Exploring a variable-resolution approach for simulating the regional climate in Southwest China using VR-CESM

Abstract

The complex terrain of Southwest China (SWC) leads to large spatial variations in its climate, which are challenging for climate models to accurately simulate. In this study, we perform a high-resolution simulation (∼0.125°) using the Variable-Resolution Community Earth System Model (VR-CESM) for SWC and evaluate the model's ability to simulate the spatiotemporal variations of precipitation and temperature in SWC. The VR-CESM results are compared with observations, as well as the simulation of the standard version of CESM at a quasi-uniform ∼1° resolution. We find that the high-resolution VR-CESM model better portrays the fine distribution of precipitation and temperature than the coarse resolution CESM model (∼1°). VR-CESM also shows some improvements in the seasonal variations of precipitation in SWC. VR-CESM reduces the overestimulation of precipitation in the Hengduan Mountains and surrounding areas. For heavy precipitation (daily precipitation >25 mm), VR-CESM better simulates its frequency than CESM (∼1°). Overall, VR-CESM has good simulation capabilities for the spatiotemporal evolution of precipitation and the occurrence frequency of extreme precipitation in SWC. Therefore, the VR-CESM model is a useful tool for understanding the mechanism driving the climate changes in SWC in the past and for projecting future climate changes in the region.