Antarctica Today: Daily Measurements of Surface Melt Extent Across the Antarctic Ice Sheet From Passive Microwave Data

Abstract:

Increased glacier and ice sheet surface melt is a major indicator of a warming global climate, and melt run-off from the Greenland ice sheet and mountain glaciers has been a major contributor to global sea level rise. Since 2013, the National Snow and Ice Data Center (NSIDC) has posted daily records of Greenland’s ice sheet surface melt extent using passive microwave satellite measurements, updating images with a 1-day lag and posting them publicly from its “Greenland Ice Sheet Today” website. The record spans the 1978 to present time-period of passive microwave observations (SMMR – SMM/I – SMMIS). The site serves as both a public-facing portal for reliable information about the Greenland ice sheet, and repository for long-term scientific data to study those trends. To date, no similar widely available public record of near-real-time daily ice sheet surface melt extent exists for Antarctica – yet surface melting is critically important for the stability of the ice sheet. In the Antarctic Peninsula, atmospheric warming and extensive surface melting drove the collapse of the Larsen B Ice Shelf in 2002, although more recent melt trends there and in other areas of Antarctica have been declining. However, the 2019-2020 austral summer in Antarctica broke records for both air temperature and surface melt intensity at many locations on the ice sheet. Using the same methodology as that used in the NSIDC’s “Greenland Ice Sheet Today” product based upon a dynamic, single-frequency threshold approach based on a simple microwave emission model, we present the “Antarctica Today” dataset. Using passive microwave remote sensing records since 1978-79, we introduce a daily record of melt extent across the Antarctic ice sheet for the past 41 years, and explore regional trends and extreme events recorded within that data set. With this dataset, we are able to put the 2019-2020 Antarctic melt season into context and present the public with a reliable instrumental record of surface melt on the planet’s southernmost ice sheet.