Geophysics/Meteorology Honours Projects 2011-2012
Course organiser: David Stevenson ([email protected]), Crew 314
Course secretary: Emma Latto ([email protected]), Grant 332
This document lists the projects on offer for senior honours (4th
year) students
registered on the Geophysics/Geophysics and Geology/Geophysics and Meteorology
programs. The meteorology projects (and potentially some of the others too) are also
on offer to Physics with Meteorology students (if Physics with Met students are
unsure whether projects are suitable, they should contact the CO/supervisor).
If you are interested in a particular project, please contact the main supervisor to
discuss what is involved in more detail. You need to choose a project and also a
second choice, for each semester (semester 2 choices can be revised later). In some
cases you won’t be able to do your first choice (for example if it is chosen by multiple
people, and the supervisor cannot run several variants of the same project). If you
can’t do your first choice, we will try and make sure you do get your first choice in
semester 2. Where projects are over-subscribed, the decision of the CO (generally in
consultation with the supervisor) will be final.
Project choices for semester 1 (and provisional choices for semester 2) should be
emailed to the CO (email address above) by Wednesday in Week 1 (21st Sept), and
finalised allocations will be made by the end of Week 1 (23rd
Sept) so that you have
sufficient time to fully tackle the project.
Exceptionally, students can propose their own projects, but they will need to identify
a suitable supervisor (amongst the geophysics/meteorology staff), and convince that
supervisor and the CO that the project is sensible and feasible. Again, students should
do this as soon as possible in the semester, to fit with the above timetable.
Most projects listed here are one semester, 20-credit projects. In some cases, semester
1 projects can be extended to be 40-credit projects (and some are offered on this basis
from the outset). If students wish to extend their semester 1 project, they will need to
get the supervisor’s and the CO’s agreement, before week 7 of semester 1.
Any projects/combinations of projects can be taken, irrespective of whether you are a
Geophysics or a Geophysics and Meteorology/Geology student.
As part of the introduction to year 4 (Thursday September 15, 10 to ~1130, in Grant
304b) projects will be introduced by the CO, along with examples of good (and bad)
practice in how students should tackle their projects, including writing them up. It is
up to students to contact potential project supervisors to discuss projects (supervisor’s
contact details should be included in the project descriptions). If supervisors cannot be
contacted, please let the CO know.
In the middle of semester 2 (during ‘Innovative Learning Week’: 20-24 February
2012), students will be expected to give a short presentation on their semester 1
project, or, if they are doing a single 40-credit project, on that. This presentation will
not count towards your final project mark, but does contribute towards the final mark
on the ‘Transferable Skills for Geophysicists’ course.
Influence of Quaternary climate change on landscape evolution at geological time scales.
Mikaël Attal, Simon Tett & Richard Essery
([email protected], [email protected], [email protected])
20 credits (S1 or S2; possibility of extending to 40 credits)
Over the last decades, theoretical, experimental and numerical modelling studies have
shown that a landscape experiencing constant uplift and climate eventually reaches a
stable form characterized by erosion rates matching uplift rates at any point in the
landscape. The morphology of these landscapes in “steady-state” has been described
by these studies. For example, the simplest model predicts concave up river profiles
and an inverse power relationship between slope and drainage area, typically with an
exponent -0.5. Scientists have been using these criteria to assess whether landscapes
are in steady-state and met some success in a number of tectonically active areas such
as Taiwan or the Oregon Coast Range (USA). However, other studies have
demonstrated that the response time of landscapes to a disturbance (tectonic or
climatic change) is typically of the order of 105-10
6 years. Climate has been changing
dramatically over the Quaternary (last 2 Ma), alternating between glacial and
interglacial periods over time scales of 104-10
5 years. One can thus ask: how can any
modern terrestrial landscape be in steady-state? Or, alternatively, can a landscape
forced by a cyclic climate exhibit features that mimic steady-state landscapes?
These are the questions that this project will address. The project will use the
Channel-Hillslope Integrated Landscape Development (CHILD) model coupled with
Matlab code to analyse the evolution and morphology of a series of well studied
catchments in the Apennines (Italy). The model will be fed with climate data which
have been generated by the regional climate model HadRM3 for the Apennines for the
present and for the Last Glacial Maximum (LGM). This study will investigate the
differences in morphology between catchments experiencing (1) constant climate and
(2) alternating glacial-interglacial periods during the Quaternary.
Figure 1: November
mean rainfall rate
(kg.m-2
s-1
) predicted
by HadRM3 for the
Pre-Industrial period
(PI) and LGM
(courtesy Ian
McKenzie).
References:
Attal, M., P. A. Cowie, A. C. Whittaker, D. Hobley, G. E. Tucker, and G. P. Roberts (2011), Testing
fluvial erosion models using the transient response of bedrock rivers to tectonic forcing in the
Apennines, Italy, J. Geophys. Res., 116, F02005, doi:10.1029/2010JF001875.
Tucker, G. E., and R. L. Slingerland (1997), Drainage basin responses to climate change, Water
Resour. Res., 33, 2031– 2047.
Detection of anomalous signals in geomagnetic observatories: the subtle impact of man-
made noise in measurements
Ciarán Beggan (BGS) [[email protected]], David Kerridge (BGS) and Kathy Whaler (School of GeoSciences)
Geomagnetic observatories have traditionally been
located in isolated areas far from the unwanted
electric and magnetic influence of daily human
activity. In the UK, the first observatories were
moved from central London to the countryside in
Devon (Hartland) and southern Scotland
(Eskdalemuir), after the start of the electrification of
the train network in 1909. However, over time, even
these remote locations have become influenced by
man-made noise, as local infrastructure such as
roads, buildings and electrical networks impinge on
the once peaceful environment (see Figure).
Geomagnetic observatories will soon move to issuing
one-second records of the magnetic field (rather than
one-minute). This will result in greater sensitivity to
unwanted noise. As we cannot realistically move the
observatories to quieter locations, we must now develop tools to detect and remove signals in the data
which do not occur naturally. Obvious spikes and offsets are detectable by the trained human eye, but
subtle noise sources can pervade the data and are particularly difficult to spot. These unwanted signals
can have a major impact on the quality of the long-term record at an observatory, degrading the
usefulness of the data over timescales of years to decades and perhaps even centuries.
We propose to use a signal processing technique employing wavelet transforms to analyse data for
certain types of noise. Wavelet transforms are often compared with the Fourier transform, in which
signals are represented as a sum of sinusoids. The main difference is that wavelets can be localized in
both time and frequency whereas the standard Fourier transform is only localized in frequency.
Wavelets are very flexible and can be defined to enhance or optimally process a particular frequency of
interest, for example. Their use in time series analysis is now widespread throughout earth and
atmospheric sciences.
The project will be broken into two parts: (a) examination of synthetic data generated by adding noise to
an observatory record to see which types of wavelet can identify the noise correctly and (b) the
examination of several observatory datasets with known issues of man-made contamination to see if
wavelets can identify the sources, and provide a possible method for reducing their influence in the data.
This project will use Matlab and/or the R programming language to process the (real and synthetic)
observatory data. Much of the code has already been developed in the (free) R package, which is well
suited to this type of analysis. Example observatory data and code will be supplied by BGS and the
student will update and adapt this code for the project, using similar skills to those learnt with Matlab.
This is envisaged as a one-semester project (available in S1 or S2), though extendable by agreement to a
two-semester project (if started in S1).
References: R Development Core Team (2008), R: A Language and Environment for Statistical Computing, R Foundation for Statistical
Computing, Vienna, Austria, ISBN 3-900051-07-0; www.R-project.org.
Reda, J., Fouassier, D., Isac, A., Linthe, H-J., Matzka J., and C.W. Turbitt (2011), Improvements in Geomagnetic Observatory
Data Quality, Geomagnetic Observations and Models, IAGA Special Sopron Book Series, Volume 5, 127-148, DOI:
10.1007/978-90-481-9858-0_6
Valens, C., (2010), A Really Friendly Guide to Wavelets, http://polyvalens.pagesperso-
orange.fr/clemens/wavelets/wavelets.html
Hartland Geomagnetic
Observatory
Encroachment of Hartland Village towards the BGS
geomagnetic observatory
Is the Earth's core 'ringing' with periods of 6, 80 or 160 years? Empirical Mode
Decomposition of long-term geomagnetic observatory data
Ciarán Beggan (BGS) [[email protected]] and Kathy Whaler (School of GeoSciences)
It has been proposed that fluid within the Earth's liquid
outer core is organised into a series of discrete
concentric rotation-axis aligned cylinders, stretching
from the inner-outer core boundary to the core-mantle
boundary (Figure 1). The flow within each adjoining
cylinder is antagonistic and allows exchange of angular
momentum between the cylinders and also the mantle. It
is suggested that these exchanges of momentum can
also be determined by carefully measuring the change in
the length of day (i.e. the time it takes the Earth to rotate
each day) known as �LOD.
Another consequence of this proposed theory is that a
series of ‘standing’ magnetohydrodynamic waves exists
in the core with a number of 'free oscillation' modes.
The magnetic fields associated with these modes,
though subtle, should be measurable by the
network of long-term geomagnetic observatories at the
surface of the Earth. A number of researchers have looked for evidence of such waves, giving
several contradictory or at least ambiguous results in the literature, though a period of 80
years is often described. Recently, it has been suggested that periods of 6 and 160 years may
also exist. Mode periods have implications for the strength of the unknown toroidal magnetic
field within the outer core which is masked by the insulating mantle (c.f. geomagnetism
course).
We propose using a method known as Empirical Mode Decomposition (EMD) on average
monthly mean values of the magnetic field from a number of observatories in order to
examine if these proposed diagnostic periods are present. EMD is a recently developed
mathematical technique which can be used to analyse noisy or incomplete data for patterns
(i.e. modes) which may not be exactly periodic or regular. This is a significant advantage over
Fourier Transform techniques for example. The code for EMD is now available as a complete
package in the Matlab programming language.
To further constrain the results, we wish to look for synchronisation of the various modes
across the observatory network and also to study the relationship to modes within the �LOD
data, which stretch back over 300 years.
The aim of the project is to analyse time series of data for the past 80-100 years from a
number of observatories around the world, and the �LOD data, using the EMD code. The
project will require manipulating the data into a suitable format for the code and analysing the
resulting modes to search for peaks which indicate quasi-periodic patterns. Matlab will be
used to perform the EMD and visualise the results. This is a one-semester project.
References: Gillet, N., Jault, D., Canet, E. and A. Fournier (2010), Fast torsional waves and strong magnetic field
within the Earth’s core, Nature, 465, 74-77 doi:10.1038/nature09010
Jackson, L. P. and J. E. Mound (2010), Geomagnetic variation on decadal time scales: What can we
learn from Empirical Mode Decomposition? Geophys. Res. Lett., 37, L14307,
doi:10.1029/2010GL043455
Figure 1: Fluid cylinders in the outer core
Coulomb stress changes and earthquakes associated with the Afar dyke sequence, 2005-2011
Andrew Bell ([email protected]) and Kathy Whaler ([email protected])
Understanding the processes responsible for earthquake triggering is an important
outstanding challenge in geophysics. Changes in the Coulomb stress (a combination
of the normal and shear stresses) acting on a fault are likely to play a role in
earthquake triggering; however, the effect is difficult to quantify in tectonic
seismicity. Coulomb stress changes are also associated with magmatic processes and
may explain the spatial distribution of earthquakes associated with magma
emplacement. In this project, the student will use a Matlab application, Coulomb 3.0
(http://earthquake.usgs.gov/research/modeling/coulomb/), to investigate the evolution
of Coulomb stress associated with a sequence of dyking episodes in the Afar region of
Ethiopia and the correlation with earthquake occurrence. A previous student installed
and tested the software, and set up data files and scripts, which are available for
modification for this project.
Afar is in the late stages of continental break-up, with
strain localised along magmatic segments, very similar
to slow-spreading mid-oceanic ridge segments, which
are episodically active. An on-going sequence of
dyking events began on the Dabbahu segment in
September 2005. In the first event, 2.5 km3
of magma
was intruded in two weeks along a 60km dyke (Wright
et al., 2006). 12 subsequent events have been
identified, intruding a further 0.6 km3 of magma,
mostly in dykes ~10km long and 0.5-2m wide. Work
on the 2005 dyke suggests a good correlation between
coulomb stress changes and earthquake occurrence and
has refined a hypothesis for earthquake triggering by
dykes. This project will test this hypothesis by
calculating time-dependent Coulomb stress changes
for the subsequent dykes (based on their propagation
direction and speed, as inferred from seismicity and
inSAR data), and comparing them to the spatial and
temporal evolution of seismicity.
References Hamling, I., A. Ayele, L. Bennati, E. Calais, C.J. Ebinger, D. Keir, E. Lewi, T.J. Wright & G.Yirgu
(2009), Geodetic observations of the ongoing Dabbahu rifting episode: new dyke intrusions in 2006
and 2007. Geophysical Journal International, doi:10.1111/j.1365-246X.2009.04163.x
Wright, T.J., C. Ebinger, J. Biggs, A. Ayele, G. Yirgu, D. Keir & A. Stork, (2006) , Magma-maintained
rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature, 442, 291-294
Belachew, M., C. Ebinger, D. Coté, D. Keir, J. V. Rowland, J. O. S. Hammond, and A. Ayele (2011),
Comparison of dike intrusions in an incipient seafloor-spreading segment in Afar, Ethiopia: Seismicity
perspectives, J. Geophys. Res., 116, B06405, doi:10.1029/2010JB007908
Calculated Coulomb stress changes
and earthquake epicentres during the
2005 dyke intrusion at Afar.
An investigation of Gurevich’s model for velocity and attenuation of partially
saturated rocks.
Mark Chapman ([email protected])
Many geophysical problems, such as hydrocarbon reservoir characterization and
monitoring of CO2 sequestration, require knowledge of the seismic properties of
rocks saturated with multiple fluids. Unfortunately, we have no uniformly accepted
model for wave propagation in such media. Various simple approaches (such as
combining the “Gassmann” and “Wood” equations) have had some success but many
problems remain. In particular, great uncertainty surrounds the modelling of seismic
attenuation. A recent paper by Gurevich et al. (2011) advances a simple model with
some appealing features.
In this project, the student will write code to implement Gurevich’s model in an
environment such as MATLAB. This will allow a numerical investigation of the
predictions of the model concerning variations in factors such as gas saturation and
fluid pressure for a variety of rock types. The predictions will be compared against
those from alternative approaches developed recently in Edinburgh, allowing the
student to judge the relative strengths and weaknesses of the models and assess the
robustness of recently proposed schemes to invert seismic data for gas-saturation on
the basis of dispersive properties.
Reference
Gurevich, B., Makarynska, D., Bastos de Paula, O. and Pervukhina, M., 2011. A
simple model for squirt-flow dispersion and attenuation in fluid-saturated granular
rocks. Geophysics, 75, No. 6, N109-120.
Measuring changes in seismic velocity beneath Eyjafjallajökull and Katla using passive seismic interferometry, and assessing
their relationship with volcanic activity
Andrew Curtis (University of Edinburgh, [email protected]) Brian Baptie (British Geological Survey)
Project Summary
A fundamental goal of volcanology is improved forecasting of volcanic eruptions through long term monitoring of changes in volcanic behaviour. This requires reliable methods to measure small changes in sub-surface properties over long periods of time that may be related to changes in volcanic activity.
Recent research has shown that the cross correlation of the background seismic noise recorded at two seismic stations can provide an effective estimate of the elastic properties of the Earth, or indeed ‘virtual’ seismograms between the two stations as though a source had existed at the location of one or other. This novel imaging method, seismic interferometry, is revolutionising subsurface monitoring as it can be used to measure tiny changes in seismic velocity that might result from magma pressurization, lava dome collapse or other changes in the stress field. The technique requires only one or a few permanent seismic monitoring stations and does not require an external earthquake or active source, so can provide information even during periods of seismic quiescence.
The aim of this study is to identify possible spatial and temporal changes in seismic velocity using data recorded during the eruption of Eyjafjallajökull on Iceland, to integrate these with new data from Katla (which is expected to erupt within the next few years), and to investigate the relationship between such changes and volcanic activity. Reference seismograms from specific time periods will be used to measure spatial and temporal changes by comparison with seismograms calculated using interferometry over shorter time periods. Any temporal changes in seismic velocity will be identified and the results will be compared with geodetic observations recorded during the course of the survey.
Improved understanding of the relationship between changes in seismic velocity measured from the seismic noise field and volcanic processes could provide valuable near-real-time information with which to monitor and predict changes in a volcano’s behaviour and, ultimately, to forecast eruptions.
[1 or 2 semester project]
Figure: The eruption of Eyjafjallajökull
on Iceland.
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Cloud properties and lightning
Ruth Doherty ([email protected]), Hugh Pumphrey ([email protected])
20 credits (S1 or S2; possibility of extending to 40 credits)
Clouds remain one of the biggest challenges for understanding feedbacks on climate.
Projections of cloud amounts and changes in cloud variables vary greatly amongst
General Circulation Models (GCM). In addition, lightning is a very important source
of nitrogen oxides which produces ozone in the upper troposphere where it is most
influential its terms of its radiative forcing as a greenhouse gas. Lightning activity is
usually predicted from cloud variables hence uncertainty in clouds also leads to
uncertainty in predictions of lightning.
This project will compare present-day and
future projections of different cloud
variables from different climate models
used in the IPCC assessment in 2007.
Present-day model results will also be
compared with satellite observations.
Insights will be gained into whether biases
in one cloud variable relate to other cloud
variables and what which variables are
most reliably simulated. These cloud data will then be use to calculate lightning flash
rates using several different formulations which will also be compared to existing
satellite observations. The difference in cloud and lightning properties between the
tropic and mid-latitudes will be compared. This project could be extended to look at
the relationship between lightning and aerosols.
GCM and satellite data will be downloaded by the supervisor and scripts will be
supplied for reading and basic analysis of the data. The student will need to have, or
rapidly learn, good skills in data analysis and a high level computer language (e.g.,
IDL, Matlab, R).
References: Climate Change 2007: The Physical Science Basis- Chapter 8 climate models and their evaluation
(Randall et al. 2007). www.ipcc.ch
A lightning primer: http://thunder.msfc.nasa.gov/primer/index.html
Waliser, D. E.,et al..: Cloud ice: A climate model challenge with signs and expectations of progress. J.
Geophys. Res., 114,D00A21, doi:10.1029/2008JD010015, 2009.
Altaratz , O., I. Koren, Y. Yair, and C. Price (2010), Lightning response to smoke from Amazonian
fires, Geophys. Res. Lett., 37, L07801, doi:10.1029/2010GL042679.
Winter storm traits and the North Atlantic Oscillation (NAO)
Ruth Doherty ([email protected])
20 credits (S2 only)
The last two winters have been extremely cold in the UK. The winter of 2010/2011
was associated with a persistent high pressure system over Greenland and low
pressure over the Baltics. The high pressure blocked westerly winds from crossing the
Atlantic and dragged bitterly cold winds out of the Arctic down over Europe. A
temperature of −21.2 °C was recorded in the Scottish
Highlands at 10 am on the 2 December. It was the coldest
December recorded in the UK since 1890 and as you may
remember the city of Edinburgh had 18 cm of snowfall! The
North Atlantic Oscillation was thought to be the culprit. The
NAO index measures the difference of atmospheric pressure
at sea level between the Icelandic low and the Azores high. A
positive NAO is associated with greater storminess and wetter
weather over northern Europe, whilst a
negative NAO is typically associated with
fewer storms and colder weather. Fred
Pearce from the media reported “the NAO is
an old friend that has swapped its raincoat
and galoshes for gloves and a fur hat.” This
is because typically the NAO has been in a
positive phase since the 1970s but it
switched to a negative phase in 2008/2009
as can be seen in the figure here. However,
in addition to the NAO, another mode of climate variability, the El Niño Southern
Oscillation, may influence weather in the eastern Atlantic (Seager et al. 2010). ENSO
was in different phases in 2009/2010 and 2010/2011.
This project will examine storminess characteristics across the Atlantic and the UK
during negative and positive phases of the NAO. It will use NAO and ENSO index
time-series data and the output from a storm track model (TRACK: http://www.nerc-
essc.ac.uk/~kih/TRACK/Track.html) to examine storm characteristics such as
frequency and intensity of storms and the prevalent locations of the storm tracks.
Questions to be addressed include: Is there a clear association between the NAO and
blocking high pressure systems over Greenland? How do storm characteristics differ
when they originate in cold Arctic air to when they originate in the western North
Atlantic? Are storm numbers and storm tracks locations during negative NAO events
influenced by the phase of ENSO?
References: T. Jung, F. Vitart, L. Ferranti, and J.J. Morcrette (2011), Origin and predictability of the extreme
negative NAO winter of 2009/10, Geophys. Res. Lett., 38, L07701, doi:10.1029/2011GL046786.
R. Seager, Y. Kushnir, J. Nakamura, M. Ting, and N. Naik (2010), Northern Hemisphere winter snow
anomalies: ENSO, NAO and the winter of 2009/10, Geophys. Res. Lett., 37, L14703,
doi:10.1029/2010GL043830.
http://www.cgd.ucar.edu/cas/jhurrell/nao.stat.winter.html
http://www.dailymail.co.uk/sciencetech/article-1341618/Why-cold-Simple--North-Atlantic-Oscillation-
-got-bit-stuck.html
Weather-related health warnings in the UK associated with projections of climate change
Ruth Doherty ([email protected]), David Stevenson ([email protected])
20 credits (S2 only)
The European heat wave of 2003 resulted in over 2000 premature deaths in the UK as
temperatures soared above 30°C in many areas of the southern UK. As a result, the UK Met
Office operates a Heat-Health Watch system in
England and Wales from 1 June to 15 September
each year in association with the Department of
Health.
The Heat-Health Watch system comprises four
levels of response based upon threshold maximum
daytime and minimum night-time temperatures for
different UK regions. For example, in North-East
England, if temperatures exceed 28°C during the
day, then fail to fall below 15°C on the following
night, and there is a 90% chance that the forecast
for the next day is also >28°C, a level 3 (the
second highest) warning is issued.
UKCP09 is the latest assessment of future climate
projections across the UK based on low, medium
and high future emissions scenarios. These
projections are based around the idea of providing
probabilistic information as opposed to a “best”
estimate of future climate change. Uncertainty estimates are associated with uncertainty in
initial conditions (chaos theory) and results from different climate models. The aim of this
project is to use UKCP09 projections of daily minimum and maximum temperature to
quantify the likelihood of issuing heat and cold warnings (extreme cold spells also have
implications for health) in the future for different regions under different scenarios. Heat
warnings will be based on Met Office heat-health guidelines for England and Wales and
extended to Scotland, and cold warnings based on evidence in the literature (e.g. Wilkinson
et al. 2004) and discussions with Met Office/health impacts colleagues. The project will
make use of the UKCIP web interface that allows multiple options for data visualisation to
enable the results to be displayed in multiple ways, as well as the UKCP09 weather
generator to statistically generate daily weather based on monthly data. If time permits the
likelihood of changes in flood warnings in relation to changes in extreme precipitation and
storm surges could also be evaluated.
References:
http://www.metoffice.gov.uk/weather/uk/heathealth/
http://ukclimateprojections.defra.gov.uk/
Wilkinson, P.; Pattenden, S.; Armstrong, B.; Fletcher, A.; Kovats, R.S.; Mangtani, P.; McMichael, A.J.;
Vulnerability to winter mortality in elderly people in Britain: population based study, British Medical Journal,
2004; 329(7467):647
Figure 1. Temperature anomalies
across Europe during the 2003
heat-wave.
Ensemble forecasting and data assimilation in the Lorenz equations
Richard Essery ([email protected])
20 credits (S1 or S2)
Geophysical systems can often only be observed with limited accuracy at a limited
number of points in space and time, so their states have to be estimated from
incomplete and noisy data. The aim of data assimilation is to produce statistically
optimal state estimates by merging information from observations and models. This
has many geophysical applications; for example, data assimilation systems are
required to produce analyses of the state of the atmosphere for initialization of
numerical weather predictions. The chaotic nature of the atmosphere means that new
analyses have to be made regularly and the forecasts restarted to maintain accuracy.
Modern atmospheric models have very large numbers of state variables and assimilate
very large amounts of data, and this presents a very large computational problem. The
famous Lorenz equations form a much simpler system with only three state variables
that nonetheless displays deterministic chaos; small errors in initial conditions can
rapidly lead to large errors in forecasts. This project will explore how synthetic
observations of one or more of the state variables in the Lorenz system can constrain
forecasts of its future state, using ensembles of forecasts to estimate error statistics.
How does the forecast accuracy and range depend on the number and accuracy of the
observations and on the number of ensemble members? A program which solves the
Lorenz equations can be supplied in Fortran, IDL or Matlab. The project will require
knowledge of one of these programming languages and a reasonable grasp of statistics
and matrix algebra (at about the level of Applicable Mathematics 3) to implement and
evaluate the data assimilation.
Background reading:
Lawless, AS. Data assimilation with the Lorenz equations (http://www.nceo.ac.uk/
media/lorenz_all.pdf)
Evensen, G, 1997. Advanced data assimilation for strongly nonlinear dynamics.
Monthly Weather Review, 125, 1342 – 1354. (http://journals.ametsoc.org/toc/mwre/
125/6)
Simulating the seasonal variability and climate sensitivity of Northern Hemisphere snow cover
Richard Essery ([email protected])
20 credits (S1 or S2; possibility of extending to 40 credits)
Snow covers a large fraction of the Northern Hemisphere land surface in winter and
has a large influence on the surface energy balance because of its high albedo, with
strong feedbacks on the climate system. Moreover, because snow cover is sensitive to
changes in temperature and precipitation, and is relatively easy to measure by remote
sensing, it can provide an important indicator of climate change. In this project, a
simple but physically-based snow model with three adjustable parameters will be
driven with gridded meteorological data over the Northern Hemisphere to predict
snow cover for the period 1983-1995. The European Space Agency has recently
released snow extent and snow water equivalent maps based on microwave satellite
data going back to 1979 (http://www.globsnow.info). How closely can the modelled
seasonal cycle of hemispheric snow cover be made to match satellite records by
adjustment of the model parameters? What conclusions can be drawn about the
climate sensitivity of snow cover and its regional variation from interannual variations
in snow cover, temperature and precipitation?
The model will be supplied as a Fortran program but is very simple and could easily
be reprogrammed in Matlab or another language of choice. The main computational
challenge will be in plotting and analyzing the model output, so some experience with
a suitable programming language will be necessary.
Background reading:
Essery, RLH, and P Etchevers, 2004. Parameter sensitivity in simulations of
snowmelt. Journal of Geophysical Research, 109, doi:10.1029/2004JD005036.
Lemke et al., 2007. Observations: Changes in Snow, Ice and Frozen Ground. In:
Climate Change 2007: The Physical Science Basis. (http://www.ipcc.ch/
publications_and_data/ar4/wg1/en/ch4.html)
Free convection: experimental results and similarity theory
Richard Essery ([email protected]) and Brian Cameron
20 credits, S1 or S2
Free convection – the transfer of heat due to fluid movements driven by buoyancy
gradients – is an important process in the mantle, the oceans and the atmosphere.
Linear stability theory gives good predictions for the onset of convection but fails to
predict the rates of heat and mass transfer, due to non-linearities in the equations of
motion. Simple models of convection are therefore often based on similarity theories
containing coefficients that have to be determined by field, numerical or laboratory
experiments.
You will recall the convection tank experiment in the Meteorology: Atmosphere and
Environment labs, which uses a water tank as an analogue of the atmospheric
boundary layer. The water in the tank is initially heated at the top and chilled at the
bottom to produce a stable stratification simulating the temperature inversion
conditions often observed in the atmosphere before dawn. The bottom of the tank is
then heated to generate convection, the convective plumes are made visible by a
KMnO4 solution and the evolving temperature profile is measured with a thermistor
array. This is examined qualitatively in the Met: A&E lab, but the apparatus can also
be used to make quantitative measurements. The aim of this project will be to
compare experimental results with similarity theory, identify sources of error and
make recommendations on how the experiment could be improved. The project will
require a careful approach to laboratory work, handling of experimental data and an
appreciation of similarity techniques in fluid dynamics.
Background reading:
Stull, RB, 1988. An introduction to boundary layer meteorology. Kluwer, Dordrecht,
666 pp. (JCM Library shelfmark QC880.4.B65 Stu)
Willis, WE, and JW Deasdorff, 1974. A laboratory model of the unstable planetary
boundary layer. Journal of the Atmospheric Sciences, 31, 1297 – 1307. (http://
journals.ametsoc.org/toc/atsc/31/5)
Modelling and measuring the radiation balance of Edinburgh’s urban canyons
Richard Essery ([email protected]) and Tim Reid
20 credits (S1 or S2; possibility of extending to 40 credits)
The underlying topography and the tenement buildings of Edinburgh’s Old Town
make some dramatic urban canyons, such as the Cowgate, in which local air
temperatures can differ from those in the more open areas of town and surrounding
rural areas. One of the reasons for this is modification of the surface radiation
balance; shadows cast by buildings reduce the solar radiation and heating at street
level during the day, but blocking of sky view reduces the loss of thermal radiation
and cooling at night. Most models of urban climate have used idealized geometries to
represent these influences, but airborne laser scanning gives a method of producing
highly detailed digital elevation maps of real urban areas. A high-resolution map of
Edinburgh is now freely available and will be used in this project for modelling
radiation geometry. Under which meteorological conditions does the radiative
influence of urban geometry contribute a net warming or cooling? Simple instruments
familiar to anyone who attended the radiation lab in Meteorology: Atmosphere and
Environment can be used to take some field measurements to evaluate model
predictions.
A certain amount of trigonometry and integral calculus will suffice for calculating
shading and sky view at selected points, but a much more detailed study would be
possible with the use of some programming language with good image processing
capabilities such as IDL or Matlab.
Background reading:
Oke, TR, 1987. Boundary layer climates. Routledge, London, 435 pp. (Darwin
Library shelfmark QC981.7.M5 Oke.)
Grimmond, S, 2007. Urbanization and global environmental change: local effects of
urban warming. Geographical Journal, 173, 83 – 88. (http://www.kcl.ac.uk/ip/
suegrimmond/publishedpapers/GJ_Grimmond2007.pdf)
Geological forcing of climate transitions
Richard Essery ([email protected]) and Linda Kirstein
20 credits (S1 or S2)
The changing locations of continents and heights of mountains on geological
timescales have major effects on atmospheric circulation and climate. The Cenozoic,
for example, was a period of major geological changes (including opening of the
Drake Passage and Himalayan uplift) and climate changes (for example, onset of the
Asian monsoon and permanent Antarctic glaciation), and it has long been thought that
these changes are related in the coupled climate system (Raymo and Ruddiman 1992).
Climate models now provide tools for investigating these suggestions, at least for
snapshots of geological time.
Rather than using realistic global topography for a particular epoch, our colleague
Jonathan Gregory at the University of Reading has provided us with output from a run
of the FAMOUS climate model in which present day topography is smoothed out
over a period of 500 years, allowing time for the climate to equilibrate. Among many
interesting features, the simulated climate without topography shows a strong
decrease of precipitation over southeast Asia. This project will investigate how much
this is due to reduction in uplift over mountains and how much due to changes in the
Asian monsoon circulation without the influence of the high Tibetan plateau (Barry
and Chorley 2003). Are the changes gradual, or are there marked transitions?
Some experience with IDL or Matlab will be required for reading, analyzing and
plotting large climate model output files.
Background reading:
Barry and Chorley, 2003. Tropical Weather and Climate. Chapter 11 in Atmosphere,
Weather and Climate, Routledge.
Raymo and Ruddiman, 1992. Tectonic forcing of late Cenozoic climate. Nature, 359,
117-122.
http://www.famous.ac.uk/
El Nino variability and teleconnections in the 20th century
Supervisor: Tom Russon and G. Hegerl (contact [email protected] if interested)
20 credit project, S2 only, more detail available in S2.
The El Nino Southern Oscillation is a mode of variability of the ocean-atmosphere
system centered in the tropical Pacific. It substantially influences interannual global
temperature and precipitation variability, and causes strong regional impacts of
climate variability across the globe, see http://www.elnino.noaa.gov/.
In order to reconstruct El Nino variability and change in the past, pre-instrumental
time, these so-called teleconnections of regional climate to the tropical Pacific are
often used to attempt to reconstruct past El Nino timing and amplitude. This project
explores, from the literature and largely timeseries analysis, how strongly the various
indicators are actually coupled to El Nino, and to what extent indices used for
reconstructions fully represent 20th
century El Nino variability.
Background reading:
Kenyon, J and G. C. Hegerl (2008): The Influence of ENSO, NAO and NPI on global temperature extremes. J. Climate 21, 3872-3889, doi 10.1175/2008JCLI2125.1
And references herein as well as a recent review paper (to be provided) Figure:
NOAA
The early 20th century warming
Supervisor: Gabi Hegerl, Chris Merchant (designed as 40 credits)
The early 20
th century warming was an event that led to record temperature extremes
and climate events that have been exceeded only recently in some regions. This
project aims at investigating how the pattern of warming differs between that early
warming and the recent warming, and how each warming manifested itself in changes
in other climate variables, such as circulation of the atmosphere, sea ice, climate
extremes and drought. A lot of the project is literature review, but it will be buffered
up by analysis of data from multiple sources, among them gridded data for surface
temperature (easy to use, with matlab reading program provided), sea level pressure,
and some station data for daily temperature and rainfall variability. The project aims
at describing the changes in climate and linking them to possible causes discussed in
the literature.
The student will investigate these questions based on a global dataset of gridded (5x5
degree) surface temperature, sea level pressure and precipitation dataset, along with
some station data. The project requires some computer literacy, using matlab or R for
graphics and simple analyses. Help will be provided with programs to read in the data,
and visualization. Simple analyses may also be possible in excel, although matlab will
make the job much easier.
Global temperature trend early 20th
century
[K/decade] courtesy Simone Morak
Recent global temperature trend
[K/Decade]
References: Hegerl, G. C., F. W. Zwiers, P. Braconnot, N. P Gillett, Y. Luo, J. Marengo, N. Nicholls, J. E. Penner and P. A, Stott: Understanding and Attributing Climate Change. In: S. Solomon et al. (ed.) Climate Change 2007. The Fourth Scientific Assessment, Intergovernmental Panel on Climate Change (IPCC), Cambridge University Press, Cambridge, 663-745. And references therein.
A comparison of seismic and electrical/EM imaging techniques at Rosslyn Glen Ian Main ([email protected]) and Kathy Whaler (two field-based
projects to run concurrently over one term, 1st semester)
The second year seismic practical currently uses data taken from a
previous 4th year project at Rosslyn Glen, a glacial valley filled with till.
The aim of this project is to carry out and interpret seismic and
electrical/EM (DC resistivity and TDEM) surveys, one student being
primarily responsible for each. The seismic lines will be shot parallel and
perpendicular to strike, with electrical/EM data collected along the same
profiles. Co-located seismic velocity and electrical resistivity information
may help resolve the interpretation ambiguity of the previous seismic
survey. Two students will act as field assistants for each other, and
collaborate on a joint interpretation after writing up their own
independently.
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Estimating sources of CO, CO2 and CH4 from Canadian forest fires during summer
2011 using aircraft and satellite measurements
Paul Palmer ([email protected])
40 credit course
The burning of boreal forests, of which approximately 5 to 20 million hectares burn
annually (mainly in Russia and North America), removes vegetation, changes land-
surface properties, and emits trace gases, aerosols, and smoke in prodigious quantities.
Consequently, wildfires are amongst the most important global contributors to a number
of key atmospheric species (e.g., CO2, CH4, CO, NOx, black carbon) and their long-range
transport impact Earth’s radiation budget, air quality and processes such as tropospheric
O3 production far from the source region.
The University of Edinburgh leads the BORTAS project (www.geos.ed.ac.uk/
eochem/bortas/) to investigate the connection between the composition and distribution
of biomass burning outflow, O3 production and loss with that outflow, and the resulting
perturbation to chemistry in the troposphere. The focal point of the project is a 3-week
aircraft campaign over the North Atlantic during July 2011 (seasonal peak of Canadian
forest fires), which involves additional measurements over mainland Canada and the
Azores. One of our main analysis tools to interpret these data is the GEOS-Chem global
3-D chemistry transport model (http://www.geos-chem.org/), which relates surface
sources and sinks of gases and particles to atmospheric concentrations.
This project will include (1) the interpretation of observed concentration observations of
CO2, CH4, CO during BORTAS using the GEOS-Chem model; and (2) the application of
an optimal estimation inverse model to estimate the sources and sinks of these trace gases
from the observed concentration measurements. The candidate will also use satellite
observations of atmospheric chemistry and land-surface properties to help interpret the
spatial and temporal distribution of burning emissions over North America during
BORTAS. The project will involve computer programming and data analysis. Ideal
candidates will have knowledge of IDL or Python.
Title: The composition of the mesosphere using ground-based mm-wave remote sensing
Area: Atmospheric physics
Contact: Hugh Pumphrey (Room 313, Crew Building, extn. 50 6026, email:
Available: 20pt in S1 or S2.
The mesosphere, lying at altitudes between 50 and 80 km, is one of the least-understood regions of the
atmosphere. One way to study its composition is to use a millimetre-wave receiver (essentially a radio
telescope) sited on the ground (preferably on a high mountain). The spectra from such an instrument
can provide information on the mixing ratio of a variety of chemical species of interest. Recent
improvements in technology are permitting easier access to higher frequencies.
This, then, poses these questions: which species might one usefully measure with this technique? What
characteristics (bandwidth, resolution, noise level) would a spectrometer require in order to make the
measurement? How badly affected would the measurement be by a wet troposphere (and hence, how
high a mountain would you need)? The basic technique of the project is to simulate a measurement
using a readily-available radiative-transfer model (ARTS: see http://www.sat.ltu.se/arts) and apply the
standard techniques of inverse theory[1] to the simulation to determine what information the
measurements would contain. Several projects along these lines would be possible, to answer such
questions as:
• Which of the various absorption lines of CO is most suitable for sounding the mesosphere?
• Is it possible to use ground-based sensing of HCl to track the chlorine loading of the middle
atmosphere?
Two years of measurements of the 230GHz carbon monoxide spectral line taken from the Norwegian Antarctic base using
the British Antarctic Survey’s microwave radiometer.
These projects would probably be 20-point projects available in either semester. It would be suitable for
students on any physics or geophysics-based degree programme. The ARTS output would be analysed
using a data analysis language such as R, MATLAB or Octave. [1] Inverse Methods for Atmospheric Sounding: Theory and practice by Clive D. Rodgers (World Scientific, ISBN 981-02-
2740-X)
Title: Using a trajectory model to track SO2 from volcanos
Area: Atmospheric physics
Contact: Hugh Pumphrey (Room 313, Crew Building, extn. 50 6026, email:
Available: 20pt in S1 or S2 extendible to 40pt
Trajectory modelling is an established technique for studying pollution from isolated point sources such
as volcanos, chemical plants, disasters at nuclear power stations, and so forth. The widely-used
trajectory model FLEXTRA is freely available (http://transport.nilu.no/flexpart) and relatively easy to
use. The wind fields needed to drive the model are also freely available. The model can either trace air
parcels forwards in time in order to see where polluted air might have gone, or backwards in time in
order to see where an airmass observed to be polluted might have come from.
The MLS instrument on NASA’s Aura satellite has been observing sulphur dioxide (SO2) in the
stratosphere since 2004. Although there have been no large volcanic eruptions in that period there have
been a number of moderate-sized ones which have injected measurable amounts of SO2 into the
stratosphere. The basic idea of the project would be to identify these events and then to run back
trajectories from the observations of high SO2 to locate the volcano from which the SO2 came.
Map on left shows an example of trajectories. These are run backwards from locations where MLS observed unusual
amounts of CO. The trajectories go past the site of the Black Saturday bush fires of February 2009 [1]. Map on right shows
MLS observations of SO2 a few days after the eruption of the volcano Sarychev in Japan. The SO2 presumably comes from
the volcano but the trajectory analysis remains to be done.
An extension of the project would be to use the Flexpart particle dispersion model to attempt to make
more detailed simulations of the plume. The basic project could be a 20-point honours project for either
the Physics or Geophysics degree programme groupings. If suitably extended it would be suitable for a
40-point geophysics project or an M.Phys project.
It should be added that because trajectory modelling has wide applicability it could provide a basis for
students to design their own projects. The project would require competence in a data-analysis
language such as MATLAB, R, Octave, IDL etc. and also good general computing competence.
[1] Microwave Limb Sounder observations of biomass-burning products from the Australian bush fires of February 2009 H.
C. Pumphrey, M. L. Santee, N. J. Livesey, M. J. Schwartz, and W. G. Read
Atmos. Chem. Phys. Discuss., 11, 6531-6554, 2011
Title: How ageostrophic is the surface wind?
Area: Atmospheric physics
Contact: Hugh Pumphrey (Room 313, Crew Building, extn. 50 6026, email:
Available: 20pt in S1 or S2
Standard meteorological theory states that friction causes winds near the surface to be slower than the
geostrophic wind and to blow somewhat towards low pressure. (The geostrophic wind is exactly
parallel to the isobars, that is, perpendicular to the pressure gradient.) Is the theory correct? One way to
test it is to compare the measured wind to a direct estimate of the geostrophic wind. To that end, I have
collected several months worth of hourly wind recordings from Edinburgh airport, together with
pressure recordings from airports across Scotland and northern England. The project would consist of
calculating a time series of the pressure gradient at Edinburgh directly from the pressure data; this is an
inverse theory problem. The geostrophic wind can then be calculated directly from the pressure
gradient and compared to the true wind. It should be possible to determine whether the ageostrophic-
ness of the wind depends on wind speed, direction, time of day etc. The project would require
competence in a data-analysis language such as MATLAB, R, Octave, IDL etc. or the ability to learn
this reasonably quickly. This would be suitable as a 20-point honours project for either the Physics or
Geophysics degree programme groupings.
Analysis of air quality over the UK – the Easter 2011 smog episode
Supervisors: David Stevenson ([email protected]) and Massimo Vieno
(CEH)
(Available S1 or S2 as a 20-credit project; may be extendable to 40-credits)
Over a few weeks in April 2011, the UK experienced unusually warm temperatures
(e.g., London > 25°C) for the time of year, associated with high pressure, light winds,
and long hours of sunshine. The fine weather was accompanied by a progressive
deterioration in air quality (e.g., Figure 1). On Thursday 21st April, Defra issued a
‘summer smog’ alert1, for high levels of the air pollutants O3 (ozone) and PM10
(particulate matter less than 10 �m in diameter).
Data (air quality and meteorological) from multiple sites across the UK are available
over the time period (e.g., hourly ozone, temperature and PM data; also vertical
temperature profiles). This project will collect together this data, to produce a
synoptic view of the episode and interpret the processes that contributed to the high
levels of pollution. It may also be possible to analyse model simulations of the
episode, to determine the model’s performance.
The project will involve data analysis, including statistics, and the student will need
some competence in using computers for data analysis of relatively large data sets.
Figure 1. Ozone and PM10 measurements from Leicester Centre site, for April 16-23,
2011.
1. http://www.defra.gov.uk/news/2011/04/21/summer-smog/
Analysis of weather station data (there is potential for several projects)
Supervisors: David Stevenson ([email protected]) and Massimo Vieno
(Available S1 or S2 as a 20-credit project; may be extendable to 40-credits)
The University of Edinburgh weather station
(www.geos.ed.ac.uk/abs/Weathercam/station) has been collecting data (pressure,
rainfall, wind, temperature, humidity, and solar flux) for over 4 years, at high
temporal resolution (every minute; e.g., see figure). There is wide scope for various
analyses associated with these data – some specific suggestions are listed below, but
students with alternative ideas are invited to put forward their own suggestions.
1) An analysis of the exceptional winter of 2010-2011 in Edinburgh. Last year’s
winter broke records, with temperatures throughout much of December remaining
sub-zero for weeks on end. How was the event recorded by the JCMB weather
station? What synoptic conditions produced such an exceptional event? Using longer
time series of data from other nearby stations, just how exceptional was last winter?
2) Characterisation of biases for the station. The station is located on the top of
JCMB, a far from standard setting, and this influences the measurements. By careful
comparison with data from nearby official Met Office stations, biases can be
estimated. Comparison could also be made to temperature and humidity data from the
Stevenson screens on top of JCMB, to characterise very local factors. A second sensor
has been set up to simultaneously log measurements from the Stevenson screen as
well as from the roof. Analysis of these two measurement streams for the same
variable reveal important information about how accurately instruments measure
temperature.
3) Fourier analyses. This should reveal the clear annual and diurnal cycles in most
variables, but there may also be other timescales of variability in the data. Some
previous analyses have found weekly cycles (or weekend effects) in meteorological
data, a clear indicator of anthropogenic influence. Sub-diurnal signals (e.g. associated
with man’s activities, such as rush-hours on the roads, or the daily cycle of activity in
JCMB) may also be present in the data
4) Windspeed analyses. Before siting a wind turbine, you are generally advised to
collect data on wind speeds and variability for periods of a few months. The existing
data could be used to calculate the viability of installing a wind turbine on the roof of
JCMB, and estimating its potential. In addition, it would be interesting to look at how
dependent the estimated potential is on the time period of data – e.g., are all 3 month
periods within 10% of the 4 year average?
Electrical resistivity studies in Sri Lanka for investigating geothermal potential
Supervisors: Kathy Whaler ([email protected]); Nick Johnson; Bruce Hobbs
(Pentland Geophysics)
There are a number of hot springs in Sri Lanka and one theory is that they are
connected to deep and extensive geothermal regions. If this is the case there is
potential for the extraction of geothermal energy. The University of Edinburgh, in
conjunction with the Institute for Fundamental Studies and Geological Survey and
Mines Bureau, Sri Lanka, conducted geophysical surveys over a number of hot spring
sites in summer 2010 in order to investigate the possibility of these springs being
associated with deep, high enthalpy regions. Our technique probes the electrical
resistivity of the sub-surface, which is very sensitive to the presence of fluids. Recent
research suggests there is a clay mineral signature associated with geothermal activity
that the method is also able to detect.
Magnetotelluric (MT) data consist of time series of horizontal electric and magnetic
field variations; the ratios of electric to magnetic field contain the information on the
electrical resistivity of the sub-surface. Spectral analysis gives the signal as a function
of period which, through the skin depth (over which electromagnetic signals are
attenuated to 1/e of their initial amplitude), acts as a depth proxy. This project will use
processed MT data from one or more of the less noisy profiles. The project will
involve several stages of data analysis and cleaning to optimise the data for two-
dimensional inversion, including correcting for distortion of the data by near-surface
inhomogeneities and determining any prominent strike direction(s) reflecting sub-
surface structures; if time permits, inversion for sub-surface resistivity will also be
undertaken.
Fortran computer code exists to undertake the necessary processing steps, with scripts
to run them and plot results. It is not necessary to understand the details of the fortran
language to undertake the project, but the student will need to modify the scripts to
treat the particular data set, and then run the various codes. The main skill and effort
will come in making sure the runs have proceeded as intended and in analysing the
results.
Amplitude of the
North electric to
East magnetic field
components as a
function of period
for one of the Sri
Lanka profiles
Crustal thickness in Africa
Kathy Whaler ([email protected])
The most reliable estimates of crustal thickness come from seismic data, but these are
unavailable in many parts of the world. Previous research suggests that the
magnetisation amplitude deduced from low orbiting satellite data correlates tolerably
well with seismic crustal thickness estimates. A recent paper (Tedla et al., 2011)
provides regularly spaced estimates of crustal thickness over Africa from a satellite-
based gravity field model, and finds good agreement with seismically determined
Moho depth estimates where available. This project will explore the extent to which
the magnetisation amplitude correlates with the gravity and seismic estimates of
crustal thickness and, if the correlation is significant, the scaling factor that converts
magnetisation amplitude to crustal thickness estimate. Before undertaking the
correlation with the gravity-derived values, it will be important to decide the
resolution of the two models, and hence how many independent estimates of
thickness/magnetisation amplitude it is reasonable to correlate. The gravity data set
will then have to be averaged or decimated to the required resolution. The statistical
significance of the resulting correlation coefficient will be calculated and interpreted.
Regional or tectonic terrane correlations can be used to determine whether the
agreement (or lack of it!) varies over the continent, as suggested by the Tedla et al.
study. An alternative to correlation is to linearly regress one data series onto the other,
which allows for a constant offset as well as a scaling factor between the two; this
could also be investigated if time allowed.
fortran code to estimate magnetisation from the model coefficients will need
modification to estimate magnetisation at the locations of the gravity and seismic
points, but this can easily be done with knowledge of a structured programming
language like matlab. It is straightforward to correlate two sets of points in matlab.
However, manipulating the gravity data set to get values at the required spacing could
be fiddly, so the project will probably only suit a student who is willing to persevere
at, and gains satisfaction from, such tasks!
Comparison of crustal thickness
estimates. Seismic estimates from
seismic refraction profiles
(diamonds) and receiver functions
(circles). Seismic symbols in green
where the seismic and gravity
thicknesses agree to within ±5 km,
in red otherwise. Background
colour is the difference between
gravity estimates and a 2º x2º
global surface wave model crustal
thickness. From Tedla,G E, et al.,
2011, A crustal thickness map of
Africa derived from a global
gravity field model using Euler
deconvolution, Geophys. J. Int.,
doi: 10.1111/j.1365-
246X.2011.05140.x