A comparative analysis between variations in wet snow zone and the main break-up and disintegration events in WILKINS ice shelf, Antarctic peninsula

摘要

This study analyses areal extent variations in the Wet Snow Zone (sigma WSZ) on the Wilkins Ice Shelf (WIS), in the austral summers from of 1978 to 2009. We used data estimated by a linear mixture analysis of SMMR and SSM/I images, in order to calculate the total area of the sigma WSZ on the WIS. We found that the austral summers of 1982-1983, 1989-1990 and 1997-1998 had the largest sigma WSZ extents. During 1992-1993, the sigma WSZ extent was approximately 36,072 km(2) (about 45% of the study area), and coincided with a major break-up event along the northern ice shelf edge. A significant break-up in this region also occurred in summer 1998-1999, and was associated with the largest sigma WSZ extent in the previous summer (45,348 km(2)). In 2002-2003, the sigma WSZ extent reached 42,785 km(2). In contrast, the 2007-2008 summer did not show a large sigma WSZ extent (15,889 km(2)), despite the break-up event in the northern and north-western of WIS in that summer and in the following year. These break-ups have been attributed to basal melting of the WIS in some studies, rather than surface-based hydrofracture, although sub-surface water and hydrofracture was implicated in a study of the 2007-2008 event. The median austral summer sigma WSZ areal extent has a declining trend of 723 km(2) y(-1) (r = 0.49), over the period of our study (1978-2009).