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Paul Tregoning: Antarctic Mass Balance Studies

Paul Tregoning: Antarctic Mass Balance Studies

Antarctic-related Student Projects

Measuring changes in Mass Balance of Antarctica


Rate of change of geopotential over Antarctica estimated derived from the French GRGS GRACE solutions
Changes in temperature of the oceans and atmosphere cause changes in the size of polar ice sheets and mountain glaciers, as well as changes in global sea level. Space-geodetic techniques (such as satellite altimetry, space-gravity missions, GPS) can be used to measure present-day changes in the volume of water stored on the continents in the form of polar ice caps. Changing volumes indicate exchanges of water with the oceans, inducing increases/decreases in sea level.

The research involves improving the geodetic analysis techniques - including in-situ validation in Antarctica - to derive more accurate mass balance estimates. This includes improving atmospheric and tidal models used in the reduction of the raw space-geodetic observations.

Publications

Tregoning, P., G. Ramillien, H. McQueen and D. Zwartz, Glacial isostatic adjustment and non-stationary signals observed by GRACE, J. Geophys. Res. , in press
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Present-day Glacial Isostatic Adjustment of Antarctica


Remote GPS installation at Landing Bluff, Antarctica
Understanding present-day melting patterns of polar ice caps and the contribution to present-day sea level variations requires first unravelling the puzzle of how the continents are still adjusting after the melting that has occurred since the Last Glacial Maximum around 10,000 years ago.

The present-day glacial isostatic adjustment of Antarctica generates uplift of the continent that is detectable by space-geodetic observing techniques. The Gravity Recovery and Climate Experiment (GRACE) is sensitive to the induced gravity changes, while satellite altimetry and ground-based GPS can measure directly the vertical movement of the surface. These effects must be removed from GRACE and altimetry estimates of temporal changes in ice in order to estimate present-day mass balance changes that might be occurring as a result of global warming.

Since 1998, we have operated remote GPS installations in East Antarctica to measure the rate of uplift currently occurring as a result of ongoing glacial isostatic adjustment. Considerable care is required in the analysis of the GPS data to ensure that rates with an accuracy of < 1 mm/yr can be estimated.

Selected relevant publications

Tregoning, P., G. Ramillien, H. McQueen and D. Zwartz, Glacial isostatic adjustment and non-stationary signals observed by GRACE, J. Geophys. Res. , in press
pdf

Tregoning, P. and T. A. Herring, 2006. Impact of a priori zenith hydrostatic delay errors on GPS estimates of station heights and zenith total delays, Geophys. Res. Lett., 33, doi:10.1029/2006GL027706.
pdf

Tregoning, P. and T. van Dam, 2005. Atmospheric pressure loading corrections applied to GPS data at the observation level, Geophys. Res. Lett., 32, doi:10.1029/2005GL024104.
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Tregoning, P., Welsh, A., McQueen, H. and Lambeck, K. 2000. The search for postglacial rebound near the Lambert Glacier, Antarctica . Earth Planets Space, 52 , 1037-1041.
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Tregoning, P., B. Twilley, M. Hendy and D. Zwartz, 1999. Monitoring isostatic rebound in Antarctica with the use of continuous remote GPS observations, GPS Solutions, 2, 70-75.
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Student Research Projects @ RSES

In the Drop down menus below choose the Degree type you are looking to complete then a subject type and if you know of a supervisor
you wish to study under select the supervisors name then click on the search button and the relevant projects will be displayed.
If you do not make any selections all available projects will be displayed.

Degree Type ? Subject?Supervisor?
Note: These projects are an indication of the topics available, you should contact your prospective supervisor asap to discuss the details of the project.
Mass variations estimated from GRACE
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS, Mathematical Geophysics, Physics, Geophysics, Computational
Degree types: Honours, M.Sc, PhD, PhB,
The Gravity Recovery and Climate Experiment (GRACE) space gravity mission provides a means of estimating changes in mass on the Earth, including hydrological processes, oceanic variations and melting of polar ice sheets. The raw measurements are actually changes in the distance (accurate to 1/10 of the width of a human hair) between two satellites orbiting at 450 km altitude and separated by ~200 km. To achieve this, we must first compute the orbit of the two satellites, taking into account gravitational effects of the Sun, Moon, ocean tides, atmospheric variations to then be able to identify the signal of the temporal changes in the Earth's gravity field. The figure shows the accumulation of mass( i.e. water) on the east coast of Australia during the 2011 January floods as estimated by GRACE.

The student will be involved in developing software and background models to derive more accurate estimates of the Earth's gravity field. They will then use the estimates to study geophysical processes on Earth.

Monitoring groundwater changes in Australia
project image
Supervisor:Tregoning, Paul
Subject keywords: Sea level change/Climate change, Geodesy/GPS, Mathematical Geophysics, Geophysics, Computational GRC
Degree types: Honours, M.Sc, PhB
Water is a critical resource for Australia. We can't begin to manage properly what we don't monitor; therefore, monitoring the changes in water resources at local- and basin-scales is becoming increasingly important. The Gravity Recovery and Climate Experiment (GRACE) satellite gravity mission enables the possibility to measure basin-scale mass changes at monthly intervals, yet such capability is not being exploited to monitor Australia\'s water systems. Considerable research is required to determine the accuracy of the technique in the Australian environment where drainage basins are relatively small. This would involve the analysis and comparison of different international GRACE solutions and simulations for the Australian region to assess the achievable accuracy. The student would conduct an interesting scientific study that should lead to unique results pertinent to water resources in the Australian region.
Climate Change and the Melting of Polar Ice Caps
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Sea level change/Climate change,Mathematical Geophysics,Physics,Computational,Fieldwork, GRC,
Degree types: PhD,
Global warming is causing increased melting in polar regions. How do we know this? Because we can measure changes in mass balance (or the amount of ice that has melted) using space-geodetic techniques that detect variations in the Earth's gravity field and changes in ice height.
How fast are Antarctica and Greenland melting and how is such melting contributing to rising sea level?
There is the opportunity to study all aspects of the effects and ramifications of climate change, from measuring sea level variations using satellite altimetry and tide gauges, measuring with GPS the rebound of the Earth's crust caused by the melting of past ice sheets, monitoring mass balance changes through GRACE observations of gravity changes and/or assimilating all these observations to develop new models of past and present ice sheets for Greenland, Antarctica and North America. This exciting area of research has direct implications for understanding the present-day effects of climate change.
Sensing water vapour in the atmosphere using GPS
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Sea level change/Climate change,Climate Dynamics,Physics,Geophysics,Computational,Analytical,
Degree types: Honours,M.Sc,PhD,PhB,
Signals transmitted from satellites orbiting the Earth are delayed as they pass through the troposphere of the Earth. This is measurable by GPS and so it is possible to measure how much water vapour is actually in the atmosphere using GPS. This is a new area of research that will involve the student learning about high-accuracy GPS analysis and modelling of the atmospheric effects. The map to the right shows the precipitable water vapour over the USA as estimated from GPS observations. Assimilating this information into weather forecasting and climate studies has not yet been attempted in Australia.

Contact the supervisor directly for more information.

Combining Very Long Baseline Interferometry and GPS in Australia
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Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Mathematical Geophysics,Physics,Computational,Fieldwork,GRC,
Degree types: PhD,
Very Long Baseline Interferometry (VLBI) involves observing radio sources with astronomy telescopes, from which very accurate estimates of distances between telescopes and estimates of Earth rotation can be made. Recently, a software program was developed at Swinburne University (Victoria) to correlate astronomic VLBI observations - which is a very significant improvement over convential correlation and provides Australian researchers with considerable independence. This PhD program will involve continuing the development of the software correlator so that it can be applied to geodetic VLBI observations as well. Once this can be done, exciting new opportunities will become available - such as observing GPS satellites using VLBI instruments, analysing for the first time the data from the new VLBI installations in Western Australia and the Northern Territory (to be commissioned in 2008). The student will be involved in developing and enhancing software, analysing VLBI data and integrating the VLBI observations to GPS satellites into existing geodetic software packages. The student will be supervised jointly by Steven Tingay (Swinburn) and Paul Tregoning (ANU).

We don't know yet what new results such research is going to uncover ...... come and find out!

Tectonic deformation of Papua New Guinea
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Tectonics/Earth Deformation/faults,Mathematical Geophysics,Geophysics,Computational,Analytical,Fieldwork,
Degree types: Honours,M.Sc,PhD,PhB,
Papua New Guinea is one of the most active tectonic regions of the world, with every possible type of plate boundary, dozens of active faults and several major earthquakes occurring every year. Measurement of ground movement from GPS observationscan tell us about deformation, strain caused by locked faults etc. Estimating earthquake locations can identify faults and explain the observed deformations. There are numerous research projects available using earthquakes and/or geodetic data to study how the Earth moves in Papua New Guinea.

Contact the supervisor directly for more information.