ANTARCTIC SEA-ICE VARIABILITY: PRE-2000 AND POST-2000 COMPARISON

摘要

Sea ice plays an important role in the state and variability of regional and global climate through thermodynamic and dynamic processes, and feedback mechanisms operating over a hierarchy of space and time scales. In contrast to Arctic. Antarctic sea ice extent shows an increasing trend, with large inter-annual variability, since 1979. This study explores the trends and variability of Antarctic sea-ice in different sectors following literature: Weddell Sea (60°W-20°E), Indian Ocean (20°-90°E), Western Pacific Ocean (90°-160°E), Ross Sea (160°E-130°W) and the Bellingshausen-Amundsen Sea (130°-60°W). Using passive microwave sea ice concentrations derived from SMMR and SSM/I-SSMIS sensors for 1979-2015, we studied decadal and regional trends pre- and post-2000. The results indicated that Weddell Sea, Indian Ocean and Pacific Ocean sectors are exhibiting an increasing sea ice trend at a higher rate post-2000, whereas, Ross Sea sector experiences a slight decline. Sea ice in Bellingshausen-Amundsen sector has been decreasing since 1979; however post-2000 there is an increasing trend which contributes to an overall sea-ice increase. On a seasonal time scale opposite anomaly is being observed pre- and post-2000. Post-2000, Weddell Sea and Pacific sectors (Indian Ocean and Ross Sea sectors) experience a decreasing (increasing) trend. Monthly anomaly of Bellingshausen-Amundsen sector shows an increasing sea ice trend from a negative anomaly to a positive anomaly post-2000; January (November) months are contributing the most in decrease(increase| of total Antarctic sea-ice, respectively. Prior to 2000, the monthly sea ice anomalies were negative with slight positive slope, which switched to positive post-2000. Of the many contributing factors (remote forcing such as ENSO, Indian Ocean Dipole, Pacific Decadal Oscillation, Southern Annular Mode; regional forcing like winds, air/sea surface temperature warming, Antarctic Circumpolar wave, etc) for sea ice variability we discuss ozone hole-Amundsen Sea Low interaction for the changes post-2000.