Assessment of Dynamical Downscaling Performance over CORDEX East Asia using MPAS-A Global Variable Resolution Model: Climatology, Seasonal Cycle, and Extreme Events

We conduct a 29-year climate simulation from January 1988 to December 2016, using the Model for Prediction Across Scale-Atmosphere (MPAS-Atmosphere), which incorporates prescribed sea surface temperature data from the ERA-Interim reanalysis to ensure accuracy. The global simulation uses variable resolution, with a mesh refinement centered over East Asia. This simulation could capture various scales of climate phenomena within a unified modeling framework. The performances of the MPAS-A experiment are evaluated from the aspects of precipitation, near-surface air temperature, and atmospheric circulation with the observations from multiple sources. Notably, the simulation exhibited deviations on a large scale, such as inaccuracies in the northward movement of rain belts, excessive rainfall over tropical ocean regions, and biases in surface air temperature that remained stationary and region-specific. These disparities were linked to how the model represented atmospheric circulation, moisture transport, and the connection between precipitation and convective available potential energy (CAPE). While the simulation accurately reproduces extreme rainfall events in the refined East Asia region. The results highlight the promise of the variable resolution (VR) approach for extracting regional climate information using a single modeling framework.