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气象:2018,44(6):771-780
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夏季江南地区暖区暴雨的统计分析
汪玲瑶,谌芸,肖天贵,李晟祺,葛蕾
(成都信息工程大学,成都 610225; 国家气象中心,北京 100081; 南京信息工程大学,南京 210044)
Statistical Analysis of Warm-Sector Rainstorm Characteristics over the Southern of Middle and Lower Reaches of the Yangtze River in Summer
WANG Lingyao,CHEN Yun,XIAO Tiangui,LI Shengqi,GE Lei
(Chengdu University of Information Technology, Chengdu 610225; National Meteorological Centre, Beijing 100081; Nanjing University of Information Science and Technology, Nanjing 210044)
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投稿时间:2017-10-16    修订日期:2018-05-14
中文摘要: 本文首先给出江南地区暖区暴雨的定义,并按天气形势将其分为暖切变型、冷锋锋前型、副热带高压(以下简称副高)型和强西南急流型四类。然后利用2010—2016年5—9月常规和自动站逐时降水等非常规观测资料统计暖区暴雨的时空分布特征和降水性质等,并对暖区暴雨的形成原因进行初步分析。最后利用NCEP FNL全球分析资料,基于中尺度分析技术给出四类暖区暴雨的系统配置:(1)四类暖区暴雨均为分散性局地降水,降水多发生于山区、平原和湖泊交界处等不均匀下垫面附近。其中,暖切变型降水范围广、强度最大、极端性最明显且主要位于江南中西部;冷锋锋前型降水集中、强度较大且具有一定极端性,主要位于江南中部;副高型降水强度较弱,主要位于江南中东部;强西南急流主要位于江南西部。(2)暖切变型和强西南急流型以夜间降水为主,副高型降水集中在午后,冷锋锋前型降水日变化不明显。(3)暖区暴雨由稳定性和对流性降水共同组成且降水量越大,降水对流性越明显。(4)在低层高湿、不稳定能量积聚等有利背景下,暖切变型、冷锋型和副高型暖区降水多由边界层(地面)中尺度辐合线配合高低空急流耦合产生,强西南急流型一般形成于低空急流上的中尺度风速脉动及地面辐合线附近,且低空急流越强,暴雨强度越大。(5)暖切变型和冷锋型暖区暴雨的落区分别位于低层850 hPa暖切变以南和地面锋前的显著湿区内,副高型和强西南急流型的暴雨落区分别位于副高内和强低空急流出口区左前侧的水汽充沛且大气层结不稳定区内。四类暖区暴雨常表现为长生命史的移动型中尺度雨团途经山区或河流湖泊等不均匀下垫面时,强度增大、移速减慢,形成暖区局地强降水。
Abstract:The warm-sector rainstorms over the southern of middle and lower reaches of the Yangtze River are defined, and they can be divided into four types based on synoptic situation, including warm shear-line, cold-front, subtropical high and severe southwest jet. By using the conventional and non-conventional observation data such as the hourly precipitation data of automatic weather station (AWS) from May to September during 2010-2016, we statistically analyzed the temporal-spatial distribution of warm-sector rainstorms and the nature of precipitation as well as the causes for their formation. In addition, based on NCEP FNL opearational global analysis data and the technology of mesoscale analysis, the system configurations of four kinds of rainstorms are built. (1) All the four types are decentralized local precipitation, and the precipitation usually occurs near the uneven surface, which is transitional zones between mountains, plains and lakes, etc. The warm shear-line type precipitation mainly happens in the mid-west of this area with wide range, most intensive intensity and most obvious extremes. The precipitation of the cold-front type is concentrated, and it has a higher intensity and a certain degree of extremes, distributing mainly in the middle of the area. The precipitation with the subtropical high often occurs in the mid-east of this area with weak intensity. The severe southwest jet mainly appears in the western part. (2) The warm shear-line and the severe southwest jet are dominated by night precipitation, and the subtropical high precipitation is mainly concentrated in the afternoon. However, the diurnal variation of the cold-front type does not show a distinct difference throughout the day. (3) The warm-sector rainstorms consist of steady and convective precipitation. The heavier the daily rainfall is, the more obvious convection the precipitation has. (4) With high humidity, unstable energy accumulation and other favorable background, the warm shear-line, cold-front and subtropical high are mostly generated by boundary layer (ground) mesoscale convergence lines, coupled with the place of the coupling of upper and low-level jet. The severe southwest jet is generally formed near the mesoscale wind velocity fluctuation and ground mesoscale convergence lines on the low-level jet stream. The stronger the low-level jet stream is, the greater the intensity of the rainfall is. (5) The rainfall region of the warm shear-line and the cold-front are respectively located in the wet zone with the south of warm shear-line in the lower level and the pre-front. The rainfall region of the subtropical high and the severe southwest jet are respectively located in the water vapor and the unstable atmosphere in the subtropical high and the left front of the strong low-level jet streams. Four types usually manifest as long-life moving mesoscale rain clusters. When it goes through mountains, rivers and lakes and other uneven surface, its rainfall intensity usually increases and moving speed slows down, which is the main reason for the formation of the local heavy rainfall of warm-sector rainstorms.
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基金项目:国家自然科学基金面上项目(41175048)、中国气象局气象预报业务关键技术发展专项[YBGJXM(2017)1A]和公益性行业(气象)科研专项(GYHY201406003)共同资助
引用文本:
汪玲瑶,谌芸,肖天贵,李晟祺,葛蕾,2018.夏季江南地区暖区暴雨的统计分析[J].气象,44(6):771-780.
WANG Lingyao,CHEN Yun,XIAO Tiangui,LI Shengqi,GE Lei,2018.Statistical Analysis of Warm-Sector Rainstorm Characteristics over the Southern of Middle and Lower Reaches of the Yangtze River in Summer[J].Meteor Mon,44(6):771-780.