Abstract An extreme rainfall event that made major calamity over the Indian peninsula region has been investigated with a focus on the physics of the cloud system as indicated from the multi-satellite observations, ground-based radar, and model forecast experiments. The vertical structure of clouds showed deep convective cores embedded in the stratiform and is dominated by warm and mixed-phase clouds. Model output indicates that moisture convergence was present in two episodes before both heavy rainfall events, and can be used as a precursor for the imminent heavy rainfall. It is the sustenance of high winds and availability of moisture content that contributed to the development of deep convective cloud bands which propagated inland, perpendicular to the coastline. These cloud systems produced deep convective cores with a deep supersaturated layer throughout the middle and upper atmosphere, introduced a significant amount of supercooled liquid water, which facilitated mixed-phase clouds. These cloud liquid drops at supercooled temperatures facilitated the production of more ice hydrometeors on freezing. The rapid growth of hydrometeors through riming and aggregation in the mixed-phase region lead to heavy and sustained precipitation. The sustenance of the system is also due to the enhanced latent heating over Western Ghats that supported low-level moisture convergence in a strongly sheared environment. Documented evidence from this study suggests that the heavy precipitation was a result of the convective cluster as illustrated through satellite observations and numerical simulations.

中文翻译：

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极端降雨事件的物理学：多卫星观测和数值模拟的调查

摘要 以多卫星观测、地基雷达和模式预报实验表明的云系统物理特性为重点，对一起在印度半岛地区造成重大灾害的极端降雨事件进行了调查。云的垂直结构显示出深对流核心嵌入层状结构，以暖相云和混合相云为主。模型输出表明，在两次强降雨事件之前的两个事件中都存在水分收敛，可以用作即将到来的强降雨的前兆。正是强风的维持和水分含量的可用性促成了垂直于海岸线向内陆传播的深对流云带的发展。这些云系统在整个中层和高层大气中产生了具有深过饱和层的深层对流核心，引入了大量的过冷液态水，促进了混合相云的形成。这些在过冷温度下的云状液滴有助于在冻结时产生更多的冰水凝物。水凝物通过混合相区域的边缘和聚集快速增长，导致大量持续的降水。该系统的维持还归因于西高止山脉上增强的潜热，支持在强烈剪切环境中低水平的水分汇聚。这项研究的书面证据表明，如卫星观测和数值模拟所示，强降水是对流星团的结果。