Validation of CAMS AOD using AERONET Data and Trend Analysis at Four Locations in the Indo-Gangetic Basin

Abstract. In this work we have validated Copernicus Aerosol Monitoring Service (CAMS) derived aerosol optical depth (AOD) at four locations (Kanpur, Gandhi College, Jaipur and Lahore) in the Indo-Gangetic Basin and used it to study the aerosol climatology and trend in AOD at these locations. Lahore and Kanpur are urban and industrial sites with agricultural activity in the neighbouring regions. Gandhi College is in a rural agricultural area, whereas Jaipur is a desert dust source area. Aerosol climatology at the four sites are examined with MODIS-derived NDVI and ESA-CCI derived soil moisture data. CAMS-derived AOD for black carbon, sulphate, dust, sea salt and organic matter at the four sites are studied and discussed. It is observed that sulphate AOD has the largest influence on the total aerosol climatology. Contribution from dust and sea salt aerosols is observed only during pre-monsoon and monsoon seasons, whereas non-zero AOD is observed for organic matter, black carbon and sulphate aerosols throughout the year at all sites. Comparison of CAMS AOD with AERONET AOD shows better correlation when aerosol climatology is dominated by coarse particles as compared to when it is dominated by fine particles (e.g., at Kanpur, R²_pre-monsoon = 0.63 and R²_winter = 0.36). Trend analysis shows largest increase in organic matter (e.g., 0.305 ± 0.021 per year at Kanpur) and least in sea salt aerosols (e.g., 0.008 ± 0.001 per year at Kanpur).