王沛东, 李国平. 秦巴山区地形对一次西南涡大暴雨过程影响的数值试验[J]. 云南大学学报(自然科学版), 2016, 38(3): 418-429. doi: 10.7540/j.ynu.20150765
引用本文: 王沛东, 李国平. 秦巴山区地形对一次西南涡大暴雨过程影响的数值试验[J]. 云南大学学报(自然科学版), 2016, 38(3): 418-429. doi: 10.7540/j.ynu.20150765
WANG Pei-dong, LI Guo-ping. Numerical experiments of the impact of Qin-Ba mountainous terrain on a rainstorm caused by southwest vortex[J]. Journal of Yunnan University: Natural Sciences Edition, 2016, 38(3): 418-429. DOI: 10.7540/j.ynu.20150765
Citation: WANG Pei-dong, LI Guo-ping. Numerical experiments of the impact of Qin-Ba mountainous terrain on a rainstorm caused by southwest vortex[J]. Journal of Yunnan University: Natural Sciences Edition, 2016, 38(3): 418-429. DOI: 10.7540/j.ynu.20150765

秦巴山区地形对一次西南涡大暴雨过程影响的数值试验

Numerical experiments of the impact of Qin-Ba mountainous terrain on a rainstorm caused by southwest vortex

  • 摘要: 利用CFSv2再分析资料和中尺度数值模式WRF V3.7.1对1次西南涡大暴雨过程进行数值试验,重点研究了秦巴山区地形对此次暴雨过程的影响.结果表明:地形通过对低涡本身和对山脉两侧南北气流的阻挡作用不利于低涡向东北方向移动;地形通过影响水汽输送和垂直运动改变降水强度及分布,随着地形的升高,雨量增大,雨带西移;地形的阻挡使水汽聚集于四川盆地,在迎风坡形成较强的水汽通量辐合,雨带的位置和强度与水汽通量辐合区相对应;地形强迫的垂直运动在迎风坡较强,其中以地形抬升作用为主,但边界层摩擦辐合作用也有贡献;降水量大值中心位于上升运动中心以南,降水区外围的弱下沉运动和其北部的强上升运动在迎风坡形成一个局地垂直环流圈,从而影响低涡与切变线的相互作用以及暴雨过程演变.

     

    Abstract: By using the CFSv2 reanalysis data and mesoscale model WRF V3.7.1,numerical experiments of a rainstorm caused by southwest vortex have been conducted.The study focuses on the impact of Qin-Ba mountainous terrain on the rainstorm.The results show that the topography is not conducive to the vortex moving to northeast by the blocking effects on vortex and on northerly and southerly flows along both sides of the mountain.Under the influence of the moisture transfer and vertical motion,the topography has changed the intensity and distribution of the rainfall.With the increasing of terrain height,rainfall begins to increase and rain belts move westward.The blocking effects of the topography make the moisture gather in the Sichuan basin,forming the strong convergence of the moisture flux on windward slope.The location and intensity of rain belts are consistent with the convergence region of moisture flux.Vertical motion forced by the topography is relatively strong on windward slope.Topographic uplift plays a dominant role while the frication convergence of a boundary layer also takes a considerable proportion.The heavy rain belt lies to the south of the ascending motion center,leading the formation of a local vertical circulation between the wake descending motion center which is outside the rainstorm region and the strong ascending motion center which lies to the north of the rainstorm region on windward slope.Thus the circulation can influence the interaction between vortex and shear line and the evolution of the rainstorm process.

     

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