Assessing the Performance of a Dynamical Downscaling Simulation Driven by a Bias-Corrected CMIP6 Dataset for Asian Climate

In this study,we aim to assess dynamical downscaling simulations by utilizing a novel bias-corrected global climate model(GCM)data to drive a regional climate model(RCM)over the Asia-western North Pacific region.Three simulations were conducted with a 25-km grid spacing for the period 1980–2014.The first simulation(WRF_ERA5)was driven by the European Centre for Medium-Range Weather Forecasts Reanalysis 5(ERA5)dataset and served as the validation dataset.The original GCM dataset(MPI-ESM1-2-HR model)was used to drive the second simulation(WRF_GCM),while the third simulation(WRF_GCMbc)was driven by the bias-corrected GCM dataset.The bias-corrected GCM data has an ERA5-based mean and interannual variance and long-term trends derived from the ensemble mean of 18 CMIP6 models.Results demonstrate that the WRF_GCMbc significantly reduced the root-mean-square errors(RMSEs)of the climatological mean of downscaled variables,including temperature,precipitation,snow,wind,relative humidity,and planetary boundary layer height by 50%–90%compared to the WRF_GCM.Similarly,the RMSEs of interannual-tointerdecadal variances of downscaled variables were reduced by 30%–60%.Furthermore,the WRF_GCMbc better captured the annual cycle of the monsoon circulation and intraseasonal and day-to-day variabilities.The leading empirical orthogonal function(EOF)shows a monopole precipitation mode in the WRF_GCM.In contrast,the WRF_GCMbc successfully reproduced the observed tri-pole mode of summer precipitation over eastern China.This improvement could be attributed to a better-simulated location of the western North Pacific subtropical high in the WRF_GCMbc after GCM bias correction.

Research progress of slippage characteristic and gas film stability enhancement methods on biomimetic hydrophobic surfaces

The biomimetic hydrophobic surface is a potentially efficient underwater drag reduction method and the drag reduction mechanism of this kind of surface comes from the interfacial slippage.For now,it is a hotspot to grasp the slippage characteristic and explore slippage enhancement strategies.This paper not only summarizes our numerical simulation and experimental results of slippage characteristic at the solid-liquid interface(SLI)of hydrophobic surfaces(HS)and the gas-liquid interface(GLI)of superhydrophobic surfaces(SHS)in recent years,but also introduces some innovative methods that can effectively improve the gas film stability and drag reduction effect of SHS.First,we used the molecular dynamics(MD)simulation method to figure out the effect of the solid-liquid interaction strength,the system temperature and the shear rate on the slippage of SLI,and expound their action mechanism from molecular scale.Then,by MD and multibody dissipative particle dynamics(MDPD)method,the slippage behavior at the GLI was studied under the influence of the microstructure size and the flow driving velocity.We proposed a new kind of hybrid slip boundary condition model to describe the slippage characteristic on GLI.In addition,we found through experiment that a three-dimensional backflow will appear on the GLI under the interfacial adsorption of surfactants,and the backflow direction will reverse with the change of GLI morphology.Finally,we put forward the wettability step structure and gas injection method to enhance the stability and drag reduction effect of the gas film on SHS.