Spatio-temporal variations in columnar aerosol optical properties over Bay of Bengal: Signatures of elevated dust

Multiyear all-season characterization of the columnar optical properties of aerosols over Bay of Bengal (BoB) has been carried out using simultaneous data from MODIS and TOMS satellite sensors. Significant spatio-temporal heterogeneity has been observed in the columnar aerosol optical properties over BoB. Latitudinally, MODIS derived Aerosol optical depths (AOD), its Small mode fraction (SMF, except pre-monsoon) has shown increasing trends towards northern latitudes of BoB. A pocket of high Aerosol Index (AI) values has been observed over the north-western part of BoB during pre-monsoon. Longitudinally, the variations in the aerosol properties are subdued comparatively. SMF values tend to increase weakly towards eastern longitudes during all the seasons. Variations in the aerosol properties are parameterised using best fit analytical functions. By simultaneous examination of AI, AOD and SMF, it has been inferred that the aerosol load responsible for the higher values of AI over BoB during pre-monsoon is dominated by the transported UV-absorbing dust.

► Large spatio-temporal heterogeneity in aerosol optical properties over BoB.
► Signatures of transported dust aerosols over BoB.
► Subdued longitudinal variations compared to latitudinal variations.