In this study, we have examined the role of implicit and explicit representation of cloud microphysics on the simulation of a monsoon depression formed over the Bay of Bengal and the associated rainfall from 0000 UTC of 13 August to 0000 UTC of 17 August 2018 using the Weather Research and Forecast model. Five different WRF model simulations are performed by changing the Cloud Micro Physics (CMP) schemes: WSM6, Goddard, Thompson, Morrison, and Thompson Scheme with Aerosol aware options in both explicit and implicit cloud models. WRF simulations are conducted by initializing the NCEP GFS analysis at 0000 UTC of 13 August 2018 and integrated up to 96-h. The boundary conditions are updated at 6-hourly intervals with the respective GFS forecasts. Our results of sensitivity simulations suggest that the Thompson Scheme with Aerosol aware scheme, followed by Goddard microphysics, captured the features of monsoon depression and associated rainfall. Microphysics schemes have an influence on the simulation of low level westerly jet, and upper level easterly jet. Implicit and explicit cloud microphysics options are able to reproduce the convection over the west-coast, but the implicit option failed in producing the prolonged convection over the east coast. The comparison of model rainfall with rain-gauge, and satellite merged rainfall estimates reveals that the large scale off-shore precipitation is better captured in CMP with the inclusion of explicit cumulus parameterization. The orographic rainfall over the wind-ward and lee-ward sides of the Eastern and Western Ghats is well predicted in the implicit CMP. The vertical distribution of the hydrometeors and rainfall analysis suggest that the Thompson Scheme with Aerosol aware scheme with the cloud-resolving explicit mode is suitable for simulating the monsoon depressions formed over the Bay of Bengal and the associated heavy rainfall over the east coast of India.

中文翻译：

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云微物理对孟加拉湾季风低压模拟的敏感性

在这项研究中，我们研究了云微物理的隐式和显式表示在模拟孟加拉湾上空形成的季风洼地以及相关降雨量从 8 月 13 日 0000 UTC 到 2018 年 8 月 17 日 0000 UTC 使用天气的作用研究和预测模型。通过更改云微物理 (CMP) 方案来执行五种不同的 WRF 模型模拟：WSM6、Goddard、Thompson、Morrison 和 Thompson 方案，在显式和隐式云模型中具有气溶胶感知选项。WRF 模拟是通过在 2018 年 8 月 13 日 0000 UTC 初始化 NCEP GFS 分析来进行的，并集成到 96 小时。边界条件根据各自的 GFS 预测每 6 小时更新一次。我们的灵敏度模拟结果表明，具有气溶胶感知方案的汤普森方案，紧随其后的是戈达德微物理学，捕捉到了季风低压和相关降雨的特征。微物理方案对低层西风急流和高层东风急流的模拟有影响。隐式和显式云微物理选项能够重现西海岸上空的对流，但隐式选项无法在东海岸产生长时间的对流。模型降雨量与雨量计和卫星合并降雨量估计值的比较表明，在 CMP 中包含显式积云参数化可以更好地捕获大规模离岸降水。隐含 CMP 中很好地预测了东高止山脉和西高止山脉的迎风侧和背风侧的地形降雨。