GRACE and ICESat Data for Estimation of Ice Sheet Surface Changes in LAS, East Antarctica

Abstract:

Knowledge of mass changes of the Antarctic ice sheet is essential for understanding global climate change, specifically, for sea-level change. This presentation reports the the results of a comparative study on changes of regional ice sheet mass and surface elevation based on observations of GRACE and ICESat satellites over the period of 2004 – 2008 in the Lambert Glacier-Amery Ice Shelf System (LAS), East Antarctica. LAS is an important drainage system in East Antarctica and one of the significant contributors to the mass budget of the Antarctic.

We fitted the GRACE monthly solutions to a model that contains a linear trend, an acceleration, annual and semiannual terms, and a 161 days tide aliasing term (S2). We employed the IJ05 R2 GIA model. For ICESat observations, we employed a modified spatial-temporal polynomial model to describe the ice surface topography and an annual elevation change rate (trend), which is solved by using repeat-track points within a moving box along the repeating tracks. Uncertainties of the source data and the estimated trends from both GRACE and ICESat data are given. The mass changes from GRACE and ICESat are compared and the differences are analyzed. A number of key issues in the comparison and mass – volume conversion are discussed. Afterwards, spatial and temporal correlations between the results at the annual change level derived from the two data sets are analyzed. Impact of firn models, GIA models, and comparison with other research results in LAS demonstrated.