Projection of Extreme Precipitation in East Asian Spring and Mei-yu Seasons in the Warmer Climate

Changes in extreme precipitation in East Asia during the spring and Mei-yu seasons under global warming are evaluated based on two sets of high-resolution simulations with various warming pattern of sea surface temperature changes (SST' _spa). In the spring season, extreme precipitation exhibits larger enhancements over the northern flank of the prevailing rainy region in conjunction with a shifting tendency of more frequent extreme precipitation events and northward enhancement in the probability distribution, indicating a northward extension of future spring rainband. Enhanced precipitation intensity in conjunction with less rainfall occurrence and prolonged consecutive dry days lead to a minor change in mean precipitation, implying a more difficult water resource management in the warmer climate. The projected enhancement in precipitation intensity is robust compared with the internal variability related to initial conditions and the uncertainty caused by SST'_spa. In the Mei-yu season, extreme precipitation is intensified with a distribution of more frequent and more intense extreme events over the prevailing rainband region. The thermodynamic component of moisture flux predominantly contributes to changes in the spring season while both the thermodynamic and dynamic components of moisture flux contribute to the enhanced moisture transport furnishing the intensification of Mei-yu extreme precipitation from southern China to northeast Asia. Projecting future Mei-yu precipitation change is more difficult because of its higher uncertainty associated with 1) the larger variability embedded in the projection of extreme precipitation and 2) the model mean state that determines the spatial distribution of precipitation enhancement.