Mesoscale convective systems (MCSs) play an important role in modulating the global water cycle and energy balance and frequently generate high-impact weather events. The majority of existing literature studying MCS activity over East Asia is based on specific case studies and more climatological investigations revealing the precipitation characteristics of MCSs over eastern China are keenly needed. In this study, we use an iterative rain cell tracking method to identify and track MCS precipitation during 2008–16 to investigate regional differences and seasonal variations of MCS precipitation characteristics. Our results show that the middle-to-lower reaches of the Yangtze River basin (YRB-ML) receive the largest amount and exhibit the most pronounced seasonal cycle of MCS precipitation in eastern China. MCS precipitation over YRB-ML can exceed 2.6 mm day⁻¹ in June, contributing over 30.0% of April–July total rainfall. Particularly long-lived MCSs occur over the eastern periphery of the Tibetan Plateau (ETP), with 25% of MCSs over the ETP persisting for more than 18 h in spring. In addition, spring MCSs feature larger rainfall areas, longer durations, and faster propagation speeds. Summer MCSs have a higher precipitation intensity and a more pronounced diurnal cycle except for southeastern China, where MCSs have similar precipitation intensity in spring and summer. There is less MCS precipitation in autumn, but an MCS precipitation center over the ETP still persists. MCSs reach peak hourly rainfall intensities during the time of maximum growth (a few hours after genesis), reach their maximum size around 5 h after genesis, and start decaying thereafter.

High-resolution meteorological datasets are urgently needed for understanding the hydrological cycle of the Tibetan Plateau (TP), where ground-based meteorological stations are sparse. Rapid advances in remote sensing create possibilities to represent spatiotemporal properties of precipitation at a high resolution. In this study, the hourly precipitation characteristics over the TP from two gridded precipitation products, one from global reanalysis (the fifth generation of the European Center for Medium-Range Weather Forecasts atmospheric reanalysis of the global climate; ERA5) and the other is simulated by Global-to-Regional Integrated forecast SysTem (GRIST) global nonhydrostatic model, are compared against satellite-gauge merged precipitation analysis (China Merged Precipitation Analysis; CMPA) from 27 July to 31 August 2014, and a satellite-retrieved precipitation estimate from the Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement (IMERG) is also evolved. Two aspects are mainly focused on: the spatial distribution and the elevation dependence of hourly precipitation characteristics (including precipitation amount, frequency, intensity, diurnal variations, and frequency–intensity structure). Results indicate that: (1) The precipitation amount, frequency, and intensity of CMPA and IMERG decrease with altitude in the Yarlung Tsangpo river valley (YTRV), but increase at first and then decrease with altitude (except for intensity) in the eastern periphery of TP (EPTP). ERA5 performed well on the variation of precipitation amount with altitude (especially in EPTP), but poorly on the frequency and intensity. GRIST is the antithesis of ERA5, but they all overestimate (underestimate) the frequency (intensity) at all heights; (2) With increasing altitude, the diurnal phase of precipitation of CMPA and IMERG shifted from night to evening in the two sub-regions. IMERG’s diurnal phase is 1 to 3 h earlier than CMPA’s, and the discrepancy decreases (increases) as the altitude increases in YTRV (EPTP). The diurnal phase of precipitation amount and frequency in ERA5 and GRIST is significantly earlier than CMPA, and the frequency peaks around midday except in the basin. GRIST’s simulation of the diurnal variation in intensity at various altitudes is consistent with CMPA; (3) ERA5 and GRIST overestimate (underestimate) the frequency of weak (intense) precipitation, with ERA5’s deviance being the most severe. The deviations increased with altitude. These findings provide intensive metrics to evaluate precipitation in complex terrain and are helpful for deepening the understanding of simulated biases for further improving performance in high-resolution simulation.

A high-impact extreme precipitation event over the Yangtze River valley (YRV) in the midsummer of 2016 is simulated using the Climate System Model of Chinese Academy of Meteorological Sciences (CAMS-CSM). After validation of the model’s capability in reproducing the climatological features of precipitation over the YRV, the Transpose Atmospheric Model Intercomparison Project (T-AMIP)–type experiment, which runs the climate model in the weather forecast mode, is applied to investigate the performance of the climate model in simulating the spatial and temporal distribution of rainfall and the related synoptic circulation. Analyses of T-AMIP results indicate that the model realistically reproduces the heavy rainfall centers of accumulated precipitation amount along the YRV, indicating that the climate model has the ability to simulate the severity of the extreme event. However, the frequency–intensity structure shows similar biases as in the AMIP experiment, especially the underestimation of the maximum hourly intensity. The simulation of two typical heavy rainfall periods during the extreme event is further evaluated. The results illustrate that the model shows different performances during periods dominated by circulation systems of different spatial scales. The zonal propagation of heavy rainfall centers during the first two days, which is related to the eastward movement of the southwest vortex, is well reproduced. However, for another period with a smaller vortex, the model produces an artificial steady heavy rainfall center over the upwind slope of the mountains rather than the observed eastward movement of the precipitation centers.

Hourly observational records are used to investigate the distinct nocturnal rainfall and related convection activities over the eastern periphery of the Tibetan Plateau (EPTP). The results show that rainfall events over the EPTP are characterized by frequent moderate rainfall with long durations, which differs from both the eastern Tibetan Plateau (TP_E) and the west Sichuan Basin (SCB_W). Although the nocturnal rainfall dominates the warm season rainfall over the EPTP and its adjacent slopes, the midnight rainfall peak is more evident over the slope and basin regions, whereas over the TP_E, the rainfall intensity tends to peak in the late afternoon. An eastwards phase delay is found from the TP_E to the downstream EPTP regions, and the signal is more evident in the intense long‐duration rainfall events. To demonstrate the regional characteristics of the rainfall processes over the EPTP and its adjacent areas, a regional rainfall event (RRE) method is applied to consider the spatiotemporal evolution of the rainfall processes. The intense long‐duration RREs over the EPTP are selected and classified into two categories, with one related to the early stage rainfall systems in the TP region (RRE_with_TP) and the other not related to the TP rainfall systems (RRE_without_TP). The RRE_with_TP cases are probably related to the propagation of rainfall systems from the plateau. By analysing the convective activity derived from the FY‐2 geostationary satellites, evidence of the close relationship between the RRE_with_TP cases and the eastwards propagation of the convective systems that develop over the TP in the late afternoon is shown, whereas the RRE_without_TP cases seem to be more locally initialized or caused by rainfall systems from eastern regions. These results provide more detailed metrics to evaluate model performances over the EPTP region where excessive rainfall has been a long‐standing problem in the simulation of the East Asian climate.

The evident nocturnal peak dominates the summer rainfall over the Sichuan Basin (SCB), which is closely related to the nocturnal intensification of low-level winds. Based on 21-year IMERG rainfall product and reanalysis data during summertime (June–August) from 2000 to 2020, the low-level winds are classified into four groups, with strong or weak daily mean wind accompanied by a large or small diurnal amplitude, to clarify their influences on rainfall over the SCB. The results show that under strong daily mean wind conditions, the westward extension of the Western Pacific Subtropical High (WPSH) determines the southwesterly monsoon airflow to be tuned to the southerly over the eastern Yunnan-Guizhou Plateau, which provides abundant warm and moist air resources for rainfall within the basin through the southeastern side of the SCB. Strong mean winds, coupled with a large diurnal amplitude due to the acceleration of easterly, strengthen the moisture convergence at night, and contribute to the rainfall increasing remarkable over the SCB with a peak at midnight. Meanwhile, there is an apparent anomalous low-level warming over the SCB, creating more unstable atmospheric conditions. In addition, the weak upward motion associated with the afternoon heating over the eastern slope of the Tibetan Plateau (TP) enhances the easterly and facilitates the development of upward motion over the western SCB in the early night, which is responsible for the larger diurnal amplitude of rainfall. On the contrary, rainfall is suppressed and the diurnal amplitude of rainfall is gentle under the condition of weak daily wind with small diurnal amplitude, due to the weak moisture transport and cooling planetary boundary layer related to the deepened midlatitude trough, as well as more active convection over the eastern slope of TP during the day. The results imply that atmospheric conditions associated with diurnal variation of low-level winds should be considered as a key component in regulating the rainfall and moisture budget over the SCB, the strength of low-level winds in the early evening may provide a predictive signal for the development of nocturnal rainfall over the SCB.