一次冷性停滞型西南低涡结构的演变特征  

The Developmental Characteristics of the Structure of a Stationery Cold Southwest Vortex

作　　者：陈贵川 谌芸 王晓芳[3] 朱岩 李强 张勇 CHEN Guichuan;SHEN Yun;WANG Xiaofang;ZHU Yan;LI Qiang;ZHANG Yong(ChongqingInstitute of Meteorological Sciences, Chongqing 401147, China;National Meteorological Centre, Beijing 100081, China;Institute of Heavy Rain, China Meteorological Administration. Wuhan, Wuhan 430074, Hubei, China;Chongqing Meteorological Bureau, Chongqing 401147, China)

机构地区：[1]重庆市气象科学研究所,重庆401147 [2]国家气象中心,北京100081 [3]中国气象局武汉暴雨研究所,湖北武汉430074 [4]重庆市气象台,重庆401147

出　　处：《高原气象》2018年第6期1628-1642,共15页Plateau Meteorology

基　　金：国家重点研发计划项目(2018YFC1507200);国家自然科学基金项目(91637211);中国气象局气象关键技术集成与应用(面上)项目(CMAGJ2015M49)

摘　　要：利用常规气象观测资料、NCEP(National Centers for Environmental Prediction,美国国家环境预报中心)再分析资料、雷达资料、卫星以及区域站资料等对2015年8月16日08:00(北京时,下同)至18日20:00四川盆地持续性大暴雨过程作了系统分析。结果表明:在西太平洋副热带高压(下称西太副高)阻塞形势下,高原涡东侧和西太副高西北侧的正涡度平流共同为西南低涡提供动力条件,前侧温度槽叠加在中低层暖性浅薄天气系统上加强了对流不稳定,冷空气缓慢侵入造成冷性停滞型西南低涡持续发展;西南低涡中的降水通过凝结潜热释放作用与西南低涡相伴增强;西南低涡成熟阶段,高低层正涡度柱几乎垂直耦合,水平流场形态上表现为近圆形,700 hPa温度、水汽及能量场均表现为"S"形非对称形态,有利于中低层维持向东北部的暖湿输送机制,这是纬向降水强于经向的重要因素;盆地地形条件下,纬向降水主要是中心中尺度对流系统MCSs(Mesoscale Convective Systems)两次稳定发展的结果,降水集中在西南低涡暖切变线南侧,地面静止锋附近,而经向降水主要是两次冷锋MCSs降水,位于西南低涡低槽前部;西南低涡中MCSs活动分为八个阶段,在动力机制维持情况下,西南低涡南侧MCSs通过影响水汽输送对中心MCSs发展形成制约机制,西南低涡东北部和东南部降水呈现此消彼长的"跷跷板"发展特征。By using data from conventional soundings and surface observation, NCEP reanalysis, radar, satellite and regional automatic stations, an incessant heavy rainstorm from 16 to 18 August 2015 in Sichuan Basin was systematically analyzed. The results showed that being blocked by the West Pacific Subtropical High (WPSH), the positive vorticity advection to the eastern side of the plateau vortex and the northwestern side of the WPSH provide the dynamic conditions for the Southwest Vortex(SV), the front temperature trough superimposed on the middle and low warm shallow synoptic systems strengthens the convective instability, the cold air invading slowly results in the stationery cold SV sustainable development. The precipitation in SV is enhanced by condensation latent heat release. In the maturation stage of SV, the vertical positive vorticity column at all levels is almost vertically coupled. The horizontal flow pattern approximately forms as a circle, while the temperature, moisture and energy fields at 700 hPa asymmetrically shape as "S". It is beneficial to maintain the heat and moisture transport mechanism to the northeast region of Chongqing at lower level, which is a crucial factor explaining why horizontal precipitation is stronger than that of meridian. Located in the basin area, the precipitation results from the stable development of central MCSs twice, clustering to the southern side of the warm shear of the SV, near the stationery front on the surface. In contrast, meridian precipitation is the outcome of MCSs triggered by cold front twice, located ahead of the trough of SV. The life history of MCSs could be divided into eight stages. With the maintenance of dynamic pump, the MCSs to the southern side of SV inhibits the evolution of central MCSs by influencing vapor transfer, resulting in the "see-saw" feature of the development of precipitation to the northeast and southeast of SV.

关 键 词：西南低涡 高原涡 大暴雨 中尺度对流系统 演变特征 

分 类 号：P458.121.1[天文地球—大气科学及气象学]