The state of Kerala located in the southwestern part of India experienced heavy to extremely heavy rainfall events from 07 to 17 August 2018 during the southwest monsoon, leading to a devastating flood and extensive infrastructure damage. Rainfall analysis suggests that the prolonged heavy rainfall event between 14 and 17 August 2018, was responsible for the major devastation. In this work, the sensitivity of prediction of heavy rainfall during 14–17 August 2018 to cloud microphysics parameterization (CMP) is investigated using the Weather Research and Forecasting (WRF) model. High resolution (1-km) cloud resolving simulations are conducted to study the sensitivity of rainfall to the cloud microphysics schemes and cloud-aerosol interactions. The model results are compared with observations such as Automatic Weather Station, Tropical Rainfall Measuring Mission, radiosonde, Global Precipitation Mission precipitation estimates and Doppler weather radar products. Comparisons of simulated hydrometeor structure with DWR estimates and thermodynamic stability indices with radiosonde reveal that the differences in microphysics formulations play a vital role on the thermodynamic profile that in turn influence the intensity of convection and hydrometeor structure responsible for the extremely heavy rainfall. Comparison of simulated rainfall with IMD observational estimates suggests that the Thomson aerosol aware scheme, followed by Goddard microphysics captured the spatial and temporal distributions of observed heavy rainfall. The Thomson aerosol aware scheme followed by Goddard produced strong convective instability conditions for heavy rainfall due to the simulation of a strong westerly jet and the formation of an offshore vortex.

2018年8月7日至17日，西南季风期间，印度西南部的喀拉拉邦经历了特大到特大降雨事件，导致毁灭性的洪灾和广泛的基础设施破坏。降雨分析表明，2018年8月14日至17日之间长时间的强降雨事件是造成重大破坏的原因。在这项工作中，使用天气研究和预报（WRF）模型研究了2018年8月14日至17日的强降雨预报对云微物理参数化（CMP）的敏感性。进行了高分辨率（1公里）的云解析模拟，以研究降雨对云微物理方案和云气溶胶相互作用的敏感性。将模型结果与诸如自动气象站，热带雨量测量团，探空仪，全球降水团降水估算和多普勒天气雷达产品。比较具有DWR估计值的模拟水凝物结构和具有探空仪的热力学稳定性指数，结果表明，微观物理学公式的差异对热力学剖面起着至关重要的作用，进而影响对流强度和造成极端大雨的水凝物结构。模拟降雨与IMD观测估计值的比较表明，汤姆森气溶胶感知方案以及随后的戈达德微观物理学捕获了观测到的强降雨的时空分布。