The Impact of Model Horizontal Resolution on Simulating Regional Climate Over East Asia Using VariableResolution CESM2
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AbstractIn this study, a variableresolution version of the Community Earth System Model (VRCESM) with mesh refinement (0.125) over East Asia is used to simulate the regional climate in this region. For the evaluation of model performance and sensitivity to model resolution, the simulated nearsurface temperature and precipitation are compared with observations and simulation results from a globally quasiuniform (1) CESM (UNCESM). Results show that VRCESM better simulates the spatial patterns and seasonal variations of mean temperature and precipitation than UNCESM over China. For extreme events, VRCESM improves the simulation of the occurrence frequency of wintertime daily minimum temperature and heavy precipitation. In regions with complex terrains, VRCESM better resolves the topographic forcing and captures the observed finescale spatial patterns of temperature and precipitation, although precipitation is still overestimated. For East Asian summer monsoon precipitation, both UNCESM and VRCESM tend to overestimate (underestimate) the precipitation over northern (southern) China, which is associated with too strong meridional water vapor transport in the models and biases in the largescale circulation in the middle and upper troposphere. Different from previous studies with different physics parameterizations and refined domains, as the model resolution increases, simulated monsoon precipitation evolution is not obviously improved, and convective precipitation intensity decreases over eastern China. Despite this, our results indicate that VRCESM simulates regional climate, topographical forcing, and largescale circulations over East Asia reasonably well, and thus it can be applied for the future climate projection in the region.
