Effects of cumulus parameterization and land-surface hydrology schemes on Tibetan Plateau climate simulation during the wet season: insights from the RegCM4 model

Abstract Dynamical downscaling generally performs poorly on the Tibetan Plateau (TP), due to region’s complex topography and several aspects of model physics, especially convection land surface processes. This study investigated effects cumulus parameterization scheme (CPS) land-surface hydrology (LSHS) TP climate simulation during wet season using RegCM4 regional model. To address these issues seek an optimal simulation, we conducted four experiments at a 20 km resolution various combinations two CPSs (Grell MIT-Emanuel), LSHSs (the default TOPMODEL [TOP], Variable Infiltration Capacity [VIC]). The simulations in terms 2-m air temperature, precipitation (including large-scale [LSP] convective [CP]), energy-water balance, as well atmospheric moisture flux transport vertical motion were compared with satellite-based observations ERA5 reanalysis dataset for period 2006–2016. results revealed that Grell TOP schemes better reproduced temperature but warm bias, part which could be significantly decreased by MIT scheme. All simulated reasonable spatial distribution precipitation, best performance experiment VIC schemes. Excessive was produced scheme, mainly overestimated LSP, while largely reduced overestimation, contribution CP total close agreement data. satisfactorily captured diurnal cycles amount frequency, although there remained some differences phase magnitude, caused CPSs. Relative yielded weaker heating reducing net radiation fluxes Bowen ratio. Consequently, anomalous substantially over southeastern TP, leading decrease precipitation. also help bias heating. Further analysis indicated high attributed destabilization low mid-troposphere, tended inhibit shallow convection, thereby decreasing CP. study’s suggest CPS interacts LSHS affect TP.