Aerosol-Cloud-Rainfall Properties Inferred from Satellite Observations Over Different Regions of the Indian Subcontinent: Variability, Trends and Relationships During the Summer Monsoon

In the present work, the variability, trends and relationships of aerosol, cloud and rainfall are explored for three regions of the Indian subcontinent: the Indo-Gangetic Plain (IGP), central India (CI) and the North Indian Ocean (NIO). The investigated properties include the monthly averages of satellite retrievals for the aerosol optical depth (AOD), angstrom exponent (AE), aerosol index (AI), cloud effective radius (R-e), cloud optical thickness (COT), cloud liquid water path (LWP) and rain rate (RR). Inter-annual and seasonal variability and long-term trends for these properties were analyzed over the regions selected. The analysis showed apparent regional and temporal variations in all seven parameters. Strong increases in aerosol properties over the IGP and CI regions over the last two decades have enabled the study of the response to cloud and rainfall properties. Further, aerosol-cloud-rain rate relationships during the summer monsoon were verified using linear fit analysis (using AOD [and AI], R-e, LWP and RR) for the three regions, respectively. A negative relation between AOD and R-e was seen over the three regions, whereas AOD and RR showed a negative relation over IGP and NIO. It was found that the AI property, which represents the aerosol number, is inversely correlated with R-e but positively correlated with RR during the monsoon season over the IGP and CI. AI and LWP showed a negative relation for CI but a positive relation for IGP and NIO. We believe that this study will help in assessing regional and global climate impacts due to aerosols.

Automated summary

This study explores the variability, trends, and relationships of aerosol, cloud, and rainfall over three regions in the Indian subcontinent. Significant increases in aerosol properties were observed over the past two decades, impacting cloud and rainfall characteristics. Linear fit analysis confirmed aerosol-cloud-rain rate relationships during the summer monsoon period.