Spaceborne observations of aerosol vertical distribution over Indian mainland (2009–2018)

Abstract

Since the past two decades, high aerosol loading is being observed over the Indian mainland. It becomes necessary to continuously monitor and understand the distribution of aerosol loading over the Indian landmass, as it might have serious health and climatic implications. Whereas there have been extensive studies reporting seasonal distribution and trends of columnar aerosol amounts over the Indian region using data from ground based as well as space borne measurements, in-depth studies on the aerosol vertical profile distribution and in particular, seasonal trends are still lacking. This paper demonstrates the seasonal variability of aerosol vertical structure over the Indian mainland using decadal daily datasets (2009–2018) from CALIOP Lidar (onboard NASA-CNES's CALIPSO satellite) augmented by the variability in columnar AOD from MODIS (onboard NASA's AQUA and TERRA platforms). The changing aerosol amounts in both vertical and total column levels have also been presented. Over Indian landmass, we could find statistically significant increasing trends in aerosol extinction within lower altitude levels during all the seasons. The trends in the vertical distribution of aerosols are also compared with respect to trends in AOD derived from MODIS (Aqua/Terra). Additionally, we have also examined the seasonal variability and trends of aerosol extinction over five selected cities (based on pollution and population levels) of the country.