| Summary: | Antarctica is the continent of all extremes (highest, coldest, windiest, and iciest) which still nowadays present a lot of unknowns, 94 years after the first human intrusion lead by R. Amundsen until the South Pole. In situ data (e.g. Automatic Weather Stations: AWS) and satellites remote sensing have greatly improved our knowledge of the area. Antarctic appears to play a key role in the complex Ocean-Atmosphere-Ice system and associated Climate. Climate changes, acts in turn on the system from which the Cryosphere appears as the best marker due to the positive ice albedo feedback: initial temperature change will be amplified (see section 2.6.1). The Antarctic ice sheet really ebbs and floods in extent within the tide of climate change, between 10 to 10'* years scale range (Drewry, 1991). The coastal Ice Shelf is a pertinent indicator of short term regional climatic change. It has a limiting air isotherm: the -5°C mean annual temperature, which was proven to move southward associated with the last fifty years warming leading Ice Shelves disintegration on the Antarctic Peninsula (Vaughan and Doake, 1996). The importance of the surface ocean temperature in this disintegration is investigated here, in the frame of the Ice Shelves basal melting processes (Talbot, 1988), as the relevance of the insitu Automatic Weather station air recording mean are questionable (Van den Broeke, 2004.) Satellites remote sensing techniques, via AVHRR and MODIS instruments operating in the electromagnetic region were used to monitor respectively the Larsen Ice Shelf (LIS) disintegration pattern and the Sea Surface Temperature (SST) associated distribution (±0.4°C). The sea ice extent around the Antarctic Peninsula (AP) appeared minimal in February and maximal in July from the Nimbus? SSM/I sensor corresponding to the SST seasonal variation obtained from MODIS. The Larsen B's abrupt, fast and almost complete disintegration (4450 km^.y-1) was clearly monitored where large meltpond areas (750 km^) and warmest SST peak (+2.5°C) appeared correlated between January-February 2002.The summer super-cool of -5°C observed in 2003 at LB stopped the previous disintegration where the southern part of LB remains and started to collapse by a 500 km^ iceberg. Also, the warming role SST was confirmed over the recent LC collapsed (1400 km^) of February 2005. Therefore, the Ice Shelf is now thought to have a SST threshold of stability, which still has to be determined by extending the monitoring spatially and temporally. Faculty of Science
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