Numerical Simulation Study of Topography Effects on a Severe Rainstorm in Shanxi Province

Zhao Haiying; Bo Yanqing; Qiu Guiqiang; Zhao Jun; Yan Hui

doi:10.16765/j.cnki.1673-7148.2017.02.014

Abstract：Using 6 h NCEP 1° × 1° reanalysis data and the mesoscale model WRF V3.2.1,a terrain sensitivity numerical simulation experiment of a heavy rain process occurred on July 29-30,2007 in southern Shanxi province is carried out for further research of effects of topography on severe rainstorm and improving the heavy rainfall forecast accuracy.The results show that:this torrential rain occurs in beneficial circumstance and special terrain,and is closely related to the influence of terrain.Altitude and topography in Shanxi have an important influence on the location and intensity of rainstorm.Reducing the altitude of Shanxi province would decrease the rainfall intensity and shift the location northwest.Removing topography relief while reducing the altitude of Taihang Mountains would cause the rainstorm move northward to the east side of Luliang Mountains and the rainfall area expand,as without the obstruction of Taihang Mountains,south warm-moist airflow at low level could move northward to eastern Luliang Mountains and then converge and uplift,obstructed by the terrain.The terrain has great influence on horizontal wind field and water vapor at low level,while changing the terrain,the intensity and location of convergence line at low level would change,the distribution of water vapor would change too.Trumpetshaped terrain has prominent enhancive effect on rainstorm.While the trumpet-shaped terrain is destroyed,the precipitation intensity would reduce dramatically.Trumpet-shaped terrain also has great effect on the distribution of vertical movement,divergence and vorticity field.