The variation characteristics of rain storms (RSs) are closely related to complex internal physical processes and external dynamic and thermodynamic conditions. Using a 17-year observational rainfall dataset from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), the diurnal cycles of various RS characteristics and their responses to the South China Sea Summer Monsoon (SCSSM) are investigated in South China (SC) during the presummer rainy season (PSRS). Before SCSSM outbreaks, the RSs in the western inland region of SC (WSC) have stronger precipitation intensities and convective features due to orographic lifting, especially at night, while those in the eastern inland region of SC (ESC) have higher RS occurrence frequencies with higher moisture transport, especially in the afternoon. The onset of the SCSSM leads to abundant moisture and sufficient convective available potential energy over the entire SC area, resulting in significant increases in the occurrence frequency, convective fraction, and precipitation top height of RSs. In the WSC, the weakened upward motion and smaller convective inhibition limit RS development, resulting in weaker rainfall intensity. In the ESC, a particularly unstable atmosphere and enhanced low-level moisture transport in the afternoon lead to a larger three-dimensional size, more active convection, and greater precipitation intensity in the RSs. These results offer fresh insight into the diurnal variation in rainfall during the PSRS and can be effectively used to evaluate numerical model simulations.

中文翻译：

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华南地区夏季雨季暴雨日周期变化


暴雨（RS）的变化特征与复杂的内部物理过程和外部动力、热力条件密切相关。利用热带降雨测量任务（TRMM）降水雷达（PR）17年的观测降雨数据集，研究了华南（SC）各种遥感特征的日循环及其对南海夏季风（SCSSM）的响应）在夏季雨季（PSRS）期间。南海夏季风爆发前，由于地形抬升，华夏西部内陆地区（WSC）的RS有较强的降水强度和对流特征，尤其是夜间，而华夏东部内陆地区（ESC）的RS出现频率较高，较高的湿度运输，尤其是在下午。南海夏季风的爆发导致整个南海区域存在丰富的水汽和充足的对流可用势能，导致RS的出现频率、对流分数和降水顶高度显着增加。在WSC，上升运动减弱和对流抑制较小限制了RS的发展，导致降雨强度减弱。在ESC中，特别不稳定的大气和下午增强的低层水汽输送导致RS中的三维尺寸更大、对流更活跃以及降水强度更大。这些结果为 PSRS 期间降雨量的日变化提供了新的见解，并且可以有效地用于评估数值模型模拟。