Antarctic Ice Sheet grounding line discharge from 1996 through 2023
Abstract. Grounding line discharge is a key component of the mass balance of the Antarctic Ice Sheet. Here we present an estimate of Antarctic Ice Sheet grounding line discharge from 1996 through to last month. We calculate ice flux at up to 100 m resolution through 16 algorithmically-generated flux gates, which are continuous around Antarctica. We draw on a range of ice velocity and thickness data to estimate grounding line discharge. For ice thickness, we use four bed topography datasets, two firn models and a temporally varying ice surface. For the ice velocity, we utilise a range of publicly-available ice velocity maps at resolutions ranging from 240 x 240 m to 1000 x 1000 m, as well as new, 100 x 100 m monthly velocity mosaics derived from intensity-tracking of Sentinel-1 image pairs, available since October 2014. The pixel-based ice fluxes and ice flux errors are integrated within all available Antarctic ice stream, ice shelf and glacier basins. Our dataset also includes the contributions to discharge from changes in ice thickness due to surface lowering, time-varying firn air content and surface mass change between the flux gates and grounding line. We find that Antarctic Ice Sheet grounding line discharge increased from 1,990 ± 23 Gt yr-1 to 2,205 ± 18 Gt yr-1 between 1996 and 2023, much of which was due to acceleration of ice streams in West Antarctica but with substantial contributions from ice streams in East Antarctica and glaciers on the Antarctic Peninsula. The uncertainties in our discharge dataset primarily result from uncertain bed elevation and flux gate location, which account for much of difference between our results and previous studies. It is our intention to update this discharge dataset each month, subject to continued Sentinel-1 acquisitions and funding availability. The datasets are freely available at https://zenodo.org/records/10183327 (Davison et al., 2023a).
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Antarctic Ice Sheet grounding line discharge from 1996 through 2023 https://zenodo.org/records/10183327
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