Simulation of Hourly Precipitation over the Tibetan Plateau by Regional Climate Dynamical Downscaling Simulations with Different Resolutions

The spatial and temporal distribution characteristics and changes of summer precipitation over the  Tibetan Plateau(TP) is quite complicated, so it is an urgent problem to simulate the precipitation over the plateau accurately. Due to the improved resolution, dynamical downscaling modelling(DDM) at kilometer scale has shown certain value-added effects in the simulation of water vapor transport and the triggering of convection over the Tibetan Plateau, but it may still not be sufficient to simulate the precipitation characteristics of mountain observations. In this study, a DDM at 4 km resolution and a DDM at 28 km resolution were conducted in summer (June 1 to August 31, 2014). Based on the station observation datasets, the hourly precipitation changes of ERA5 reanalysis data and the above simulation results with different resolutions were evaluated. It indicates that CPM has a significant advantage in simulating precipitation in daytime precipitation simulation, but it underestimates the precipitation at night obviously, while the performance of ERA5 and DDM show acceptable performance.Meanwhile, this situation varies greatly among different basins on TP, which is worth further analysis. The key of this study is to to fully consider small-scale physical processes and the turbulence problems involved in boundary layer processes on the basis of 4km resolution simulation, so as to explore the optimal resolution of hourly precipitation simulation over TP. The physical mechanism behind this is related to the different feedback of scale interactions caused by different resolutions, which may involve the different characterization of terrain and underlying surface features.