AREM模式对“04·08”豫中大暴雨的数值模拟和诊断分析

Numerical Simulation and Diagnostic Analysis of the “04·08” Rainstorm in Central Henan with AREM Model

利用中尺度有限区域数值模式AREM,对2004年8月4日豫中一次大暴雨过程进行数值模拟和诊断分析。模拟结果表明:暴雨中心位于河南省中南部,中心强度达200 mm;高空冷平流南下,地面冷空气入侵,中低层有较强的辐合气流。模拟的暴雨落区与实况相一致,但中心强度较实况151 mm略大;模拟的环流形势也与实况环流形势一致。对模拟物理量诊断分析结果表明,在有利的垂直速度、散度场和比湿条件下,暴雨区中低空存在明显的水汽辐合,且水汽辐合区位于700 hPa及以下,强水汽辐合区位于900 hPa附近,从低层到高层较强的水汽辐合,暴雨区的水汽充分辐合上升,是造成此次大暴雨天气的主要原因。

A rainstorm process on 4 August 2004 in central Henan has been simulated and diag-nosed using AREM mesoscale model. The simulated results show that the rainstorm center is in the cen-tral and south of Henan province,with a rainfall maximum of 200 mm,the southward movement of upper-level cold advection,the intrusion of the surface cold air and the strong convergence of lower-level flow. The simulated rainfall location is close to the observation,while the simulated rainfall intensity is slightly stronger than the observation,which was 151 mm. The simulated circulation situation is close to the ob-servation,too. The diagnostic analysis of simulated physical variable indicates that,under the favorable environments of vertical velocity,divergence and specific humidity,there exits obvious moisture conver-gence in the low-level of rainstorm area. The moisture convergence is below 700 hPa,with strong mois-ture convergence at about 900 hPa. The strong moisture convergence in the lower to upper level,which leads to the upward movement of moisture in the rainstorm area,is the main cause of the extremely rain-storm weather.