Airdrop-oriented Numerical Simulation Of 3D Wind Field On The Qinghai-Tibet Plateau With High Spatial And Temporal Resolution

As the highest plateau in the world,the Qinghai-Tibet Plateau has complex terrain and bad climate,which is a great challenge to the parachute landing and aviation safety.The numerical weather prediction model can make up for the lack of plateau observation data and simulate the process of land-atmosphere energy exchange in the boundary layer,which is of great significance to the wind speed prediction and aviation safety in the plateau boundary layer.In this paper,the numerical weather research and forecasting model(WRF),three-dimensional variational assimilation system(WRFDA-3DVar)and large eddy simulation system(LES)are coupled to build the DA-LES system to simulate the wind fields of different scales on the Qinghai-Tibet Plateau.Compare with the reanalysis data and the wind data at the station,the effects of AMVs data assimilation on mesoscale wind field simulation,large eddy simulation on complex terrain wind field simulation,and the improvement of wind simulation by DA-LES system are evaluated respectively.Finally,the DA-LES system is applied to the sensitive area of the Qinghai-Tibet Plateau to simulate the regional atmospheric elements.The main results are as follows:(1)After the quality control of FY-4A(Feng Yun-4A)AMVs of infrared channels with quality indicator,high-quality data meeting the needs of assimilation can be selected out.The default observation error of WRFDA-3DVar are replaced by the new observation error.Assimilating FY-4A AMVs data can significantly improve the middle and upper atmospheric wind field and the upper level wind speed RMSE(Root Mean Square Error)decreases by about0.2 m·s^-1.(2)The access of high-precision terrain data can improve the simulation effect of large eddy simulation on surface wind speed,MBE(Mean Bias Error)is improved by 0.35 m·s^-1;The boundary layer scheme has poor simulation effect on 40 m horizontal resolution wind speed and the error increases by about 1 m·s^-1 compared with the large eddy simulation.For the middle and upper atmosphere,large eddy simulation can improve the wind field simulation results at most levels(3)In the LES scheme,the change of the constant term coefficient for calculating the vorticity viscosity coefficient will have a great impact on the simulation results.Comprehensively compare the sensitivity test conclusions of the two sub-grid stress models,when the scheme is the 1.5 order TKE closure scheme and the coefficient is 0.1,the wind speed simulation result is the best.The MBE of surface wind speed is only 0.67 m·s^-1,MAE(Mean Absolute Error)is 1.56 m·s^-1 and RMSE is 2.06 m·s^-1.(4)The DA-LES system has a good simulation effect on the wind speed on the Qinghai-Tibet Plateau,and can reduce the positive deviation of 10 m wind speed and most of the wind speed errors in the middle and upper atmosphere.The system is applied to the sensitive area of the Qinghai-Tibet Plateau,namely Bangonghu Lake,DA-LES system can simulate the high-resolution atmospheric element field in this area and ensure the local aviation safety.