Variation of aerosol optical and physical properties and their impact on rainfall over Indo-Gangetic Basin

Aerosols are one of the important constituents of the atmosphere which can disturb the Indian monsoon by affecting the precipitation over Indian subcontinents. To investigate the consequence of aerosol properties on rainfall, we have analysed the long-term annual trends and annual correlation between aerosol properties and rainfall using ground-based AErosol RObotic NETwork (AERONET) data and satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) data. We have used four diverse sites in Indo- Gangetic Basin (IGB); Gandhi College, Jaipur, Lahore, and Kanpur. A significant trend of aerosol optical depth (AOD) and angstrom exponent (AE) along with the trend of imaginary refractive index (IRI)/ real refractive index (RRI) followed by the trend of single scattering albedo (SSA) over Gandhi College, Jaipur and Lahore suggests enhancement of coarse mode scattering and absorbing aerosols. In contrast, over Lahore, a significant reduction in fine mode absorbing aerosols is found. The trend of Aerosol Radiative Forcing (ARF) is found to be decreasing over Gandhi College, Lahore, and Kanpur while it is found to be increasing over Jaipur. A significantly increasing trend of rainfall over Lahore and Kanpur while a considerably decreasing trend over Gandhi College and Jaipur is, found. AOD shows a positive correlation over all locations and AE also indicates a positive correlation over three locations instead of Jaipur. SSA exhibits a negative correlation with rainfall over Jaipur, Kanpur, and Gandhi College while it is found to have a positive correlation over Lahore. RRI shows a negative trend overall locations except Kanpur. In contrast, IRI shows a negative trend with rainfall over all of Lahore and Kanpur and a positive trend over Jaipur and Gandhi College. And, ARF displays a constructive correlation with rainfall over all the locations.