Assessment of long-term trends in chlorophyll-a and sea surface temperature in the Arabian Sea and their association with aerosols using remote sensing

Aerosols over the oceanic region significantly influence Earth's energy budget and climate change. Therefore, this study examines the spatiotemporal patterns of MODIS retrieved aerosol optical depth, sea surface temperature, Chlorophyll-a, Sea-WiFS retrieved aerosol optical depth, and MERRA-2 model dust mass concentrations over the Arabian Sea (4o N-26o N to 50o E- 78o E) during the period 2002-2020. The effects of dust aerosols on phytoplankton blooms using the Mann-Kendall and Theil Sen-slope are also analyzed in this study. An increase in aerosol optical depth (AOD) was observed within the latitudes of (4o N-26o N). The AOD shows an increasing trend at 13.4% per year over the Arabian Sea (AS). The highest value of Chl-a (-7 mgm 3) was observed along the coast of Pakistan, Iran, and Oman. Moreover, a negative correlation is found between AOD and sea surface temperature (SST) along the coast of Oman and Somalia, while a strong positive correlation (-0.99) is observed between AOD and Chlorophyll-a (Chl-a) along the coasts of Oman and Somalia.

Automated summary

This study examines the spatiotemporal patterns of aerosol optical depth, sea surface temperature, Chlorophyll-a, and dust mass concentrations over the Arabian Sea. It also analyzes the effects of dust aerosols on phytoplankton blooms. The results show an increasing trend in aerosol optical depth and a negative correlation between aerosol optical depth and sea surface temperature, as well as a strong positive correlation between aerosol optical depth and Chlorophyll-a along the coasts of Oman and Somalia.