Abstract/Summary

The East Asian Summer Monsoon (EASM) plays a pivotal role in redistributing water across East Asia, including a considerable flood risk due to the potential of localized extreme precipitation. To gain insights into future EASM changes, it is crucial to explore the dynamics of a core driver of extreme precipitation during the EASM, the Mei-yu front. While prior studies have examined various EASM aspects in climate models, the comprehensive assessment of the dynamically important Mei-yu front, remains largely unexplored. In this study, we evaluate the Mei-yu front representation in 38 CMIP6 models from May to August with ECMWF Reanalysis version 5 (ERA5) as reference. Our findings reveal that several CMIP6 models struggle to accurately reproduce the MYF climatology, with performance varying by month. By categorizing models based on the east-west bias of MYF position in May, we identify distinct monthly evolutions in these biases during the monsoon season. Our study shows that a significant association between the misrepresentation of MYF climatology in CMIP6 models and the misrepresentation of the Western North Pacific High, particularly its western edge. Other potential sources of biases based on misrepresentation of the other large-scale circulation pattern, such as South Asian High, are also discussed.