This paper presents the seasonal mean, rain integral parameters, and gamma parameters at the surface associated with the different precipitating systems over a coastal station Thumba (8.53°N, 76.87°E). The primary datasets consist of Joss-Waldvogel disdrometer (JWD) observations collected during 2007–2015 and 2018 over Thumba. The precipitating cloud systems observed over three seasons (pre-monsoon: March-May, Monsoon: June-September and post-monsoon: October and November) are classified into convective, transition and stratiform rain based on the ratio of mass-weighted mean diameter (D_m) and rain rate (R). The results show a distinct difference in raindrop size distribution (DSD) patterns in the convective, transition and stratiform rain types. In general, the mean DSD spectra for convective precipitation is found to be broad compared to that of the transition and stratiform rain types. The DSD spectra in the convective precipitation have relatively higher (smaller) number concentration of large (small) raindrops as compared to other precipitation types, resulting in larger D_m values than the other two rain regimes. These differences in DSD for the convective, transition and stratiform resulted in a systematic variation in Z-R relationships. A distinct inverse relationship is found between A and b for convective and stratiform rain types irrespective of seasons. The coefficient A (exponent b) is found to be larger (smaller) for stratiform (convective) rain regime. Out of about 1826 h of total precipitation, stratiform rain is observed for 63% of the time, while convective and transition rain is observed for about 8% and 29% respectively. However, the contribution of stratiform rain is 11% of total rainfall, while that of convective and transition rain are about 55% and 35% respectively, consistent with the earlier studies.

本文介绍了沿海站点Thumba（8.53°N，76.87°E）上与不同降水系统相关的地表的季节平均，降雨积分参数和伽玛参数。主要数据集由Joss-Waldvogel测速计（JWD）观测值在2007–2015和2018年期间通过Thumba收集。根据质量加权平均直径的比率，将三个季节（季风前：3月至5月，季风：6月至9月以及季风后：10月和11月）观测到的降水云系统分为对流，过渡和层状降雨。 （_米）和降雨率（R）。结果表明，在对流，过渡和层状降雨类型中，雨滴尺寸分布（DSD）模式存在明显差异。通常，对流降水的平均DSD谱与过渡型和层状雨型的DSD谱相比较宽。与其他降水类型相比，对流降水中的DSD谱具有较大（较小）雨滴的相对较高（较小）数量浓度，导致D _m较大值比其他两个降雨体制高。DSD在对流，过渡和层状方面的这些差异导致ZR关系的系统变化。对流和层状降雨类型与季节无关，在A和b之间发现明显的反比关系。对于层状（对流）雨区，发现系数A（指数b）较大（较小）。在约1826小时的总降水量中，观察到层状降雨的时间为63％，而对流和过渡降雨的时间分别为8％和29％。然而，层状雨的贡献占总降雨量的11％，而对流雨和过渡雨的贡献分别约为55％和35％，与早期研究一致。