Remote sensing of upwelling in the Arabian Sea and adjacent near-coastal regions

Abstract

Upwelling is a dominant mechanism in the Arabian Sea that occurs annually during southwest monsoon summer season. This results in abundance of phytoplankton and zooplankton in the region and has profound influence on the coastal fisheries. During the southwest monsoon, an intense low-level wind jet blows diagonally across the Arabian Sea generating coastal upwelling along the coasts of Somalia, Oman and the southeastern Arabian Sea. In this study, a synergy of different parameters like sea surface winds, chlorophyll (chl-a), sea surface temperature (SST) and sea level anomaly (SLA) retrieved from remote sensing were used to make a more detailed analysis on upwelling features for the summer seasons of the years 1982-2015. From the analysis, it is observed that upwelling in the Arabian Sea is not homogeneous across the basin despite being driven by monsoon winds. During the study period, Ekman transport, SLA and SST anomaly showed positive trend, whereas chlorophyll showed negative trend of varying strengths. Increased Ekman transport has not generated increased productivity indicating the role of other governing mechanisms on the availability of nutrients in the region.