Based on the hourly gauge-satellite merged precipitation data with the spatial resolution of 0.1° × 0.1° during 2013 ~ 2018, we have evaluated the performance of the convection-permitting Weather Research and Forecasting model at Nanjing University (WRF_NJU) in forecasting the precipitation diurnal variation and the associated atmospheric circulation over the eastern Tibetan Plateau and its surrounding regions during summer. Results indicate that WRF_NJU model can well reproduce the diurnal cycle of the summer precipitation in terms of the diurnal peak time, duration and magnitude. In addition, the eastward propagation of rainfall systems with long duration along the eastern Tibetan Plateau (ETP) and its adjacent areas can also be properly captured. The WRF_NJU model can reasonably reproduce the relevant atmospheric circulation during summer as well. However, the model tends to underestimate the summer precipitation amount (PA) and precipitation frequency (PF) over most time of a day. Relatively larger biases in the occurring time and magnitude of PA and PF diurnal peaks can be noted over the ETP and Sichuan Basin. Further analysis suggests that the underestimation of PA over the ETP is attributed to the much lower moisture supply, weaker low-level southwesterly winds and less convective available potential energy (CAPE) in the WRF_NJU model than in ERA5. Over Sichuan Basin, the underestimated PA is related to the weaker upward motion, which is corresponding to the cold biases of surface air temperature in WRF_NJU. Findings of this study provide the basic model biases and may be helpful to further improve the model physical processes.

基于2013〜2018年的小时尺度卫星合并降水数据，空间分辨率为0.1°×0.1°，我们评估了南京大学对流允许天气研究和预报模型（WRF_NJU）在预报降水方面的性能夏季，青藏高原东部及其周边地区的日变化和相关的大气环流。结果表明，WRF_NJU模型可以从日峰值时间，持续时间和强度方面很好地再现夏季降水的日周期。另外，也可以正确地捕捉到降雨系统沿青藏高原东部及其附近地区向东传播的时间。WRF_NJU模型也可以合理地再现夏季的相关大气环流。但是，该模型往往会低估一天中大部分时间的夏季降水量（PA）和降水频率（PF）。在ETP和四川盆地，PA和PF日峰值出现的时间和幅度的偏差较大。进一步的分析表明，与EERA5相比，WRF_NJU模型中的水分供给低，西南风偏弱以及对流可用势能（CAPE）较低，导致PA对ETP的低估。在四川盆地上空，偏低的PA与向上运动较弱有关，这与WRF_NJU中地表气温的冷偏差相对应。