Assessment of dynamical downscaling performance over cordex east Asia using MPAS-A global variable resolution model: climatology, seasonal cycle, and extreme events

A 29-year variable resolution climate simulation is conducted from January 1988 to December 2016 using the Model for Prediction Across Scale-Atmosphere (MPAS-A), with prescribed sea surface temperatures obtained from ERA-Interim reanalysis. The global variable resolution configuration employs a mesh refinement of 92-25 km centered over East Asia. Model validations against combined observed datasets highlight that MPAS-A demonstrated advantages over three selected Regional Climate Models (RCMs) in terms of the spatial distribution of precipitation and spatial variability of the near-surface air temperature but struggled with accurately depicting temporal precipitation patterns. MPAS-A's anomalies in mid-latitude circulation and wave activity fluxes explained the weaker cold air activities during winter in eastern China and the northward shift of the Meiyu rain belt. Common issues with reference RCMs exist in MPAS-A, such as excessive zonal moisture transport over the ocean and unrealistic interannual variability over the northwest Pacific Ocean. The wet biases over the ocean are associated with systematically higher Convective Available Potential Energy (CAPE) for MPAS-A. However, the extreme rainfall indices such as R95pTOT and R99pTOT are not completely dominated by these wet biases and still exhibit reasonable results. This finding underscores the robustness and potential of the variable resolution (VR) approach in obtaining regional information within a single model framework. center dot A global variable resolution simulation is conducted from 1988 to 2016 following CORDEX-East Asia framework.center dot MPAS-A demonstrates superior spatial correlation in precipitation and better spatial variability in near-surface air temperature compared to three RCMs from CORDEX-EA-II.center dot MPAS-A and RCMs exhibit similar anomalies in moisture transport, but MPAS-A performs better over the northwest Pacific Ocean.