Inter-annual variability of phytoplankton blooms in the northern Arabian Sea during winter monsoon period (February-March) using IRS-P4 OCM data

Abstract

Phytoplankton bloom has been observed and interpreted utilizing Indian Remote Sensing Satellite (IRS-P4), Ocean Colour Monitor (OCM) sensor retrieved chlorophyll images for the northern Arabian Sea for three years period (2000-2002). The overall mean chlorophyll concentration was found higher in year 2001, when compared to years 2000 and 2002 in the selected bloom waters north of 15º N latitude. The algal blooms were most intense during the year 2001. The monthly sea surface temperature (SST) and its anomaly data retrieved from NOAA-NCEP archive have been correlated with the phytoplankton blooming conditions in the study area during February-March, 2000-2002. The SST maps of January and February show similar trend in the bloom (~26ºC) and non-bloom (~29ºC) water, but in March month the SST has been raised by about 3ºC in both the bloom and non-bloom waters for the three years. The SST anomaly has been observed to be of higher range (-3º to +4ºC) in February and March 2001 and the gradient is having significant link with the algal bloom period. The phytoplankton bloom and the hike in chlorophyll concentration during the winter monsoon season has been linked with winter cooling and the detrainment phenomenon and it’s relationship with SST and SST anomaly has been discussed.