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
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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.
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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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