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 (chl a) and sea‐ice concentration in the Antarctic Divergence (AD) region near 140° 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° 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° 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.