A numerical simulation and diagnostic analysis of two westward typhoon rainstorm process in Yunnan

By NCEP reanalysis data and Mesoscale Weather Research and Forecast Model (WRF model),a series of numerical simulation experiments of two rainstorm processes with westward typhoon influencing Yunnan was carried out by three-nested grid model on 20th 8:0021st 8:00,July 2014,and on 17th 8:0018th 8:00,September 2014,and experiment results had been diagnosed contrastively.The results show that WRF model can impersonally simulate their heavy precipitation area,intensity and basic characteristics of westward typhoon rainstorm processes,but rainstorm center is consistent with the tropical depression center without upper cold air influencing and rainstorm center is departure from the tropical depression center when tropical depression periphery is intruded by cold air.At the same time it can preferably simulate westward typhoon's moving direction and influencing area.But without consideration of terrain effect,simulative influencing system and precipitation areas slightly move towards west and north than actual situation and simulative intensity is also weaker.However,as a whole the simulative height,temperature and circulation pattern are almost the same with the actual situations.In addition the WRF simulation results of relative humidity,velocity and vertical speed can precisely indicate high-humidity environmental condition,positive vortex tube effect and strong profound ascending motion condition during heavy precipitation,which presents a good indication for the heavy precipitation area and occurrence time.