J. C. Comiso
NASA Goddard Space Flight Center,
Code 971
Greenbelt, MD 20771
comiso@joey.gsfc.nasa.gov
The results of trend analysis, using
two decades of passive microwave satellite data, reveal a remarkably stable
sea ice cover over the southern hemisphere with the ice extent and ice
area changing only by 0.4 ± 0.3 %/decade and 1.7 ± 0.3 %/decade,
respectively. Regionally, however, large interannual and decadal changes
are apparent. For example, the ice extent at the Bellingshausen/Amundsen
Seas has been decreasing at a rate of -8.1 ± 1.4 %/decade. This
reflects the large change in the physical characteristics of the ice cover
in the region, especially at the Bellingshausen Sea. In the latter, much
of the region is free of ice during the summer in the 1990s compared to
that in the 1980s. This also means that the older and thicker ice types
in the region are gradually disappearing. On the other hand, an almost
equal but opposite rate of 7.0 ± 1.0 %/decade is observed in the
Ross Sea. This may suggest that the ice cover that has been lost in the
Bellingshausen/Amundsen Seas has actually migrated to the Ross Sea. The
two adjacent regions, however, appear to be under the influence of two
different climatic systems since a warming is observed in the adjacent
Antarctic Peninsula while a slight cooling is observed in the Ross Ice
Shelf region over the last two decades. Although the trend in extent is
basically null at the other regions, large spatial changes are also apparent,
especially at the the Weddell Sea region. This appears to be partly influenced
by big icebergs that calved from the Filchner Ice Shelf. Spatial changes
in the annual anomalies in the sea ice cover, with especial emphasis on
those of most recent years including 2001, has been evaluated and will
be presented.