Abstract

Aerosol microphysical and optical properties play a crucial role in cloud microphysics, precipitation physics, and flood formation over areas characterised by complex monsoon
regimes. This research presents a multi-source data integration approach to analyse the spatio – temporal interaction between precipitation, aerosols and flooding the state of
Kerala, incorporating air mass trajectory analysis to examine its potential contribution to flooding. Results show that Aerosol Optical Depth (AOD) values were high in the coastal
districts (>0.8) in the La Niña year (2021) but low in the El Niño year (2015). On the precipitation side, 2018 and 2021 were both years with a high degree of anomalies, resulting in heavy rainfall that led to widespread flooding in the Thrissur district, among others. Trajectory analysis revealed that the Indian Ocean controls precipitation during the southwest monsoon and the pre-monsoon. Post-monsoon precipitation is mainly sourced from the Arabian Peninsula and Arabian Sea, transferring marine aerosols along with desert aerosols. The overall study depicts that variability in aerosol and precipitation is more subject to change by the meteorological dynamics, as well as influenced by the regional changes in land use and land cover, causing fluxes in the land-atmosphere interactions. In conclusion, the present study highlights the possible interactive functions of atmospheric dynamics and anthropogenic land use modifications in generating flood hazard. It provides essential information for land management policies and disaster risk reduction.