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Abstract

Using satellite measurements of surface melt and output from MetUM simulations at a spatial resolution of 12 km, we report enhanced surface melting in summer (December-January-February) over several West Antarctic ice shelves during summer season since the late 1990s. Significant positive trends were detected over Ross and Sulzberger ice shelves, Pine Island and Thwaites glaciers, as well as over a large part of Marie Byrd Land during DJF, 1998-2018. During this period, a decreasing trend in geopotential height anomalies over the coastal West Antarctica causes an increasing trend in northerly wind over the coastal ice shelves leading to excessive surface melting. In contrast, these ice shelves experienced a decreasing trend in surface melting during DJF, 1979-1996. Our analysis shows that melt indices are closely tied to sea surface temperature and outgoing longwave anomalies over the central Pacific and South Pacific Convergence Zone. Our analysis suggests that the shift in trend across the late 1990s is linked to the shift in Interdecadal Pacific Oscillation in the late 1990s.