The characteristics of precipitation microphysics during various stages of the tropical cyclone (TC) Nisarga (2020) as observed over an orographic station of Western Ghats, India has been highlighted in this paper. The study examines the evolution of convective rain along with the features of surface raindrop size distribution (DSD) within the rainbands and eyewall of the cyclone “Nisarga” based on the observational data of Doppler weather radar and disdrometer during June 02–03, 2020. The cyclone Nisarga, which formed in the Arabian sea, had passed over the Western Ghats after its landfall in the south-western coast of Indian sub-continent. The thermodynamical and microphysical features of the prevailing cloud exhibits strong intensity over the oceanic region than that of over the orographic one along the track of the cyclone. While looking into the impact of rainbands of cyclone as observed by Doppler weather radar over the orographic region, a continuous rise in precipitation is visible when the flow of the cyclone is oriented along the upslope of the terrain. The precipitation intensity and the percentage of occurrences of convective rainfall increased as the primary eyewall of the cyclone reached the orographic station. These are basically due to the presence of the deep convective clouds surrounding the eye of the cyclone, which produces heavy precipitation over the orographic station. Moreover, the orographically generated cloud water along with the shallow convection also plays an important role for the modification of precipitation microphysics over this region of Western Ghats. Thus, these heterogeneous features of rainfall occurrences over the orographic region during the propagation of TC exhibits different radar reflectivity-rain rate (Z-R) relationship which suggests the necessity of a variable relationship for quantitative precipitation estimation (QPE) in different sectors of the TC.

本文重点介绍了在印度西高止山脉的一个地形站上观测到的热带气旋 (TC) Nisarga (2020) 各个阶段的降水微物理特征。该研究基于 2020 年 6 月 2 日至 3 日期间多普勒天气雷达和偏差计的观测数据，研究了对流雨的演变以及气旋“尼萨尔加”的雨带和眼墙内的表面雨滴尺寸分布 (DSD) 特征。在阿拉伯海形成的气旋尼萨尔加在登陆印度次大陆西南海岸后越过西高止山脉。盛行云的热力学和微物理特征在海洋区域比在沿气旋轨迹的地形上表现出更强的强度。在研究多普勒天气雷达在地形区域上观察到的气旋雨带的影响时，当气旋的流动沿着地形的上坡定向时，可以看到降水持续增加。随着气旋的主要风眼墙到达地形站，降水强度和对流降雨发生的百分比增加。这些基本上是由于气旋眼周围存在深对流云，从而在地形站上产生强降水。此外，地形生成的云水以及浅层对流也对西高止山脉该地区降水微物理的改变起着重要作用。因此，Z- R) 关系表明在 TC 的不同部门中定量降水估计 (QPE) 的变量关系的必要性。