1998年武汉大暴雨过程的切变涡度及非绝热加热垂直结构分析

RESEARCH ON VERTICAL SECTION OF SHEAR VORTICITY AND DIABATIC HEATING WITH WUHAN TORRENTIAL RAIN IN 1998

文中通过比较 1 998年武汉大暴雨期间相对涡度、切变涡度和纬向切变涡度 (ζs1) ,发现ζs1中心与暴雨中心位置有更好的对应关系 ,其在时序上高空负纬向切变涡度发展要超前强降水出现约 1 d。暴雨发生前高空反气旋性涡度增强 ,且与此同时 ,低层要求有正涡度发展。暴雨发生时段对应着 Q1,Q2 的高值区 ,并具有强上升运动 ,且 Q1,Q2 两者之间存在较强的耦合。视热源中心在 45 0 h Pa,而水汽汇中心主要在 6 0 0 h Pa附近。Q1,Q2 局地变化和平流变化是反位相分布的 ,共同的作用是减小对加热的贡献。Q1中局地变化可省略 ,但 Q2 中局地变化在第2次强降水时段可达 4K/d左右 ,因此不能省略。垂直输送项在 Q1,Q2

Comparing the different vorticity components on Wuhan torrential rain in 1998, the results show that zonal shear vorticity has a corresponding connection with heavy rainfall center while the upper-negative shear vorticity develops and the low-positive vorticity increases. Analysis of case and statistics present that the development of zonal shear vorticity over 200 hPa is one day ahead of heavy rainfall occurrence. Meantime, the high apparent heat source (Q 1) and moist sink (Q 2) as well as strong ascending motion go with torrential rain stage. The source center is located at 450 hPa, and the sink center at 600 hPa. Evidences suggest that the transportation term plays an important role in atmospheric diabatic heating processes. However, the local variation term is small and reverse to advection term in apparent heat source vertical section, so it is often ignored, but it can not be neglected in moist sink.