梅汛期江淮切变线暴雨与非暴雨演变过程的合成对比分析研究  

Composite Analysis of the Evolving of Yangtze River and Huaihe River Shear Line with Heavy Rain and without Heavy Rain in Meiyu Period

作　　者：李晓容[1] 张雪蓉[1] 濮梅娟[1,2] 

机构地区：[1]南京信息工程大学,南京210044 [2]江苏省气象局,南京210008

出　　处：《高原气象》2014年第1期199-209,共11页Plateau Meteorology

基　　金：江苏省重大科技支撑与自主创新示范工程项目(BE2008618)

摘　　要：利用气象观测资料和NCEP再分析资料对梅汛期江淮切变线暴雨类个例与切变线非暴雨类个例演变过程进行了合成对比分析。结果表明,形成暴雨切变线的演变历程中,存在南北风加强,切变线发展,且西南风急流引起的风速辐合加强了低空辐合。同时江苏处于高空急流入口区的右侧,高低空急流相耦合,形成了高空辐散、低空辐合的动力机制,降水过程中动力结构配置的演变特征十分鲜明。切变线南侧热力不稳定条件较好,水汽输送丰富,水汽辐合强烈,这些都有利于暴雨中尺度系统的发生、发展。因为动力、热力条件强度的不同对应不同强度的降水,区域性大暴雨的动力系统比一般暴雨更深厚,不稳定条件更强,水汽输送也更充沛。而切变线非暴雨类中,高低空风场的配置不利于降水的增强。南北风增强不明显,切变线不能得到发展,同时其南侧西南风急流没有建立,风速辐合较弱。高空急流核远离江苏,江苏上空的辐散场很弱,高空辐散、低空辐合的动力机制未能建立,动力结构的配置演变特征不明显。切变线南侧的热力不稳定度也不如暴雨类强,水汽的辐合较弱,不利于中尺度系统的发生、发展。Based on the observed data and NCEP reanalysis data, with the evolution process of Yangtze River and Huaihe River shear line with heavy rain and without heavy rain was composite analyzed. The results show that reinforcement of meridional wind leads to shear line development and wind direction convergence is strength- ened in the evolution process of shear line with heavy rain. In the south of shear line, enhancement of southwest wind jet stream causes wind speed convergence. West wind on 200 hPa increase to jet stream. Convergence in the low level and divergence in the upper level is dynamic mechanism. Power convective instability, bountiful water vapor transporting and intense water vapor convergence are in favor of mesoscales development in south of shear line. At the same time, different intensity of dynamic and thermal condition, correspond to different inten- sity precipitation in shear line with heavy rain. In culture heavy rainstorm, dynamic system is deeper, the insta- ble energy is powerful and water vapor is more bountiful than common heavy rain. In shear line without heavy rain, the wind in low and high level of configuration isn＇t beneficial to precipitation development. Meridional wind doesnt increase obviously and the shear line doesn＇t enhance. Without southwest jet, wind speed conver- gence is week. On 200 hPa, the center of jet is so far away from Jiangsu that the divergence of high level isn＇t powerful. The mechanism of convergence in the lows level and divergence in the upper level is not established. Configuration of dynamic, thermal condition and water vapor txansporting in south of shear line without heavy rain is adverse to mesoscale＇s development.

关 键 词：暴雨 切变线 高低空急流 非地转湿Q矢量 垂直螺旋度 

分 类 号：P458.1[天文地球—大气科学及气象学]