Factors affecting fast-ice break-up frequency in Lützow-Holm Bay, Antarctica
Author: Ushio, Shuki
Source: Annals of Glaciology, Volume 44, Number 1, November 2006 , pp. 177-182(6)
Publisher: International Glaciological Society
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Abstract:
Antarctic fast-ice variation is investigated using satellite images and ship's ice navigation logs, focusing on break-up phenomena in Lützow-Holm Bay. Although spatio-temporal scales for break-up events vary somewhat for each event, their commencement is generally in autumn and almost always in the same region. Specifically, the 1997/98 break-up event occurred over a wide area and continued for a long time after the initial break-up. Since then, break-ups have recurred until 2004, and a total of 20 annual events have been detected and monitored since 1980. Moreover, information from icebreaker navigation logs shows that unstable fast-ice conditions occurred in the 1980s and after the late 1990s. From the analysis of surface meteorological data and the offshore pack-ice distribution, anomalously shallow snow-cover depths and a peculiar retreat pattern of the ice edge are found to be factors that favour fast-ice break-up. The pack-ice distribution controls the propagation of ocean swell inside the bay; encroaching swells are likely to mechanically disintegrate fast-ice during autumn prior to the annual formation of the protective pack-ice cover to the north. Less snow cover also leads to fast-ice weakening as the melt season progresses and broken floes are then transported offshore by prevailing southerly winds.Document Type: Research article
DOI: 10.3189/172756406781811835
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