Inter-annual variability of chlorophyll and sea-ice in the Antarctic Divergence region: an attempt to derive their quantitative relationship

Inter-annual variability in chlorophyll a (ch a) and sea-ice concentration in the Antarctic Divergence (AD) region near 140 degrees E was examined using satellite sensor data in order to derive a quantitative relationship between the two. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) derived chl a and Special Sensor Microwave/Imager (SSM/I) derived sea-ice concentration data during 1997-2003 were analysed. Mean chl a concentration south of 64 degrees S during the period between September and April (from austral spring to autumn) of each year was calculated. The mean chl a in 2001/2002 was extremely high (1.08 mg m(-3)) within the six periods between 1997/1998 and 2002/2003. Simply integrated indices on sea-ice amount, such as the maximum sea-ice extent in the winter season, annual integration of coverage area over ice edge to coast, were not able to explain inter-annual variation of chl a, especially the highest chl a value in 2001/2002. We found a high correlation between the chl a south of 64 degrees S and the sea-ice index, which might be due to the surface meltwater of the sea-ice from the AD zone as a result of eddies. The quantitative relationship might have contributed to the prediction of phytoplankton blooms in this coastal region and demonstrated the impact of the sea-ice extent on the Antarctic marine ecosystem.