Study of the Long-term Average Concentration of Chlorophyll a and Its Relation to Variations in Sea Level Temperature and Aerosol Optical Depth over the Sea of Oman and the Persian Gulf (2003-2020)

Chlorophyll concentrations in marine environments indicate phytoplankton levels and ultimately the production of marine ecosystems. Chlorophyll concentration is not constant and depends on quantities such as sea surface temperature and aerosols optical depth, it also has seasonal variations and the correlation between these factors is various at different depths. Investigating the long-term relationship (2003 to 2020) between sea level temperature changes and aerosol optical depth with chlorophyll concentration on the Persian Gulf and the Sea of Oman coasts using daily MODIS products shows a considerable correlation in coastal areas. This correlation is the highest in shallowest water depths. The trend of sea-level temperature and light depth of aerosols changes in the two regions of the Persian Gulf and the Sea of Oman is similar, and its highest values are observed in summer, while its lowest is observed in winter. Remarkably, this seasonal trend is reversed in chlorophyll concentrations, with the lowest values observed in summer and the highest in winter. Additionally, the study of dust occurrence on July 30, 2018, showed the possibility of time delay in the correlation between sea-level temperature and aerosol optical depth with chlorophyll-a concentration.