Towards an Improved Representation of Dust Aerosol–Rainfall Relationship Influenced by 2018 Dust Event over Indian Region by Using Regional Climate Model: Impact of Horizontal Resolution

Abstract

By using the Regional Climate Model (RegCM), this study aims to determine the influences of dust aerosols on the Indian summer monsoon and the shift of the Indian summer monsoon-related atmospheric features during the 2018 dust event. We integrate the RegCM over the Indian region at two distinct horizontal resolutions. The results obtained from the model simulations demonstrate reasonable similarities to observational and reanalysis data. We identify the diverse phases of the variation in the mean distribution of monsoon-associated characteristics in response to the dust event. Dust accumulation along the Tibetan Plateau's slopes in May creates an atmospheric column over the region, dragging the monsoonal flow towards the Foothills of the Himalayas (FoH) before the conventional arrival of the southwest monsoon. As a result, rainfall tends to increase along the FoH and decrease over central India in June. The EHP phenomenon completely dissipated in July. The atmospheric conditions further intensified during August. Apart from that, we also explore the consequences of horizontal resolution in representing the impact of dust events on rainfall in the Indian region. We have discovered that the inclusion of dust at a 25-km horizontal resolution has resulted in a decrease in rainfall in certain regions of the north-western, Indo-Gangetic Plain, and southern India. The increasing resolution shows distinct patches of reduced rainfall over the Indian region, which indicates that the dust aerosols may impact rainfall significantly over local regions.