Interannual variability in phytoplankton size class distribution derived from pigment analysis in the central Arabian Sea (summer monsoon)

The present data set contains some of the key physical (temperature, dissolved oxygen), biological (phytoplankton pigment), and chemical (nutrients) parameters from the upper ocean (mostly euphotic layers surface-120 m) of the central Arabian Sea (64° E; 11° N–21° N) collected during the summer monsoon (August 2017 and 2018) onboard R. V. Sindhu Sadhana. In this study, we have described the results from two cruises along the central Arabian Sea that experiences open ocean upwelling in its northern flank and downwelling in the south during the summer monsoon. Atmospheric forcing was found to directly control the hydrography, nutrient availability, and phytoplankton size class distribution across the central Arabian Sea with a distinct interannual difference. The phytoplankton size classes (micro, nano, and picophytoplankton) constructed using the marker pigment data showed prominent spatial and interannual variability that was consistent with the microscopic study.