Satellite estimates of the long-term trend in phytoplankton size classes in the coastal waters of north-western Bay of Bengal

•Better performance of Sahay et al (2017) phytoplankton size class model in coastal waters.•Dominance of microphytoplankton throughout the year in Visakhapatnam coastal waters.•Dominance of picophytoplankton in coastal waters off Gopalpur during the southwest monsoon.•Recurring bloom elevated microphytoplankton levels off Gopalpur during pre-monsoon.•Precipitation induced terrigenous influx fueled microphytoplankton in post-monsoon.