Empirical estimation of present-day Antarctic glacial isostatic adjustment and ice mass change

• Main Authors: Gunter, B.C., Didova, O., Riva, R.E.M., Ligtenberg, S.R.M., Lenaerts, J.T.M., King, M.A., Broeke, M.R. van den, Urban, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Aardwetenschappen; Natuur- en sterrenkunde; Amundsen Sea; Antarctic; East Antarctica; West Antarctica; Antarc*; Antarctica; Ice Sheet
• Online Access: https://dspace.library.uu.nl/handle/1874/290649

This study explores an approach that simultaneously estimates Antarctic mass balance and glacial isostatic adjustment (GIA) through the combination of satellite gravity and altimetry data sets. The results improve upon previous efforts by incorporating reprocessed data sets over a longer period of time, and now include a firn densification model to account for firn compaction and surface processes. A range of different GRACE gravity models were evaluated, as well as a new ICESat surface height trend map computed using an overlapping footprint approach. When the GIA models created from the combination approach were compared to in-situ GPS ground station displacements, the vertical rates estimated showed consistently better agreement than existing GIA models. In addition, the new empirically derived GIA rates suggest the presence of strong uplift in the Amundsen Sea and Philippi/Denman sectors, as well as subsidence in large parts of East Antarctica. The total GIA mass change estimates for the entire Antarctic ice sheet ranged from 53 to 100 Gt yr−1, depending on the GRACE solution used, and with an estimated uncertainty of ±40 Gt yr−1. Over the time frame February 2003–October 2009, the corresponding ice mass change showed an average value of −100 ± 44 Gt yr−1 (EA: 5 ± 38, WA: −105 ± 22), consistent with other recent estimates in the literature, with the mass loss mostly concentrated in West Antarctica. The refined approach presented in this study shows the contribution that such data combinations can make towards improving estimates of present day GIA and ice mass change, particularly with respect to determining more reliable uncertainties.