摘要
利用NCEP 1°×1°再分析资料和常规资料对2009年5月发生在河北中南部的强对流暴雨天气过程进行了数值模拟。低空700 hPa流场的中尺度扰动和涡度场的加强说明:发生在河北中南部的短时强对流暴雨与东北回流密切相关,低空东北风的辐合,使地转平衡遭到破坏,从而引发水平辐合和辐散及铅直运动,在地转适应过程中,700 hPa中尺度环流偶在河北中南部形成并加强,对应的正负涡度对也出现并增大,使辐合上升运动增强,强对流暴雨出现在辐合场和辐散场之间区域。高空急流中心右前侧辐合导致气流下沉,向南的一支引起低空北风加大。加强的东北回流与低空较强偏南气流在河北南部相遇,耦合上升。可见,垂直环流的形成及东北回流的加强是此次强对流暴雨产生的重要原因。
Based on NCEP reanalysis data and conventional weather maps,one heavy rainfall in south cental Hebei province in 2009 was simulated using WRF model.The results of high-resolution model simulation show：Strengthening of mesoscale disturbance and of vorticities in 700 hPa wind field shows a strong relation between the short-time strong convective storm in the central and southern Hebei Province and northeast returning flow.Convergence of low-level northeasterly winds destroys the geostrophic balance,inducing horizontal convergence and divergence and vertical movement,700 hPa mesoscale circulation cells form and strengthen in the central and southern Hebei Province during the process of geostrophic adaptation,while the corresponding positive and negative vorticities form and increase,inducing enhancement of convergent upward motion and the formation of convective storm.The largest precipitation appears in the area between convergence and divergence.Convergence on the right front side of jet center leads to sinking air,while a southern branch induces enhancements of northerly wind and the northeast returning flow.Due to the uplift of convergence,upward branch appears in the central and southern Hebei.The strengthening of the low-level northeasterly winds and the formation of vertical circulation play important roles in inducing the convective storm.
出处
《气象科学》
CSCD
北大核心
2011年第3期332-338,共7页
Journal of the Meteorological Sciences
基金
国家基础研究发展项目计划(973计划)项目(2009CB421503)
国家自然科学基金资助项目(40775033)
关键词
强对流暴雨
高空急流
耦合
Severe convective storms
Upper-level jet
Coupling
