Scatter of mass changes estimates at basin scale for Greenland and Antarctica

Abstract

Abstract. During the last decade, the GRACE mission has provided valuable data for determining the mass changes of the Greenland and Antarctic ice sheets. Yet, discrepancies still exist in the published mass balance results, and comprehensive analyses on the sources of errors and discrepancies are lacking. Here, we present monthly mass changes together with trends derived from GRACE data at basin scale for both the Greenland and Antarctic ice sheets, and we assess the variability and errors for each of the possible sources of discrepancies, and we do this in an unprecedented systematic way, taking into account mass inference methods, data sets and background models. We find a very good agreement between the monthly mass change results derived from two independent methods, which represents a cross validation. For the monthly solutions, we find that most of the scatter is caused by the use of the two different data sets rather than the two different methods applied. Besides the well-known GIA trend uncertainty, we find that the geocenter motion and the recent de-aliasing corrections significantly impact the trends, with contributions of +13.2 Gt yr −1 and −20 Gt yr −1 , respectively, for Antarctica, which is more affected by these than Greenland. We show differences between the use of release RL04 and the new RL05 and confirm a lower noise content in the new release. The overall scatter of the solutions well exceeds the uncertainties propagated from the data errors and the leakage (as done in the past); hence we calculate new sound total errors for the monthly solutions and the trends.We find that the scatter in the monthly solutions caused by applying different estimates of geocenter motion time series (degree-1 corrections) is significant -contributing with up to 40% of the total error.For the whole GRACE period (2003-2011) our trend estimate for Greenland is −234 ±20 Gt yr −1 and −83 ± 36 Gt yr −1 for Antarctica (−111 ± 15 Gt yr −1 in the western part). We also find a clear (with respect to our errors) increase of mass loss in the last four years.

The effect of signal leakage and glacial isostatic rebound on GRACE-derived ice mass changes in Iceland.

“…Satellite gravity data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission (Tapley et al 2004) has since 2002 provided important and unique information about the mass changes of both the large ice sheets (e.g. Velicogna 2009;Sasgen et al 2012;Barletta et al 2013;Velicogna et al 2014) and smaller ice caps and glaciers (e.g. Chen et al 2007;Luthcke et al 2008;Jacob et al 2012;Gardner et al 2013), including those in Iceland.…”

Climatogenic Dynamics of Solifluction in the Permafrost Zone of Central Siberia

“…спутника GRACE (Gravity Recovery and Climate Experiment), позволяющего измерять аномалии гравитационного поля Земли, обусловленные, в частности, изменениями водной массы в Ар-ктике, Антарктике, а также в зонах вечной мерзлоты Сибири и Аляски [12][13][14][15][16][17][18][19].…”

Water Mass Dynamics in Cryolithozone of Central Siberia Based on Grace Remote Sensing Data

“…С 2002 г. работает спутниковая программа GRACE (Gravity Recovery and Climate Experiment), которая позволяет измерять аномалии гравитационного поля Земли, связан-ные с перемещением масс. Применив материалы GRACE, исследователи обнаружили зна-чительное сокращение водной массы в ледниках арктической и антарктической зон [5][6][7]. В мерзлотной зоне Сибири, по данным GRACE, выделены регионы с возрастающими тренда-ми водной массы в начале XXI в.…”