【作者】 姜学恭； 李夏子； 李彰俊； 云静波；

【Author】 Jiang Xue-gong1,Li Xia-zi2,Li Zhang-jun3,Yun Jing-bo1 1 Inner Mongolia Autonomous Region Meteorological Observatory,Hohhot China 010051 2 Inner Mongolia Autonomous Region Meteorological Observatory,Hohhot China 010051 3 Inner Mongolia Meteorological Institute,Hohhot China 010051

【机构】 内蒙古自治区气象台； 内蒙古气象科学研究所； 内蒙古自治区气象局；

【摘要】 利用常规和地面加密观测资料、卫星云图、NCEP再分析资料及MM5高分辨率模拟结果,对2006年7月23日阻塞型华北暴雨过程进行了诊断分析和数值模拟,结果表明:本次暴雨过程发生以东西伯利亚阻高为典型特征的大尺度鞍型场背景下,宽广低压区及高、低空急流次级环流为MCS的发生、发展提供了适宜的环境和动力强迫;水汽条件的分析表明,700hPa、850hPa天气尺度的偏西水汽输送和低涡北侧的偏东水汽输送改善了环北京地区的环境水汽条件,暴雨发生前850hPa中尺度西南水汽输送对北京暴雨发生具有直接影响;MM5成功再现了导致暴雨的MCS形成及演变过程;MCS的结构分析表明,β中尺度MCS是本次暴雨的直接触发系统,其水平尺度约为0.5个经距,垂直方向由地面伸展到300hPa左右,具有典型的暖心结构,辐合和辐散中心分别位于900hPa和400hPa;MCS北侧强垂直次级环流为旺盛对流的产生创造了有利条件,同时,MCS南侧相当位温的强梯度高能区及该区域的不稳定能量输送,也是暴雨发生的重要条件。更多还原

【Abstract】 By using the routine and intensive observational data,the NCEP reanalysis data,the satellite images and high resolution simulation result by MM5,a diagnosis and numerical study on a block type convective rainstorm process occurred at North China on July 23,2006 were conducted.The result showed that the process happened in a col pressure field circulation environment,in which the EAST Siberia Block was the main feature.The broad low pressure area and the vertical secondary circulation induced by the jet stream provided valuable environmental condition and dynamic forcing for rainstorm.The synoptic scale water vapor transportation,which was westerly direction at south of 40oN and easterly direction at north of the low,improved the environmental moisture conditions around Beijing.Just before the occurrence of rainstorm,the mesoscale moisture transportation with south-westerly direction at 850hPa is crucial to the rainstorm.MM5 successfully reproduced the formation and evolution process of the mesoscale convective systems(MCS),which was the weather system causing the rainstorm directly.The MCS crossed 0.5 longitudes horizontally and from surface to 300hPa vertically with a typical warm heart construction.The strong vertical secondary circulation,which was consistent with strong divergence at 400hPa and convergence at 900hPa,produced a favorable condition for the exploding of strong convection.Meanwhile,the instable energy transportation at south of the MCS,in which the intensive potential equivalent temperature gradient appeared,contributed to the rainstorm evidently.更多还原