The paper investigates the physical phenomena that govern raindrop size distribution and cloud characteristics across the diverse climatic regions of the Indian subcontinent. The study focuses on four locations, Kolkata, Bhopal, Desalpar, and Kavaratti Island, during the monsoon period from 2014 to 2016. It employs various techniques, encompassing ground-based measurements from disdrometers, space-borne observations from MODIS, along with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, MEERA-2, and ERA-5 reanalysis outputs. The study found that there is a predominance of larger raindrops in Kolkata and Kavaratti Island during the monsoon season. This is due to the high atmospheric instability in these regions, which is expressed through convective available potential energy (). Locations with noticeable diurnal variations also exert influence over rainfall rates and the occurrence of raindrop sizes at different times throughout the day. Airflow patterns combined with anthropogenic activities affect aerosol levels in India. Bhopal and Desalpar have high dust levels during monsoon due to airflow from desert regions. In urban centers with significant anthropogenic activity, such as Kolkata and Bhopal, sulfate aerosols dominate, while Desalpar and Kavaratti Islands are characterized by a greater prevalence of sea salt aerosols. The dominance of different aerosol types impacted the cloud features, and, as a result, the occurrence of mean raindrop sizes at the four locations. The investigation also found that regions characterized by the predominance of larger raindrops during the monsoon season exhibit a lower cloud-effective radius normalized by the liquid water path. The variability of the raindrop size distribution impacts the empirical relationships between radar reflectivity () and rain rate (, as well as between mass-weighted mean drop diameter () and , over the four locations. The study emphasizes the importance of considering varying relationships for accurate estimation of rain rates from radar reflectivity measurements in different climatic regions.

中文翻译：

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研究印度地区季风雨滴大小与相关大气参数的关系

本文研究了控制印度次大陆不同气候区域雨滴大小分布和云特征的物理现象。该研究重点关注 2014 年至 2016 年季风期间的四个地点：加尔各答、博帕尔、德萨尔帕和卡瓦拉蒂岛。它采用了各种技术，包括测距仪的地面测量、MODIS 的星载观测以及混合观测单粒子拉格朗日积分轨迹 (HYSPLIT) 模型、MEERA-2 和 ERA-5 再分析输出。研究发现，季风季节期间，加尔各答和卡瓦拉蒂岛主要出现较大的雨滴。这是由于这些地区的大气高度不稳定，这通过对流可用势能 () 来表示。昼夜变化明显的地点也会对降雨率和全天不同时间雨滴大小的出现产生影响。气流模式与人为活动相结合影响印度的气溶胶水平。由于来自沙漠地区的气流，博帕尔和迪萨尔帕在季风期间灰尘含量很高。在加尔各答和博帕尔等人类活动频繁的城市中心，硫酸盐气溶胶占主导地位，而德萨尔帕岛和卡瓦拉蒂群岛的特点是海盐气溶胶更为普遍。不同气溶胶类型的主导地位影响了云的特征，从而影响了四个地点平均雨滴尺寸的出现。调查还发现，季风季节以较大雨滴为主的地区表现出较低的液态水路径归一化的云有效半径。雨滴尺寸分布的可变性影响四个地点的雷达反射率 () 和降雨率 (，以及质量加权平均雨滴直径 () 和 之间的经验关系。该研究强调了考虑不同关系的重要性根据不同气候地区的雷达反射率测量准确估计降雨率。