Study of aerosol-cloud-precipitation-meteorology interaction during a distinct weather event over the Indian region using WRF-Chem

Abstract

The impact of aerosols on cloud microphysical properties, as well as precipitation during a wintertime hot weather event, occurred in February 2016 is analyzed. The chemistry module embedded within Weather Research and Forecasting model (WRF-Chem) is primarily used for this study. During the pre-mature and mature phases of the event, hot and dry westerly winds found to be dominating, and consequently, a significant amount of aerosol transport observed. Temperature is relatively higher during the mature and dissipating phases from the simulations when compared with that of the 30-years mean climatology from ERA-Interim. The convergence of westerly and easterly winds is evident over the north-eastern and eastern parts of the study region during the dissipating phase. A significant amount of relative humidity and water vapor mixing ratio found over the north-eastern and eastern parts. Rainfall occurred over the north-eastern and eastern parts of the study region during the dissipating phase. All simulations overestimated rainfall over a few locations, whereas underestimation by the model is over most of the regions. DEF and INDEF simulated results indicate that AOD is overestimated in most of the parts of the study region, while underestimated over a few areas. Vertically integrated cloud fraction value is moderate to high during the dissipating phase over the location where precipitation occurred. Positive AOD and rainfall relationship indicates invigoration effect, which possibly enhanced the precipitation during the dissipating phase in the presence of aerosols. However, the variability of cloud condensation nuclei within 600 hPa from the surface does not necessarily correspond to the hydrometeor variations to impact the rainfall occurrence, amount, and spatial distribution. A combined effect of thermodynamic, dynamic, and microphysical processes is realized for determining the clouds and precipitation response to aerosols during the weather event.