Diurnal variation of precipitation is a fundamental periodic signal of local climate. Comprehensive study of diurnal variation of precipitation is helpful in studying the formation of local climate and validating satellite precipitation products. In this study, a comparison is drawn between precipitation gauge observations and Tropical Rainfall Measuring Mission (TRMM) 3B42 data on diurnal variation of precipitation. First, using the K-means clustering algorithm, stations with gauge observations and pixels with TRMM data are divided into different groups according to the diurnal variation of precipitation, respectively. In each group, the stations have similar diurnal variation of precipitation. Then maps of diurnal variation of precipitation for gauge observations and TRMM data are obtained. According to these maps, the diurnal variation of precipitation over the contiguous United States (CONUS) presents seasonal variability in both gauge observations and TRMM data. In addition, the diurnal variation of precipitation shows clustered features in space. However, the spatial patterns of the obtained maps do not match, and the TRMM satellite data perform poorly in capturing the hourly precipitation event. Finally, the possible mechanism behind the prevailing nocturnal precipitation over the middle of the CONUS is discussed, with the prevailing nocturnal precipitation judged likely to be strongly related to the mountain-plains solenoid (MPS) circulation.

中文翻译：

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CONUS季节性降水的日变化：量表观测与TRMM数据的比较

降水的日变化是当地气候的基本周期性信号。对降水日变化的综合研究有助于研究当地气候的形成和验证卫星降水产物。在这项研究中，比较了降水量表的观测值和热带降水量测量任务（TRMM）3B42的降水日变化数据。首先，使用K-均值聚类算法，具有观测值的观测站和具有TRMM数据的像素分别根据降水的昼夜变化分为不同的组。在每个组中，这些站的降水日变化相似。然后获得降水的昼夜变化图，用于观测观测和TRMM数据。根据这些图，连续美国（CONUS）上降水的日变化在量具观测和TRMM数据中都表现出季节性变化。此外，降水的日变化显示了空间上的聚类特征。但是，获得的地图的空间模式不匹配，TRMM卫星数据在捕获每小时降水事件方面表现不佳。最后，