Spatiotemporal variability of MODIS-Aqua-derived aerosol and its impact on surface chlorophyll-a in the Indian coastal and offshore waters

Abstract

Observation was made to understand the spectral behavior of aerosol from the NASA moderate resolution imaging spectroradiometer (MODIS-Aqua) sensor data. The 869 nm central wavelength band MODIS-Aqua-derived images were retrieved and interpreted. The aerosol concentration was found to be higher during December (Northeast monsoon) over the Bay of Bengal (BoB). Its characterized distinct plume with higher aerosol optical depth (AOD) ranged between 0.05 and 0.25. The coastal aerosol concentration was higher than the offshore region, with decreasing trend (AOD∼0.05 ). To understand aerosol’s link with ocean biological productivity in terms of phytoplankton pigment, the ocean surface chlorophyll was retrieved from 8-years monthly datasets (2002 to 2010). MODIS-Aqua-derived monthly scale aerosol and chlorophyll data were analyzed in the northern Indian Ocean (NIO) region during July 2002 to June 2010. Their interrelationship was found to be significant (r 2 =0.663 and 0.584) over pockets in the BoB and Arabian Sea. Land to seaward movement of wind and aerosol plays a significant role to increasing ocean productivity. This study is very important and interesting to understand the precise composition of aerosol dust like iron (Fe) and increase in sulfate ions, nitrates, etc., and their link to phytoplankton biomass and the related productivity in the Indian water and attempted for the first time in the NIO water.