Separating Long‐Term and Short‐Term Mass Changes of Antarctic Ice Drainage Basins: A Coupled State Space Analysis of Satellite Observations and Model Products

M O Willen,T Broerse,M Horwath,A Groh,L Schröder,P Kuipers Munneke,B Wouters,M R Van Den Broeke

doi:10.1029/2020jf005966

Abstract

AbstractSatellite gravimetry and altimetry measurements record gravity and elevation changes, respectively, which are useful for determining mass and volume change of the Antarctic Ice Sheet. Common methods employ products from regional climate modeling and firn modeling to aid interpretation and to link volume changes to mass changes. Estimating deterministic parameters over defined time periods is a conventional way to evaluate those changes. To overcome limitations of deterministic analyses with respect to time‐variable signals, we have developed a state‐space model framework. Therein, we jointly evaluate four mass and volume data sets by coupling of temporal signal variations. We identify long‐term signals of ice drainage basins that are observed by the satellite gravimetry mission GRACE and several satellite altimetry missions from April 2002 until August 2016. The degree to which we can separate long‐term and short‐term variations strongly depends on the similarity of the mass and volume change time series. For the drainage system of the Pine Island Glacier (West Antarctica), our results show noticeable variations of the long‐term trend with an acceleration of the contribution of ice dynamics to the mass balance from −11 ± 8 to −58 ± 8 Gt a−1. Our results in Dronning Maud Land (East Antarctica) show a positive long‐term contribution to the mass balance at almost a constant rate. The presented approach can fit time‐variable changes without artificial selection of periods of interest. Furthermore, because we only enforce common long‐term time variations between mass and volume data, differences in mean trend rates help to uncover model discrepancies.

Highlights

The response of the Antarctic Ice Sheet (AIS) to climate change is a major public concern due to its potential impact on sea level rise. Meredith et al (2019) concluded that the ice mass loss of the West Antarctic Ice Sheet (WAIS) has increased during the last two decades
The residual, irregular term absorbs the uncorrelated noise of grace–csmba, but is negligible in case of alt– fdm
When we compare between the mean rates of grace–csmba and alt–fdm for the focus basins 6, 13, and 22, we find differences of ∼2.1, ∼1.5, and ∼0.9 Gt a−1, respectively

Summary

Introduction

The response of the Antarctic Ice Sheet (AIS) to climate change is a major public concern due to its potential impact on sea level rise. Meredith et al (2019) concluded that the ice mass loss of the West Antarctic Ice Sheet (WAIS) has increased during the last two decades. The response of the Antarctic Ice Sheet (AIS) to climate change is a major public concern due to its potential impact on sea level rise. Meredith et al (2019) concluded that the ice mass loss of the West Antarctic Ice Sheet (WAIS) has increased during the last two decades. Some drainage basins of the East Antarctic Ice Sheet (EAIS) show both mass losses and mass gains (Rignot et al, 2019). The Gravity Recovery And Climate Experiment (GRACE) mission and its follow-on (GRACE-FO) mission have monitored gravity changes due to mass redistribution. Several altimetry missions have monitored WILLEN ET AL.

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