摘要
利用ARW-WRF模式对2014年7月4日12时—5日06时发生在安徽中南部的一次由江淮气旋引发的强降水过程进行模拟,得到暖锋上雨带的雷达回波结构,与实况有较好的一致性。对气旋暖锋上出现的多个小对流带的结构与成因进行了分析,发现暖锋小对流带的高度模拟和实况均在300 hPa以下,其生命史约2~3 h,最长100 km,宽10 km,带与带间距50~100 km,均随高度向东南方向倾斜。其环流特征为对流区东部从低层到高层多对应暖空气上升;对流区西部中上层多为冷区控制;近地面则有类似冷池存在,对流带南部的上升气流有利于对流云的后向新生和形成带状结构。小对流带上,800 hPa有0<Ri<1和I EPV<0区域,稳定层结内出现滚轴状流场分布,有重力波存在的结构特征;600~700 hPa为对流不稳定,对流带间I EPV>0。可见暖空气沿暖锋爬升时,在800 hPa附近,由于满足条件性对称不稳定条件,触发条件性对称不稳定和重力波,暖空气继续上升时触发700 hPa之上的对流不稳定,即影响本次暖锋小对流带形成的原因主要为对称-对流不稳定。
This paper simulated a heavy rainfall case caused by a Jiang-Huai cyclone which occurred in southern Anhui Province from 1200 UTC July 4 to 0600 UTC July 5,2014.The simulated results on the warm front are consistent with the observations,and are used to investigate multiple convective rain belts structure and the causes for their appearance near the warm front.The results indicate that the single convections in both the simulated and observed situations are all under 300 hPa,and continued for around 2—3 hours,with maximum lengths of 100 km and widths of 10 km.Between bands,their spacings are about 50—100 km,and all of them are tilting east-southern with height.All of the single convective bands have several common circulation characteristics:on the east of the convective region there is a corresponding warm rising air distributed from its low-level to high-level;the upper western convective zones are controlled by cold areas;and close to the ground,there is a similar cold pool,while the updraft south of the convective belts is favored by the convections back building and forming belted structures.On the single convective rain belts,there is an area of 0<Ri<1 at 800 hPa and an area of I EPV<0.In stable stratification,the wind field is distributed in a roller shape,with the structure characteristics of the existence of gravitational waves.There is convective instability at 600—700 hPa and an area of I EPV>0.It can be concluded that warm rising air under conditional symmetric unstable conditions around 800 hPa triggered conditional symmetric instability and gravity waves,along with convective instability above 700 hPa.This implies that the main cause of the single convective rain belts formation is symmetric-convective instability.
作者
丁治英
刘瑾
赵向军
王瑾婷
DING Zhiying;LIU Jin;ZHAO Xiangjun;WANG Jinting(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/College of Atmospheric Sciences,Nanjing University of Information Science&Technology,Nanjing 210044,China;Sanya Meteorological Bureau,Sanya 572000,China)
出处
《大气科学学报》
CSCD
北大核心
2019年第5期778-789,共12页
Transactions of Atmospheric Sciences
基金
国家重点基础研究发展项目规划(2013CB430103)
国家自然科学基金资助项目(41975054
41530427
41375058)
关键词
暖锋小雨带
环流结构
重力波
对称-对流不稳定
small warm frontal rainbelt
circulation structure
gravity wave
symmetric-convective instability
