关中地区两次初夏区域性暴雨过程特征分析  

Characteristic Analysis on Two Regional Rainstorms at Guanzhong in Early Summer

作　　者：张雅斌 马晓华 冉令坤[3] 侯建忠 

机构地区：[1]陕西省西安市气象台,西安710016 [2]陕西省气象台,西安710004 [3]中国科学院大气物理所,北京100029

出　　处：《高原气象》2016年第3期708-725,共18页Plateau Meteorology

基　　金：陕西省社会发展攻关项目(2013K13-04-04);科技部社会公益项目(GYHY201306006);国家自然科学基金项目(41175060);中国科学院重点部署项目(KZZD-EW-05)

摘　　要：使用1°×1°的NCEP再分析资料、常规观测及云图资料,从环流形势、物理量和TBB特征出发,结合盛夏暴雨过程对比,分析总结2006年6月2-3日("0602"过程)和2013年5月25日("0525"过程)关中地区两次初夏区域性暴雨特征。结果表明,关中初夏暴雨发生前,青藏高压明显偏南、偏弱,暴雨区北侧200 hPa急流形态、位置变化小,急流轴南侧的风速经向切变明显增大。初夏暴雨期间无西太平洋副热带高压和远距离台风作用,上游与周边西风带影响系统差异导致低层水汽输送与辐合明显弱于盛夏暴雨,分布形态不同。850 hPa大陆东部高压稳定维持有利于初夏暴雨低层偏东南气流发展、维持。初夏暴雨发生在位势稳定层结环境,暖湿空气沿着低层冷空气向北爬升,暴雨中心等熵面随高度向北倾斜,存在能量锋生和对称不稳定。暴雨区上空中高层深厚的正位涡和低层浅薄的负位涡垂直差异增大,300 hPa以上增幅明显,存在位涡异常。初夏暴雨中心以东约300 km处纬向中尺度垂直环流有利于暴雨区上升运动维持,但上升中心强度、高度和低层高能轴附近不稳定能量明显小于盛夏暴雨。总螺旋度显著增幅区对初夏暴雨落区有指示作用,其正负区相交零线、正值区增大中心分别和大雨、暴雨落区北界一致。同时,关中以北存在显著负螺旋度区,总螺旋度正值范围、强度明显偏小,中心移动、增大区偏南,局地螺旋度垂直方向正值中心区域相对分散。关中初夏暴雨云系范围大,结构复杂,主要由对应高层显著反气旋区的北部盾状中高云区和南部带状低云区组成,云团中心TBB>-60℃、云顶偏低,暴雨主要位于南北云区交汇处的窄带强回波附近,而非TBB中心区或梯度大值区附近。NCEP 1°×1° reanalysis data,conventional observation data and satelite data are used to analyse characteristics of circulation pattern,physical field and Temperature of Black Body（TBB） for two early summer rainstorms at Guanzhong from 2 to 3 June 2006（the ＇0602＇） and on 25 May 2013（the＇0525＇） with midsummer case comparison.Results show that：before early summer rainstorms happen,Tibetan High is weak and located obviously southward,which cause morphology and location changes of 200 hPa Jet north to rainstorm are small.At the same time,wind longitudinal gradient at the south side of 200 hPa Jet increases significantly.During early summer rainstorm there are no impacts of West Pacific Subtropical High and remote typhoon,meanwhile,westerlies influence systems at upstream and surrounding area are different,which lead to vapor transportation and convergence at low levels are significantly weaker than midsummer cases and different distributions.Stability of high pressure around China eastern continent on 850 hPa is contributed to duration of southeast vapor transportation to rainstorm area.Early summer rainstorms happened under potential stable stratification and warm and moist air climbe northward along the low level cold air.Isentropic surface tilted northward with height increasing along rainstorm centre and it exist energy front genesis and symmetric instability.Moist Potential Vorticity（MPV） anomaly appear over rainstorm area.Meanwhile,vertical difference between deeply positive MPV at mid-high levels and shallowly negative at low level increases.MPV above 300 hPa increase significantly.Zonal vertical circulations about 300 km east to early summer rainstorms contribute to upward movement maintaining.The maximum of vertical velocity,central height and unstable energy near high energy ridge at low level during early summer rainstorms are obviously lower than midsummer cases.Total helicity significantly increased zone is indicative to early summer rainstorm beginning.Zero line between positi

关 键 词：初夏暴雨 环流形势 物理量 红外云顶亮温 

分 类 号：P458.121.1[天文地球—大气科学及气象学]