低层暖平流强迫背景下湖南两次飑线过程对比分析
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摘要
利用常规观测资料、多普勒天气雷达资料以及NCEP/NCAR再分析资料等,对2017年5月11日和6月5日发生在湖南的两次飑线过程(以下分别简称"5·11"飑线过程和"6·5"飑线过程)进行了对比分析。结果表明:(1)两次过程均发生在低层暖平流强迫背景下,"5·11"飑线过程发生前冷平流较明显,"6·5"飑线过程发生前暖湿气流更强盛,副热带高压位置不同导致后一过程水汽条件更好;(2)"5·11"飑线过程中层更干,0℃度层高度更低,有利于出现较大范围雷暴大风和小冰雹,而"6·5"飑线过程自由对流高度(LFC)相对较低、低层湿度更大,则易产生更大强度的短时降水;(3)"5·11"飑线过程产生大范围雷暴大风的环境条件明显好于"6·5"飑线过程,但后一过程因地面倒槽发展、暖湿气流更强、低涡东移使大气对流不稳定增大等原因,更有利于形成局地致灾性大风;(4)"6·5"飑线过程中气旋少且维持时间短,以及垂直风廓线产品(VWP)、径向速度图上雷暴大风特征不够典型,其预警难度更大。
Based on conventional observations, Doppler weather radar date, NCEP/NCAR reanalysis data with 1°×1° resolution and other data, we have performed a comparative analysis between two squall line events(hereinafter referred to as the"5·11"event and the"6·5"event, respectively) occurred in Hunan on 11 May and 5 June of 2017. Results are as follows.(1) Both events occur under the condition of low-level warm convection forcing, in which the cold advection is obvious before the"5·11"event occurred, and the warm and wet airflow prevails before the"6·5"event occurred. The difference in the position of the subtropical high results in that the latter event has better water vapor condition than the former one.(2) During the"5·11"event, atmosphere in the middle layer is drier, and the height of 0 ℃ layer is lower(0.6 km), which is conductive to the formation of thunderstorm gale and small hail over a broad area. Meanwhile, during the"6·5"event, the free convection level(LFC) is relatively low, and humidity in the low-level is greater, which is beneficial to produce greater short-term severe precipitation.(3) The environmental conditions in which a widespread thunderstorm gale occurred in the"5·11"event is better than that in"6.5"event, while in the latter case, the strengthen of atmospheric convective instability is due to the development of surface inverted trough,the intensive warm and wet airflow and the eastward-moving of low vortex, which is more conductive to the emergence of local disastrous gale.(4) In the"6·5"event, there is only one mesocyclone which lasted only for a short time, and the characteristics of thunderstorm gale in the vertical wind profile(VWP) and radar radial velocity chart are not typical enough, which increases the difficulty of early warning to it.
Based on conventional observations, Doppler weather radar date, NCEP/NCAR reanalysis data with 1°×1° resolution and other data, we have performed a comparative analysis between two squall line events(hereinafter referred to as the"5·11"event and the"6·5"event, respectively) occurred in Hunan on 11 May and 5 June of 2017. Results are as follows.(1) Both events occur under the condition of low-level warm convection forcing, in which the cold advection is obvious before the"5·11"event occurred, and the warm and wet airflow prevails before the"6·5"event occurred. The difference in the position of the subtropical high results in that the latter event has better water vapor condition than the former one.(2) During the"5·11"event, atmosphere in the middle layer is drier, and the height of 0 ℃ layer is lower(0.6 km), which is conductive to the formation of thunderstorm gale and small hail over a broad area. Meanwhile, during the"6·5"event, the free convection level(LFC) is relatively low, and humidity in the low-level is greater, which is beneficial to produce greater short-term severe precipitation.(3) The environmental conditions in which a widespread thunderstorm gale occurred in the"5·11"event is better than that in"6.5"event, while in the latter case, the strengthen of atmospheric convective instability is due to the development of surface inverted trough,the intensive warm and wet airflow and the eastward-moving of low vortex, which is more conductive to the emergence of local disastrous gale.(4) In the"6·5"event, there is only one mesocyclone which lasted only for a short time, and the characteristics of thunderstorm gale in the vertical wind profile(VWP) and radar radial velocity chart are not typical enough, which increases the difficulty of early warning to it.
引文
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[15]叶成志,唐明晖,陈红专,等.2013年湖南首场致灾性强对流天气过程成因分析[J].暴雨灾害,2013,32(1):1-10
[16]尹忠海,刘应军,黎祖贤,等.湘中“6.26”雷暴大风过程的多普勒雷达产品分析[J].暴雨灾害, 2007,26(4):319-322
[17]王彦,唐熠,赵金霞,等.天津地区雷暴大风天气雷达产品特征分析[J].气象,2009,35(5):91-96
[18]肖艳姣,马中元,李中华.改进的雷达回波顶高、垂直积分液态水含量及其密度算法[J].暴雨灾害,2009,28(3):210-214
[2]徐双柱,韦惠红.关于强对流天气预报的几点思考[J].暴雨灾害,2016,35(3):197-202
[3]许爱华,孙继松,许东蓓,等.中国中东部强对流天气的天气形势分类和基本要素配置特征[J].气象, 2014,40(4):400-411
[4]郑媛媛,姚晨,郝莹,等.不同类型大尺度环流背景下强对流天气的短时临近预报预警研究[J].气象,2011,37(7):795-801
[5]冯晋勤,俞小鼎,蔡菁,等.福建春季西南急流暖湿强迫背景下的强对流天气流型配置及环境条件分析[J].气象,2017,43(11):1 354-1 363
[6]陈立祥,刘运策.广州地区强对流天气的统计特征和分类特征[J].热带气象学报, 1989(2):170-179
[7]蔡荣辉,姚蓉,黄小玉,等,洞庭湖区域雷暴大风分型及预报分析研究[J].气象,2017,43(4):450-462
[8] Bluestein H B, Jain M H. Formation of mesoscale lines of precipitation:Severe squall lines in Oklahoma during the spring[J]. J Atmos Sci,1985, 42(16):1 711-1 732
[9]俞小鼎,姚秀萍,熊庭南,等.多普勒天气雷达原理及业务应用[M].北京:气象出版社,2006:122-123, 234-236
[10]俞小鼎.关于冰雹的融化层高度[J].气象,2014,40(6):649-654
[11]朱乾根,林锦瑞,寿召文,等.天气学原理和方法[M].北京:气象出版社,2000:349
[12]陆汉城,杨国祥.中尺度天气原理和预报[M].北京:气象出版社,2004:23-31
[13]方翀,郑媛媛.新一代天气雷达中气旋产品特征值统计和个例分析[J].气象,2007,11(33):16-20
[14]俞小鼎,姚秀萍,熊庭南,等.多普勒天气雷达原理及业务应用[M].北京:气象出版社,2006:186-187
[15]叶成志,唐明晖,陈红专,等.2013年湖南首场致灾性强对流天气过程成因分析[J].暴雨灾害,2013,32(1):1-10
[16]尹忠海,刘应军,黎祖贤,等.湘中“6.26”雷暴大风过程的多普勒雷达产品分析[J].暴雨灾害, 2007,26(4):319-322
[17]王彦,唐熠,赵金霞,等.天津地区雷暴大风天气雷达产品特征分析[J].气象,2009,35(5):91-96
[18]肖艳姣,马中元,李中华.改进的雷达回波顶高、垂直积分液态水含量及其密度算法[J].暴雨灾害,2009,28(3):210-214