ClimateClimate Research in Nepal Research in Nepal HimalayasHimalayas

Saraju K. Baidya (Department of Hydrology & Meteorology)

“Mountains, witnesses of global changes. Research in the Himalaya and Karakoram: SHARE-Asia Project”, 16-17 November 2005

PhysiographyPhysiography

Meteorological Station Network

• Precipitation 337• Climatic 68• Agro-met 22• Synoptic 9• Aero-Synoptic 6• Total 442• Automatic 16

8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8

L o n g i t u d e ( ° E )

2 7

2 8

2 9

3 0

Lat

itu

de

(°N

)

8 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8

L o n g i t u d e ( ° E )

2 7

2 8

2 9

3 0

Lat

itu

de

(°N

)Spatial Distribution of Mean Monsoon

Precipitation (mm)

Altitude determines the spatial distribution of

rainfall

Climatic Trends in Nepal

Shrestha et. al, 1999

Nepal Summer Monsoon Rainfall Trend

y = 3.2325x + 1449.2

R2 = 0.04211000

1100

1200

1300

1400

1500

1600

1700

1800

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

Rai

nfa

ll (m

m)

Maximum Temperature Trends in the Himalaya (1971-94)

No significant trend in rainfall

Climate ResearchClimate Research

The glaciological and meteorological observations in Nepal The glaciological and meteorological observations in Nepal Himalayas started in 1973 and 1974 as the "Glaciological Himalayas started in 1973 and 1974 as the "Glaciological Expedition to Nepal (GEN)". Expedition to Nepal (GEN)".

Nepal Himalayas: 2% of World’s FreshwaterNepal Himalayas: 2% of World’s Freshwater

Snowmelt:10% of annual flowSnowmelt:10% of annual flow

The studies show that these glaciers are retreating at an The studies show that these glaciers are retreating at an alarming rate. alarming rate.

Many researches in this field highlight the impacts on Many researches in this field highlight the impacts on water resource management and Glacier lake outburst water resource management and Glacier lake outburst Floods (GLOF).Floods (GLOF).

ActivitiesActivities

Operation of 7 Hydrometeorological stations

Hydrological and Meteorological data (Elevation 2700 - 4300 m) collection and publication

Glacier and glacier lake studies

Model development for snow and glacier melt runoff

Snow and Glacier Snow and Glacier StudiesStudies

(i) Temperature(i) Temperature(ii) Relative Humidity(ii) Relative Humidity(iii) Precipitation(iii) Precipitation(iv) Solar radiation(iv) Solar radiation(v) Wind speed/ direction(v) Wind speed/ direction(vi) River stage/discharge(vi) River stage/discharge(vii) Water equivalent of (vii) Water equivalent of snowsnow

ParametersParameters

Langtang

Tsho R olpaM akalu

H um la

Kanjiroba

Annapurna

D ingboche

Gauging Stations, Annapurna Region

Automatic Water Level Recorder,Langtang

Automatic Weather Station

Khumbu

Snow survey for Snow survey for determination of determination of water equivalent of water equivalent of snowsnow

Snow pitSnow pit

Snow samplerSnow sampler

Retreat of AX010 Glacier

Retreat from 1978-1989Was 30 m

Imja Lake (Khumbu region)Imja Lake (Khumbu region)

SOURCE: WECS

SOURCE: DHM

2002 Area: 0.86 Km2, 14.7% more than in 1999

Nepal Himalayas are highly vulnerable to the climate Nepal Himalayas are highly vulnerable to the climate change. It has wide impact on water resources and change. It has wide impact on water resources and agriculture of Nepalagriculture of Nepal

His Majesty’s Government (HMG) of Nepal instituted His Majesty’s Government (HMG) of Nepal instituted a Country Study program on Climate Change in 1994 a Country Study program on Climate Change in 1994 under the support of US Country Studies Program. under the support of US Country Studies Program.

For the first time in Nepal, General Circulation Models For the first time in Nepal, General Circulation Models (GCMs) Outputs were used and climate change (GCMs) Outputs were used and climate change scenarios were developed.scenarios were developed.

Climate Change Studies

Climate Change StudiesClimate Change Studies

• Four modelsFour models

– CCCMCCCM: Canadian Climate Centre Model (2 Grid pts.): Canadian Climate Centre Model (2 Grid pts.)– GFD3GFD3: Geophysical Fluid Dynamics Laboratory R-30 : Geophysical Fluid Dynamics Laboratory R-30

Model (2 Grid pts.)Model (2 Grid pts.)– UK89UK89: United Kingdom Meteorological Office Model : United Kingdom Meteorological Office Model

(2 Grid pts.)(2 Grid pts.)– GISSGISS: Goddard Institute of Space Science Model (1 : Goddard Institute of Space Science Model (1

Grid pt.)Grid pt.)

• For 2XCO2 (22 stations)For 2XCO2 (22 stations)– Precipitation increasePrecipitation increase

•CCCM : 36%

•GFD3: 67%

– Increase in Monsoon season and decrease in dry Increase in Monsoon season and decrease in dry (winter) season(winter) season

– Temperature increaseTemperature increase•CCCM: 1.4oC to 4.1oC; 2.9oC

•GFD3: +1.7oC to 4.2oC; 3.1oC

• Limitation:Limitation: low resolution low resolution

Climate Change StudiesClimate Change Studies

Status of Climate Models Status of Climate Models inin Nepal Nepal

• Rough topography of Nepal requires high Rough topography of Nepal requires high resolution modelsresolution models

• Currently Nepal is experimenting on two RCMsCurrently Nepal is experimenting on two RCMs – RegCM3 (ICTP, Italy)– PRECIS (Hadley Centre, UK)

• Main aim of these models is to study the impact Main aim of these models is to study the impact of climate change of climate change

• Currently, we are on the process of validation Currently, we are on the process of validation experimentsexperiments

8 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8

2 7

2 8

2 9

3 0

75 km50 km

30 km

RegCM3 Results of 1997 JuneRegCM3 Results of 1997 June

-100 100 300 500 700 900 1100 1300 15000

Observation

50 km 75 km

RegCM3: 1997 monsoon RegCM3: 1997 monsoon NestedNested

8 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8

2 7

2 8

2 9

3 0

-200 200 400 800 1200 1600 2000 2400 2800 3200 3600 40000

Observation

Nested: 15 km75 km

Time required for 1 month simulationTime required for 1 month simulation

8.0

5.3

1.30.7(16hrs)

0

1

2

3

4

5

6

7

8

9

15 30 50 75Horizontal Resolution (km)

App

roxi

mat

e tim

e re

quire

d (d

ays)

• Major issues Running RCMMajor issues Running RCM– Time constraint to run high resolution modelsTime constraint to run high resolution models– Computing facilitiesComputing facilities

Monsoon Study

• A project was developed in 1999 and number of meteorological stations ranging from 500 m to 4400 m were installed in the Marsyangdi river basin in central Nepal and Monsoon Himalayan Precipitation Experiment (MOHPREX) was carried out during June 2001 to study the interaction of the Himalayas and the Asian summer monsoon

Source: Ana P. Barros and Timothy J. Lang (2001)

• The mountains act as barriers to the south-easterly monsoon flow from BOB and consequently low level convergence occurs.

• Upslope and upvalley flows reduce this convergence. The upslope flow leads to high level convection and secondary peak in precipitation.

• with the absence of upslope winds, and prevalent down slope winds, strong convergence of the moist advected monsoon flow occurs which acts to force convection which lead to the nocturnal peak in rainfall in these areas.

Source: Monitoring the Monsoon in the Himalayas: Observations in Central Nepal, June 2001, Ana P. Barros and Timothy J. Lang

Concluding RemarksConcluding Remarks

• Nepal deserves special attention in climate Nepal deserves special attention in climate related research becauserelated research because– Complex Topography Complex Topography – Himalayas are highly vulnerable to climate Himalayas are highly vulnerable to climate

changechange– Himalayas are the water tower for South Asia Himalayas are the water tower for South Asia

where most of the poorest people livewhere most of the poorest people live– Himalayan range plays an important role in Himalayan range plays an important role in

Asian Summer MonsoonAsian Summer Monsoon

• Need of special research on Climate models Need of special research on Climate models in Himalayan regionsin Himalayan regions

Thank You