山东省春秋季暴雨天气的环流特征和形成机制初探  

Preliminary Study on Circulation Characteristics and Mechanism of Rainstorm in Spring and Autumn of Shandong

作　　者：杨晓霞[1] 万丰 刘还珠 薛德强[1] 华岩[1] 

机构地区：[1]山东省气象中心,济南250031 [2]国家气象中心,北京100081

出　　处：《应用气象学报》2006年第2期183-191,共9页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(40135020);山东省气象局"引发山洪等地质灾害的气象预报预警方法"项目共同资助

摘　　要：对山东省春秋季暴雨的气候特征和影响系统进行了分析,制作了春秋季暴雨的平均环流形势图。分析了2003年春秋季两次大范围暴雨的环流特征和影响系统及暴雨期间大气的热力特征和水汽输送特征,应用k-螺旋度和倾斜涡度发展理论,分析了暴雨的形成机制。结果表明:4月暴雨均受气旋影响,10月暴雨以冷锋影响居多。2003年4月17—18日为气旋暴雨,10月10—12日为切变线冷锋暴雨。两次暴雨前都有低空偏南风急流向暴雨区输送水汽,大气强烈增温增湿,对流不稳定度增大,湿斜压性增强。强冷锋南下触发对流不稳定能量释放,产生暴雨。暴雨期间低层正k-螺旋度猛烈发展。暴雨前期中低层MPV1<0且MPV2>0,冷锋影响期间MPV1>0且MPV2<0,都有利于倾斜涡度发展,增强了上升运动。The climate characteristics and the influencing systems associated with the heavy rain in spring and autumn in Shandong Province are analyzed, and the mean circulation charts are also given. The circulation characteristics and the weather systems causing the two large scale rainstorm events in 2003 spring and autumn are undertaken with the thermal characteristics and water vapor transfer mechanism during the rainstorm discussed. The mechanisms of the two heavy rain processes are studied by using the k-helicity and slantwise vorticity development theory. The result shows that all the rainstorms in spring are caused by cyclones, and the majority of rainstorms in autumn are caused by cold front, The heavy rain during 17-18 April 2003 is caused by cyclone and that during 10-12 Oct 2003 is caused by wind shear line and cold front. There is a low-level southerly jet which transports the watervapor to the storm area, and the temperature and the humidity increase rapidly, also the convective instability and the moist baroclinity increase in heavy rain area. The strong cold front triggers the release of the convective instability energy which leads to the heavy rain. The low-level positive k-helicity develops im- petuously during the two events, The warm and humid and goes up in spiral way, and flows out anticyclonicly air in low-level flows into the rain storm area cyclonicly in high-level. The positive k-helicity center in cyclone rainstorm appears in the east of low-level eddy and moves towards the northeast, but that in cold front rainstorm occurs near wind shear line which locates in the north of Shandong Province and moves to the southeast. The rainstorms occur in the moist baroclinic atmosphere and the development of slantwise vorticity is very important in the two cases. The wet potential vorticity augments intensively during the rainstorm period. The southward moving cold air encounters the warm air, which makes the convective instability and moist baroclinic are both prone to the forming of the rainstorm. The MP

关 键 词：春秋季暴雨 水汽输送 低层k-螺旋度 倾斜涡度发展 

分 类 号：P434[天文地球—大气科学及气象学]