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

Abstract This study analyses areal extent variations in the Wet Snow Zone ( σ 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 σ WSZ on the WIS. We found that the austral summers of 1982–1983, 1989–1990 and 1997–1998 had the largest σ WSZ extents. During 1992–1993, the σ 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 σ WSZ extent in the previous summer (45,348 km 2 ). In 2002–2003, the σ WSZ extent reached 42,785 km 2 . In contrast, the 2007–2008 summer did not show a large σ 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 σ WSZ areal extent has a declining trend of 723 km 2  y −1 ( r  = 0.49), over the period of our study (1978–2009).