Abstract
AbstractPassive microwave satellite observations are used to identify the presence of surface meltwater across Antarctica at daily intervals from July 1979 to June 2020, with a focus on ice shelves. Antarctic Peninsula ice shelves have the highest number of annual days of melt, with a maximum of 89 days. Over the entire time period, there are few significant linear trends in days of melt per year. High melt years can be split into two distinct categories, those with high melt days in Dronning Maud Land and Wilkes Land, and those with high melt days in the Antarctic Peninsula and the Bellingshausen Sea sector of West Antarctica. The first pattern coincides with significant negative correlations between melt days and spring and summer Southern Annular Mode. Both patterns also form the primary modes of spatial and annual variability in the dataset observed by Principal Component Analysis. Areas experiencing extended melt for the first time in years tend to show large decreases in subsequent winter microwave emissions due to structural changes in the firn. We use this to identify the impact of novel melt events, particularly over the austral summers of 1991/92 and 2015/16 on the Ross Ice Shelf.
Highlights
Mass loss of the Antarctic ice sheet has the potential to surpass Greenland in contribution to sea-level rise by 2100 (Pörtner and others, 2019)
This approach is designed to detect the large jumps in brightness temperatures due to the emergence of liquid water, which are much larger than the differences between satellites or instruments. As such we do not apply a calibration to the measured brightness temperatures of different satellites. To validate this approach we tested the passive microwave calibration detailed in Nicolas and others (2017), and we found that in the 6 years in which there was overlap between the satellites detailed in their calibration, only 0.06% of the annual melt day totals for ice shelf pixels were altered
Results are shown for the entire Antarctic ice sheet but further analyses are focused on the ice shelves
Summary
Mass loss of the Antarctic ice sheet has the potential to surpass Greenland in contribution to sea-level rise by 2100 (Pörtner and others, 2019). The majority of potential Antarctic mass loss this century arises from ocean-driven and ice dynamic mechanisms (Golledge and others, 2019), yet surface melt is an increasing component of the mass budget as the atmosphere warms (DeConto and Pollard, 2016). Increasing melt is expected to result in mass loss due to increased runoff (Kittel and others, 2021), and surface melt is related to dynamic ice loss mechanisms. Surface meltwater reaching the bed has led to increased sliding resulting in acceleration of Antarctic Peninsula outlet glaciers (Tuckett and others, 2019)
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