摘要
利用10年(2013-2022年)4-10月逐日700 hPa高空图、西南低涡年鉴资料、欧洲中心ERA5再分析资料、陕西省站点降水数据对陕南西南涡暴雨个例进行了统计与诊断分析。结果表明:(1) 10年间共有119个暴雨日,其中由西南涡引起的暴雨日数38天,约占总暴雨日数的三分之一(32%),主要发生在5-9月,6月最多,根据统计降水时段多开始于夜间,结束于白天。(2)影响陕南的西南涡,源地主要是盆地涡,一般东移12~24 h后可造成陕南地区暴雨天气。陕南西南涡暴雨区主要位于700 hPa西南涡中心的东北象限附近,切变线以南区域,假相当位温的梯度大值区,500 hPa西风槽和副高外围西南气流的交汇区域且对应200 hPa强辐散区。(3)对西南涡的垂直结构研究表明,700 hPa强辐合中心位于正涡度中心东侧。这一区域与暴雨落区对应较好。高空急流下的强辐散引起空气质量调整,低层辐合,促使锋生。(4)存在三支水汽输送:通道一来自孟加拉湾西部的暖洋面;通道二源于孟加拉湾东部暖洋面;通道三源于南海洋面。暴雨期间秦巴山区地形产生的气旋式涡度、散度、水汽通量散度与系统性的涡度、散度和水汽通量散度叠加,增强低层辐合,这也是陕南西南涡暴雨形成的一个重要因素。
Using daily 700 hPa geopotential height charts from October 2013 to October 2022,Southwest Vortex(SWV)annual data,European Centre for Medium-Range Weather Forecasts(ECMWF)ERA5 reanalysis data,and precipitation data from stations in Shaanxi Province,a statistical and diagnostic analysis was conducted on individual cases of heavy rain induced by the Southwest Vortex in southern Shaanxi.The results reveal the following insights:(1)Over the course of 10 years,there were a total of 119 days with heavy rain,among which 38 days were associated with heavy rain caused by the Southwest Vortex,accounting for about one-third(32%)of the total heavy rain days.These events were mostly observed from May to September,with the highest frequency in June.Statistically,the precipitation tended to start at night and end during the day.(2)The Southwest Vortex influencing southern Shaanxi originates primarily from the basin vortex,and typically,its movement eastward by 12 to 24 hours can lead to heavy rain in the region.The heavy rain area associated with the Southwest Vortex is mainly located in the northeast quadrant of the 700 hPa vortex center,to the south of the shear line,in the area with a large gradient of potential pseudo-equivalent potential temperature,at the intersection of the 500 hPa westerly trough and the outer southwest flow of the subtropical high,corresponding to the region of strong divergence at the 200 hPa level.(3)The study of the vertical structure of the Southwest Vortex indicates that the strong convergence center at 700 hPa is located to the east of the positive vorticity center.This region corresponds well with the heavy rainfall area.Strong divergence under high-altitude jet streams leads to air quality adjustment,lower-level convergence,and frontal genesis.(4)There are three moisture transport channels:one comes from the warm sea surface of the western Bay of Bengal,the second originates from the warm sea surface in the eastern Bay of Bengal,and the third derives from the South China Sea.During heavy rain p
作者
姚静
李培荣
肖贻青
蒋伊蓉
王晓虎
YAO Jing;LI Peirong;XIAO Yiqing;JIANG Yirong;WANG Xiaohu(Shaanxi Provincial Meteorological Observatory,Xi'an 710014,Shaanxi,China;Yulin Meteorological Bureau,Yulin 719000,Shaanxi,China;Weinan Meteorological Bureau,Weinan 714000,Shaanxi,China)
出处
《高原气象》
CSCD
北大核心
2024年第3期655-666,共12页
Plateau Meteorology
基金
自然科学基金气象联合基金项目(U2242202)
中国气象局复盘总结专项(FPZJ2023-130)
秦岭和黄土高原生态环境气象重点实验室开放研究基金课题(2022G-1)。
关键词
西南涡
地形涡度
锋生
对流不稳定
水汽追踪
southwest vortex
terrain vorticity
frontogenesis
convective instability
moisture tracing
