Evaluation of Regional Climate Models Using Regionally Optimized GRACE Mascons in the Amery and Getz Ice Shelves Basins, Antarctica. Issue 23 (10th December 2019)

• Record Type: Journal Article
• Authors: Mohajerani, Yara; Velicogna, Isabella; Rignot, Eric
• Is Part Of: Geophysical research letters. Volume 46:Issue 23(2019)
• Page Start: 13883
• Page End: 13891
• Publication Date: 2019-12-10
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL084665
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We develop regionally optimized Gravity Recovery and Climate Experiment (GRACE) solutions to evaluate the mass balance of the drainage basins of Amery Ice Shelf, East Antarctica, and Getz Ice Shelf, West Antarctica. We find that the Amery region is near balance, while the Getz region is rapidly losing mass. We compare the results with the mass budget method (MBM) combining ice discharge along the periphery with surface mass balance derived from three regional climate models: (1) Regional Atmospheric Climate Model (RACMO) 2.3p1 and (2) 2.3p2, and (3) Modèle Atmosphérique Régional 3.6.41. For Amery, MBM/RACMO2.3p1 agrees with GRACE, while MBM/RACMO2.3p2 and MBM/MAR3.6.41 suggest a positive mass balance. For Getz, all estimates agree with a mass loss and the GRACE results are robust to uncertainties in glacial isostatic adjustment derived from an ensemble 128, 000 forward models. Over the period April 2002 to November 2015, the mass loss of the Getz drainage basin is 22.9 ± 10.9 Gt/yr with an acceleration of 1.6 ± 0.9 Gt/yr 2 . Plain Language Summary: We use a regional optimization methodology for processing data from the Gravity Recovery and Climate Experiment (GRACE) to evaluate the ice mass change of the drainage basins of two major ice shelves in Antarctica and evaluate the performance of regional climate models (RCMs). The Getz Ice Shelf basin in West Antarctica has shown previous disagreements between various mass balance estimates and is influenced by heterogenous conditions that make it vulnerable and challenging to study. We find this region to be in a state of accelerating mass loss. Furthermore, all three examined RCMs are in good agreement with GRACE in this region. The Amery Ice Shelf in East Antarctica is the third largest Antarctic ice shelf with a basin that has enough ice to raise sea level by 7.8 m but has presented challenges in previous mass balance efforts. We find that the mass in this drainage basin is not changing significantly. Furthermore, only one out of the three examined RCMs agrees with GRACE observations in this region. These results suggest that the RCMs may need to be revisited in some regions of the ice sheet. Key Points: The drainage of Getz Ice Shelf, West Antarctica, is rapidly losing mass, whereas the drainage of Amery Ice Shelf is near balance The GRACE mass balance agrees with the mass budget method with several regional climate models on Getz but only with RACMO2.3p1 on Amery The GRACE‐based methodology helps evaluate RCMs and increase confidence in mass balance estimates around Antarctica