Winter blooms of phytoplankton in the Arabian Sea as observed by the Coastal Zone Color Scanner

Abstract

Mean phytoplankton chlorophyll concentrations as estimated by the Nimbus-7 Coastal Zone Color Scanner are presented for December 1978 to April 1979 and November 1979 to March 1980 for 8 offshore areas of the Arabian Sea North of 10 degree N. Appreciable regional differences in levels and timing of changes of concentration were found, with large blooms being especially common in late winter north of about 20 degree N. Differences between the 2 autumn/winter periods in the timing of blooms were marked. Monthly means of surface water temperatures (for 2 degree x 2 degree squares) and winds (for 5 degree x 5 degree squares) did not provide explanations for the changes in pigment concentrations. Average chlorophyll concentrations North of about 20 degree N were significantly higher than those between about 10 degree and 15 degree N both prior to and during the months of seasonally elevated pigment levels.