Convection-permitting modeling over the Tibetan Plateau improves the simulation of Meiyu Rainfall during the 2011 Yangtze Plain flood

Abstract

The Tibetan Plateau (TP) plays a complicated impact on summer extreme precipitation in downstream areas like Yangtze Plain, and the convection-permitting modeling (CPM) over the TP has obvious added value for regional climate simulation. This study investigates whether the CPM over the TP can improve the simulation of a typical extreme Meiyu rainfall in Yangtze Plain and the possible mechanism. To address these issues, we conduct three experiments with the Weather Research and Forecasting (WRF) model using a combination of nesting feedback and different resolution topography. Results reveal that the CPM over the TP better reproduces the regional climate over the TP in terms of the precipitation and temperature. The more realistic representation of the regional climate over the TP can further improve the simulation of the spatial distribution of rainfall, the maximum center of rainfall and heavy rainfall processes of Meiyu rainfall in June 2011 but with a wet bias, which could be attribute to too much convective precipitation caused by the cumulus parameterizations. These improvements mostly benefit from the detailed representation of the complex topography over the TP, which contributes to capturing more reasonable eddy kinetic energy at 500 hPa. Consequently, middle atmospheric cold and downward wind bias over the TP as well as the bias of thermal and mechanical circulation fields (e.g., monsoon flow and South Asia High) are reduced. This work demonstrates the potential for the more realistic representation of atmosphere and land surface information over TP to improve the simulations and prediction of extreme Meiyu rainfall.