2009年“8·17”鲁南低涡暖式切变线极强降水分析  

Analysis on an excessive precipitation process triggered by warm shear line with low vortex in southern Shandong on 17 August 2009

作　　者：杨晓霞[1] 蒋义芳[2] 胡顺起 姜鹏[1] 高留喜[1] 华雯丽[4] 

机构地区：[1]山东省气象台,济南250031 [2]江苏省气象台,南京210008 [3]山东省临沂市气象台,临沂276004 [4]成都信息工程学院,成都610225

出　　处：《暴雨灾害》2013年第3期224-234,共11页Torrential Rain and Disasters

基　　金：2011年和2013年中国气象局预报员专项(CMAYBY-2011-026;CMAYBY-2013-040);山东省气象局2012年和2013年科研项目(2012sdzd03;2013sdqx01)

摘　　要：利用各种观测资料及NCEP/NCAR 1°×1°再分析资料,对2009年8月17—18日鲁南极强降水进行多尺度分析。结果表明:强降水由500 hPa西风槽、850 hPa暖式切变线和地面倒槽共同影响产生。强降水发生前,中低层湿层深厚且有弱的水汽辐合,大气对流不稳定,并有较高对流不稳定能量。低层暖式切变线辐合、暖平流以及中高层正涡度平流、侧向辐合和倾斜涡度发展,使垂直涡度增大、上升运动发展;低层东南气流与高空槽配合产生次级环流,其上升支使上升运动增强,触发对流不稳定能量释放并产生强对流,造成强降水。强降水期间,中高层弱冷空气侵入使对流加强和降水强度加大。中尺度对流云团产生在地面低压倒槽东部和中尺度辐合线附近,地面加热和冷却不均匀导致低压倒槽中小尺度温度梯度加大,极端强降水中心出现在小尺度温度梯度区。强降水由长条形中尺度对流系统及其北端发展的圆形中尺度对流云团产生;中尺度对流系统(云团)自西向东缓慢移动,在回波强度图上表现为气旋性向北汇合的带状强回波。Multi scale analysis of an excessive precipitation process occurred in the southern Shandong from August 17 to 18 in 2009 is per- formed using various observation data and reanalysis data with resolution 1°×1° from NCEP. The results indicate that this process is caused by the interaction of westerly trough at 500 hPa, warm shear line at 850 hPa and inverted trough in ground layer. Before the excessive precipi- tation occurred, there are deep moist layer and weak vapor convergence in the mid- and low-level. The atmospheric stratification shows con- vective instability with more unstable energy. The convergence of warm shear line and warm advection in the low-level together with the posi- tive vorticity advection, side convergence and development of slantwise vortieity in the mid-and upper-level make the vertical vorticity in- creased and ascending motion developed. The southeast airflow in the low-level coordinating with the upper trough generate a secondary cir- culation whose vertical upward branch makes ascending movement strengthened triggering convective unstable energy release to generate se- vere convection, and then form severe precipitation. During the severe precipitation, intruding of weak cold air in the mid-and upper-level makes convection strengthened and precipitation reinforced, Mesoscale convective clusters originate in east part of inverted trough with low pressure and near the mesoscale convergence line in ground layer. The inhomogeneous heating and cooling on the ground lead to enhance the small scale temperature gradient of the inverted trough with low presure, and the center of excessive precipitation emerges in the temperature gradient zone. The severe precipitation is generated by both mesoscale convective systems with long strip shape and round-shape mesoscale convective cloud clusters developed in the north tip of the above-mentioned convective system. Both mesoscale convective systems and meso- scale convective cloud clusters move slowly from west to east showing belt-shaped strong ec

关 键 词：强降水 西风槽 低涡暖式切变线 干冷空气 地面辐合线 中尺度低压 对流云团 

分 类 号：P458.121.1[天文地球—大气科学及气象学]