青藏高原东侧突发性暴雨的湿位涡诊断分析  

Diagnostic Analysis of Moist Potential Vorticity for Abrupt Rainstorm in Eastern Qinghai-Tibetan Plateau

作　　者：井喜 李明娟[2] 王淑云 胡春娟[2] 

机构地区：[1]陕西榆林市气象局,719000 [2]陕西省气象台 [3]河北沧州市气象台

出　　处：《气象》2007年第1期99-106,共8页Meteorological Monthly

摘　　要：利用MICAPS系统提供的常规观测资料对2004年6月29日、2004年8月10日发生在关中和陕北的突发性大暴雨进行湿位涡诊断分析。分析表明,700hPa等压面上,MPV1≤-0.3PVU中尺度对流不稳定区的生成、伴随对流不稳定区临近上游MPV1≥0.3PVU中尺度对流稳定区的生成,是形成突发性暴雨的湿正压场特征。伴随高原槽东移入河套(或关中),槽后有MPV2<0湿斜压中心生成,槽前有MPV2>0湿斜压中心生成,正负湿斜压中心在暴雨区及其临近上游生成MPV2等值线密集区,形成了突发性暴雨的700hPa湿斜压场特征。暴雨区上空有深厚湿位涡负值层的形成,伴随暴雨区上游对流层中低层有正湿位涡柱东移在暴雨区形成陡直的湿位涡等值线密集区,对突发性暴雨的发生有指示意义。扰动湿位涡的三维空间结构及其演变也是青藏高原东侧突发性暴雨预报当中可利用的重要信息。Using the observational data provided by MICAPS, the characteristics of the moist potential vorticity of two abrupt torrential rain events in Guanzhong, Shaanxi on June 29, 2004, and in northern Shaanxi on August 10, 2004 are analyzed. The results show that at 700 hPa level, the generation of a mesoscale convective instable area with MPV1 ≤ - 0. 3 PVU and a mesoscale convective stable area with MPV1 ≥0.3 PVU at the upper stream, is favorable for moist barotropic features, and contributes to the occurrence of abrupt torrential rains. The favorable moist baroclinic features develop at 700hPa level, while the plateau trough moves eastwards to Hetao area or Guanzhong area. A moist baroclinic center with MPV2 〈 0 generates at the rear of the trough, as a moist baroclinic center with the MPV2〉0 is in front of the trough. The positive and negative moist baroclinic centers above rainfall location and its neighboring upper stream, form an isoline-concentrated zone of MPV2, which coupled with the mesoscale convective instable center with MPV1≤ - 0.3 PVU accords to the rainfall location. On MPV1 zonal cross-section chart, an MPV column, nearly through upper and low levels, builds up in west-tilting with height at neighboring upper stream of the rainfall location before the Guanzhong torrential rain. While at Ansai, a funnel-like positive MPV extends from upper level down to the lower troposphere, which overlaps the negative MPV area developing in the boundary layer. The deep negative MPV layer develops above the rainfall location. Simultaneously, at the mid-low level of troposphere, the positive MPV column moves eastwards to the rainfall location to form a steep isoline-concentrated zone of MPV, which holds indicative meaning to the occurrence of abrupt torrential rains. The MPV disturbance owns the characteristic of spreading from high to low latitudes. Its three-dimensional structure and evolution are the useful information in predicting abrupt torrential rain occurring in the eastern Tibetan Plateau.

关 键 词：青藏高原东侧 湿位涡 突发性暴雨 诊断分析 

分 类 号：P458.121.1[天文地球—大气科学及气象学]