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气象:2020,46(12):1621-1632
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杭州地区夏季午后雷暴大风环境条件分析
樊李苗,俞小鼎
(浙江省杭州市气象局,杭州 310051;中国气象局气象干部培训学院,北京 100081)
Analysis on the Environment Conditions of Afternoon Thunderstorm in Hangzhou
FAN Limiao,YU Xiaoding
(Hangzhou Meteorological Bureau of Zhejiang Province, Hangzhou 310051;China Meteorological Administration Training Centre, Beijing 100081)
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投稿时间:2019-11-17    修订日期:2020-03-27
中文摘要: 选取杭州地区2013—2018年6—8月28次午后雷暴大风个例进行研究。结果表明:杭州夏季午后雷暴大风依照发生频率多少主要影响路径依次为西北向偏东移(28%)、西南向东北移(25%)、东南向偏北移(22%)、杭州局地生成(19%);杭州西北、西南山区和东北部平原是雷暴触发和增强关键区。夏季午后雷暴大风天气概念模型按照副热带高压与周边系统相互作用分为:高空冷平流强迫型、低层暖平流强迫型和准正压型,其中准正压型杭州地区更多的是与边界层辐合线和东风带系统影响这一类。抬升触发机制多为近地层中尺度辐合线,这与弱冷空气侵入、海陆分布、地形等因素有关。其T-lnp图特征包括:对流有效位能(CAPE)中等偏强,中层为干空气层结,中低层有较浅薄湿层,低层〖JP2〗环境大气温度垂直递减率接近干绝热,湿层下温湿廓线呈倒“V”型。CAPE、下沉有效位能(DCAPE)均在1 〖KG-*5〗000 J·kg-1以上,DCAPE平均值更大。中层(700~400 hPa)〖JP〗平均温度露点差均值为13.7℃,最大温度露点差均值为21.5℃,可以很好地表征中层干层特征。夏季午后雷暴大风天气一般发生在弱的垂直风切变条件下,大风指数命中率可达79%,但是要注意其虚警次数也较多。
Abstract:In this paper, 28 cases of afternoon thunderstorm in Hangzhou from June to August in 2013-2018 were selected for research. There are four main paths (from more to less frequent): northwest moving to eastward, southwest to northeast, southeast to northward, and locally generated in Hangzhou. From the evolution of dual-polarization radar echo, three key areas of thunderstorm can be seen, including northwest, southwest and northeast. Three types of thunderstorm conceptual model are: cold advection forcing category, warm advection forcing category and quasi-barotropic category, of which, the quasi-positive pressure type in Hangzhou Area is mostly combined with boundary layer convergence line and east wind belt system. The near-surface meso-scale convergence line is the lifting trigger mechanism, which is related to boundary weak cold air invasion, subtropical high control, land and sea distribution, topography and other factors. The characteristics of the T-lnp diagram are: a moderate intensity CAPE, dry air in mid and high level, a shallow wet layer in the lower layer, the lapse rate of atmospheric temperature in the lower atmosphere, close to dry adiabatic, and an inverted “V” shape, shown by the temperature and dew point profile under the wet layer. The average values of CAPE and DCAPE are above 1 〖KG-*5〗000 J·kg-1. The average temperature-dewpoint difference of middle layer and the maximum temperature-dewpoint difference of single layer can well represent the dry air of middle layer. In summer, thunderstorms usually occur under the condition of weak vertical wind shear. The wind index has some indication.
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基金项目:中国气象局预报员专项(CMAYBY2019-047)资助
引用文本:
樊李苗,俞小鼎,2020.杭州地区夏季午后雷暴大风环境条件分析[J].气象,46(12):1621-1632.
FAN Limiao,YU Xiaoding,2020.Analysis on the Environment Conditions of Afternoon Thunderstorm in Hangzhou[J].Meteor Mon,46(12):1621-1632.