Mesoscale convective systems (MCSs) are major contributors to extreme precipitation events and have attracted significant attention in the context of global warming. In 2020, large parts of East Asia, downstream of the Tibetan Plateau (TP), experienced an exceptionally wet rainy season and suffered intense MCS precipitation, resulting in severe impacts and losses. Here, based on the first ensemble run of K-scale WRF simulation (~4km) of Water Year 2020 (WY2020) within the CORDEX-FPS-CPTP framework, we investigated the performance of these simulations in simulating MCS precipitation characteristics, using the GPM-IMERG product and the CMA Multi-source merged Precipitation Analysis (CMPA) for comparison. The results indicate that while each member can generally captures the spatial distribution of MCS precipitation, notable differences emerge among the single-physical perturbation runs: Simulations using the Morrison and WSM5 microphysical scheme closely resemble the observations, while simulations using the SBU_Ylin or WDM6 microphysical schemes significantly underestimate MCS precipitation. In terms of boundary layer (PBL) scheme sensitivity, the K-scale simulations using the YSU and ShinHong schemes perform better than those using the MYNN3 scheme. Despites these differences, further analysis reveals an interesting phenomenon: all K-scale simulations collectively underestimate the MCS rainfall area by 30.9% to 43.0%, while overestimating MCS precipitation intensity by 59.4%~64.1%. This indicates that the simulated MCS precipitation tends to be smaller in size but more intense. Expanding the model domain to double its original size (from [15.0N–50.0N; 65.0E–125.0E] to [5.0N–55.0N; 45.0E–160.0E]) for the WY2020 run shows that after the domain expansion, the model not only captures the heavy MCS rainfall center over the Western North Pacific Ocean (south of Japan), but also better reproduces MCS precipitation features than other WRF K-scale WY2020 runs. It even outperforms the GPM product over eastern China, particularly in capturing the local enhancement of heavy MCS precipitation influenced by mountainous terrain. The K-scale WY2020 ensemble run provides a valuable resource for improving our understanding of MCS behavior and the hydrological cycle over the TP and its downstream areas.

Mesoscale Convective System,K-Scale simulation,convection-permitting modelling,Tibetan Plateau,CORDEX-FPS-CPTP