High-Resolution WRF Simulation of Extreme Heat Events in Eastern China: Large Sensitivity to Land Surface Schemes

Regional climate models with high-resolution simulation are particularly useful for providing a detailed representation of land surface processes, and for studying the relationship between land surface processes and heat events. However, large differences and uncertainties exist among different land surface schemes (LSSs). This study comprehensively assesses the sensitivity to different LSSs based on two extreme heat events in eastern China using the Weather Research and Forecasting (WRF) model. Among the five LSSs (i.e., 5TD, CLM4, Noah, Noah-MP and RUC), Noah is closest to observations in reproducing the temperatures and energy fluxes for both two heat events. The modeled warm biases result mainly from the underestimation of evapotranspirative cooling. Our results show that how each LSS partitions the evapotranspiration (ET) and sensible heat largely determines the relationship between the temperature and turbulent fluxes. Although the simulated two extreme heat events manifest similar biases in the temperatures and energy fluxes, the land surface responses (ET and soil moisture) are different.

Automated summary

This study assessed the sensitivity to different land surface schemes based on two extreme heat events in eastern China, finding that Noah scheme closely reproduced temperatures and energy fluxes compared to observations. Warm biases were mainly attributed to underestimation of evapotranspirative cooling, emphasizing the importance of how each land surface scheme partitions evapotranspiration and sensible heat in determining the relationship between temperature and turbulent fluxes. Though the simulated heat events had similar biases in temperatures and energy fluxes, land surface responses differed.