the post monsoon period (SON) and is attributed to the maximum in
rainfall for the region during the months of JJA. To attribute the changes seen in the land
carbon variables, influence of climatic drivers such as precipitation, temperature and remote
influences of large scale phenomenon such as ENSO on the land carbon of the region are also
estimated in the study. It is found that although changes in precipitation shows a good
correlation to the changes seen in NEE, remote drivers like ENSO do not have much effect
on them.
Effects of large-scale deforestation on precipitation in the
monsoon regions: Remote versus local effects
N. Devaraju1*, Govindasamy Bala1, Angshuman Modak1
1Divecha Centre for Climate Change & Centre for Atmospheric and Oceanic Sciences,
Indian Institute of Science, Bangalore 560012, India
In this paper, using idealized climate model simulations, we investigate the biogeophysical
effects of large-scale deforestation on monsoon regions. We find that the remote forcing from
largescale deforestation in the northern middle and high latitudes shifts the Intertropical
Convergence Zone southward. This results in a significant decrease in precipitation in the
Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South
Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions
(South Africa, South America, and Australia). The magnitude of the monsoonal precipitation
changes depends on the location of deforestation, with remote effects showing a larger
influence than local effects. The South Asian Monsoon region is affected the most, with 18%
decline in precipitation over India. Our results indicate that any comprehensive assessment of
afforestation/ reforestation as climate change mitigation strategies should carefully evaluate
the remote effects on monsoonal precipitation alongside the large local impacts on
temperatures.
A Modelling Study on Role of Aerosols Cloud Liquid Water
interaction During Active-Break Cycle of
Indian Summer Monsoon
Anwesa Bhattacharya1*
Arindam Chakraborty1
V. Venugopal1
1Centre for Atmospheric and Oceanic Sciences
Indian Institute of Science
In our study, the Weather Research and Forecast Model (WRF), coupled with Chemistry, is
used to study aerosol-cloud water interaction during the active-break cycles of the Indian
summer monsoon. Two sets of simulations are performed to study this interaction, one with a
fixed aerosol concentration (control) and one with an observation-based prescription of the
rate of change of aerosol concentration as a function of precipitation (modified). This
prescription is derived based on satellite-retrieved daily rain rate and concurrent observations
of aerosol optical depth from Aerosol Robotic Network (AERONET). The proposed
modificationis necessitated by the lackof realistic emission estimates over the Indian region
as well as the presence of inherent biases in monsoon simulation in WRF.
In the modified simulation, unlike in the control run, we find that the break-to-active
monsoon phase has more cloud liquid water (CLW) and less rain efficiency than in the
active-to-break phase. This is primarily due to the indirect effect of increased aerosol loading
in the break phase. We also find that the proposed interactive aerosol loading results in higher
spatial variability in CLW and enhances the likelihood of increased cloud cover via formation
of larger clouds.
Ocean upwelling during the late Miocene: Evidence from the
diatom assemblages of Neil Island, Andaman and Nicobar Arindam Chakraborty1& Amit K.Ghosh1
1BirbalSahni Institute of Palaeobotany
53 University Road, Luck now – 226 007, INDIA
E-mail: [email protected], [email protected]
Late Miocene sediments are well exposed in the eastern and north-eastern part of Neil Island
belonging to Ritchie’s Archipelago in Andaman and Nicobar Islands. Eighty five species of
diatoms belonging to 19 centric and 17 benthic genera those include 37 planktonic and 48
benthic species have been identified from 21 samples collected from 9.5 meter thick outcrop
near cave point situated in the north-eastern part of the island. PCA analysis reveals that some
samples are closely related owing to dominance of benthic diatoms e.g.,
Thalassionemanitzschioides and some are closely related due to abundance of planktonic
diatoms e.g., Coscinodiscus sp. Five biozones have been proposed with the help of CONISS
cluster analysis. To ascertain high resolution biozones SHEBI analysis was carried out, that
envisages seven diatom assemblage zones. The outcrop is characterised by presence of late
Miocene marker radiolarian Didyomocyrtispenultima. The benthic and planktonic ratio as
well as C: P (Centric vs. Pennate) ratios of the diatoms show evidence of sea level
fluctuations during that period. The overall analysis indicates a strong monsoonal system;
however, there are evidences of intermittent weaker monsoonal activity. The upwelling taxon
Thalassionemanitzschioides confirms strong monsoonal activity during late Miocene in the
Andaman Sea.
Urban flood modelling – parameterization of flood model
Arjun B M1*, Bharat Lohani1, Ashu Jain1
1Department of Civil Engineering, IIT Kanpur
Global climatic change has triggered the weather pattern which leads to heavy and drastic
rainfall in different parts of world. The impact of heavy rainfall largely and severely affects
urban areas. In order to understand the effect of heavy rainfall induced flooding it is
necessary to model the entire flooding scenario more accurately. Availability of high
resolution data from LiDAR has potential to improve flood modelling. In this study,
modelling of flooding in urban areas due to heavy rainfall is carried out considering IIT
Kanpur as the study site. The existing model MIKE FLOOD, which is accepted by Federal
Emergency Management Agency (FEMA), is used along with the high resolution airborne
LiDAR data. The aim of the study is to identify correct parameters for flood modelling. Once
the model is setup it is made to run by changing the parameters such as resolution of Digital
Elevation Model (DEM), roughness coefficients, soil types, impervious nature of the terrain
and various hydrological parameters. Parameterization of the model will be done once the
model has been setup to arrive at the right set of parameters for the model. In order to arrive
at the right set of parameters, results obtained from the model run are compared with the field
observations. Results obtained from the above study demonstrate the significant impact of
resolution of DEM, initial losses, hydrological reduction, catchments, manning’s value on
urban flood modelling.
Sea Surface Temperature Changes Over the Indian Ocean
Arulalan T1*,Krishna AchutaRao1
1Centre for Atmospheric Sciences,
Indian Institute of Technology Delhi
Sea surface temperature (SST) over the Indian Ocean is directly connected with circulation,
winds, precipitation, humidity, etc. over India. Increased SSTs are a major consequence of
climate change driven largely by anthropogenic factors. We examine changes in the SST over
the Indian Ocean using two observational datasets; HadISST (v1.1) and ERSST (v3b). Based
on trend differences between two time periods (1979-2009 and 1948-1978) we identify four
regions in the Indian Ocean with different signatures of change - Bay of Bengal, Arabian Sea,
Southwest- and Southeast Indian Ocean.
We quantify the observed SST trends over multiple time-scales (20, 30, 50 and 100-years)
and making use of long control run simulations from the Coupled Model Intercomparison
Project Phase-5 (CMIP5) we find that the observed trends at longer time-periods are outside
of the range climate internal variability.
We also explore the contributions of the various natural and anthropogenic forcings by
making use of the suite of experiments (namely piControl, historical, historicalNat,
historicalAnt, historicalGHG, and historicalAA) from CMIP5.
Study of Martian Atmosphere using PlanetWRF: Role of Water
Vapour and Dust
ArunPrasaad G*, Ravi S Nanjundiah
*Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science
Using PlanetWRF, an atmospheric model based on NCAR's WRF, we have studied the
Martian atmosphere. We present some preliminary results from this study. We conducted a
simulation for 2500 Martian days. We have looked at the general circulation of Martian
atmosphere using this model. The variation of polar ice caps between seasons is also being
studied. Distinct zonal jets that occurred during summer and winter seasons of the north and
south hemispheres were noticed. We find that winds and temperature have interannual and
intra-annual periodicities. We are also comparing our simulations with earlier simulations of
this planet and propose to present this also.Also, keeping the above result as a bench mark,
three more simulations have been done by including and excluding atmospheric dust and
water cycles. The simulations show that polar ice caps, zonal jets and Hadley circulation are
sensitive to the variations in these parameters on seasonal time-scales. Seasonal assymetries
in some of these variables were noticed and the same would also be presented.
Orographic control on precipitation over Bay of Bengal Cold Pool
during Indian Summer Monsoon Season
Arushi P V1*
Arindam Chakraborty1,
Ravi S Nanjundiah1
*Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science
Although there exists a considerable spatial variability in the intensity of seasonal mean
rainfall over India and its surroundings during Indian Summer Monsoon season, most of the
domain experience rainfall with intensity higher than 6 mm/day. However, Bay of Bengal
Cold Pool (CP) experiences rainfall less than 2 mm/day. Over CP, vorticity above boundary
layer is positive with a magnitude comparable to that over the monsoon trough and sea
surface temperature (SST) is maintained well above the threshold value for convection.
However, even after having all favorable conditions for convection to occur, the region
receives very less rainfall throughout the monsoon season. We investigate the reason of this
paradox using an Atmospheric General Circulation Model (AGCM) with perturbed
simulations. We carry out simulations with varying height of Western Ghatmountains (from 0
to 2 times the present height) in the model and investigate its influence on the CP
precipitation. We find that there is an inverse relationship between the height of WG and
precipitation over CP. Decrease in height of WG reduces the inhibition of convection over
CP by increasing the moisture convergence in the boundary layer and weakening descent
related to mountain lee wave over the region.
Multi-Year Megha-Tropiques-ScaRaB observations of the
seasonal mean cloud radiative forcing over tropics
Ashok Kumar Gupta (1),K. Rajeev (1), Anish Kumar M. Nair (2), Manoj Kumar Mishra
(1)Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram
(2) National Atmospheric Research Laboratory, Tirupati
Radiation budget of the Earth-atmosphere system is predominantly regulated by clouds.
Accurate estimate of cloud radiative forcing (CRF) is essential to quantify the impact of
clouds and further understand the cloud feedback processes. Uniqueness of the low-
inclination (20°) MT-ScaRaB satellite payload to observe the diurnal variation of upwelling
SW and LW radiative fluxes during the satellite’s orbital precession cycle of 51 days has
been utilized to estimate the seasonal mean diurnal variations of shortwave, long wave and
net CRF (SWCRF, LWCRF and NCRF) at the top-of-atmosphere over the tropics during the
period of July 2012 – February 2014. Estimates of CRF are averaged at 3 hourly local time
intervals during each season (following ‘equivalent day analysis’) with a geographical
resolution of 1°x1°. The LWCRF shows intensification and deepening of organized
convection during night over deep convective oceanic regions. This is clearly evident at the
ITCZ as well as the ascending limbs of the Walker cell. This results in a diurnal variation of
LWCRF with amplitude of about 10 to 20 Wm-2, which is over 20% of the magnitude of
mean LWCRF over deep convective regions. The diurnal variation in LWCRF is
insignificant over the subsidence zones dominated by marine stratus clouds.
Effect of planetary rotation and baroclinicity on atmospheric
circulation, heat transport, and turbulent convection
Ayan Kumar Banerjee1*, AmitabhBhattacharya1, Sridhar Balasubramanian1,
Avik Das2
Geophysical and Multiphase Flow Lab 1Department of Mechanical Engineering, IIT Bombay
2Department of Civil Engineering, IIT Bombay
Turbulent thermal convection in the presence of background rotation is an important
geophysical fluid dynamics problem due to its impact on climatic systems. Heat transport in
rotating fluid with radial temperature gradient occurs due to baroclinic instability, which is
also the primary mechanism of heat transport in planetary atmosphere. These large-scale
atmospheric flow phenomenon are modeled experimentally with the help of a set up
comprising of a differentially heated (peripheral heating and central cooling) rotating
cylindrical annulus. The main governing non-dimensional numbers for this problem are:
Thermal Rossby number (ROT) and the Taylor number (Ta). The presence of rotation
inhibits the onset of convective turbulence and renders it two-dimensional, in a specific
parameter range of ROT and Ta. This regime is tagged as “geostrophic turbulence” and in
this regime the heat transport occurs in form of vertical columns. Experiments are done in the
range 1.9×107 < Ta < 4.57×107, and 4.73 <RoT< 10.6 corresponding to different ΔT and Ω.
The preliminary results show formation of very stable lobes within which flow is anti-
cyclonic, motion in between any two lobes is cyclonic, and the entire flow structure has a
cyclonic motion with a very low phase speed.
Peak Electricity Demand and Global Warming in the Industrial
and Residential areas of Pune: an Extreme Value Approach
T. Jayaraman1, Kamal Kumar Murari1, AyushMaheshwari1*
*School of Habitat Studies at Tata Institute of Social Sciences, Mumbai
Peak electricity load during summer season has an impact on electricity infrastructure and it
is expected to increase further due to global warming mainly due to cooling demand. Very
few studies have explored the relationship between peak electricity load and temperature
changes. The present study investigates the nature of electricity demand in Pune and
estimates the additional demand as a consequence of temperature rise due to the global
warming using extreme value theory. The results indicate that in the areas dominated by
residences, peak power demand registers an average increase of 3-4% due to global warming
under IPCC RCP 4.5 scenario. This indicates that electricity demand in residential areas are
highly sensitive to temperature changes, whereas, we found that industrial demand of
electricity is not significantly dependent on temperature changes. The study also provides
evidence for the use of solar energy to meet the peak electricity demand and establish a scope
for investigation of future peak electricity load and the load on electricity infrastructure.
Although the analysis takes empirical evidence for electricity demand data of Pune city,
however, the methods are useful to estimate the peak power load attributed to global warming
in other geographical regions.
Agricultural paddy residue fires are a significant contributor to
rising ambient concentrations of benzene in the N.W. IGP
B. Praphulla Chandra* and Vinayak Sinha
*Department of Earth and Environmental Sciences, Indian Institute of Science
Education and Research Mohali, Sector 81, S.A. S. Nagar, Manauli PO, Punjab, 140306,
India
Open paddy residue burning during the months of October/November in north west Indo-
Gangetic Plain (28 N -33 N and 72 E -79 E) is a major anthropogenic activity that perturbs
atmospheric composition and significantly affects regional air quality. Despite this activity
being banned by the government, fire count data obtained from remote sensing satellite over
the last decade (2004-2014) for the post-harvest paddy season (11 October-15 November)
suggest no decline. Average ambient CO and benzene concentrations over the
agriculture/rural fetch region (1800-3150 to the measurement site) obtained from high
resolution in-situ dataset (n>1000 measurements) during 2012, 2013 and 2014 were 1.4-1.9
times higher in post-harvest paddy season relative to the control period (10 September – 10
October) due to open fires. In all these years, concentrations of carcinogenic benzene during
post-harvest paddy season exceeded the annual exposure limit (1.6 ppb at NTP) aggravating
the health risk. Using relationship of fire counts with ambient CO and benzene concentration,
relative contributions of paddy residue and other open biomass fires to ambient benzene
enhancement during the post-harvest paddy season were determined to be 43% and 57%
respectively. This shows that effective mitigation of paddy residue fires alone can cause a
potential 43% reduction in the carcinogenic benzene.
Year-Round Aerosols Growth Events Observed At a
Representative Site of Delhi
B. SARANGI, S.G. AGGARWAL*, AND P.K. GUPTA
CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012, India
(*Correspondence to [email protected])
The newly formed aerosols become climatically important if they are able to grow to sizes of
50 nm or more. Particles in this size range can act as cloud condensation nuclei (CCN) and
thus contribute to indirect aerosol effect on the climate. Furthermore, if the particles grow to
sizes above ~100 nm they can scatter light much more effectively, and this effect is known as
direct effect (cooling) on the Earth climate. In order to determine the causes of atmospheric
nucleation event, and to better understand the characteristic of these events in different
environments, it is important to know the underlying processes causing the particle growth
and the physiochemical mechanisms controlling their formation and growth processes.
Therefore, the number size distributions (14 – 661 nm) of aerosol particles were measured
using a scanning mobility particle sizer (SMPS) at National Physical Laboratory, which is
located at the central part of New Delhi for at least three days in every month from January to
December 2013 and March - April 2014. In each month, a subsequent particle growth was
experienced, where these growths were observed to be sustained for comparatively a longer
period in February, March, April and December. Year-round average particle growth rate was
calculated to be 9.56 ± 2.6 nm/h, and the average particle number concentration was found to
be 1.53 × 104 (#/cm3). Springtime (March - April of 2013 and 2014) aerosol properties, trace
gas concentrations, and meteorological data were analysed to evaluate the conditions
favourable for daytime new particle formation and nighttime fine particle growth events.
Growth events were typically observed on nights which had both biogenic and anthropogenic
influences as indicated by high concentrations of nitrate and sulphate determined in PM1.0
filter samples collected parallel with SMPS measurement in spring. Consecutive nights with
growth events were well characterised by low wind speed and high relative humidity.
Observed strong correlations between particulate (PM1.0) water-soluble organic carbon
(WSOC) and nitrate/sulphate suggest that possibly a considerable portion of this nitrate and
sulphate are organic in nature, and are responsible for the observed particle growth in night in
springtime.
Effects of aerosols on Indian summer monsoon rainfall during El
Niño
Suvarna Fadnavis1, Chaitri Roy1*, Ashok Karumuri2, AyantikaDey Choudhury1,
T.P. Sabin1
1Indian Institute of Tropical Meteorology
2University of Hyderabad, India
We evaluate potential impacts of aerosol loading on the Indian summer monsoon rainfall
during concurrent El Niño years, using observed sea surface temperature (SST) and Total
Ozone Mapping Spectrometer (TOMS) aerosol index datasets for the 1979-2005 period. Our
analysis of the TOMS observations indicates a higher-than-normal aerosol loading over the
Indo-Gangetic plains (IGP) during the summer monsoon season (June~September) with a
concurrent El Niño, which exacerbates the El Niño-induced negative rainfall anomalies over
the Indian region. Our multi-ensemble sensitivity experiments with ECHAM5-HAMMOZ, a
fully-coupled aerosol chemistry climate model, confirm this finding. Interestingly, our
analysis also shows anomalously-high aerosols over IGP during April-May months (pre-
monsoon) of El Niño years. Further, we find that, in contrast to the impacts from the co-
occurring aerosols during summer monsoon, any enhanced pre-monsoon aerosol loading
induces positive precipitation anomalies over north India in the following summer monsoon
season and reduces the severity of drought during El Niño. This is apparently related to the
aerosol-induced warm core over the Tibetan plateau (TP) and related ’Elevated-Heat-Pump
(EHP)’ effect from the increased loading of pre-monsoon absorbing aerosols over the IGP
region.
Inter-annual variability and long term changes in the extreme sea
levels along the east coast of India and at the head of the Bay of
Bengal
Charls Antony1*, A. S. Unnikrishnan1, Philip L. Woodworth2
1CSIR-National Institute of Oceanography, Goa
2National Oceanographic Centre, Liverpool, U.K
Analysis of hourly sea-level data (1974-2007) was carried out to understand the changes in
sea level extremes along the east coast of India (Chennai, Visakhapatnam and Paradip) and at
the head of the Bay of Bengal (Hiron point). Linear regression method was used to compute
the trends for each percentile time series.The 99th sea-level percentiles at Hiron Point shows
significant positive trend (5.2 mm/yr) at 95% confidence level, whereas negative trends in the
99th sea-level percentiles along the east coast of India which are not statistically significant.
The increase in extreme high sea levels, especially at Hiron Point can be explained in terms
of the trends in mean sea level (50th percentile) itself. Earlier studies have shown that large
trends in the mean sea level in this region are partly caused by subsidence of the delta. The
99th sea level percentile time series at Hiron Point, Paradip, Visakhapatnam and Chennai are
correlated with indices of regional climate such as IOD and ENSO. Sea level extremes are
correlated well with the climate indices, suggesting that inter-annual variability associated
with IOD and ENSO also influence sea level extremes in the Bay of Bengal.
Cloud System Resolving Model Simulation of cumulus convection
Bay of Bengal during Onset of the Indian Summer Monsoon
Authors:
Deepeshkumar Jain1*,
Arindam Chakraborty1,
Ravi S. Nanjundiah1,
Affiliation :
*Centre For Atmospheric and Oceanic Sciences,
Indian Institute of Science,
Bangalore
An understanding of the mesoscale circulation associated with the Indian summer monsoon
season is critical in improving the predictability of the phenomenon. Cloud system resolving
model (CSRM) simulation of the onset phase of Indian summer monsoon is performed using
Weather Research and Forecast (WRF) model. The focus of the present study is to investigate
the mesoscale organization and propagation of cumulus convection over the Bay of Bengal
during the onset phase of the monsoon. Circulations associated with the propagation of
convective structures in meridional direction during onset phase of the monsoon at such high
resolution show the mechanism driving such propagations and highlights the importance of
model resolution in simulating such processes properly.
A Model based Investigation of the Relative Importance of CO2-
fertilization, Climate Warming, Nitrogen deposition and Land
Use Change on the Global Terrestrial Carbon Cycle in the
Historical Period
N. Devaraju1, G. Bala1, K. Caldeira2, R. Nemani3
1Divecha Centre for Climate Change & Centre for Atmospheric and Oceanic Sciences
Indian Institute of Science, Bangalore -560012, India 2Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, CA
94305, USA 3NASA Ames Research Centre, Moffett Field, CA 94035, USA
In this paper, using the fully coupled NCAR Community Earth System Model (CESM), we
investigate the relative importance of CO2-fertilization, climate warming, anthropogenic
Nitrogen deposition and land use and land cover change (LULCC) for terrestrial carbon
uptake during the historical period (1850-2005). In our simulations, we find an increase in net
primary productivity of about 4 PgC yr-1 (8.1%) during this period with a contribution of 2.3
PgC yr-1 from CO2-fertilization and 2.0 PgC yr-1 from Nitrogen deposition. Climate
warming also contributes an increase of 0.35 PgC yr-1 but LULCC causes a decline of 0.7
PgC yr-1. These results indicate that the recent increase in vegetation productivity is most
likely driven by CO2 fertilization and Nitrogen deposition. Further, we find that the global
terrestrial ecosystem has been a net source of carbon during 1850-2005 (release of 45.1±2.4
PgC) which is largely driven by historical LULCC related CO2 fluxes to the atmosphere.
During the recent three decades (early 1970s to early 2000s), however, our model simulations
show that the terrestrial ecosystem acts as a sink and has taken up about 10 PgC mainly due
to CO2 fertilization and Nitrogen deposition. Our results are in good qualitative agreement
with recent studies that indicate an increase in vegetation production and water use efficiency
in the satellite era and that the terrestrial ecosystem is net sink for carbon in the recent
decades.
Detection and attribution of observed near-surface temperature
change over India
Dileepkumar R1*
Krishna AchutaRao1
1Centre for Atmospheric Sciences
Indian Institute of Technology Delhi
Numerous Detection and Attribution (D&A) studies have shown that over the last few
decades, anthropogenic activities have contributed significantly to changes in near surface
temperature at global, continental and sub-continental scales. Detecting and attributing the
changes over regional scale is more difficult than over global scale due to lower signal-to-
noise ratio. We analyze the near surface temperature between 1901-2005 over India and
seven homogeneous temperature zones within (as identified by IITM), using five observed
datasets (CRU-3.22, ERA, IITM, IMD & NCEP) and simulations of Coupled Model
Intercomparison Project Phase-5 (CMIP5).We apply formal D&A techniques to analyze
Annual mean and DJF, JJA, and SON seasonal mean temperatures. We defined a signal that
concisely expresses both spatial and temporal changes found in the model runs with
greenhouse, natural and control simulations. Using an optimal fingerprinting method we
quantify the effects of well-mixed greenhouse gases and other anthropogenic forcings over
the selected regions.
Response of the Bay of Bengal to Cyclone Phailin
Dipanjan Chaudhuri1, R. Vekatesan2, M. Ravichandran3, D. Sengupta1
1 CAOS, Indian Institute of Science, Bangalore,
2 National Institute of Ocean Technology (NIOT), Chennai, 3 Indian National Centre for Ocean Information Services (INCOIS), Hyderabad.
Cyclone Phailin is the second-strongest tropical cyclone ever to makelandfall in India (IMD
2014, Venkatesan 2013).Phailin matured over theBay of Bengal (BoB) during 9-14 October
2013. The response of the upper-ocean to Phailin is analyzed with the help of in situ
observations from an NIOT mooring BD10 and Argo float 2901335 directly under the storm;
and NIOT moorings BD08, BD09 and an INCOIS mooring near 18 N, about 200 km to the
right of the storm track. We also use satellite observations: Aquarius Sea Surface Salinity
(SSS) and TMI/AMSRE Sea Surface Temperature (SST). Our main findings are that (i) As
expected for post monsoon cyclones in the north Bay of Bengal (Sengupta 2008), SST
cooling is small (≈ 0.2 deg C). (ii) Post-storm SSS increases by 1.6 psu at the three moorings
near 18 N; the change in Aquarius SSS agrees with the moored observations. SSS increases
by 2-4 psu close to the storm track, due to storm induced vertical mixing to at least 50m
depth. (iii) SSS increases throughout the western Bay after the passage of the storm. (iv) The
largest-amplitude inertial currents (0.5 m/s) are observed directly under the cyclone. (v)
Velocity observations from an Acoustic Doppler Current Profiler (ADCP) on mooring BD09
and simulations from a 1D model (Price et al. 1986) suggest that shear-induced mixing
(D'Asaro 2014) deepens the mixed layer from pre-storm values of less than 10m to about 50
m after the storm. (vi) Estimates of energy input from wind stress indicate that about 60
percent of the energy goes into increased potential energy of the water column due to vertical
mixing.
Vulnerability of Dairy Based Livelihoods to Climate Variability
and Change, a study of Western Ghat Region- Wayanad, Kerala
Jancy Gupta1*,Aparna Radhakrishnan1
1Dairy Extension Division, NDRI, Karnal
Climate variability can reduce milk and meat production and lower reproduction rates as
proven by many research findings in Hot Spot Biospheres of India particularly the Western
Ghat ecosystem and the impact depends on the level of vulnerability or exposure of farmers
to these changes. This paper aims at assessing the vulnerability of Dairy Based Livelihoods to
Climate Variability and Change and for this purpose; data were aggregated to a complex
Livelihood Vulnerability Index (LVI) to Climate Change underlying the principles of IPCC,
using 28 indicators. Primary data were collected through participatory rural appraisal and
personal interviews from 120 randomly selected dairy farmers of three talukas of Wayanad
district complemented by thirty years of gridded weather data to quantify the indicators. The
empirical observations in terms of vulnerability revealed that out of the three talukas of
Wayanad, Pulpallytaluka is having more vulnerability to climate change i.e. 48.33% farmers
having high level of vulnerability as compared to Sultan battery (15.97%) and
Mananthawady (32.11%) in terms of the overall LVI. The major impacts of climate change
are the deterioration of the quality of milk, delay in transportation due to landslides, frequent
disease occurrences, unavailability of quality fodder etc.
Expanding tropics in the changing climate
A.A. Deo1*, D.W.Ganer1
1Indian Institute of Tropical Meteorology,
Pune-411008.
According to the recent assessment of the IPCC, increases in greenhouse gases and other
human-induced climate forcings would lead to warming of the troposphere, cooling of the
stratosphere, rise of the tropopause, weakening of tropical circulation patterns, poleward
migration of mid-latitude storm tracks, an increase in tropical precipitation, etc. Many of
these have already been seen in observations covering the last few decades or more. Taken
together these changes might relate to variations in the width of the tropical belt, and it is
only recently that this question has received the attention. Several recent studies
foundimplication for expansion of tropics as the Earth warms.
In the present study, the width of Hadley cell which is one of the parameters defining the
tropical belt is examined for poleward expansion. The metric used here to characterize the
Hadley circulation is mean-meridional mass stream-function obtained by vertically
integrating monthly meridional winds using different reanlaysis data sets e.g. NCEP/NCAR,
NCEP/DOE.
Further, to examine the consistency among results, the Hadley cell expansion is also
investigated by analyzing OLR dataset. The subsidence regions associated with the Hadley
circulation, due to their dry troposphere and lack of high clouds, are identified as the regions
with high OLR. The locations of the poleward edges of the Hadley circulation are defined as
the most poleward latitudes where the zonal-mean OLR equals 250W/m2.
Preliminary analysis from OLR shows that poleward extension in Hadley cell over northern
(southern) hemisphere is about 1-2o (0.7o) latitude over the period 1979-2014. Warming of
troposphere, cooling of stratosphere along with the increase in tropopause height obtained
from reanalysis data also demonstrates the expansion of Hadley cell.
Sea level fluctuations during 21 to 13 Ma in the Andaman Sea: A
case study based on multiple microfossils from Havelock Island
Amit K. Ghosh*, AbhijitMazumder&Arindam Chakraborty
BirbalSahni Institute of Palaeobotany
53 University Road, Luck now – 226 007, INDIA
*E-mail: [email protected]
The Neogene sequence exposed in isolated islands of Andaman and Nicobar Basin is unique
as it represents thick deposition of marine sediments rich in microfossils. Havelock Island in
the South Andaman is the largest island of the Ritchie’s Archipelago. Two lithological
successions viz., Inglis and Long formations are exposed in this island. The present study has
been undertaken on the samples of Inglis Formation exposed near Kalapathar Beach of
Havelock Island. Litho logically it is chiefly composed of soft, creamish- white nano-foram
chalk. Based on nannofossils (NN 4 - NN 5 Zone) the sequence has been precisely dated as
Burdigalian-Langhian (21-13 Ma). The age has also been reconfirmed by marker radiolarians
(RN 4 Zone). The sediments also yielded well preserved diatoms represented by both centric
and pennate as well as benthic and planktic forms. The diatom biozones have been
demarcated with the help of CONISS cluster analysis and further reasserted by SHEBI
analysis. PCA has been done on the abundance of diatom taxa to test the relatedness.
Benthic/Planktic ratio and C/P (Centric/Pennate) ratios of diatoms have been deduced that
indicate the evidence of sea level fluctuations. Palaeoenvironmental interpretation has been
made on the possible reason of sea level fluctuations.
Recent trends and tele-connections among South and East Asian
summer monsoons
B Preethi, M Mujumdar, RH Kripalani* and R Krishnan
*Indian Institute of Tropical Meteorology, Pune 411008
The Asian summer monsoon system incorporates two large regional subsystems: the South
and the East Asian monsoon. Summer monsoons over South and East Asian regions are
interrelated, but they also exhibit secular variations in their relationship. The rainfall
variations over central India, northern parts of China, are in phase; however these regions
depict out of phase relationship with rainfall variations over northeast India up to southern
parts of China, South Korea, and southern parts of Japan. During recent decades, a decreasing
trend has been observed in the summer monsoon rainfall over South Asia (India) and over
northern China, however an increasing trend is observed over Southern China, South Korea
and Japan. While drought conditions were observed over India and northern China during the
summer monsoon of 2014, heavy rainfall activity over southern China and South Korea was
reported, confirming the recent intensification of the contrast between the two monsoons.
Changes in SST forcing and large scale dynamics linked to both the monsoons are diagnosed
to unravel the possible reasons for the recent trends and associated changes in tele-
connections between the two monsoon systems. The study brings out the role of recent Indo-
Pacific SST warming in modulating the monsoon tele-connections.
Emerging role of Indian Ocean on Indian northeast monsoon
Ramesh Kumar Yadav1
Indian Institute of Tropical Meteorology,Pashan,Pune-411008. INDIA
Email: [email protected]
This study examines the emerging role of Indian Ocean sea surface temperature (SST) on the
interannual variability (IAV) of Indian north-east monsoon rainfall (NEMR). The IAV of
NEMR is associated with the warm SST anomaly over east Bay-of-Bengal (BoB) (88.5oE–
98.5oE; 8.5oN–15.5oN) and cool SST anomaly over east equatorial Indian Ocean (80.5oE–
103.5oE; 6.5oS– 3.5oN). The gradient of SST between these boxes (i.e. northern box minus
southern box) shows strong and robust association with the Indian NEMR variability in the
recent decades. For establishing the teleconnections, SST, mean sea level pressure, North
Indian Ocean tropical storm track, and circulation data have been used. The study reveals that
during the positive SST gradient years, the inter-tropical convergence zone (ITCZ) shifts
northwards over the East Indian Ocean. The tropical depressions, storms and cyclones formed
in the North Indian Ocean moves more zonally and strike the southern peninsular India and
hence excess NEMR. While, during the negative SST gradient years, the ITCZ shifts
southwards over the Indian Ocean. The tropical depressions, storms and cyclones formed in
the North Indian Ocean moves more northwestward direction and after crossing 15oN
latitude re-curve to northeast direction towards head BoB and misses southern peninsular
India and hence, deficient NEMR.
Indian Ocean warming – its extent, and impact on the Monsoon
and Marine Productivity
Roxy M. K. 1*, K. Ritika 1, A. Modi 1, P. Terray 2, R. Murtugudde 3, K. Ashok 1, B. N.
Goswami 1, S. Masson 2, V. Valsala 1, P. Swapna 1, S. Prasanna Kumar 4 and M.
Ravichandran 5
1 Indian Institute of Tropical Meteorology, Pune
2 Sorbonne Universites, Paris, France
3 University of Maryland, Maryland, USA
4 National Institute of Oceanography, Goa
5 Indian National Centre for Ocean Information Services, Hyderabad
Indian Ocean warming has captured the attention of a handful of studies in the recent years,
but the cause and effect of this warming has remained elusive. In the current study, we
demonstrate that the Indian Ocean has been warming for more than a century, at a rate and
magnitude larger than what was thought before (1.2°C in 100 years). This intense,
monotonous warming turns out to be the largest contributor in-phase with the global ocean
surface warming, with a firm grip on the global climate. We find that the long-term warming
trend over the Indian Ocean is due to an increase in the frequency and magnitude of El Nino
events during recent decades. Consequences of this excessive warming of Indian Ocean are
large, especially on the physical and biological dynamics over the South Asian domain, and
eventually on the socio-economic livelihood of the surrounding countries. Our analysis with
observed data and model simulations show that the Indian Ocean warming has resulted in
weakening the land-sea thermal contrast, an essential driver of the monsoon. This has
weakened the monsoon circulation, and in turn reduced the rainfall over a large area
extending from Pakistan through central India to Bangladesh. The excessive warming have
also resulted in the ocean surface stratification over the western Indian Ocean–one of the
most biologically productive regions among the tropical oceans. We find that these
increasingly stratified ocean waters have suppressed the upwelling of nutrients from the
subsurface waters, and have resulted in a reduction of up to 20% in the marine primary
production. Altogether, the Indian Ocean warming is a factor to be vigilant of, while
assessing long-term changes in the monsoon, the marine productivity, and the global climate.
References:
1. Roxy et al. 2014, Journal of Climate
2. Roxy et al. 2015, Nature Communications
3. Roxy et al. 2015, PNAS, Revised.
Potential Soil Organic Carbon Sequestration in Reclaimed
afforested
Post-Mining Sites of Raniganj Coalfield, India
Sanjoy Kumar1, Subodh Kumar Maiti2, Subrata Chaudhuri3&Prosenjit Ghosh1
1Centre for Earth Science, Indian Institute of Science, Bangalore, Karnataka-560012,
India 2Department of Environmental Science & Engineering, Centre for Mining
Environment, Indian School of Mines, Dhanbad, Jharkhand-826004, India 3Department of Mining Engineering, Indian School of Mines, Dhanbad, Jharkhand-
826004, India
The concept of terrestrial carbon sequestration in soils of post-mining sites, especially in
surface coal mines, is of interest because of its prospective function in mitigating increasing
global climate change. They are characterized by low soil organic matter content, low
fertility, and poor physicochemical and biological properties, limiting their quality,
capability, and functions. Reclamation of these minesoils has potential for sequestering some
of the C lost and mitigating CO2 emissions. A case study was initiated with the following
objectives like to enumerate the amount of soil carbon accumulation in terrestrial ecosystem
of reclaimed mine soils to examine several physical properties (soil texture and bulk density),
chemical (pH, soil organic carbon and organic matter) and biological processes of microbial
dynamics (soil enzymatic activities, microbial biomass carbon, and soil CO2 flux
measurements) that govern the amount of C-sequestrated into minesoil. A chronosequences
approach was used to studies soil C-sequestration potentiality in afforested reclaimed mine
sites (2, 5, 9, 15 and 21 years) and compares with natural forest (control site), Raniganj
Coalfield, India. The rate of C accumulation was found higher (2.6 Mg C ha-1yr-1) in the
initial period and decreased to as low as 1.6 Mg C ha-1 yr-1 after 21 years. Lowest SOC
concentration in younger minesoil, there is a large potential for rate of soil C-sequestration.
Proper reclamation and post-reclamation management may enhance SOC sequestration and
add to the economic value of the mined sites. Management practices that may enhance SOC
sequestration include increasing vegetative cover by deep-rooted perennial vegetation and
afforestation, improving soil fertility, and alleviation of physical, chemical and biological
limitation using suitable amendments.
Analysis of cyclonic structures from TRMM retrieved rain
products
C.Balaji1* and C.Krishnamoorthy1
1Indian Institute of Technology Madras
Chennai-6000 036, India
In the past few decades, remote sensing is being extensively used to understand cyclone
structures and other precipitation systems. In particular, the advent of space borne sensors
like microwave imager, infrared sounders and synthetic aperture radars has opened up new
vistas to improve our scientific understanding of major weather events. The combined use of
Microwave Imager (MI) and Precipitation Radar (PR) in the Tropical Rainfall Measuring
Mission (TRMM) has enabled the community to retrieve vertical profiles of hydrometeors in
a raining atmosphere, which was hitherto impossible in the open ocean. In this paper, we
present several cases of cyclones that originated in the North Indian Ocean region between
2003 to 2010. For each of which there was at least one TRMM overpass. Initial profiles were
generated from a community based numerical weather prediction model Advanced Research
Weather Research and Forecasting (ARW-WRF) with a spin-up time of 6hrs. Numerically
generated vertical profiles of Pressure, Temperature, Relative humidity and hydrometeors in
30 layers were interpolated into fourteen layers and these were input to a polarized radiative
transfer code which was developed in-house to simulate the upwelling radiance
corresponding to TMI frequencies and Quickbeam, a radar simulation package that can return
radar reflectivities at various vertical levels of atmosphere corresponding to PR frequency.
Using Empirical Orthogonal Functions (EOFs) the numerically generated profiles were
perturbed in order to match up the simulated and observed radiances corresponding to TMI
and PR. The matched up profiles were then used in a Bayesian framework to retrieve various
rain parameters for cyclones namely NARGIS and PHAILIN. The retrieved vertical
hydrometeor profiles were then used to analyze the vertical rainfall structure and the
underlying physics. Spatial and temporal variation of rainfall are presented.
Dust Aerosols and the Indian Summer Monsoon Rainfall
V. Vinoj*
*Indian Institute of Technology Bhubaneswar, Email:[email protected]
Scientific studies (using observational and modeling approaches) in the past have mostly
focused on aerosol induced local climate effects (Indian monsoon) on seasonal timescales,
but short-term and non-local links have not been explored or identified. In this talk, we will
discuss an observational evidence and numerical modeling result demonstrating a remote link
between aerosols over the Arabian Sea/West Asia and the Indian summer monsoon rainfall.
Simulations using a state-of-the-art global climate model support this link and indicate that
the variability indust aerosol loadings influences atmospheric radiative heating thereby
inducing changes to larger scale circulation and thus modulating the moisture transport and
convergence over central India. This leads to changes in monsoon rainfall on a relatively
short time scales (in about a week). This investigation highlights the importance of natural
dust aerosols in influencing the strength of the Indian summer monsoon rainfall.
Influence of land surface albedo on the Asian Summer Monsoon
in a coupled ocean-atmosphere model
Guillaume Samson1(1LEGOS, Toulouse, France)
Sebastien Masson2(2LOCEAN, Paris, France)
Fabien Durand1* (1LEGOS, Toulouse, France and IFCWS, I.I.Sc, Bangalore)
The South Asian Summer Monsoon (SASM) simulated with a 0.75° coupled tropical-channel
model over the 1989-2009 period is presented. The model biases are comparable to those
commonly found in global coupled models: the Findlater jet is too weak, precipitations are
underestimated over India while they are overestimated over South East Asia and the
Maritime Continent. We show that land surface temperature biases are responsible of the
monsoon circulation biases: a cold bias over the Middle-East region weakens the Findlater jet
while a warm bias over India strengthens the monsoon circulation in the Bay of Bengal. A
surface radiative heat budget analysis reveals that the cold bias in the Middle-East is due to
an overestimated albedo in this desert region. A new simulation with a satellite-observed land
albedo shows a large improvement in terms of monsoon circulation and precipitations. These
results highlight the strong sensitivity of the SASM to the land heating pattern and amplitude,
especially in the Middle-East region.
Surface Freshwater Extent and Storage Variability at Basin-to-
Global Scale from Multi-Satellite Observations.
Fabrice Papa (1, 2), Catherine Prigent(3), Filipe Aires (4), Frederic Frappart(5),
V. Venugopal(6, 7)
1 Institut de Recherche pour le Developpement IRD, LEGOS, France;
2 IFCWS, Indo-French Cell for Water Sciences, IRD-I.I.Sc-NIO-IITM Joint
International Laboratory, Indian Institute of Science, Bangalore; 3 LERMA-CNRS, Observatoire de Paris, Paris, France;
4 Estellus, France; 5OMP-LEGOS-GET, Toulouse, France;
6 Centres for Oceanic and Atmospheric Sciences, Indian Institute of Science, Bangalore,
India; 7Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
Terrestrial waters, despite being less than 1 % of the total amount of water on Earth’s ice-free
land, play a major role in the global water cycle and climate variability. As a consequence,
there is a widespread demand for accurate and long‐term quantitative observations of their
distribution over the whole globe. Here, we present a dataset, based on retrievals from
multiple satellites, that quantifies the monthly and 10-day distribution and area of land-
surface open water at the global scale (∼25 km sampling intervals) over 15 years (1993–
2007). In addition to a good agreement of the variability of the inundation extent with that of
precipitation and river discharge, our analysis suggests an overall decline in global average
maximum inundated area of 6% during the fifteen-year period, primarily observed in tropical
and subtropical South America and South Asia. Moreover, the largest declines of open water
are found where large increases in population have occurred over the last two decades,
suggesting a global scale effect of human activities on continental surface freshwater. We
will then present case studies, in which we combined surface water extent estimates with
radar altimeter observations and DEM data to derive the spatio-temporal variability of surface
freshwater storage in the Amazon and Ganges-Brahmaputra river basins. Finally, we will
illustrate how these new 15-year data sets of surface water extent and storage represent an
unprecedented source of information for continent-to-global hydrological, land surface and
climate studies.
Returning to the Weakening Teleconnections of Tropical Pacific
and Indian summer Monsoon Rainfall
Feba Francis1* and Ashok Karumuri1
1Centre for Earth and Space Sciences,
University of Hyderabad, Hyderabad,
Telangana
Here we explore the decadal variability of teleconnection from tropical pacific to the Indian
Summer Monsoon Rainfall (ISMR) over the period 1951 to 2008, using various
Observational and Reanalysis datasets for the period 1951 to 2008. In conformation with the
earlier findings, Warm Water Volume (WWV) of the equatorial pacific has a lead predictive
skill for ISMR over the whole period. However, we find that the interannual correlations
between the ENSO and ISMR have continued to weaken since 1950s, irrespective of the
choice of an index for tropical pacific variability- be it the NINO4 index or even the Tropical
Pacific Warm Water Volume index. To understand the decadal weakening, we carry out a
preliminary analysis by exploring the low level circulation over the tropical pacific that
influences the Indian summer monsoon variability. Our analysis suggests that, in the post-
1977 period, the western boundary of the Walker circulation, which is important for the
ISMR variability, is confined to the east of 120E. This may be due to a basin wide
broadening of the cross-equatorial flow in the equatorial Indian Ocean in the recent decades.
Performance of chemistry transport models over Indian region
Gaurav Govardhan-1, Ravi S. Nanjundiah-1, 2, S.K. Satheesh-1, 2, K. Krishna Moorthy-3
and T. Takemura-4
1Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru,
India 2Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru, India
3Indian Space Research Organization Headquarters, Bengaluru, India 4Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan
Numerical models underestimate aerosol scenario over Indian region, mainly due to
shortcomings related to meteorology and emission-inventories used. In this context, we have
evaluated the performance of two such chemistry-transport models: WRF-Chem (an on-line
chemistry model) and SPRINTARS (an off-line chemistry model), which differ in
meteorological forcing that drives the chemistry within the models, over an India-centric
domain. Despite their inherent differences, these models captured the spatial patterns of
Black Carbon (BC) mass concentration , with a spatial correlation of 0.9, and with a
reasonable estimate of the concentration, though both of them under-estimated the
measurements. This suggests that formulation of meteorological forcing has only a limited
impact in simulating BC; rather emissions inventory is important. However, simulations of
Aerosol Optical Depth, differ significantly, with WRF-Chem having a better agreement with
satellite observations as regards the spatial pattern. Models differ in simulations of spatial
pattern of mineral dust and sea-salts over the Indian region. We find that both meteorological
forcing and emission formulation contribute to these differences. Thus our study highlights
that meteorological forcing and emission formulation can have differing impact on simulation
of different aerosol species.
Variability of Indian Summer Monsoon on different time scales
Gaurav Srivastava1*, Ravi S. Nanjundia1, Arindam Chakraborty1
1Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science
Indian Summer Monsoon (ISM) is one of the most complex climate phenomena that is tightly
associated with the economy of the subcontinent. It exhibits a wide spectrum of variability,
on daily, Intra-seasonal and inter-annual time scales. Our studies on relationship between El
Nino and ISM (Inverse relationship) reveal that it’s not constant, rather varies on different
temporal scales and times. We made an effort to study the variation of this relationship on
monthly scale. Our studies till now reveal that El Ni no and Indian Monsoon rainfall
relationship also varies on the intraseasonal time scales. The one to one analysis of the Pacific
Ocean SSTs versus rainfall over India during summer monsoon season reveals that the
inverse relationship changes intra-seasonally. We also find that this relationship is extremely
weak for August month for last four decades and on one occasion the August month was
found to record drought out of eight Indian Summer Monsoon season droughts for recent four
decadeds. Also suring seasonal drought years, diurnal rainfall intensity over core monsoon
zone is found to be of the climatological order.
Ocean Atmosphere Coupled Dynamics and Seasonal Prediction of
South Asian Monsoon
Gibies George1*, D Nagarjuna Rao1, Sabeerali C T1, and A Suryachandra Rao1
1Program for Seasonal and Extended Range Prediction of Monsoon,
Indian Institute of Tropical Meteorology
Using carefully designed coupled model experiments; we have demonstrated that the
prediction skill of the All India Summer Monsoon Rainfall (AISMR) in CFSv2 model
basically comes from the ENSO-Monsoon teleconnection. On the other hand, contrary to
observations, the Indian Ocean coupled dynamics have no crucial role in controlling the
prediction skill of the AISMR in CFSv2. We show that the inadequate representation of the
Indian Ocean coupled dynamics in CFSv2 is responsible for this dichotomy. Hence, the
improvement of the Indian Ocean coupled dynamics is essential for further improvement of
the AISMR prediction skill in CFSv2.
Understanding the dynamics of Breaks in the Monsoon and its
revival
D. Govardhan1, V. B Rao2 and K. Ashok3
1 University Centre for Earth and Space Sciences, University of Hyderabad,
Hyderabad-500046,
2Emeritus ,INPE, Brazil,
3on lien from the Indian Institute of Tropical Meteorology, Pune-411008
Email: [email protected]
The dynamical mechanism behind the revival of Indian Summer Monsoon after break period
remains unclear. In this context, we carry out a diagnostic analysis using the datasets from
National Centers for Environmental Prediction reanalysis-2 for the period 1979-2007 to
identify a robust mechanism that typifies breaks and subsequent revival of monsoon. We find
that during the peak of significant breaks, an anomalous southward shift of subtropical
westerly jet stream, which is invariably accompanied by anomalous northward shift of a
stronger-than-normal easterly jet. These major changes during a break facilitate an instability
mechanism that apparently leads to formation of a synoptic disturbance in the head of the
Bay of Bengal. Formation of such a disturbance is often critical in the subsequent revival of
summer monsoon. Our computation of energetics suggests an increase in the eddy kinetic
energy at the expense of the mean kinetic energy during the breaks in agreement with the
formation of the synoptic disturbance in Bay of Bengal. This demonstrates that barotropic
instability in the presence of a monsoon basic flow is the primary physical mechanism that
controls monsoon breaks, and subsequent revival of summer monsoon in the Indian region.
Hydrological extremes over foot hills of Himalayas during
southwest monsoon period
Hamza Varikoden1, J. V. Revadekar1, V. M. Shakuntala1
1Centre for Climate Change Research, Indian Institute of Tropical Meteorology,
Pashan, Pune-08
V. M. Shakuntala, S. A. Ahmed2 2Department of Geology, Central University of Karnataka, Gulbarga, Karnataka 585
311, India
In the scenarios of changing climate, it is relevant to study the frequency and intensity of
hydrological extremes especially rainfall. Rainfall over the foot hills of Himalayas are vitally
important due to its unpredictable nature and frequent occurrence of floods and flash floods.
Many studies are reported that the extreme events are increasing in the last few decades.
Therefore, we concentrate in the foot hills of Himalayas based TRMM 3B42 rain rate and
wind patterns from NCEP-NCAR reanalysis data set for the last decade. From the analysis,
we found that, number of flood events (>100 mm/day) and extreme events (>150 mm/day)
are more during the month of July in the last decade. The average number of extreme events
was 5.6 per season with a standard deviation of 2.32. However, the trend of these events are
decreasing during July and increasing during September. The floods having three days or
more were generally occurred over the eastern regions of the foot hills. The wind pattern for
individual events are unique, however, during the flood events, the Low Level Jetstream
(LLJ) is abnormally strong and it shows a convergence zone over the flood area and
divergent zone at the upper levels.
Flow dynamics of dispersed particle-laden buoyant plumes
Harish N Mirajkar1*,Sridhar Balasubramanian1
1Department of Mechanical Engineering
Indian Institute of Technology, Bombay
When a turbulent plume (e.g. volcanic eruptions, hydrothermal vents) intrudes into the
stratified atmosphere, it constantly entrains dense fluid surrounding the source. Gradually, the
plume reaches a level where its density becomes equal to the ambient. At this height, the
plume starts spreading as gravity current, known as Umbrella cloud. In general, a plume
always consists of the fine particles that influence the dynamics, stability and longevity of
umbrella cloud. Understanding the physics of dispersed particles in turbulent plume is the
motivation of the present work. An experimental facility consisting of two tanks is used. One
of them is the stratification tank, which is linearly stratified (∂ρ/∂z < 0) with buoyancy
frequency N=0.67s-1. The mixture of fresh water/particle is injected into the stratified tank to
study the plume dynamics. Particles used were glass beads with mean size, DP=100µm,
density ρp=2500 kg/m3, and volume fraction, ϕv ranging from 0-0.7%. In particular, we look
at few questions such as, how does the low volume fraction of particles affect the maximum
height of plume, its spreading height, the umbrella cloud and its radial propagation. Our
results indicate that presence of even small concentration of particles could have tremendous
effect on the plume behaviour.
Water-Budget in the Indian sub-continental River basins under
the Projected Future Climate
Harsh L. Shah 1*and Vimal Mishra1
1Civil Engineering, Indian Institute of Technology (IIT) Gandhinagar
Understanding the water availability in the projected future climate in the Indian sub-
continental river basins is vital for the fresh water and food security in the region. It has been
observed that the Indian summer monsoon became erratic in the last few decades leading to a
significant decline in the water availability in the central India. While observations show a
declining trend in precipitation, which in turn leads to reduced total runoff and water
availability, majority of the CMIP5 models are unable to simulate the observed drying. We,
therefore, used statistically downscaled and bias corrected data to develop projection of
hydrologic variables (total runoff, evapotranspiration (ET), and soil moisture) in the future
climate. The Variable Infiltration Capacity (VIC) model was used to simulate hydrologic
variables in the Indian sub-continental river basins for the projected future climate after the
successful calibration and evaluation using the in situ and satellite based observations of
streamflow, soil moisture, and ET. The projections suggest that a majority of the sub-
continental basins may experience a warmer and wetter climate in the 21st century. However,
changes in the water availability become significant during the late 21st century. Despite
intermodel uncertainty, the results show plausible scenrios related to water availability that
may provide valuable insights for policy making.
Data Assimilation for Aerosol Optical Depth over Indian Region
Harshavardhana Sunil Pathak1*, Ravi Nanjundiah1, S. K. Satheesh1,
S. Lakshmivarahan2
1CAOS, I.I.Sc Bangalore
2School of Computer Science, University of Oklahoma, Norman
In the present study, an attempt has been made to develop a comprehensive data set for
Aerosol Optical Depth (AOD), a measure of fraction of incoming radiations lost because of
scattering and absorption by a column of aerosols, by assimilating satellite data (MODIS and
MISR, LEVEL-3, monthly mean) with ground station AOD data (ARFINET and AERONET,
monthly mean) for the Indian region.
The satellite retrieved data is more continuous in space and time but it has biases associated
with surface reflectance, glint, cloud contamination as well as micro-physical properties of
aerosols and it suffer from various serious problems related to instrument calibration. On the
other hand, AOD data measured by ground stations has lesser biases but it lacks the spatial
coverage. We have attempted to develop a new gridded AOD data set which combines the
positive sides of both of its parents. We have used 3D-VAR as well as Successive Correction
Method (modified version by Cressman $(1959) $) for assimilating both data sets.
The assimilated AOD data averaged over small sub-regions is found to be more close to
ground observations than satellite retrievals. The yearly trends of assimilated AOD averaged
over small sub-regions are also better matched with trends in area averaged ground data than
in satellite retrievals.
Quantifying the contribution of long-range transport to
Particulate Matter (PM) loading at a suburban site in the North-
Western Indo Gangetic Plain (IGP)
Harshita Pawar1*,Saryu Garg1,Vinod Kumar1,Himanshu Sachan1,Ruhani
Arya1,Chinmoy Sarkar1,Praphulla Chandra1,Baerbel Sinhaa1
1All authors affiliated to Indian Institute of Science Education and Research Mohali
Many sites in the densely populated Indo Gangetic Plain (IGP) frequently exceed the national
ambient air quality standard (NAAQS) of 100 μgm-3 for PM10 and 60 μgm-3 for PM2.5
mass loadings throughout the year.We quantify the contribution of long range transport
(LRT) to elevated PM levels and the number of exceedance events through a back trajectory
climatology analysis of air masses arriving at the IISER Mohali Atmospheric Chemistry
facility (30.667, 76.729E; 310 m a.m.s.l) for the period August 2011-June 2013. Air masses
were classified into 6 clusters using k-means clustering and the average PM mass loadings
and number of exceedance events associated with each air mass type were quantified season-
wise. LRT from the west and south-west (Arabia, Thar Desert, Middle East & Afghanistan)
leads to significant enhancements in the average coarse mode PM and fine PM mass loadings
during all seasons which varies between 9% and 57% of the total PM10-2.5 mass and
between 4% and 31% of the total PM2.5 mass. The south easterly air masses (Eastern IGP)
were associated with significantly lower coarse mode and fine PM mass loadings during all
seasons. Using simultaneously measured gas phase tracers we demonstrate that most PM2.5
was emitted from combustion sources. The fraction of days in each season during which the
PM mass loadings exceeded the NAAQS was controlled by LRT to a much lesser degree. For
the local cluster, which represents regional air masses (NW-IGP), the fraction of days during
which the NAAQS of PM2.5 was exceeded, varied between 22% of the days during monsoon
season and 85% of the days during winter season; the fraction of days during which the
NAAQS of PM10 was exceeded, varied between 37% during monsoon season and 84%
during winter season. LRT was responsible for bringing air masses with a significantly lower
fraction of exceedance days from the Eastern IGP. In order to bring PM mass loadings in
compliance with the NAAQS and reduce the number of exceedance days, mitigation of
regional sources in the NW-IGP needs to be given priority.
Wet Scavenging Efficiency of Monsoon Rains for Reactive
Volatile Organic Compounds inthe North-West Indo Gangetic
Plain
HaseebHakkim, Chinmoy Sarkar, B. P. Chandra and Vinayak Sinha*
Department of Earth and Environmental Sciences, Indian Institute of Science
Education and Research Mohali, Sector 81, S.A. S. Nagar, Manauli PO, Punjab, 140306,
India
*Email address: [email protected]
At the Atmospheric Chemistry Research Facility (30.667N; 76.729E) located in the N.W.
IGP we studied the role of monsoon time rainfall in controlling ambient volatile organic
compounds (VOCs) concentrations through wet scavenging during period June- September
2013. VOCs are important as they play a major role in the oxidation chemistry of the
atmosphere leading to the formation of atmospheric pollutants such as ozone and secondary
organic aerosols. This work reports first such data anywhere in the world as VOCs have not
been the focus of previous wet scavenging studies extant in the literature, due to the technical
challenges associated with measuring them in real time. We used high temporal resolution
VOC data (one minute) acquired with India’s first proton transfer reaction mass spectrometer
(PTR-MS) and meteorological parameters (e.g. rainfall, WS, WD, radiation). Methanol,
acetone, acetonitrile, isoprene, acetaldehyde, toluene, benzene, sum of xylenes and sum of
trimethyl benzenes were quantified during both wet and dry spells of the monsoon season in
2013. We ascertained the influence of boundary layer dilution, photochemistry and change in
emission sources on the ambient concentrations of the VOCs in order to constrain the wet
scavenging efficiency for these compounds.
The Impact of Aerosol on Cloud and Precipitation over Madurai
from Satellite Observations
G. Indira1*, B. Vijay Bhaskar1
1Department of Bioenergy, School of Energy, Environment and Natural Resources
Madurai Kamaraj University
Madurai -21
Abstract
Aerosol, clouds and precipitation interactions are thought to nature the behaviour of the
climate system. Atmospheric aerosols play an important role in Earth’s radiative budget,
weather and climate systems. Urban environment’s impact on rainfall will be increasingly
important in ongoing climate diagnostics and prediction. Aerosols involves in the formation
and also the obstruction of clouds and precipitation. The paper presents aerosols, clouds and
precipitation dynamics over a semi-arid region Madurai, India based on satellite observations.
Descriptive statistics and Pearson correlation analyses were carried out between aerosols,
cloud parameters and precipitation to provide a better understanding of aerosol–cloud
interaction. Highest average of AOD was in 2011 and the lowest aerosol concentration was in
2010 along with maximum precipitation. Hysplit trajectory analysis carried out for the long-
range transportation of aerosol particles, airmasses sources to the observing site are from the
Arabian Sea, Bay of Bengal and from semi-arid region, and high values of AODs have also
been influenced by biomass and agricultural burning and frequent incidents of forest fire at
local regions.
Keywords: Aerosol optical depth; Cloud parameters; Rainfall; MODIS
Near-surface stratification and submesoscale fronts in the North
Bay of Bengal in August-September 2014
J. Sree Lekha1*, Shiva Prasad.S 2, Ravichandran. M 2, Sengupta.D1
1. CAOS, Indian Institute of Science, Bangalore
2. INCOIS, Hyderabad
A shallow layer of freshwater with a strong halocline underneath influences air-sea
interaction and bio-geochemistry in the north Bay of Bengal. In this study, we use 1800
kilometers of underway-Conductivity-Temperature-Depth (uCTD) data, collected from the
ORV SagarNidhi during 22 August-4 September 2014, to understand the physical processes
that maintain the shallow stratification. At ship speeds of 4-5 knots, the horizontal resolution
is of order 1 km, and vertical resolution is 1m. These are the first observations from the Bay
of Bengal with enough resolution to study submesoscale (1-20 km) salinity-dominated
surface density fronts. Dynamical instability of submesoscale fronts can lead to slumping of
heavier water under lighter water, i.e., fronts can enhance vertical stratification of the near-
surface ocean, a process known as restratification. We identified 16 distinct submesoscale
fronts along the ship track, out of which 13 fronts show a shallow mixed layer under the
front, suggesting active restratification. We propose that submesoscale fronts associated with
pools/filaments of river and rain water maintain shallow stratification in the north Bay of
Bengal.
Climatic impacts of global river discharge
Jahfer Sharif1*, P. N. Vinayachandran1,R. S. Nanjundiah1
1CAOS, I.I.Sc
River discharge can affect ocean surface temperature by altering the surface stratification.
Blocking of global runoff in a climate model resulted in anomalous warming of Surface
Ocean to the north of equator and cooling to the south. Cross-equatorial winds triggered by
this gradient, blow towards northern hemisphere and shift the Inter Tropical Convergence
Zone (ITCZ) northward, increasing the precipitation in the northern hemisphere.All the
northern hemispheric monsoon systems strengthened (by~10%) while southern hemispheric
monsoons weakened in the absence of global runoff.Associated with this, substantial cooling
in the central equatorial Pacific (~1oC during DJF) altered large-scale ocean-atmosphere
circulation, including El Nino-Southern Oscillation (ENSO). Modulation of ENSO frequency
and intensity and northward shift in ITCZ explains much of the strengthening of monsoon
systems in the northern hemisphere. The present study suggests that large-scale inland
diversion of ocean-reaching rivers for irrigation, household purposes, and over-exploitation
of natural streams etc. can have a significant impact on the global climate system.
Simulation of Daily Rainfall Series Using Generalised Linear
Models
Jany George1*, J. Letha2, P. G. Jairaj3,
1College of Engineering, Trivandrum, Kerala,
2Department of Civil Engineering, Cochin University of Science and Technology,
Kochi, Kerala 3Department of Civil Engineering, Rajiv Gandhi Institute of Science and
Technology, Kottayam, Kerala
In this work an attempt is made to simulate the daily rainfall as a stochastic process based on
atmospheric circulation patterns and historical data. Daily rainfall is modeled in two stages
using Generalised Linear Models. Occurrence of rainfall is predicted on multivariable data
using logistic regression models. The intensity of rainfall on a wet day is modeled using a
gamma distribution. Intensity and occurrence of rainfall also depend on rainfall on previous
days accounting for persistence. Inter-site dependence and interaction between the predictors
are also considered for model development. The covariates in the model include site effects
representing spatial variation, year effects giving long term trends, month effects which
account for seasonality and day effects describing temporal auto correlation. Rainfall series
can be simulated for multi sites including ungauged stations. The methodology is applied in
the catchment of Idukky reservoir in Kerala. Atmospheric predictors such as mean sea level
pressure, wind velocity components, wind speed, air temperature and dew point temperature
derived from NCEP/NCAR re-analysis data and historical rainfall data are used for the
simulation process. The performance of simulations is assessed by calculating a variety of
summary statistics and comparing the distributions of these statistics with the observed value.
Regional Climatology of Aerosol-Cloud Relationship over India
K. Vijayakumar1*, P.C.S. Devara2, P.D. Safai1
1Indian Institute of Tropical Meteorology, Pune - 411008.
Amity University Haryana, Gurgaon - 122 413
Interaction between aerosols and clouds is the subject of recent scientific research due to its
importance in regulating the climate and climate change. These interactions induce large
uncertainty in climate modelling. Aerosols vary in time and space, and can lead to complex
variations in the cloud microphysics and dynamics. In this paper, we examined the
spatiotemporal variations of aerosols and their impact on different cloud state variables in the
territory of India using the Moderate resolution Imaging Spectro-radiometer (MODIS) on
board NASA’s Terra satellite data for the 12-year period from 2000 to 2011. Furthermore, the
study also uses the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT)
model for trajectory analysis to obtain the origin of air masses in order to understand the
space-time variations in aerosol concentration. Seasonal study of aerosol optical depth (AOD)
shows higher value in the monsoon season (June-August) over the study regions. We also
analyzed the relationship between AOD and some prime cloud parameters such as cloud
fraction (CF), cloud-top pressure (CTP), cloud-top temperature (CTT) and associated water
vapor (WV). Regional correlation maps for aerosol and cloud parameters provided better
understanding of aerosol-cloud interaction. The study revealed a positive correlation between
AOD and WV for high-altitude, urban and coastal stations, while it exhibited negative
correlation for island stations. CF showed increase (positive correlation) with AOD and
decrease (negative correlation) with CTP and CTT over most regions. The findings bring-out
the possible association between concurrent aerosol and cloud parameters, which provide an
insight into aerosol-cloud coupled processes for climate studies.
Exploring uncertainties in future climate change over India
Krishna AchutaRao*
*Indian Institute of Technology Delhi
Reliable future climate information is necessary for the scientific and policy-making
community. The CMIP5 database has been used to assess future climate over India by
numerous authors (for e.g. Chaturvedi et al., 2012). However, these projections come with
uncertainties due to various sources. In this talk, an attempt is made to unpack the causes of
uncertainty and explore ways to reduce uncertainty over the Indian region using objective
criteria.
Andaman Sea Circulation in a high resolution OGCM
P N Vinayachandran1, Kiran S R1*
1CAOS, I.I.Sc
The role of the Monsoon in driving the circulations of the Indian Ocean has been researched
extensively in the field of physical oceanography due to its uniqueness and fascinating
features. But, Andaman Sea, which is located to the south-east of Bay of Bengal, has not
come to the mainstream research, perhaps due to its coverted geographical nature. The
circulations in Andaman Sea may be influenced by the Monsoon in the Indian subcontinent,
exchange of water between the straits that connect Bay of Bengal to Andaman Sea, etc.
Besides, the Kelvin waves excited by the post-monsoonal westerly jet called Wyrtkijet may
intervene the circulations in Andaman Sea. These form the prime motivation for studying the
dynamics of Andaman Sea. This study emphasised on understanding the circulations using a
high resolution Ocean General Circulation Model (OGCM) and subsequent validation of its
results.
Coastal upwelling and downwelling along the northern coast of Indonesia has stemmed from
the seasonal reversal of wind system over the region. Monsoon play an indisputably
imperious role in determining the circulation in Andaman Sea, as a result the contribution to
vertical velocities from remote effects are dominant only during postmonsoon period. Eddy-
like structures, both cyclonic and anticyclonic, occur within the basin at different parts of the
year. Transports across the straits, that connect the Andaman Sea to the Bay of Bengal, are
found to follow semi-annual cycle.
Application of Empirical Mode Decomposition method on Indian
seasonal rainfall data
Kokila Ramesh*
*Centre for Disaster Mitigation, Jain University
The method of empirical mode decomposition is applied to all India seasonal data (three
seasons in anyear namely Pre monsoon, Monsoon and Post monsoon). This method
decomposes long range data into ten intrinsic mode functions (IMFs), which are uncorrelated
among each other. This helps in separating the data into non Gaussian and nearly Gaussian
parts, so as to model them separately. The non-Gaussian part of the data is modelled by ANN
technique and the remaining part is modelled by simple regression model. This model
explains about 70% to 80% of the inter seasonal variability. The advantage of using three
seasons a year is to have continuity in the data. The successful modelling of the seasonal data
is used in one step ahead forecast for monsoon rainfall.
Rhizosphere Carbon Sequestration Potential of Agricultural
Crops in Designed Plant Growth Chamber
Gadpayle Kritika1* and Fulekar M.H1
1School of Environment and Sustainable Development
Central University of Gujarat,
Sector 30, Gandhinagar, Gujarat-382030
The aim of the current study is to assess the carbon sequestration potential of the crops of the
agricultural importance at elevated levels of CO2 in designed plant growth chamber. The
study was carried out in designed plant growth chamber having dimension 66×24×25 inches.
Random sampling was done to assess the changes in plant and soil parameters and the results
were analyzed statistically.
Agricultural crops Triticumaestivum, Sorghum vulgare and Vigna radiate were grown using
pot culture technique in mycorrhizal soil in the designed plant growth chamber. The CO2 was
induced into the plant growth chamber after every five days at the rate of 5 Liters per minute
to maintain the level of carbon dioxide upto 500± 50ppm into the plant growth chamber and
plant’s growth was studied. A similar set up without CO2 supply served as control. Soil’s
physico-chemical parameters, plant’s morphological and biochemical characteristics were
studied for both treatments.
The study reveals that plants studied at elevated levels were found to have higher growth rate
as compared to plants studied at ambient CO2 levels. The study proved that agricultural crops
studied Triticumaestivum, Sorghum vulgare and Vignaradiata, have high carbon
sequestration potential under elevated CO2 conditions and hence will help in mitigation of
climate change
Vertical structure of aerosols and mineral dust transport over
Bay of Bengal using multi-year space-borne observations
Lakshmi N B1*, S Suresh Babu1, Vijayakumar S Nair1, Prijith S S2,K Krishna
Moorthy3,
1SPL
2NRSC 3ISRO
Spatial and vertical distribution of aerosols and their seasonal dependency are examined in
detail over the Bay of Bengal (BoB), a small oceanic region to the east of Indian
subcontinent. The region experiences seasonally varying aerosol system, which is
significantly influenced by distinct aerosol types of natural and anthropogenic origin from
surrounding landmasses including India and East Asia. Evidences of dust transport over Bay
of Bengal is indicated by previous studies, which assumes importance as dust is capable of
scattering the incoming short wave radiation and absorbing the outgoing long wave radiation,
resulting in surface cooling as well as atmospheric heating, which impose alterations in
atmospheric circulation and cloud cover. Current study quantifies the mineral dust transport
at different altitudes over BoB is observed in accordance with seasonal circulation pattern
changes. Major data set used includes aerosol extinction coefficient, Back-scattering
coefficient and particulate depolarization ratio (PDR) from multi-year Cloud-Aerosol Lidar
and Infrared Pathfinder Satellite Observations (CALIPSO) measurements along with wind
information from MERRA reanalysis fields. While aerosol extinction coefficient provides
aerosol abundance at different elevations, PDR indicates relative dominance of spherical
particles in the aerosol system.Vertical profiles of dust extinction coefficient is estimated
using the measured depolarization values and with a priori knowledge of depolarization ratio
for dust, depolarization ratio for non-dust and also lidar ratio of dust.
Amount effect in peninsular India and Sri Lanka aids the choice
of 18-O based monsoon proxy sites
Lekshmy P R1*, Midhun M1, Ramesh R1,
1Physical research Laboratory
The negative relation between the monthly rainfall and its 18-O content observed in the
tropics is used for paleoclimate reconstruction from proxies such as tree rings and cave
calcites. Since this relation exhibits significant spatial variation, retrieval of past climate from
18-O based proxies is complex. Here, using the rainfall 18-O observations made by us and
from the Global Network of Isotopes in Precipitation (GNIP), a systematic investigation of
spatio-temporal variations in the rainfall-δ18O relation (amount effect) on local, regional and
annual scales was done for peninsular India and Sri Lanka. Significant rainfall occurs during
two different seasons (south-west and north-east monsoons) in this region. We report a
significant spatial variation of rainfall- δ18O relation (slope) attributable to the varying ratio
of summer and winter rain amounts: paleomonsoon proxies with high seasonal resolution
chosen from locations of ratio <1 could use the local amount effect to reconstruct winter rain,
while those from regions of ratio >1 could be used to reconstruct summer rain using the
regional/seasonal/annual amount effects. Our study provides an important advancement on
the site selection and interpretation of the 18-O based Indian monsoon proxies
Understanding land surface response to changing South Asian
monsoon in a warming climate
Ramarao M.V.S1*, R. Krishnan1, J. Sanjay1 and T.P.Sabin1
1Centre for Climate Change Research,
Indian Institute of Tropical Meteorology,
Pune, India
Recent studies have drawn attention to a significant weakening trend of the South Asian
monsoon circulation and an associated decrease in regional rainfall during the last few
decades. While surface temperatures over the region have steadily risen during this period,
most of the CMIP (Coupled Model Intercomparison Project) global climate models have
difficulties in capturing the observed decrease of monsoon precipitation, thus limiting our
understanding of the regional land surface response to monsoonal changes. Our results from
two long-term simulation experiments, with and without anthropogenic forcing, using a
variable resolution global climate model having high-resolution zooming over the South
Asian region indicate that anthropogenic effects have influenced the recent weakening of the
monsoon circulation and decline of precipitation. The simulated increase of surface
temperature over the Indian region during the post-1950s is accompanied by a significant
decrease of monsoon precipitation and soil moisture. This summer time soil drying is
detectable under RCP4.5 scenario by the end of the 21st century.
Characteristics of optical properties of coastal waters: to study
the climate change
Madhubala Talaulikar1*, T. Suresh 1
1National Institute of Oceanography
The simple truth is – light is the source of life on the planet Earth. Phytoplankton in the
global ocean (70% of the Earth’s surface) was identified as an essential climate variable
(GCOS, 2011). It absorbs light for photosynthesis and plays vital role in regulating the CO2
concentration of the surface ocean. Thus, monitoring phytoplankton using remote sensing
tools can provide information on the climate change. However, in coastal ocean (7% of the
global ocean), it is not only the phytoplankton that controls the light penetration but also the
other optically active components that include dissolved material, detritus and suspended
particles. Hence monitoring phytoplankton in coastal waters will only tell the part of the
story.
In this study, we present the characteristics of the various inherent and apparent optical
properties rather than phytoplankton alone which can be used for better understanding of the
variations of various parameters associated with the optical properties such as functional
types of phytoplankton, algal blooms, primary productivity, transport of sediments, UV light
penetration, radiant heating rates, underwater visibility etc. The optical properties measured
using state of the art instruments, derived from radiative transfer model and derived from
ocean colour remote sensing satellites are used in this study.
Indian Summer Monsoon Dynamics in a Changing Climate:
Performance evaluation of CMIP5 models
M. Venkat Ratnam1*, P. Kishore2, G. Basha3 and A. Jayaraman4
1National Atmospheric Research Laboratory (NARL), Gadanki, Tirupati, India.
2Dept. of Earth System Science, University of California, Irvine, California, 92697, USA 3Masdar Institute of Science and Technology, P.O. Box 54224, Abu Dhabi, UAE
Indian Summer Monsoon (ISM) is mainly characterized by seasonal wind reversal in low
level jet (LLJ) stream and tropical easterly jet (TEJ) among several other elements of
monsoon systems. In the recent past, several changes have been reported in the monsoon
dynamics that took place in the recent decade. Since TEJ is synoptic in nature, changes in its
strength are considered as one of the indicators of long-term changes in atmospheric general
circulation. In the context of changing climate, large reduction in its extent and weakening of
its strength were reported. Using high resolution measurements, we report here the
observation of a sharp strengthening of the TEJ during the recent warmest decade (2001–
2010), reaching its 1970s value. We also show that this change is reflected in the tropical
cyclone systems (1901-2010) and finally on the precipitation patterns over the Indian region
as they are interlinked. We attribute this unusual change partly to the change in the
circulation due to the tropospheric warming and lower stratospheric ozone recovery.
Interestingly, only few models of CMIP5 showed such changes from 2006 although their
ensemble means clearly show the increasing trend in TEJ intensity from 2010 to 2099.
Real Time Measurement of Carbon Dioxide Levels at the
Periphery of the Indian Institute of Science (I.I.Sc) Campus
Mahesh Kashyap1*, Vijay Misra2, Navakanta Bhat3,
1Consultant, Karnataka State Council for Science and Technology (KSCST),
Indian Institute of Science Campus, Bengaluru.
2Technology Manager, Centre for Nano Science and Engineering (CeNSE), Indian
Institute of Science, Bengaluru.
3Centre for Nano Science and Engineering (CeNSE), Department of Electrical
Communication Engineering, Indian Institute of Science, Bengaluru.
Carbon Dioxide (CO2) is the major Greenhouse Gas that is precursor to climate change. On-
road vehicles burning fossil fuel are the second largest CO2 emitters after fossil fuel fired
power plants. Localized CO2 concentration depends on the local traffic conditions and other
sources, if any. For I.I.Sc campus gates, the main source of CO2 is from the vehicles. CO2
emission from the vehicles depends on the type of vehicle, age, fuel used, road condition and
driving pattern. A preliminary study of CO2 levels around the periphery of Indian Institute of
Science (I.I.Sc) campus was conducted using the sensor developed by Centre for Nano
Science and Engineering (CeNSE). Measurements of CO2 showed that the concentrations to
be between 361 ppm to 530 ppm. Monitoring data was available on a real time basis at a
remote location. Traffic volume and CO2 levels were measured at the gates of the campus
and at a major nearby traffic junction.
Remote sensing based monitoring of forest fires in Andhra
Pradesh, India
G. Manaswini1&2& C. Sudhakar Reddy2
1 & 2 Centre for Environment, Jawaharlal Nehru Technological University, Hyderabad –
500 085, India 2 *Forestry & Ecology Group, National Remote Sensing Centre, Balanagar, Hyderabad-
500 037, India
*manu.ganjam @gmail.com
India’s CO2 emissions in 2012 with the share of 6.8% making it the fourth largest CO2
emitting country. Forest fire has been identified as one of the key environmental issue.
Knowledge of fire occurrence, extent and damage intensity is essential for forest fire
management and environmental studies. The present work was carried out to estimate the
spatial extent of forest burnt areas and fire frequency using ResourcesatAWiFS data (2009,
2010, 2012, 2013, and 2014) in Andhra Pradesh, India. The spatio-temporal analysis shows
that an area of 7514.10 km2 (29.22% of total forest cover) have been affected by forest fires.
GIS overlay analysis was used to find forest fire frequency. GIS intersect analysis was used
to correlate vegetation types and burnt area. The spatial and temporal distribution of burnt
areas was analyzed across 5 km x 5 km grid cells. Among the five forest types, dry deciduous
forests are highly vulnerable to forest fires. District wise analysis shows that Kurnool,
Prakasam and YSR districts are subjected to large scale forest fires. The estimate of total
forest burnt area covering protected areas ranges between 6.9% to 22.3%. The analysis of
cumulative fire occurrences from 2009 to 2014 has helped in delineation of conservation
priority hotspots. Spatial grid-cell approach was used for delineation of conservation priority
hotspots. The spatial database generated in the study will be useful in forest fire risk
modelling, accounting of carbon emissions and biodiversity conservation.
Validation of δ18O as a Proxy for Past Monsoon Rain by Multi
GCM
simulations
Midhun M *and Ramesh R
*Geosciences Division
Physical Research Laboratory
Stable oxygen isotope ratios (δ18O) of tree cellulose and speleothems are useful proxies for
past monsoon rain, as for every 100mm increase in monthly rain, its δ18O decreases by
~1.5‰. This amount effect varies spatially; therefore a local calibration, with actual
measurements of rain amount and its δ18O is preferred; which are limited over India. To
circumvent this difficulty, isotope-enabled General Circulation Models are used to aid the
interpretation of 18O proxies; however such simulations have never evaluated together over
Indian Summer Monsoon (ISM) region against observations. We examine such ten GCM
simulations carried out by the Stable Water Isotope Intercomparison Group-2. The spatial
patterns of ISM rainfall and its δ18O are in good agreement with the observations.
Simulations nudged with observed wind fields show better skill in reproducing the observed
spatio-temporal pattern of rainfall and its δ18O. A large discrepancy is observed in the
magnitude of the simulated amount effect over the Indian subcontinent between the models
and observations, probably due to the differences among models on the spatial distribution of
monsoon precipitation. Nudged simulations show that interannual variability of rainfall δ
18O at speleothem sites are controlled by either regional (rather than local) rainfall or
upstream rain out.
Methane Oxidation in D13c Signature of Cap Carbonate Cement
From Lesser Himalayan Proterozoic Strata
VASILIEV M.V1, GHOSH P1, SRINIVASAN R1
1Indian institute of Science, Bangalore, 560-012
Tremendous impact of methane into atmosphere is supported to explain the possible
deglaciation at the end of Marionoan “snowball Earth” ice at ~635 M.y. ago. This hypothesis
explains idea of highly depleted d13C in post-glacial cap dolostones as a product of methane
oxidation at the time of deposition and a signature for rising temperature. Resent works
(Kaufman et al. 2006; Bristow et al. 2011) prove this investigation by analysing cap
carbonates from Doushantuo formation from south Chine in the end of Marinoan age. Its
temperature of carbonate formation and depleted d13C correlated with methane oxidation. In
our work we analysed different sets of carbonate samples (cap dolomites, diamictites and
stromatoletes) from Mussooriesycline, Lesser Himalaya of India which belongs to Blaini
formation and corresponds to ~635 M.y. ago. “Clumped-isotope” technique, which was
applied in this study, showed variability in precipitation of d18O in carbonate from –16 to –
30‰ and interpreted as an early diagenicinprints. Our d13C signature is drifted from –1.4 to
–2.4‰ and is in agreement with data from previous work (Kaufman et al. 2006). Our
investigation is proceeding but we support the idea of drastic release of methane in
atmosphere and its oxidation dolostones what might increase the surface temperature in
atmosphere.
Modelling India's long term HFC Emissions: A detailed sectoral
perspective within an integrated assessment modelling framework
VaibhavChaturvedi, Mohti Sharma*, ShourjomoyChattopadhyay
Hydrofluorocarbons (HFC) are short term climate forcers with very high global warming
potential. They are conventional replacement option to Ozone depleting substances and have
been used extensively in developed world. Currently, India’s HFC emissions are 2% of
global HFC emissions but they are expected to rise with progress in imminent
Hydrochlorofluorocarbons (HCFC) Phase-out Management Plan. The Indian government has
proposed phase down of HFCs with its proposal to amend the Montreal Protocol. Our first of
kind modelling study utilises an integrated assessment modelling framework and bottom up
analysis of end-use sectors to estimate India’s long term HFC emissions from 2010 till 2050.
HFC use includes cooling and refrigeration applications for buildings, cars, buses and
industrial applications such as foams, aerosols and solvents. HFC emissions will grow by 186
times between 2010 and 2050 to 500 million tonne CO2-eq. Comparing with national level
carbon emissions, we find that HFCs contribute to 5.6% of total carbon dioxide equivalent
emissions in 2050, though the contribution is much higher for residential air-conditioning,
commercial air-conditioning, commercial refrigeration, and car sectors. We highlight
implications of a low growth scenario, as well as other key sensitivity on leakage rates.
Study of mixing of passive scalars in the Bay of Bengal
NiharPaul*, Jai Sukhatme1
1Center for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore
Abstract:
The mixing of passive scalars (or tracers) driven by the surface geostrophic currents in the
Bay of Bengal is studied. The data spans 20 years (AVISO project) and comprises of a two-
dimensional (2D) non-autonomous flow field. Based on its circulation, the Bay is divided
into smaller regions, and mixing in each of these regions by both the time mean as well daily
time dependent flow is characterized. The parameters used in the characterization comprise
of the Finite Time Lyapunov Exponent (FTLEs), Finite Size Lyapunov Exponent (FSLEs),
pair dispersion and pair velocity decorrelation. In addition, a comparison between the FSLE
and the more traditional Eulerian Okubo–Weiss parameter is also presented. In essence we
find that the mixing is chaotic, one or two more important features.
Trends in intensity of monsoon ISO and its association with
extreme events over India in a warming climate
Nirupam Karmakar1*, Arindam Chakraborty1, Ravi S Nanjundiah1,
1CAOS, IISC
Intraseasonal oscillatory (ISO) modes of Indian summer monsoon manifested by active and
break phases, and their association with extreme rainfall events play a crucial role in
probabilistic estimation of flood-related risks in a warming climate. Here, using multichannel
singular spectrum analysis on ground based observed rainfall data, we define an index to
measure the strength of monsoon ISO modes and show that the relative strength of the
northward propagating low-frequency ISO (20-60 days) modes have a significant decreasing
trend during past six decades. This can be possibly attributed to the weakening of large-scale
circulation in the region during monsoon season. This reduction is compensated by a gain in
synoptic-scale (3-9 days) variability. The decrease in low-frequency ISO variability is
associated with significant decreasing trend in percentage of extreme events during active
phase of the monsoon. However, this decrease is balanced by significant increasing trends in
percentage of extreme events in break and transition phases. We also find a significant rise in
occurrence of extremes during early- and late-monsoon months, mainly over eastern coastal
regions. Our study highlights the redistribution of rainfall intensity among periodic (low-
frequency) and non-periodic (extreme) modes in a changing climate scenario.
Multidecadal and Centennial Periodicities in Indian Monsoon
Inferred from High Resolution Stalagmite δ18O Record
AUTHORS 1P. K. Gautam, A. C. Narayana
2M. G. Yadava, R. Ramesh 3Chung-Che Wu, Chuan-Chou Shen
AFFILIATIONS 1 Centre for Earth & Space Sciences, University of Hyderabad, Gachibowli, Hyderabad-
50046, India
2Physical Research Laboratory, Navrangpura, Ahemadabad-380009, India
3 High-Precision Mass Spectrometry and Environmental Change Laboratory
(HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617,
Taiwan, ROC
In the recent past, high resolution δ18O data from absolutely dated stalagmites have been
considered a robust proxy to study Asian monsoon variability. Although a few high
resolution stalagmite isotopic results have been reported from Asia, there exist many spatial
and temporal gaps which need to be filled for a better understanding of monsoonal
variability. We report here a first high resolution stalagmite δ18O isotope data set that
corresponds to the recent deglacial period.
The sample was obtained from the Kailash Cave located in Chhattisgarh, a core monsoon
region in central India. Linear age-depth model constructed from six U-Th dates suggests that
the sample grew for ~2.4 kyr from ~14.6 ka to ~12.2 ka with varying resolutions i.e., from ~6
months to ~8 years. δ18O results appear to be cyclic in nature varying in the range from
+0.37‰ to -6.07‰.We performed time-series analyses on the δ18O records to delineate the
influence of both solar and non-solar frequencies during the recent deglacial period. REDFIT
(Schulz &Mudelsee, 2002) with Monte Carlo simulations, allowing the spectrum to be bias-
corrected, was used to estimate red noise. Spectral analysis of the δ18O time series suggests
statistically, the most significant periodicity (>95% confidence level) centered around 590
years. The other significant periodicities observed are at 42, 37, 19, 18, 16, and 14.5 years.
Earlier, based on the δ18O variations in a sediment core form the Arabian Sea (3268G5),
samples at 120 yr resolution, Sarkar et al., (2000) reported periodicities in the monsoon
rainfall for the Holocene period. The prominent period was 700 yr, but a significant peak at
590 yr was also seen (Fig. 6 of Sarkar et al., 2000). Our results, with a much higher time
resolution, confirm this periodicity.Further, based on δ18O variations in an annually resolved
stalagmite from Akalagavi cave (Northern Karnataka) that spanned 331 yrs, Yadava and
Ramesh (2007) reported periodicities of 59, 21 and 18 yrs. These are very close to the
periodicities we report here. There may not be an absolute match between the periodicities
obtained from different samples because of the different resolutions of sampling and
analytical uncertainties in the dating. Notwithstanding these problems, we see that there is a
reasonable concordance among these periodicities.
Indian summer monsoon intraseasonal oscillation in different
phases of El Nino in present and future climate
Prasanth A Pillai1*, D.A Ramu1 and J.S Chowdary1
1Indian Institute of Tropical Meteorology, Pune
The present study investigates the characteristics of active and break cycles of the Indian
summer monsoon (ISM) during developing and decaying phase of El Niño and in the years in
which Indian Ocean Dipole (IOD) co-occurred with El Niño. The study points out that the
monsoon intraseasonal oscillation (ISO) characteristics including its intensity, northward
propagation, spatial distribution, number of active/break days etc are modified by the
different background anomalies induced by these SST anomalies. Active and break spells are
more organized with accurate northward propagation in El Nino developing year only. The
study observes the preference of peculiar phase of ISO circulation and rainfall by El Nino
developing and decay years. The present study put forward the argument that the contrasting
persistent circulations over Indo-west Pacific regions favor particular phase of ISO in
developing and decay phase of El Nino. These long lasting circulations advect anomalous dry
(moist) air to ISM region for longer period, resulting in long lasting break (active) events in
El Niño developing (decay) years. 30-60 day periodicity of ISO undergoes modification in
these years compared to high frequency 10-20 day periodicity. Suit of coupled model
simulations from CMIP5 examine the relationship in present and future climate scenarios.
Aerosol Optical Properties over Gorakhpur in the IGP from
Ground-Based observations and Remote Sensing
Prayagraj Singh 1*and Shantanu Rastogi1
1Department of Physics, DDU Gorakhpur University, Gorakhpur– 273009, India
One year, 2014, of aerosol optical properties and their temporal heterogeneities over
Gorakhpur in the Indo-Gangetic Plain (IGP) region are analyzed utilizing data from the
ground based Multi-wavelength Sun Radiometer (MWR) and Moderate Imaging
Spectroradiometer (MODIS). Mean aerosol optical depth at 500 nm (AOD500) of 0.67±0.43
along with a moderate Angstrom coefficient (α) of 1.01±0.51 is found using MWR data. A
monthly high AOD500 of 1.8 is observed for the month of June while low corresponds to the
month of December with AOD500 of 0.28. Coarse mode aerosol particles dominate during
summer months, while fine-mode aerosol particles are dominant during the winter months, as
evident from the variability of α and turbidity coefficient (β). Comparison of MWR
observation with MODIS observation indicates a good correlation between ground-based and
satellite derived AODs. HYSPLIT Lagrangian model is used to investigate long-range
transport of aerosols and source apportionment of Black Carbon (BC) over the IGP. The
extremely high BC concentrations, often exceeding 25 μg m-3 and mainly originating from
the industrialized North West part of the region, having large diurnal variation prevailed
during winter months.
Changes in Summer Monsoon Precipitation over Coastal
Karnataka in Warming Environment
P.K. Murumkar1, 2, H. Varikoden1, S.A. Ahmed2 and J.V. Revadekar1*
1Centre for Climate Change Research, Indian Institute of Tropical Meteorology,
Pashan, Pune-411008; *[email protected] 2Department of Geology, Central University of Karnataka, Gulbarga-585 311
The Indian summer monsoon accounts for 80% of the rainfall in India. During the summer
monsoon season between June and September, the Western Ghats acts as a barrier to the
moisture laden clouds. The heavy, eastward-moving rain-bearing clouds are forced to rise and
in the process deposit most of their rain on the windward side. Rainfall in this region
averages 3,000–4,000 mm with localized extremes. The eastern region of the Western Ghats
which lie in the rain shadow.
The rainfall during Indian summer monsoon season show considerable inter-annual & inter
seasonal variability. Summer monsoon rainfall over coastal Karnataka is much higher
compared to All-India. Long term All India summer monsoon rainfall is trend less, but
coastal Karnataka long term trend is towards positive side. Recent decade show rainfall is
declining over coastal Karnataka. During which Coastal Karnataka show strong positive
relationship with Indian Ocean Dipole. However it is weak for equatorial pacific sea surface
temperature. Niño 3 region show negative relationship. Circulation patterns are also
examined for extreme monsoon years for coastal Karnataka. In general an attempt is made in
this study to analyze changes in summer monsoon precipitation over Coastal Karnataka in
warming environment.
Retrieval of Atmospheric Temperature and Humidity Profiling
using Ground based Microwave Radiometer
Raju Pathak1, G Pandithurai2,J S Pillai and A. Agrwal3,Anand Karipot1
1Department of Atmospheric and Space Sciences, SavitribaiPhule University of Pune
2Indian Institute of Tropical meteorology (IITM), Pune 3Society for Microwave Electronics Engineering and Research (SAMEER), IIT Bombay
Atmospheric profiling through the network of in situ radiosonde (RS) observation and remote
sensing (satellite) observations is of great importance to represent the initial three
dimensional structure of atmosphere to numerical prediction models. These two approaches
have their own limitations as radiosonde along the path followed by drifting balloon and also
its operation is costly. In satellite obtained horizontal and temporal resolution is coarse for the
present day to high resolution numerical prediction models. An alternative to that ground
based microwave radiometer is getting more importance due to their capability to profile
temperature and humidity at high temporal and vertical resolution in lower troposphere. The
process of retrieving these parameters from the measurement of radiometric brightness
temperature (TB) includes inverse model which uses prior information from forward model.
In the present study, an algorithm development and evaluation of forward and inverse model
for a ground based microwave radiometer being done by SAMEER and IITM of India.
Initially the analysis of absorption coefficients and weighting function is made to select
channel. A comparison between model simulated brightness temperature and radiometer at
Mahabaleshwar (77.66oE and 17.93oN) is done and showing good agreement between them.
Further, neural network based inverse model is trained by 6 year radiosnde and forward
model simulated brightness temperature. A comparison of inverse model retrieved
temperature and humidity is done by radiosonde and radiometer for two regions over
Mumbai and Mahboobnagar. The annual temperature and humidity variation is analysed to
check how temperature and humidity is changing during different seasons over Mumbai and
compared with radiosonde observed annual variation. Finally, evaluation of the inverse
model i.e. accuracy in retrieval is computed by taking mean error for 120 days out of 6 year.
The inverse model evaluation shows good agreement with radiosonde in lower troposphere
and less in higher troposphere.
Keywords: Radiosonde; microwave radiometer; brightness temperature; forward model;
inverse model; neural network.
Change in climate change will influence wood decomposition?
Rashmi Ramesh Shanbhag and R. Sundararaj1
1Institute of Wood Science and Technology, 18th Cross, Malleswaram, Bangalore
560003, India
Wood decomposition is a complex process that involves biotic and abiotic influences, as well
as the mechanical and chemical properties of the wood itself. For some types of wood
decomposition climate is a very important factor, at least in the early stages of
decomposition. Many researches considered climate to be the dominant factor influencing
decomposition in areas subjected to unfavourable (dry and cold) weather conditions. It is
hypothesized that the relative contribution of soil fauna (as opposed to micro-flora) to
decomposition was dependent on the climatic region, being greatest at mid latitudes and
decreasing towards the poles. When it comes to termite mediated wood decomposition
climate seems to play a major role. Therefore, a significant difference in the rate of
decomposition may signal either a change in termite species diversity or in the conditions of
biotic or abiotic resources at a site. To test the hypothesis wood decomposition experiments
were carried out at different agro climatic zones of India. Wood species were subjected to
grave yard test. Data generated were subjected to Kruskale Wallis analyses and Friedman’s
repeated measures analysis of variance. Results indicated the Factors such as climatic
conditions where wood is put in use; the wood’s place of origin, abundance of major wood
destroying termites along with Physical characteristics and chemical composition of wood
play major roles. These characteristic-wood decomposition relationships will help us to
develop proper modelling for wood decomposition at regional and eventually also on the
global scales.
Effect of large-scale vertical motions on SST-Cloud relationships
observed over Tropical Indian Ocean
V. Ravi Kiran1, M.Rajeevan2, H.Gadhavi1 and A.Jayaraman1
1National Atmospheric Research Laboratory (NARL), Gadanki, India
2Indian Institute of tropcial meteorology (IITM), Pune, India.
Clouds play a key in regulating hydrological cycle, modifying Earth’s radiation budget and in
determining large scale atmospheric circulations. The cloud properties over the Oceanic
regions are found to be a non-linear function of sea surface temperature (SST). This is
attributed to the influence of thermo dynamical (lower tropospheric stability, surface
divergence, tropopause layer thickness etc.,) and dynamical (large scale rising and sinking
motions) parameters. In this study, the vertical structure of cloud liquid/ice water content
derived from CloudSat is sorted into SST bins of 0.5oC. This approach is known as regime-
sorting technique found to be an ideal method for model-observation comparisons. The SST-
Cloud variations are observed distinct over the tropical Indian Ocean (10oS-20oN; 50oE-
100oE) and tropical Pacific Ocean (10oS-20oN; 100oE-150oE). Using the vertical velocity at
850 hPa as proxy for large scale vertical motions, the SST-Cloud variations are understood
by stratifying the large scale motions in to four categories. The strong subsidence present
over the tropical Pacific Ocean is controlling vertical development of cloud system. However,
large-scale rising motions are conducive for formation of clouds over the tropical Indian
Ocean. These results have demonstrated the role of dynamical parameters on cloud formation
over Oceanic regions. Detailed results will be discussed.
Recession of Milam glacier,Kumaon Himalaya from Stereo data
of
CORONA TO CARTOSAT
REMYA S. N1* and K. BABU GOVINDHA RAJ 2
1Indian Institute of Surveying and Mapping (IISM),
Survey of India (SoI), Hyderabad
2Geosciences Group
National Remote Sensing Centre (NRSC)
Indian Space Research Organisation (ISRO), Hyderabad
In the field of glaciology, satellite remote sensing has proven to be the best tool because;
many of the glaciers are located at very high altitude, cold weather and rugged terrain
conditions, making it a tedious, hazardous and time-consuming task to monitor by
conventional field methods. Satellite remote sensing technology facilitates to study the
behaviour of ice masses of the Himalaya systematically with a cost to time benefit ratio.
CORONA and Cartosat-1 satellite aft and fore images are mainly used in research. CORONA
and Cartosat-1 aft and fore stereo image is acquired on 26th September1968 and 12th
December 2011 respectively. These data are useful to identify the changes in recession rate of
Milam glacier during the year of 1968 to 2011. DEM (Digital Elevation Model) and ortho
image generated from both Cartosat -1 and CORONA stereo images. DEM of both images is
created in using LPS software. These data were analyzed to find out the altitude and snout
position of Milam glacier.
The data analysis shows that the Milam Glacier in the Goriganga Basin, Kumaon Himalaya
have receded 1100 m laterally and 106.69 m vertically from 1968 to 2011.
Microwave radiometer observations of vertical structure of water
vapor and characterization of local convections over a tropical
station
Renju R*, C. Suresh Raju,Nizy Mathew, K. Krishnamoorthy
The study of water vapor variability over a tropical station is important to understand the
influence of water vapor on small scale weather phenomena like convection to complex and
organized phenomena like monsoon. This paper presents results of multi-year (2010-2014),
multi-frequency microwave (Ka& V bands) radiometer profiler (MRP) measurements from
the tropical coastal station, Thiruvananthapuram (TVM), are used for the characterization of
intra-seasonal and inter-annual variability of atmospheric water vapor and water vapour
vertical distribution and its link with the strength of monsoon over the station. The potential,
accuracy and consistency of MRP of water vapor over equatorial coastal condition including
the monsoon period have been established by comparing the concurrent and collocated
measurements of PWV by MRP and GPS using a station-based regression model between
PWV and GPS wet delay component for TVM. Significant diurnal and intra-seasonal
variations of PWV are observed during winter and pre-monsoon seasons. There is large inter-
annual PWV variability during pre-monsoon, owing to frequent local convection and summer
thunderstorms whereas during monsoon, low inter-annual variability due to water vapor
advection by southwest oceanic monsoon winds. However, significant inter annual variability
is seen for the humidity in the 2 to 6 km height altitude layer and that is also linked to the
monsoon strength over the station. Prior to the onset of monsoon over the station, the specific
humidity increases up to 5-10 g/kg in the altitude layer above 5 km and remains consistently
so throughout the active spells. Apart from the studies of organized systems like monsoon,
radiometric observations have also been used to characterize the occurrence of local
convective events, their genesis, strength and finally to derive a methodology for now-casting
in terms of brightness temperature variations. This study assumes significant important for
study of monsoon and tropical convection.
Regional Scale Analysis of Climate Extremes in an SRM
Geoengineering Simulation
Rohi Muthyala1*, Bala Govindasamy1
1CAOS, I.I.Sc
*[email protected],[email protected]
In this study we perform a comprehensive analysis of the climate extremes for SRM
Geoengineering Simulation, with reference to the preindustrial climatic conditions, using
several indices on a regional scale. Very few studies in the past have investigated the
statistics of extreme events under geoengineering simulation, using a limited number of
extreme indices. Here, we consider a subset of indices available in EIA (ETCCDI Indices
Archive) to represent the climate extremes in two different types, i.e., Intensity based indices
and Frequency based indices. Regional analysis over 22 Giorgi land regions is also
performed. Extremes are substantially reduced in geoengineering simulation: the magnitude
of change is much smaller than those that occur in a simulation with doubled CO2. Over all,
when compared to control simulation, we find the change in frequency of extreme events in
geoengineering simulation to be lesser than or equal to zero globally while the change in
intensity of these events still persists over Extra Tropical Land regions in Northern
Hemisphere and vary regionally depending on local conditions. We also find that, with
reference to control simulation, the Meridional variation of both temperature and
precipitation extremes is nullified in geoengineering simulation.
Interannual variability of the Arabian Sea Warm Pool:
Observations and governing mechanisms
Rokkam R Rao*
Indian Institute of Tropical Meteorology Ministry of Earth Sciences
*[email protected], [email protected]
The near-surface layers in the Arabian Sea progressively warm up from February to early
May resulting in the formation of pool of warm waters popularly known as the Arabian Sea
Warm Pool (ASWP). The availability of high quality TMI sea surface temperature (SST) data
for the years 1998–2010 is exploited to describe the evolution of the ASWP on seasonal and
interannual time scales and to explain the associated governing mechanisms. The multi-year
(1998–2010) averaged TMI SSTs during April–May show peak values of the ASWP in
excess of 30°C with its core >30.5°C extending offshore as a well-marked southwestward
tongue stretching from the southwest coast of India. The ASWP shows both seasonal and
interannual variability in the evolution of spatio-temporal characteristics such as amplitude,
phase and spatial extent. Among these 13 years, the ASWP was most (least) pronounced
during 1998, 2003 and 2010 (1999, 2000, 2001 and 2008). The mechanisms that govern the
observed interannual variability of the ASWP are examined addressing the most relevant
issues such as –
1) Dynamic pre-conditioning: background pycnocline topography influenced by the
westward propagating Rossby waves during October–May
2) Thermal pre-conditioning: background SST/heat content signal during October–January
influenced by the strength of the preceding year’s summer monsoon and the post-monsoon
cyclones during October–December
3) Haline pre-conditioning: near-surface vertical salinity stratification during November–
February influenced by the advection of low saline waters from the Bay of Bengal
4)Influence of surface net heat flux forcing during February–May and
5) Influence of El Nino/La Nina.
Estimation of Aerosol radiative forcing using ground based
spectral irradiance measurements
Roshan R Rao *
Prof J Srinivasan *
Prof S K Satheesh*
*affiliation - CAOS, I.I.Sc
Aerosols are one of the most uncertain components today in climate studies due to its
variability in space and time. Its complexity increases further as its influence on radiative flux
changes when it’s physical and chemical properties changes. Thus estimation of of radiative
forcing of aerosols depends on the understanding of their radiative properties and availability
of database on its chemical composition. Due to the unavailability of adequate chemical
composition data, indirect methods have been found to estimate aerosol radiative forcing. In
our study we have used the ground based measurement of spectral irradiance and radiative
transfer model to estimate spectral aerosol radiative forcing. Spectral irradiance
measurements at the surface have been made between 350 and 1050 nm wavelength at the
urban location of Bangalore and semi arid location of Challakere using portable
Spectroradiometer. A simple aerosol model which is optically equivalent has been developed
for each location which can simulate the measured spectral irradiance using the OPAC data
and SBDART model. On using the simple model, spectral aerosol radiative forcing has been
estimated.
The great Indian haze revisited: aerosol distribution effects on
microphysical and optical properties of warm clouds over
peninsular India
R. Ghanti(1) and S. Ghosh (2, 3)
1 Civil Engineering Dept, IIT- Delhi, India.
2 School of Earth and Environment, University of Leeds, Leeds, UK 3 School of Mechanical and Building Sciences, Vellore Institute of Technology, Vellore,
India
Rapid urbanization in Indian subcontinent has led to concomitant increase in air pollution
much of which can be attributed to the infamous great Indian haze phenomena. One observes
that the aerosol size distributions vary considerably along the Bay of Bengal (BOB), Arabian
Sea (AS) and the Indian Ocean (IO), although, the dynamical attributes are very similar,
particularly over the BOB and the AS during this season. Ours is the first modelling study
over this important region where a time-tested model is used to obtain cloud microphysical
and optical properties from observed aerosol size distributions. Un-activated aerosol particles
and very small cloud droplets have to be treated specially to account for non-ideal effects-our
model does this effectively yielding realistic estimate of cloud droplet number concentrations
(Nc). Empirical relationships linking aerosol concentration to (Nc) yield a disproportionately
higher Nc suggesting that such empirical formulations should be used with caution. Our
modelling study reveals that the cloud’s microphysical and optical properties are very similar
along the AS and the BOB despite them having disparate dry aerosol spectral distributions.
There is some increase in cloud droplet numberswith increased haze concentrations but much
less than a simple proportion would indicate.
Long-term tendencies and variabilities of tropical UTLS water
vapour mixing ratio
S. Sridharan1and M. Sandhya 1, 2, M. Indira Devi2
1(National Atmospheric Research Laboratory, Gadanki 517 112, Pakala, India)
2(Department of Physics, Andhra University, Visakhapatnam 530003, India)
Long-term variabilities and tendencies in the tropical (30°N-30°S) monthly averaged zonal
mean upper troposphere and lower stratospheric (UTLS) water vapour mixing ratio (WMR)
obtained from the microwave limb sounder (MLS) instrument onboard earth observing
system (EOS) satellite for the period 2005-2014 are studied using multivariate regression
analysis. It is found that there is a decreasing trend in WMR below 100 hPa and the trend is
positive above 100 hPa. The response of WMR to solar cycle is positive below 50 hPa. It is
significantly negative in the height range 56-38 hPa and it remains weakly negative above 31
hPa. The QBO response is negative below 146 hPa and above 50 hPa and is positive in the
range 120-56 hPa. The response of WMR to Brewer-Dobson circulation is negative below 68
hPa and positive at 68-46 hPa. It again becomes negative at 38-20 hPa and insignificant
above 20 hPa. The ENSO response is positive in the UTLS region (177-68 hPa) and weakly
negative at most of the heights above 50 hPa. The response of WMR to tropopause
temperature is largely positive (0.37 ppmv/K) around tropopause (121-80 hPa) as expected
and the positive response decreases above 80 hPa and becomes insignificant at and above 56
hPa.
Multi-year model simulations of mineral dust distribution and
transport over the Indian Subcontinent during summer monsoon
seasons
S Sijikumar1*, S Aneesh1, and K Rajeev1
1Space Physics Laboratory
Vikram Sarabhai Space Centre
Thiruvananthapuram
Aerosol distribution over the Arabian Sea and the Indian subcontinent during the northern
hemispheric summer is dominated by mineral dust transport from the West Asian desert
regions. This study examines the transport of mineral dust over the West Asian desert, the
Indian subcontinent and the surrounding oceanic regions during summer monsoon season
with help of a regional scale model, WRF-Chem. Geographical locations of prominent dust
sources, altitude ranges of mineral dust transport and their inter-annual variations are
examined in detail. Multi-year model simulations were carried out during 2007 to 2012 with
a model integration from 15th May to 31st August of each year. Six-year seasonal mean
(June to August) vertically integrated dust amount from 1000 hPa to 300 hPa level shows
prominent dust loading over the eastern parts of Arabian desert and northwestern part of India
which are identified as two major sources of dust production. The model simulations clearly
show that most of the dust distributed over the Indo-Gangetic plane originates from the
Rajasthan desert, whereas dust observed over the Central and South Peninsular India and over
the Arabian Sea are mainly transported from the Arabian desert.
Effect of higher temperature on the enzyme activities and
biochemical changes in selected organs and tissues of hill stream
fish, Nemacheilustriangularis
Sabu.K*, Prasad.Gand Sukanya. B S
Department of Zoology, University of Kerala, Kariavattom,
Thiruvananthapuram, Kerala, India, 695 581
*Email: [email protected].
The potential impacts of climate change are severe in the Western Ghats particularly within
the region bordering the state of Kerala. The maximum temperature is likely to rise by 1°C -
4°C in this region which has importance to ectotherms especially to fresh water fishes. The
experimental design used herein superimposed an additional 2°C upon the natural thermal
regime of model fish, Nemacheilustriangularis as an estimate of global warming. The fishes
were exposed to different acclimated temperatures (30°C, 31°C, 32°C and 33°C) for a period
90 days and the changes on metabolic enzymes like Alkaline phosphatase, (ALP) Aspartate
aminotransferase (AST) Alanine aminotransferase (ALT), Sodium-potassium ATPase
(Na+/K+- ATPase in gill) and Glutamate dehydrogenase (GDH) in gill, liver and muscle
tissues were assessed. The study also elucidated the effect of temperature on the biochemical
changes of glycogen, total proteins and lipid in gill, liver and muscle tissues. The study
revealed elevated activities of enzymes such as ALP (275.73±2.097; liver), AST
(185.52±2.498; gill) ALT (245.92±2.78; liver) and GDH (0.647±0.005; liver) maximum sub
lethal temperature (33°C). A decreased Na+/K+-ATPase activity (11.45±0.215) was recorded
in fishes exposed to 33°C temperature and it is significantly different (p≤ 0.01) from control
group (18.87±0.515). Enzyme activity in all the organs increased significantly (p<0.01) with
the increasing temperature. This indicates that the increasing temperature interfere the
transamination and metabolic process. Biochemical analysis of protein, glycogen and lipid in
different tissues showed significant (p<0.05) decreasing trend and this could be due to the
high energy demand to meet the thermal stress. The changes in the activities of the enzymes
can be used as possible stress biomarkers to assess the impact of changed thermal conditions.
Key words: Nemacheilustriangularis, high temperature, enzyme activity, AST, ALT,
biochemical parameters.
Rain water isotope study across Westernghat: Implication to
moisture recycling and its ensuing effect in paleoclimate
interpretation
SaikatSengupta1, Trina Bose2, Supriyo Chakraborty1
1Indian Institute of Tropical Meteorology, Pune
2Physical Research Laboratory, Ahmadabad
During paleomonsoon reconstructions on multidecadal timescales carried out using oxygen
isotopes of speleothem and tree ring samples across Western Ghats (WG), it was seen that the
underlying principle involving isotope –rain amount correlations were extremely site specific.
Considering a large latitudinal extent of the mountain (from 10°N to 20°N), the site specific
variation could be due to either change in the moisture sources in the precipitation or altitude
or local factors. In order to understand the role of altitude or location on rain amount isotope
correlation, daily rain water samples were collected from four stations across WG for three
years (2011 – 2013) for isotopic analysis. Two of these (Pune and Paud) are situated on the
leeward side of the mountain and two stations in the windward side (Bhira and
Mahabaleshwar). The windward sides receive ~6 times more cumulative JJAS rainfall than
the leeward stations. All four stations roughly fall along E-W mean JJAS 800mb trajectory.
Three years data show except few 4-7 days events, mean d18O values of all four stations are
nearly similar (-1.4± 1) per mil in both intra and inter season. RHI scan of K Band Radar
Dopler indicates that low isotope value events correspond with large scale convective
systemsover the WG. Moreover, synchronous high and low isotope values in all four stations
indicate precipitation mainly occur in this area from large scale systems where rain isotope
composition depend on initial vapour isotopic composition. Further, rainfall amount across
WG is dominantly controlled by orography induced microphysical changes in cloud as
discussed in many earlier literatures. This possibly explains poor rainfall amount –isotope
correlation in most of the events. Hence, we conclude that such correlation can only be used
for climate reconstruction with caution.
Statistical Analysis of the SST in the northern Indian Ocean
Samiran Mandal1*
Affiliation- 1School of Basic Sciences,
Indian Institute of Technology, Bhubaneswar
Bhubaneswar.
Sourav Sil2
Affiliation- 2School of Earth, Ocean and Climate Sciences,
Indian Institute of Technology, Bhubaneswar
Bhubaneswar.
The regional climate in the Indian subcontinent primarily depends on the variability in the
northern Indian Ocean. The climate changes and sea level rises motivate to explore the
oceanic temperature and its variability. The project work focuses mainly on the short term
and long term variability of the sea surface temperature (SST) time series in the northern
Indian Ocean using different statistical techniques. Monthly SST for the duration of 140 years
(1871 – 2010) from Simple Ocean Data Assimilation (SODA) product at three locations
along Indian coastline near Mumbai, Kochi and Puri in the northern Indian Ocean are
selected for the analysis. The trend analysis indicates the increase in SST in all three locations
by 0.67 ℃, 0.84 ℃ and 0.50 ℃ in the last 140 years respectively. Secondly, Fast Fourier
Transforms (FFT) and Wavelet Analysis were performed to identify the occurrence of the
dominant frequency of the signals. The spectrum with de-trended time series showed that
presence of semi-annual and annual signal in all three locations. For the location near Puri,
the amplitude of annual signal is higher than the semi-annual, while in other two locations the
both signals are dominating. The climatology removed time series is then analyzed to identify
the long-term variability in the SST at those locations. It is observed there is 3-4 years
variability from FFT analysis. The wavelets analysis depicts that the years of the higher
amplitudes of long-term variability coincide with the variability of ENSO signal to indicate
the influence of the Pacific region in the northern Indian Ocean. The outcome of short-term
(monthly) and long-term (Climatology removed) variability may help to understand the
regional climate in the Indian region and it will also help toward the numerical ocean and
climate models.
Empirical evidence of direct impact of extreme temperatures on
wheat yield in the Indian region of Indo-Gangetic Plain
Sandeep Mahato1
Kamal Kumar Murari2
ThiagarajanJayaraman1
1 Tata Institute of Social Sciences, School of Habitat Studies, Mumbai, India
2IITB-Monash Research Academy, Powai, India
Exposure to extreme temperatures during the grain filling stage of winter wheat may lead to
reduction in the yield. The Indo Gangetic plain (IGP) is a particular concern since an optimal
temperature for wheat production already exists in the region. Previous studies conducted in
this region have found a strong impact of extreme temperatures causing an early occurrence
of senescence in wheat. This shift in senescence period has led to shortening of growing
season length. However, the direct effect of extreme temperatures on the yield data has not
yet been looked at, which reflects the impact of extreme temperature at different growth
stages including anthesis and the grain-filling stage. Here in this study, we explore the
relationship of extreme heat conditions on the yield using fixed-effect panel data model for
the districts in the IGP region. The result indicates approximately 14% reduction in wheat
yield with 1˚C rise in mean growing season temperature. Under extreme temperature
conditions we found that the yield decreases between 15% - 22% for each degree rise in
growing season temperature. Our result confirms the findings previous studies that warming
presents a greater challenge to wheat yield in IGP region.
Mass Balance Modeling of Himalayan Glaciers
Sathiyaseelan R*, Krishna AchutaRao*
* Indian Institute of Technology Delhi
Glacier changes illustrate climatic changes in a highly visible and also physically
understandable way. Significant impacts are seen in global sea-level rise and river flow
caused by retreating glaciers. Annual mass balance of glaciers provides a robust way to
ascertain whether in a given year there has been a net loss or gain of ice from the glacier. The
mass balance reflects all of the meteorological forcing of the glacier - both the snow added
over the course of the year and the losses dealt by the combined effects of the ablation and
sublimation.
We follow the methods of Radic& Hock (2010) to compute the mass balance of 12 chosen
Himalayan glaciers in response to temperature and precipitation changes. The mass balance
model calibration is carried out for the chosen glaciers over the Himalayan region and
compared against 36 glaciers from other regions used by Radic and Hock (2010). We use
available mass balance observations, ECMWF reanalysis (ERA-40) temperature and
VASClimO (GPCC) precipitation datasets for calibration and hindcasts of mass balance.
Recent Trends in Aerosol Characteristics over the Indo-Gangetic
Plains
Satyendra K. Pandey1*,V. Vinoj1
1SEOCS, IIT BBS
Indo-Gangetic Plain (IGP) is one of the most densely populated basins over the Indian region.
The rapid pace of development and associated industrial activities in this region has caused
significant increases to anthropogenic aerosol emissions. In addition, due to its unique
geography this region is influenced by seasonally reversing monsoon winds and associated
changing air mass characteristics. This seasonality also leads to long range transport of
natural dust aerosols over this region. Our study attempts to understand recent changes/trend
during the period 2001 to 2014 in the aerosol loading over Indo-Gangetic Plain (IGP) using
ground (AERONET) and satellite (MODIS & MISR) based measurements. Our analysis
shows that overall, a statistically significant increasing trend is observed in background
column AOD values irrespective of the data sources (viz. MODIS, MISR and
AERONET) and seasons. Also, the major contribution to the overall trends comes from the
highest quartile of AOD’s. However, on a seasonal scale, the trends exhibited large
variability, which is attributed to the combined influence of both local emissions and long
range transport of aerosols. For example, June to August (JJA) and March to May (MAM)
period exhibits a slightly decreasing trend in mean AOD’s. Whereas, September to November
(SON) and December to February (DJF) exhibits increasing trends. In addition, a recent study
has shown that IGP is a net aerosol source region during SON and DJF. This along with our
finding that these trends are being dominated by the upper quartile in AOD’s suggests that
long range transport (especially associated with mineral dust) over this region is changing.
Additional analysis confirms that the cause for this varying trends is the changing dust
transport associated with long range transport.
Impact of AQUARIUS sea surface salinity assimilation in
improving the coupled CFS monsoon forecast
Vivek S a*, Sreenivas .P a, Prasad K.V.S.R b, and Gnanaseelan. C a
a Indian Institute of Tropical Meteorology, Pune
b Dept. of Meteorology & Oceanography, Andhra University,
Visakhapatnam
*email: [email protected]
Seasonal and Extended range prediction of Indian summer monsoon has been a challenging
task for meteorological communities. It is a well established fact that accurate representation
of ocean state is very essential for better seasonal as well as short term weather forecast. Any
inaccuracy in the representation of upper ocean thermal structure in the ocean initial state will
lead to drastic errors in coupled model forecast. The data assimilation techniques have
promising role in achieving an accurate ocean state in the context of recent advances in ocean
and atmospheric observational networks. The structure of ocean salinity controls the density
field and thereby playing a major role in influencing the ocean dynamics. It has been a
challenging task to understand the strong intra-seasonal and inter-annual variability of
salinity structure in the regions of large fresh water discharge and high precipitation such as
Bay of Bengal. Even the well organized assimilation schemes/models have limitations in
producing accurate salinity analysis due to the lack of significant salinity observations (both
spatially and temporally). Recent advancement in satellite technology has made possible the
measurement of sea surface salinity (SSS) with unprecedented spatio-temporal coverage.
Aquarius is the recent operational mission which measures the global SSS since 2011. We
assimilated Aquarius SSS in the Global Ocean Data Assimilation (GODAS) for the period
2011 to 2014. GODAS is the assimilation module for MOM4 (ocean component of CFS, the
forecast model used in India and many other countries). The assimilation scheme in GODAS
is 3DVAR. The present study addresses the impact of assimilating Aquarius SSS in
improving the ocean analysis and intern it impact in improving the monsoon from CFS based
monsoon forecast.
Glacial and Holocene Nitrogen Dynamics and Productivity
Changes in the South-eastern Arabian Sea
Selvaraj Kandasamy1, Veeran Yoganandan2, Shuh-Ji Kao1, Chen-Tung Arthur Chen3,
Richard W. Murray4
1State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen,
China 2Department of Marine Sciences, Bharathidasan University, Tiruchirappalli, TN, India
3Department of Oceanography, National Sun Yat-sen University, Kaohsiung, Taiwan 4Department of Marine Science, Chinese Naval Academy, Kaohsiung, Taiwan
5Department of Earth Sciences, Boston University, Boston, MA 02215, USA
The Eastern Arabian Sea (EAS) is well known for a significant loss of nitrogen through the
subsurface denitrification, although available nitrogen isotopic records are inadequate to
understand the N dynamics on glacial-interglacial timescales. Here we report stable isotopic
(δ13C and δ15N) and trace elemental (Fe, Cr, Cu, Ni, V and Zn) data from two sediment
cores, SK-177/11 and SK-215/5, collected at water depths 776 m and 460 m, respectively.
Chronology of these cores was established through adequate number of radiocarbon (14C)
dates on foraminiferal shells and bulk organic carbon. Our coarse resolution records of δ13C,
δ15N and C/N ratio in core SK-177/11 preserve glacial-Holocene denitrification changes
with enriched δ13C and low δ15N values during the glacial period (~35–18.5 ka BP). From
18.5 to ~13.5 ka BP, the δ13C record shows a drastic depletion while δ15N increased ~2.5‰
suggested an intensified oxygen minimum zone during the deglacial period and increased
denitrification, consistent with the global denitrification pattern, in the study region. Down
core patterns of trace elements almost track the organic carbon pattern and thus document the
glacial-deglacial-Holocene N dynamics and productivity changes on millennial timescales.
Consistent to core SK-177/11, our high resolution δ13C and δ15N records from core SK-
215/5 indicated increased productivity and denitrification during the early Holocene,
consistent with intensified SW monsoon and associated upwelling in the Arabian Sea.
Gradual decrease of δ13C and C/N ratio since early Holocene to the Present further attested
an increased marine productivity as δ13C values move from lighter to heavier values towards
the late Holocene. These interpretations are consistent with trace elemental records, which
showed lower but more stable elemental values since around 6 ka BP. This study provides
high resolution δ15N and trace elemental records from the south-eastern EAS for the glacial-
Holocene interval and documents an increased denitrification during the deglacial period.
Analysis of Aerosol optical properties and its Radiative Forcing
over a Dehradun-case study winter season (Nov2014 – Jan 2015)
ShaikDarga Sahib1*,Yogesh Kant1, Rajkumar Sign1
1Indian Institute of Remote Sensing (ISRO), Dehradun
The role of atmospheric aerosols and their radiative effects on Earth's climate is uncertain.
The spatio-temporal variations in aerosols distribution combined with their radiative effect
highlight the need to study aerosol optical properties and Radiative Forcing on seasonal as
well as regional scales.Aerosol samples are collected using a multi wavelength sun
photometer (MICROTOPS II) and The estimated spectral values of aerosol optical properties
using a modelling tool OPAC, including aerosol optical depth, aerosol single scattering
albedo, and asymmetry parameter for each day of measurement are incorporated in a Discrete
Ordinate Radiative Transfer model Santa Barbara DISORT Atmospheric Radiative Transfer
(SBDART) to estimate the short-wave (SW, 0.25 to 4 μm) aerosol radiative forcing at the
surface, atmosphere, and the top-of-atmosphere (TOA). The monthly mean columnar ozone
and water vapor for the study site at Dehradun are obtained from the Total Ozone Mapping
Spectrometer (TOMS). The surface albedo is obtained from MODIS.
Present work, the aerosol optical properties and its Radiative Forcing (RF) has been estimated
for the clear-sky condition over Dehradun from November 2014-January 2015(winter
season). Spectral dependence of AOD with higher values at smaller wavelengths and vice
versa. The seasonal average AOD observed at 500nm was ≈ 0.312 with an average angstrom
exponent ≈1.15. The seasonal AOD and angstrom exponent range from ≈0.127 to 0.686 and
0.341 to 1.49 respectively. Consequently, the seasonal mean Radiative Forcing (RF) at
Surface(SUR) was found ≈-48.43 w/m^2 and ranging from -54.03 w/m^2 to -40.83w/m^2
and at Top of the Atmosphere (TOA) was found ≈-21.20w/m^2 and in the range -23.55
w/m^2 to -63.60 w/m^2, whereas in the Atmosphere (ATM) it was ≈+27.23 w/m^2 and in
range +24.18 w/m^2 to +30.63 w/m^2. High Radiative Forcing was observed during the
month of November at SUR ≈ -54.03 w/m^2, at TOA ≈ -23.39 w/m^2 and at ATM ≈ +30.63
w/m^2.
Trends of Extreme Rainfall Events in Uttarakhand and Jammu
Regions
Shakuntala, V. M1, 2, J. V. Revadekar1, S. A. Ahmed2 and H Varikoden1*
1Indian Institute of Tropical Meteorology, Pashan, Pune-08; *[email protected]
2Department of Geology, Central University of Karnataka, Kalaburgi, Karnataka 585
311, India
Indian southwest monsoon season occurs from June to September and it accounts for 70-90%
of the annual rainfall. Indian population and agriculture is heavily dependent on the monsoon
rains. The frequent floods over Indian subcontinent lead to natural disasters and even loss of
human life and thus it effects severely on socioeconomic conditions of the country. Here, we
made an attempt to study the floods over Jammu and Uttarakhand regions; there the floods
are more affected in recent periods. The study was carried out using Aphrodite daily rainfall
data with a spatial resolution of).25 latitude-longitude grid from 1961 to 2007.
From the analysis of rainfall data of Uttarakhand region and Jammu region, we observed that
the behaviour of rainfall is unique even during southwest monsoon period. From the area
averaged rainfall analysis in both the regions, we found that the number of extreme events
(>20 mm/day and >30 mm/day) is decreasing significantly over the Uttarakhand region and
increasing over the Jammu region. The monthly analysis showed that the maximum of
extreme events are found during the month of August in Jammu region. However, over the
Uttarakhand region, the events >20 mm/day are observed more during August and the
extremes (>30 mm/day) are found more in the month of July.
An Approach to Quantification of Uncertainty in the Context of
Climate Change, Its Implications on Coastal Infrastructure
Shardul S Manurkar*
T Jayaraman (Guide)
Kamal Kumar Murari (Co-guide)
The prospect of climate change and consequent sea level rise puts additional burden on
coastal cities and infrastructure. However uncertainty associated with rise in mean sea level
and its subjective interpretation impairs effective resource management and policy decisions.
This study uses Dempster-Shafer theory of belief function to objectively quantify uncertainty
associated with future sea level rise by combining evidences from historical data and regional
level future projections provided by IPCC in AR5. Visakhapatnam, a city along the east coast
of India has been used as a case study to illustrate the research. The result suggests that
distribution of annual maximum sea level at a given time in the future shifts towards right by
projected values in future. This indicates that hydrological designs and flood risk assessment
along the coast needs to be revised by accounting sea level rise due to climate change. The
study also provides a robust methodology to assess the vulnerability of coastal areas.
Revisiting CASA ecosystem model for Global NPP study: a new
perspective
SheshakumarGoroshi*, Raghavendra P Singh, Rohit Pradhan and Jai Singh Parihar
*Space Applications Centre (ISRO), Ahmadabad 380 015, India
In this study, we have modified the CASA (Carnegie Ames Stanford Approach) ecosystem in
multiple aspects: 1) new method for estimating biome specific maximum Light Use
Efficiency (LUE), 2) simplified method for estimating moisture stress coefficient and 3)
extensive validation using Eddy flux towers and field measurements. Based on this model,
we have produced global net primary productivity (NPP) at monthly interval for the year
1982 to 2006. Analysis of agreement between CASA derived NPP and flux tower NPP over
different biomes indicated a good agreement with the Willmott’s index ranging from 0.81
(Evergreen needle leaf forest) to 0.99 (Open Shrublands). Spatial assessment of terrestrial
NPP averaged for the study years showed the lowest values (0 to 200 gC m-2 year-1) in hot
and cold deserts and the highest values (1400 to 1600 gC m-2 year-1) in dense forest regions.
Global total terrestrial NPP for the study years varied from 47.57 PgC year-1 (1988) to 58.39
PgC year-1 (2001) with an average of 50.32 PgC year-1. We estimated a linear growth rate of
global annual NPP with 0.28 PgC year-2, which is equivalent to 5.7% in the last 25 years.
Grid level correlation analysis indicated a strong influence of regional climatic parameters on
interannual variability of NPP. Our findings are consistent with the earlier regional/global
studies and indicate that this modified CASA ecosystem model has the capability to detect
spatial and temporal variability of terrestrial NPP and effects of regional/global climatic
variations over a wide range of terrestrial ecosystem types.
Possible Interactions between Subsurface Ocean Biases and the
Surface Interannual Variability in Coupled Models
Shikha Singh*,VinuValsala
*Indian Institute of Tropical Meteorology, Pune
Analysis for the possible impacts of deep ocean biases on the surface variability of
interannual signatures in the model is carried out. Few candidate models (CFSv2 and IITM-
Earth System Model) and outputs from selected CMIP-5 models are analyzed. CFSv2 is a
coupled ocean atmosphere model by NCEP and it is the core-part of the IITM-ESM. Both in
CFSv2 and in IITM-ESM, when used for climate simulations of hundred-years, the models
develop internal warm bias in the Indian Ocean, which is a property commonly observed in
other CMIP-5 candidate models considered here as well. In CFSv2 and IITM-ESM, it is also
seen that there are occurrences of Indian Ocean Dipole in the early part of the year within
Jan-April, whereas in reality, IOD starts in May-June, peaks in Sept and decays by Nov-Dec
of the year. The possible role of internal biases in the IOD is hypothesized using the relation
between the Brunt-Vaisala frequency and baroclinic wave speeds (i.e. WKJB approximation).
Using both WKJB approximation and the normal mode decomposition (Chelton et al., 1998),
it is seen that most of the models analyzed here have a higher baroclinic speed compared to
the observations. Since the wave dispersion is faster, it has a possibility to affect the planetary
scale events such as IOD in terms of their life cycle, periodicity, seasonality and the
duration.Further analysis based on simple ocean-atmospheric coupled models is utilized to
examine the role of ocean biases in the interannual variability of the tropical oceans.
Understanding the relevance of ocean dynamics in the
productivity of the western Equatorial Indian Ocean
Authors:
G Shiva Kumar*
S.Srilakshmi
A.C. Narayana
Affiliation:
*Centre for Earth & Space Sciences
Studies on the Equatorial Indian Ocean (EIO) are considered to be important compared to
other equatorial regions of the world oceans for its reversal of the wind system and lack of
upwelling in the region. In this paper, the MODIS Aqua satellite-derived Chlorophyll-a (Chl-
a) and TOPEX Sea Surface Height Anomaly (SSHA) for the Equatorial Indian Ocean
bounded by 5oN – 5oS and 45oE – 65oE over the period of 2002-2012 were analyzed to
investigate the coherent variability between them. This region roughly reprints the Western
pole of the IOD activity. The phase relatively confirms that the anomalous increase in sea
surface height has resulted in decreased productivity in these years. The cross-wavelet spectra
of SSHA-Chlorophyll depicts statistically coherent powers at 30 months (Oct-06 to Dec-09)
and 18-20 months (Dec-09 to Mar-11), all significant at 95% confidence level. Interestingly,
the ~30 month coherent signal is prominent during 2006 and 2008, when three positive IOD
events occurred consecutively. These preliminary results provide new information on the
primary production and transport of nutrients in the Equatorial Indian Ocean.
Assessment of the performance of CORDEX-South Asia
experiments for monsoonal precipitation over the Himalayan
region during present climate: Part I
Ghimire, S. Choudhary, A. Dimri, A. P.*
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi - 110067 *Corresponding Address: A. P. Dimri, School of Environmental Sciences, Jawaharlal
Nehru University, New Delhi, India, 110067. Email: [email protected]
The suite of 11 combinations from 6 Regional Climate Models (RCMs) with 10 initial and
boundary conditions from different Global Climate Models (GCMs) collectively referred here
as 11 Coordinated Regional Climate Downscaling Experiment in South Asia (CORDEX-
South Asia) are considered to study precipitation sensitivity associated with the Indian
Summer Monsoon (ISM) over the Himalayan region for the present climate (1970-2005). The
summer monsoon precipitation climatology over the study area has not been studied with the
help of CORDEX data. An approach has also been made to study the degree of agreement
among individual experiments compared with the gridded observational dataset to quantify
uncertainty among them. The experiments though show a wide variation among themselves
with time and space in simulating precipitation distribution, but noticeably show dry
precipitation along the foothills of the Himalayas against the corresponding observation. The
experiment driven by Irish Center for High-End Computing (ICHEC) and downscaled using
RossbyCenter regional Atmospheric model version 4 developed by Swedish Meteorological
and Hydrological Institute (SMHI) simulate precipitation closely in correspondence with the
observation. Overview of the study suggests that these experiments facilitate precipitation
evolution and structure over the Himalayan region with certain degree of uncertainty.
Sensitivity of Precipitation Simulation to Soil Moisture condition
in GCM over the Indian Region
Shubhi Agrawal1*, Arindam Chakraborty1
1CAOS, I.I.Sc
Soil Moisture and precipitation are coupled and the strength of coupling varies from region to
region. The coupling strength is high over the core monsoon zone of India.
Model experiments were performed to understand the sensitivity of precipitation to Soil
Moisture conditions over the Indian region using a global general circulation model forced
with monthly climatological sea surface temperature. Three runs were performed. One with
variable hydrology (control), and two with non-varying soil moisture conditions (a dry
condition and a wet condition). It was observed that the experiment with soil moisture close
to dry simulated higher precipitation over northern India as compared to the the simulation
with wet soil moisture. This can be attributed to higher advection of moisture toward this
region that exceeded the increased evaporation in the wet simulation. A bi-stable nature of
the control simulation was noticed that was closer to the dry simulation in the early part of
the monsoon season and closer to the wet simulation during the later part of the season,
which was unlike in the observations.
Effect of Non-Uniform Delays in models of El-Nino Oscillations
Shweta Kumari*
Sudeshna Sinha
*IISER Mohali
We investigate a simple nonlinear model, modelling the El Nino /Southern Oscillation
phenomenon, which arises through the strong coupling of the ocean-atmosphere system. An
important feature of this class of models is the inclusion of a delayed feedback which
incorporates oceanic wave transit effects, namely the effects of trapped ocean waves
propagating in a basin with closed boundaries. The model allows multiple steady states.
When these fixed points becomeunstable, one obtains self-sustained oscillations. Thus this
class of models provide a simple explanation of ENSO, and provide insights on the key
features that allow the emergence of oscillatory behaviour.
Southern Ocean Sea Ice Variability around the Indian Antarctic
Stations
Siddhartha Chatterjee1*, Anurag Kumar1,2,Suneet Dwivedi1,2,
1K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad,
Allahabad, UP 2M N Saha Centre of Space Studies, University of Allahabad, Allahabad, UP 211002,
India
The realistic simulation of the sea ice concentration (SIC), sea ice thickness (SIT), and ice
drift speed is performed in the Southern Ocean region [9°E-78°E; 45°S -72°S] during the
years 1994-2013 using an ocean circulation model and associated sea ice package. The model
domain incorporates the Indian Antarctic Stations, Maitri [11.7°E; 70.7°S] and Bharthi
[76.1°E; 69.4°S]. The model uses an eddyresolving horizontal resolution of 15 km and
vertical resolution of 5 m near the surface. The trend of the SIC is computed and it has been
found that the SIC is increasing at a rate of nearly 1% per year in
the ice covered regions. The monthly SIC variability near Maitri and Bharthi is also
investigated. The covariability of the surface temperature and SIC is analyzed. The surface
temperature is shown to be strongly anti-correlated to the SIC. The ice-drift speed is
computed and its variability is explained in terms of ocean current and near surface winds.
Keywords: Sea Ice Concentration; Ocean Modeling; Ice drift speed; Southern Ocean;
Antarctic
Biotic Records of Indian Summer Monsoon Variability from the
South-eastern Arabian Sea
A. Sivachandran1*,V. Yoganandan1, K. Selvaraj2,
1Department of Marine Science, BharathidasanUniversity,Tiruchirappalli,Tamil Nadu,
India
2State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen,
China
Indian summer monsoon (ISM), an important component of the Earth's climate system, play a
significant role in the socioeconomic conditions of the Indian subcontinent, yet ISM
variability in the past remains poorly understood. Previous studies have employed a number
of biological, sedimentological, geochemical, biogeochemical and isotopic proxies for the
reconstruction of past ISM changes from the cored sediments of the western and eastern parts
of the Arabian Sea. Among these proxies, planktonic foraminifera are deemed as very
sensitive to changing oceanographic conditions in response to monsoon variations in the
Arabian Sea. Here we investigate a 4.82-m long gravity core collected from the south-eastern
Arabian Sea (SK-313; water depth: 513 m) for planktonic foraminifera abundances to
understand the ISM variability during the Holocene. We calculated the percentage of five
planktonic foraminiferal dominant species, Globigerina bulloides, Globigerinoidesruber,
Neogloboquadrinadutertrei, Globorotaliamenardii and Globigerinoidessacculifer, at 1-2 cm
intervals. Our results show that G. bulloides and G. ruber increase their abundances in top
100 cm, whereas N. dutertrei decreases in the top 150 cm of core SK-313. Given that, in the
Arabian Sea, these three species can be indicators of wind-driven upwelling, mean annual sea
surface hydrographic conditions and the thermocline variability, respectively, our data favor
an increased upwelling and a shoaling of thermocline due to increased ISM since the early
Holocene to Present. This study provides down-core variations in relative abundances of
dominant planktonic foraminiferal species with unprecedented resolution from the south-
eastern Arabian Sea.
Aerosol climatology over a free-tropospheric location in western
trans-Himalayas: Results from multi-year measurements of
aerosol physical and optical properties
Authors: Sobhan Kumar Kompalli1*, S.Suresh Babu1, Mukunda M. Gogoi1, Lakshmi
N.B1.
Affiliation: 1SPL, VSSC, ISRO, Trivandrum-695022
Long-term observations of aerosol properties over climatologically sensitive pristine
Himalayan locations are important not only due to their affect on regional circulation and
glaciers, also to understand the regional as well as global aerosol background features. In this
study, the results from multi-year (August 2009 to March 2015) observations of aerosol black
carbon mass concentrations (MBC) and spectral aerosol optical depths (AOD) carried out
from high altitude remote location, Hanle (32.78 °N ,78.96 °E,4520 m amsl) in western trans-
Himalayas are presented. The values of long-term mean MBC (~ 60 ± 51 ng m-3) and AOD
at 500 nm (0.06 ± 0.04) are very low compared to other Himalayan locations. Annually, a
characteristic ‘spring-time enhancement’ has been noticed in both surface as well as
columnar aerosol loading, which, possibly, is associated with the strength of sources and
transport pathways. Examination of extinction coefficient vertical profiles also suggested the
presence of elevated aerosol layers at higher levels during spring. It is found that the potential
source regions contributing to aerosol loading through long range transport are located to the
west and southwest of Hanle. Spring enhancement in MBC, its inter-annual variability and
implications to regional climate will be discussed
Experimental study of plume dynamics in linearly stratified
environments.
Harish N Mirajkar1, Sridhar Balasubramanian1*
1Department of Mechanical Engineering, IIT Bombay, India
The entrainment dynamics of a positively buoyant jet into a linearly stratified medium is
discussed based on the evolution of large-scale flow structures. The experimental facility for
this study consists of two square acrylic tanks. One of them is the main tank, which is linearly
stably-stratified to obtain the required buoyancy frequency (N). The experiments were carried
out for different values of gradient Richardson number (Rig) to understand the effects of
momentum and buoyancy fluxes on the entrainment mechanism. The plume spreading at the
neutral layer can be characterized by three regimes, namely, Regime I: radial momentum
balanced by inertia, Regime II: inertia-buoyancy regime, and Regime III: viscous-buoyancy
regime. Bulk flow parameters such as maximum plume height, spreading height, radial
intrusion, plume thickness, and mixing layer width were obtained from these experiments. It
was found that the entrainment values obtained in our experiments were lower than that
reported by Morton et al. in their seminal work. The radial plume propagation at the neutral
layer was found to follow a power law with time, RF=t^ {0.75}. The thickness of the plume
was found to be constant in Regime I, but increased consistently with time in Regime II.
On the Cloud Microphysical Properties during Cloudburst Event
near Leh
SudeshnaPurakait1*& Charu Singh1
1Marine and Atmospheric Sciences Department, Indian Institute of Remote Sensing,
ISRO Dehradun, India
Cloudburst is a sudden extreme rainfall (>100mm/hour) in a localized area .Sometimes it is
associated with hail and thunder depending on the microphysical characteristics of the cloud.
Cloudburst is very common in the orographically dominant Himalayan region during
monsoon season when monsoon cloud from Bay of Bengal and Arabian Sea moves
northward across Gangetic planes, reaches onto Himalaya and sometime bursts in heavy
precipitation depending upon the certain atmospheric conditions. In the present work, we
examine one such cloudburst event near Leh town of Ladakh region in Jammu and Kashmir
around 0130–0200 hours IST on 6th August, 2010 leading to flash flood and mud slides over
the region. Myriad model studies have been performed previously to simulate the above
mentioned cloud burst event. This study is aimed to focus on the estimation of microphysical
properties of this cloudburst event based on TRMM (Tropical Rainfall Measuring Mission)
2A12 and LIS data whose primary goal is to better understand the internal structure of the
clouds and to measure the flashes during a lightning activity from a thunder cloud. Cloud
microphysical properties deal with the properties of a cloud in a micro scale like droplet
concentration, ice crystal formation, rain drop formation etc. The preliminary results show
that the vertical distribution of latent heat products from TRMM measurement enables new
insights to investigate the complexities of the life cycle of such disastrous events. Greater
details will be presented during the conference.
Keywords: LEH, Cloudburst, TRMM, 2A12, LIS, Cloud Microphysics
Intra-seasonal to inter-annual variability of Sea Surface
Temperature and
Air Temperature relation in the Indian Ocean
Sudheer Joseph*, M. Ravichandran, Praveen Kumar B
and J.V.S Raju
The impact of turbulent exchanges of heat and momentum between upper-ocean and lower-
atmosphere is reflected in the variability of SST and air temperature (Tair). Hence, co-
variability of these two climatically sensitive and mutually dependent parameters attracted
the attention of climate scientists for many decades. We have carried out an analysis of spatio
- temporal co-variability of SST and Tair using Tropflux data from the Indian Ocean at intra-
seasonal to inter-annual time scale. We identify eastern equatorial Indian Ocean (EEIO) and
south western Indian Ocean (SWIO) as two distinct regions with consistently different
characteristics of Tair-SST relation. Sample time series from eachregion is obtained for
detailed analysis of the Tair - SST relation in terms of their amplitude and phase differences
using their first four harmonics. In case of EEIO, the annual harmonic of both Tair and SST
are in phase with former showing slightly higher amplitude than later. It explains 37 % and
28 % of total variance of SST and Tair respectively. For second and third harmonics, Tair
leads SST. SST (Tair) explain 4 (.6) % and 0.07 (0.01) % of variance of in case second and
third harmonics respectively. For the fourth harmonic, SST explains 0.5% of variance and
leads Tair, which explain 0.09 % of its total variance. Thus, at EEIO, it is noticed that the
lead of atmospheric process shown at lower harmonics switches to oceanic processes, with
SST leading Tair as one reach to forth harmonic. In contrast, at SWIO, the phase difference
between Tair and SST is much smaller across the four harmonics. Also, at SWIO 92 %( 89
%) of the total variance of SST (Tair) is explained by annual harmonic which was less than
half of this at EEIO. However, the lead of Atmosphere (Tair) at lower harmonics and the
transfer of it to ocean (SST) at higher harmonics prevail for SWIO also as seen at EEIO. We
have used cross wavelet analysis for looking at Tair-SST relation during inter-annual climatic
processes like IOD and identified distinct changes in Tair-SST relations from both EEIO and
SWIO. We corroborate our results using observed data from RAMA buoys.
Low frequency modulation of jets in quasigeostrophic turbulence
Suhas D L*
*Centre for Atmospheric and Oceanic Sciences,
Indian Institute of Science
Quasigeostrophic turbulence on a β-plane with a finite deformation radius is studied
numerically, with particular emphasis on frequency and combined wave number-frequency
domain analyses. Under suitable conditions, simulations with small-scale random forcing and
large-scale drag exhibit a spontaneous formation of multiple zonal jets. The first hint of
wave-like features is seen in the distribution of kinetic energy as a function of frequency;
specifically, for progressively larger deformation scales, there are systematic departures in
the form of isolated peaks (at progressively higher frequencies) from a power-law scaling.
Concomitantly, there is an inverse flux of kinetic energy in frequency space which extends to
lower frequencies for smaller deformation scales. The identification of these peaks as Rossby
waves is made possible by examining the energy spectrum in frequency-zonal wave number
and frequency-meridionalwave number diagrams. In fact, the modified Rhines scale turns out
to be a useful measure of the dominant meridionalwave number of the modulating Rossby
waves; once this is fixed, apart from a spectral peak at the origin (the steady jet), almost all
the energy is contained in westward propagating disturbances that follow the theoretical
Rossby dispersion relation. Quite consistently, noting that the zonal scale of the modulating
waves is restricted to the first few wave numbers, the energy spectrum is almost entirely
contained within the corresponding Rossby dispersion curves on a frequency-meridionalwave
number diagram. Cases when jets do not form are also considered; once again, there is a hint
of Rossby wave activity, though the spectral peaks are quite muted. Further, the kinetic
energy scaling in frequency domain follows a −5/3 power-law and is distributed much more
broadly in frequency-wave number diagrams.
Comparison of Dynamically and Statistically Downscaled Wind at
Selected Indian Offshore Locations
Sumeet Kulkarni*
*IIT Bombay
Wind data obtained from Canadian General Circulation Model (CCCMA) has been
statistically downscaled. Further this output, has been compared to dynamically downscaled
wind derived from South Asia CORDEX dataset at three offshore locations: Jakhau,
Kanyakumari and Rameswaram identified by Government of India for offshore wind
farming, assuming CFSR reanalysis dataset as reference. RCP 4.5 scenario has been adopted
for simulating future wind. Monthly wind for the past 26 years (1979-2005) and future 26
years (2006-2035) was considered. The bias in the CCCMA and CORDEX outputs was
minimized using the quantile mapping technique. While both dynamic and statistical
downscaling methods modelled mean and standard deviation well, the statistical downscaling
was more attractive in simulating high wind occurrences. For selection of appropriate
reference dataset in bias correction, performance of ERA interim, NCEP/NCAR and CFSR
reanalysis datasets was analysed, wherein the CFSR dataset was found to be more close to the
satellite observations. Further, changes in annual mean and annual maximum were studied
over the entire Indian coastline based on following datasets: Three CMIP5 GCMs, CORDEX
dataset and a multi-model ensemble. This indicated that across these data, variations in the
extreme wind were more pronounced over the offshore regions than the inland one. However
the mean wind was fairly consistent across them.
First Frost-point hygrometer observations of water vapour in the
tropical upper troposphere and lower stratosphere over India
S V Sunilkumar*, M Muhsin, GeethaRamkumar, K Rajeev, Maria Emmanuel
*Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum-695022
Water vapour is one of the most important greenhouse gases in the atmosphere and plays a
key role in the atmospheric part of the climate system. The water vapour distribution in the
upper troposphere and lower stratosphere (UTLS) region is of central importance in several
ways: (i) plays a pivotal role in ice cloud formation and dehydrates the upper troposphere, (ii)
regulates the atmospheric motion by absorbing radiation, and (iii) plays a key role in the
UTLS chemistry. Water vapour in the UTLS region originates mostly from deep convection
that penetrates, the so called Tropical Tropopause Layer (TTL), but dehydrated as it passes
through cold region, forming ice clouds by freeze-drying and cold trap mechanisms. Deepest
atmospheric convection over the entire globe occurs over the Bay of Bengal during the Asian
summer monsoon season. Which can pump significant amount of water vapour into the lower
stratosphere. However, the amount of moist air entering the stratosphere and how it is freeze-
dried, are not well understood. In spite of its importance, not many in situ measurements of
water vapor in the UTLS region has been made. This is mostly because of the difficulty in
making accurate measurements of extremely low water concentration by using conventional
detectors. Frost Point Hygrometer (FPH) accurately measures water vapour in the altitude
region from surface to 25 km. First direct measurements of the trace amount of water vapour
in the UTLS over the Indian region was carried out using balloon-borne Frost Point
Hygrometer (FPH) launched from Thumba at 17:00 IST on 17 April 2014. Regular
observations of water vapour in the UTLS region are being carried out using FPH from
Trivandrum and Hyderabad since May 2014 as part of Tropical Tropopause Dynamics (TTD)
Experiment under GARNETS (GPS Aided Radiosonde Network Experiment for
Troposphere-stratosphere Studies) program. In general, water vapour mixing ratio (WVMR)
decreases with increase in altitude in the troposphere and varies by four orders of magnitude
from ~20,000 parts per million by volume (ppmv) near the surface to less than 10 ppmv
above 15 km. The minimum value of ~1 to 3 ppmv is observed near the cold point
temperature (CPT), which acts as a trap for freeze drying and dehydration of the air that
enters into the stratosphere through stratosphere-troposphere exchange (STE) process. In the
lower stratosphere, the WVMR slowly increases with altitude to attain a value of ~4-5 ppmv
around 25 km altitude during winter season which is almost double of that at CPT. The
increase above CPT is caused by the long residence time of water vapour in the lower
stratosphere and plays a significant role in the chemistry and thermodynamics of this region.
The water vapour distribution in the UTLS region over Indian region during different seasons
will be discussed.
Zonal scales of Madden-Julian Oscillation in model experiments
with and without continents
Surajit Das1*, Debasis Sengupta1, Arindam Chakraborty1, Jai Sukhatme1,Raghu
Murtugudde2
1Indian Institute of Science E-mail: [email protected]
2University of Maryland E-mail: [email protected]
We use the aqua planet version of the Community Atmospheric Model (CAM-5), with
zonally symmetric sea surface temperature (SST), to study tropical intraseasonal oscillations
(ISO), including Madden Julian Oscillation (MJO). In the first two experiments, we specify
zonally symmetric SST profiles that mimic observed climatological July and January
conditions. In the January SST simulation, we find a zonal wave number 1 mode, moving
east at about 6 m/s. This mode, which resembles the MJO, is absent for July SST simulation.
This shows the importance of the meridional gradient of SST on generation of MJO in this
model.
For further investigation of the influence of tropical SST on ISO and convectively coupled
equatorial waves (CCEW), we conduct experiments with idealized symmetric SST profiles
having different widths of warm ocean centered at the equator. When the latitudinal extent of
warm SST is comparable to or larger than the equatorial Rossby radius, we find a dominant
low frequency eastward MJO-like mode. However, in all the aqua planet simulations, the
MJO variance occurs at zonal wave number one. To understand the role of land-sea
distribution on zonal wave number of MJO, we perform a third set of experiments by
introducing continents with realistic orography in the model. These experiments show a much
more realistic MJO-like mode with higher zonal wave number, in the presence of broad
meridional SST profiles. Moreover, the variance of westward propagating low frequency
Rossby waves is considerably enhanced in the presence of continents.
Land Surface Temperature Pattern and Normalized Difference
Vegetation Index for different Seasons Land Use Land Cover
Types of Jaipur City
Suresh Chandra1*, Devesh Sharma1
1Central Universality of Rajasthan, NH-8 Bandarsindari, Dist.Ajmer-305801, Rajasthan
[India]
[email protected], [email protected]
The objective of the study is to identify typical and specific features of land surface
temperature (LST) and Land cover type’s distribution in the Jaipur city and its surroundings
with the use of Landsat/TM data. The paper contains a detailed description of the study area
and complete methodology of LST retrieval. Extracted LST records have been standardized
in order to ensure comparability between satellite images acquired during two different
seasons. The study identifies the cold and hot region in the city of Jaipur using this Spectral
Radiance Scaling Method. The research includes spatial analysis of the standardized LST
with regard to different land cover types: seven land cover types were Identify: Shrubs,
Urban Settlement, Vegetation, Crop Land, Barren Land, Forest and Hilly areas (including the
shadow of elevation), Water body. The results obtained from the most obvious dependence of
the LST on different land cover types shows Minimum 28.3˚C and Max. 48.2˚C and similarly
the result obtained from Normalized Difference Vegetation Index (NDVI) value is in the
range of +0.68 to -0.04 according to the different land cover types and different seasons. The
possible factors investigated and responsible for the continuous change in LST and NDVI are
emission of anthropogenic heat, seasonal changes of vegetation and weather conditions and
Land cover types.
Radiative impact due to black carbon over rural environment in
Indo-Gangetic Plains
S. Tiwari1*, D. S. Bisht1, A. K. Srivastava1
1Indian Institute of Tropical Meteorology, Pune, India
As a short-lived climate forcing agent, called black carbon (BC) which is one of the most
uncertain drivers of the global climate change and ultra fine particle plays an important role
in climate change and human health were conducted during monsoon, 2014 under a national
research programme called "Ganga Basin Ground based Experiment-2014". In this study,
continuous measurements of BC and particulate matter (PM) using a micro-Aethalometer
(AE-51) and optical particle counter (GRIMM-1.108) at a rural environment in Indo-
Gangetic Plains (IGP) was conducted and analyzed for its surface temporal variability and
climate impact. Daily mean mass concentrations of BC was 4.03 ± 0.85 μg m-3 within the
range of 2.4 –5.64 μg m-3, however, near ultrafine (PM1), fine (PM2.5) and inhalable
(PM10)] were 29.1±16.2, 34.7±19.9 and 43.71±28.3 μg m-3 respectively. The contribution of
BC in PM1 was approximately 13% which is significantly higher. Diurnally, the mass BC
was highest (mean: 5.89 μg m-3 ) in between 20:00 to 22:00 hrs local time due to burning of
biofuels as wood, dung, straw, crops residue mixed with dung which is the major sources of
fuel in rural environment for making food and impact of boundary layer. The contribution of
PM1 in fine particle was around 84% and its diurnal trend was also similar to BC with
significant correlation (0.74) between then indicating similarity in sources. During the study
period, the atmospheric radiative forcing was 78.3, 44.9 and 45.0 Wm-2 for composite and
42.2, 35.4 and 34.3 Wm-2 for BC during the month of June, July and August respectively.
The corresponding atmospheric heating rate (AHR) due to BC was in the order of 1.99
(June), 0.99 (July) and 0.96 (August) K day−1 with a mean of 1.05 K day−1 which is 33%
lower than the composite aerosols during the entire study period. This high AHR was due to
the presence of absorbing type of aerosols which are entrained into the atmosphere due to
burning of biofuels over this region.
Assessment of Chilika Lake Sediments as Paleo-Proxy for
Climate Reconstruction
S.S.Barik1*, Raj K. Singh1, S. Tripathy1
1 School of Earth, Ocean and Climate Sciences, Indian Institute of Technology
Bhubaneswar, Odisha, India
*Corresponding author email: [email protected]
Chilika, situated in Odisha; is the largest brackish water lake connected to Bay of Bengal
through narrow channels. It also receives a huge amount of fresh water and sediments from
the tributaries of river Mahanadi. In the recent past sediment deposition has narrowed down
the channels connections of this lake with the bay resulting changes in the salinity level
thereby impacting indigenous flora and fauna.
During this study, representative samples of sediment were collected around the seaward
channel and fresh water input channel to assess their suitability for paleoclimatic
reconstruction. Litholog preparation, grain size analysis, mineralogical characterization, total
carbon content and micropaleontological analysis were carried out to characterise sediment
and to understand the depositional pattern and environment for paleoclimatic reconstruction.
The preliminary data suggest that the sediments near the freshwater input channels were
reworked while those around the seaward channel are better preserved and contained well
preserved shallow benthic foraminifera which can be utilized for the paleoclimatic
reconstruction.
Keywords: Chilika Lake, Mahanadi, Paleoclimate, Grain size analysis
Estimating the equilibrium line altitude from satellite-derived
transient snow lines and in situ temperature and precipitation
data
Sayli A. Tawde 1*, Anil V. Kulkarni 1, G. Bala 1
1 Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
E-mail: [email protected]
Abstract
Identification of the snowline at the end of the glaciological year, i.e. equilibrium-line altitude
(ELA), using remote sensing is difficult because of temporal gaps, cloud cover and
intermediate snowfall on glaciers. This leads to large uncertainty in glacier mass-balance
estimates by the conventional accumulation–area ratio (AAR) method that uses satellite-
derived ELA. The present study suggests a new approach to improve estimates of ELA
location. First, positions of modelled snowlines are optimized using satellite-derived
snowlines in the early melt season. Secondly, ELA at the end of the glaciological year is
estimated by the melt and accumulation models driven using in situ temperature and
precipitation records. From the modelled ELA, mass balance is estimated using the empirical
relationship between AAR and mass balance. The modelled mass balance is validated using
field measurements on Chhota Shigri and Hamtah glaciers, Himachal Pradesh, India. The
new approach shows a substantial improvement in glacier mass-balance estimation, reducing
bias by 46% and 108% for Chhota Shigiri and Hamtah glaciers respectively. The cumulative
mass loss reconstructed from our approach is 0.85 Gt for nine glaciers in the Chandra basin
from 2001 to 2009. The result of the present study is in agreement with climate warming
reported in this basin.
Climate Change Impact on Snowmelt Runoff Modeling For
Alaknanda River Basin
Tanmoyee Bhattacharya1*, P.V Raju1, Abdul Hakeem K1
1National Remote Sensing centre, Hyderabad
Variable Infiltration Capacity hydrology model is a physically based, Semi-distributed
macroscale hydrological model that represents surface and subsurface hydrologic process on
spatially distributed grid cell. In mountainous watersheds Snow melt can have a significant
impact on the water balance and at certain times of the year it could be the most important
contribution to runoff.
In this study the Variable Infiltration Capacity Hydrology model has been successfully
applied for Alaknanda River Basin. As input to the model long-term(1999-2008) daily
meteorological data such as temperature, precipitation, wind speed and geospatial data such
as land cover data, Elevation data , soil data were provided from multiple sources
(NRSC,NBSS&LUP,NOAA and IMD). In addition, the spatial distribution of runoff, snow
cover and snow depth were analyzed and compared with the monthly stream flow data from
obtained from rudraprayag (lat-30.285, lon-78.98), MODIS 8 day snow cover product
(MOD10A2) and AMSRE snow depth product. The model runs resulted in an increase in
Snowmelt Runoff for the period of record (2001–2006), as a result of decrease in Snow
Cover and Snow Depth for the monsoon period. In this study Nash–Sutcliffe efficiency is
0.92 which indicate a good fit between observed and simulated runoff.
Reconstruction of recent climate change in Antarctica using ice
cores from coastal Antarctica
Thamban Meloth *
*National Centre for Antarctic and Ocean Research
Headland Sada, Vasco-da-Gama
Antarctic ice cores offer an excellent natural archive that provide reliable proxy records of
atmospheric circulation, temperature, precipitation and sea-ice condition that effectively
extend beyond the instrumental records. To reconstruct the shifting climatic regime in
Antarctic region and its regional/global linkages, we have conducted a high-resolution study
of dust fluxes, stable isotope and glaciochemical composition in ice cores from the coastal
East Antarctica. The estimated surface air temperatures using the d18O profiles of two ice
cores revealed a significant warming by 0.6-1°C per century, with significantly enhanced
warming during the past several decades (~0.4°C per decade). Reconstructed proxy records
of dust and trace metal fluxes in an ice core revealed a doubling of dust deposition since
1985. We show that large-scale atmospheric circulation and climate variability in seasonal to
decadal scale in the mid to high latitude Southern Hemisphere is primarily caused by the
shifts in Southern Annular Mode (SAM). A strong positive correlation between dust flux and
SAM suggests a causal role of SAM in the dust deposition over East Antarctica, through the
strengthening of the westerly winds. Modelled back wind trajectories also supported the
increase in dust deposition is associated with the air parcels originating from the southern
South America. Proxy records of moisture source variability [deuterium excess (d-excess)] as
well as sea ice extent [methane sulphonic acid (MSA) and sea-salt sodium (ss-Na+)] in the
ice core revealed synchronous changes in these during the last century in coastal DML,
supporting the relation between SAM and Antarctic sea ice extent.
Stable water isotopes and tropical amount effect: Convection vs.
Amount of precipitation
Thejna Tharammal1*, Govindasamy Bala1
1Center for Atmospheric and Oceanic Science, Indian Institute of Science, Bangalore-
560 012
Stable water isotopes are used as climate proxies to reconstruct the tropical precipitation
based on the “amount effect” - the inverse relationship between the amount of precipitation
and the ratio of heavy to light isotopes in precipitation (denoted by , Dprecip for
hydrogen).
It is debated whether the amount effect corresponds to the local amount of rainfall or to the
large scale convection. We conduct a series of experiments using the NCAR Community
Atmospheric Model with water isotopes tracers (IsoCAM) to control the amount of
precipitation from the deep convective scheme, by changing the convective relaxation time
scale, Tau, from one hour to 8 hours at two hours interval.
The deep convective precipitation is consistently decreased with the increase of Tau,
whereas, shallow convective and large scale precipitation are increased. Over monsoon
regions, the Dprecip anomalies of Tau-8 hr experiment from Tau-1 hr simulation are
significantly correlated to the deep convective precipitation anomalies than to total
precipitation anomalies. The decreasing slope between the monthly total precipitation and the
Dprecip values with increasing Tau, for the oceanic grid points in the tropics indicate a
weaker amount effect. These results show that the amount effect may relate more to the
convective activity than to the total precipitation amount.
Formation of the southern Bay of Bengal cold pool
Authors: Umasankar Das1*, P.N. Vinayachandran1,Ambica Behera1
Affiliation: 1Centre for Atmospheric and Oceanic sciences, Indian Institute of Science,
Bangalore
A pool of relatively cooler water, called here as the southern Bay of Bengal (BOB) cold pool,
exist around India and Sri Lanka during the summer monsoon. This cold pool is surrounded
by the larger Indian Ocean warm pool and is believed to affect the intra-seasonal variations of
summer monsoon rainfall over India. In this study, we have investigated the mechanisms
responsible for the formation of the cold pool during the year 2009, using high resolution
satellite data and simulation using an Indian Ocean model. SST within the cold pool, after the
steady increase during February- April months, cools first during a pre-monsoon event during
the first week of April and then during the monsoon onset during the last week of May. The
onset cooling is stronger (1.8 degC) than the pre-monsoon cooling (0.8 degC) and culminates
in the formation of the cold pool. Analysis of the model temperature equation show that a
reduction in air-sea heat gain is the major factor responsible for the SST decrease during both
events with entrainment playing a secondary role. The changes in air-sea heat gain are
affected by the arrival of cloud bands over the cold pool, during these periods. The cloud
band causing the pre-monsoon cooling originates in the eastern equatorial Indian Ocean and
that during the onset cooling in the western equatorial Indian ocean. A lead lag correlation
calculation shows that the SST responds in 5 days to the rainfall. These sequence of events
occur every year with certain amount of inter-annual variability.
Recent land use land cover changes and its impact on the
evolution and structure of thunderstorm in New Delhi
Unnikrishnan C.K*, AshuMamgain, Saji Mohandas,
G. R. Iyengar and E.N. Rajagopal
Satellite observations show changes in Land use/Land cover (Lu/Lc) during last two decades.
This study investigates the impact of changes in Lu/Lc in the prediction of thunderstorm
evolution and structure. This preliminary study focus on a damaging thunderstorm event
which occurred on 30th May at New Delhi in 2014. This thunderstorm is marked with heavy
surface wind speed during 12 - 13 UTC. NCMRWF 1.5 km regional Unified Model (NCUM)
is used to predict this thunderstorm event. Two separate experiments are performed, one with
IGBP Lu/Lc data (1992-1993 period data) and another with recent period ISRO AWiFS
satellite Lu/Lc data (2012). Recent period Lu/Lc shows an increase in urban build up and
increase in bare soil fraction over New Delhi region. The model predicted the exact time
period of storm. The model prediction at 12 UTC matches well with observed Skew-T
diagram derived from radiosonde observation at New Delhi. The Lu/Lc impacts are visible on
vertical structure of temperature and the vertical structure of near surface wind speed. It is
observed that, the wind speed at surface is strong and occurrence period is also extended with
Lu/Lc data. These preliminary results suggest that the thunderstorm activity, its evolution and
vertical structure is modulated by the underlying land use land cover.
Evaluation of performance of RegCM4.4 for monsoon
intraseasonal oscillations over South Asian CORDEX domain
U Umakanth1*, Amit P Kesarkar1
1NARL
In the present study, we use latest version of International Center for Theoretical Physics
(ICTP) regional climate model RegCM4.4 coupled with CLM4.5 and is comprised with
newly added UW–PBL scheme. The performance of the RegCM is evaluated to simulate the
seasonal mean and intraseasonal variability of monsoon over South Asian CORDEX domain.
Two sets of model runs were conducted for a 13-year continuous simulation i.e. 2000–2012
with different combination of cumulus schemes I, e. Case1: Emanuel for both land and Ocean
and Case2: Emanuel over land and Grell over ocean. The model reasonably well simulates
the mean monsoonal circulation patterns with a notable bias in precipitation patterns over
land and the ocean. The spatial pattern of mean 25-90 day filtered JJAS rainfall variance is
produced reasonably well by case1 compared to the case2. It is also observed that case1
produces more variance over the Equatorial Indian Ocean whereas it is completely absent in
the case 2. In both the cases the model captures the evolution of active and break condition
with a lag of 15 days. On the whole the model with UW–PBL scheme and the combination of
Emanuel for both land and ocean performs well.
Investigation of Effect of Aircraft Wake on the Distribution of
Water Vapour Content in the Atmosphere
Venkat Prasad Padhy1*, P. Srinivasa Murthy2, N. Balakrishnan1
1SERC, IISc, Bangalore
2ADE, Bangalore
Computational Fluid Dynamics (CFD) analysis has been carried out for the flow past Boeing
777 Aircraft (Fig.1) for the landing configuration. The case analysed were M=0.3, angle of
attack 10 deg. About a million tetrahedral elements were generated for the aircraft grid
system. The governing flow equations solved were continuity, momentum and energy
equations in three dimensional coordinate system. But in addition to basic governing equation
one more passive scalar equation is solved for the water vapour transport in the aircraft wake
system. The results are analysed at several cross sectional planes (Figs 2-5) behind the
aircraft. It has been found that due to the rotational action of the wing tip vortex the water
vapour content of the atmosphere is re-distributed around the vortex core forming thin
laminar layers which are evident from the contour plots of water vapour distribution. Also
seen from the contour plots were the diffusion of water layers around the vortex core as the
cross sectional plane moved behind the aircraft. This study is of significant interest due to the
modification of the climate due to the aircraft wakes vortices which may result in
condensation trails which will persist for several kilometers behind the aircraft. Formation of
contrails leads to development of cirrus clouds in the upper atmosphere.
Contrast in circulation associated with equatorially symmetric
and off-equatorial marine ITCZ
Vishal Dixit1*, J Srinivasan1
1Centre for Atmospheric and Oceanic Science and Divechacentre for Climate change,
I.I.Sc, Bangalore
Recent advancement in the investigation of the vertical structure of inter-tropical
convergence zone (ITCZ) has shown that the shallow meridional circulation (SMC) is a
salient feature of the associated circulation. We have used reanalysis data to show that, the
shallow meridional circulation is absent when equatorial double ITCZ is formed in East
Pacific during March while it is strong when off-equatorial ITCZ is formed during
September. In most months, though the flow reversal occurs just above the boundary layer, a
strong SMC is formed only to the south of ITCZ while it is absent to the north of ITCZ. The
already proposed mechanisms appeal to reversal of meridional pressure gradients and are not
adequate to explain these detailed features of SMC.
Decreasing trend in the frequency of monsoon depressions over
the Bay of Bengal: A quantitative analysis on the role of the
enviromental variables
Vishnu S Nair1*, Francis P A1, S S V S Ramakrishna2, S. S. C. Shenoi1
1INCOIS, Hyderabad
2Department of Meteorology and Oceanography, Andhra University,
Visakhapatnam
Several recent studies have suggested that the frequency of Monsoon Depressions (MD) over
Bay of Bengal (BoB) shows a decreasing trend in the past decades. While some of the studies
have attributed this to the decrease in moisture availability over the Bay of Bengal, there are
no quantitative estimates of different factors that contribute to the formation and
intensification of the monsoon depressions. Using an empirical index, called genesis potential
index (GPI), the relative contribution of large scale environmental variables to the decreasing
trend in the frequency of MDs over the Bay of Bengal is studied here. It is found that the
change in the mid-tropospheric relative humidity contributes about 62% to the total change in
the frequency of the MDs. A moisture budget analysis over BoB to evaluate the respective
contributions of local evaporation and moisture advection to the net reduction of relative
humidity suggests that compare to the reduction in the local evaporation, the decrease in the
Moisture Flux Convergence (MFC) plays a significant role to the decreasing trend in the
moisture content over the Bay of Bengal. It is also found that the observed reduction of
moisture advection into the BoB has strong spatial correspondence with intensity of the Low
Level Jet (LLJ). It is shown here that, at the expense of the reduction of the moisture which is
being advected to the Arabian Sea and Bay of Bengal, there is an anomalous convergence of
the Vertically Integrated Moisture over the western equatorial Indian Ocean and enhanced
precipitation over this region.
Monitoring of Atmospheric Carbon Dioxide and Other GHG’s in
India
Yogesh K. Tiwari1*, K. Ravi Kumar1, Ramesh K1
1Vellore Centre for Climate Change Research, Indian Institute of Tropical Meteorology,
Pune
India has one of the largest and fastest growing economies among the South Asian nations,
and is emerging as a major contributor to CO2 emissions among developing nations.
However, the routine monitoring of atmospheric CO2 over India is rather very limited till
date. The total fossil-fuel CO2 emissions from India estimated by the Carbon Dioxide
Information Analysis Center (CDIAC), USA, is 189 TgC in 1990, 324 TgC in 2000, 385 TgC
in 2005 and 508 TgC in 2009, with a significant rate of increase during 2005-2009.
According to a recent report published by the Ministry of Environment and Forest (MoEF),
Government of India, the total greenhouse gases emissions in India have grown from 1252
million tons in 1994 to 1905 million tons in 2007 with an annual growth rate of 3.3%.
Notably, the cement production (6 %), electricity generation (5.6%), and transport (4.5%)
indicated significant growth in GHG emissions during 1994-2007. Without refuting this
increase, this study aims provide a scientific rationale behind this significant increase in
GHGs over India through the use of CO2 and other trace gases observations and transport
model simulations in order to understand the GHG budget over the South Asian region.
