Impact of Sea Surface Temperature and Sea Surface Winds on Chlorophyll-a and its seasonal variations in Northern and Northwestern Arabian Sea

The magnitude of change in Chlorophyll-a (Chl-a) concentration in the Northern Arabian Sea (NAS) and northwestern Arabian Sea (NWAS), associated winds and Sea Surface Temperature (SST) that could potentially contribute to the fisheries management policies were investigated. The aforementioned parameters were examined from 2003 to 2021 by considering the area into 7 regions. Off Oman, monthly average winds delineate the presence of weak anticyclonic circulation during October and another one from February strengthening and migrating southwards till April. This feature is absent in May. For the first time, the warming in different regions was investigated and observed a temperature range from 0.4 °C to 0.8 °C with highest off Iran and least off central Oman. The Ekman Mass Transport (EMT) decreased with the highest off Pakistan (18.91%) and least off central Oman (0.55%). The decrease in Chl-a concentration was highest off Iran and least off Oman. The correlation of Chl-a with SST off Yemen was highest (-0.55) indicating that any change in SST will more conclusively influence Chl-a off Yemen than the rest of the regions. From 2003 to 2021 the wind speed off Oman increased up to 0.46 m/s while the other regions show decreased wind speed. The maximum correlation between winds and Chl-a was observed off Oman, indicating that changes in winds are more likely to affect Chl-a concentration in this region compared to other regions. The study statistically establishes the differential influence of SST and Sea Surface Winds (SSW) in the study area.