南疆西部暴雨过程的动力热力结构分析
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摘要
利用常规气象观测资料和ECMWF提供的ERA-Interim 0.125°×0.125°再分析资料,通过对2012年5月21~23日和2013年5月26~29日南疆西部两次暴雨过程中等熵面特征的对比分析,得到暴雨过程中的动力热力结构模型。结果表明:南疆西部暴雨过程是在中亚低涡系统影响下,高、中、低空急流耦合并叠加地形强迫的综合作用下形成的。中亚低涡前部中高层向东输送的冷空气翻山后下沉,与低层南疆盆地东部向西输送的冷空气汇合抬升,与中层暖空气交汇,同时上升运动加强促使水汽辐合凝结,是降水的重要原因,短时强降水时冷空气强度弱于暖空气,持续性降水时反之。中低层等熵面位涡与降水关系密切。
Using the conventional meteorological observation data and ECMWF ERA-Interim data( 0. 125° ×0. 125°),the isentropic surface characteristic of two rainstorms,which were occurred in the west of south Xinjiang on May 21 to May 23,2012 and on May 26 to May 29,2013 respectively,were analyzed to establish the thermal dynamic model of the rainstorm process. The results indicated that the rainstorm came from a synthetic action of topographic forcing and jet streaming coupling among high,medium and low level jet streams when there was a Central Asian low vortex. At the high level of troposphere,the South Asia High appeared in a zonal distribution with its west part being northward raised obviously and its subtropical trough being extended southward to central Asia. Therefore a strong high-altitude southwest jet stream was formed over the west of south Xinjiang which intensified the chimney effect and caused a strong divergence formed at high altitude over the precipitation region. The cold east-deflected jet at the low level was also spread into the precipitation region which caused an intense convergence. This region has the terrain with high altitudes in its west side and low altitudes in its east side,westward airflow is lifted. The overlay of the dynamic effects from both high level and low level pushed strongly the ascending motion which provided the force condition for the rainstorm. The south-deflected airflow at middle level and the east-deflected airflow at low level carried abundant water vapor into the precipitation area which produced the vapor condition for the rainstorm. The cold air in the front of the Central Asian Vortex,which has high values of vortex,climbed over the west Tianshan adding more water vapor content at the middle level over the precipitation area. Part of the cold air slid along the geographic surface and joined the cold air at the low level and this convergence pushed the ascending motion further. The lifted cold air encountered the warm air at the middle level which made the water vapor coagulate into rain. There was a significant correlation between the potential vorticity of the isentropic surface and the heavy rainfall. The isentropic potential vorticity was increased when the precipitation began,and it was decreased when precipitation was over. Rainfall was triggered by the convergence of cold air and worm air. The intensity of the cold air was weaker than that of the warm air when there was a short-time strong rainfall,and it was the other way around when there was a persistent precipitation.
Using the conventional meteorological observation data and ECMWF ERA-Interim data( 0. 125° ×0. 125°),the isentropic surface characteristic of two rainstorms,which were occurred in the west of south Xinjiang on May 21 to May 23,2012 and on May 26 to May 29,2013 respectively,were analyzed to establish the thermal dynamic model of the rainstorm process. The results indicated that the rainstorm came from a synthetic action of topographic forcing and jet streaming coupling among high,medium and low level jet streams when there was a Central Asian low vortex. At the high level of troposphere,the South Asia High appeared in a zonal distribution with its west part being northward raised obviously and its subtropical trough being extended southward to central Asia. Therefore a strong high-altitude southwest jet stream was formed over the west of south Xinjiang which intensified the chimney effect and caused a strong divergence formed at high altitude over the precipitation region. The cold east-deflected jet at the low level was also spread into the precipitation region which caused an intense convergence. This region has the terrain with high altitudes in its west side and low altitudes in its east side,westward airflow is lifted. The overlay of the dynamic effects from both high level and low level pushed strongly the ascending motion which provided the force condition for the rainstorm. The south-deflected airflow at middle level and the east-deflected airflow at low level carried abundant water vapor into the precipitation area which produced the vapor condition for the rainstorm. The cold air in the front of the Central Asian Vortex,which has high values of vortex,climbed over the west Tianshan adding more water vapor content at the middle level over the precipitation area. Part of the cold air slid along the geographic surface and joined the cold air at the low level and this convergence pushed the ascending motion further. The lifted cold air encountered the warm air at the middle level which made the water vapor coagulate into rain. There was a significant correlation between the potential vorticity of the isentropic surface and the heavy rainfall. The isentropic potential vorticity was increased when the precipitation began,and it was decreased when precipitation was over. Rainfall was triggered by the convergence of cold air and worm air. The intensity of the cold air was weaker than that of the warm air when there was a short-time strong rainfall,and it was the other way around when there was a persistent precipitation.
引文
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[9]李如琦,李建刚,唐冶,等.中亚低涡引发的两次南疆西部暴雨中尺度特征对比分析[J].干旱气象,2016,34(2):297-304.[LI Ruqi,LI Jiangang,TANG Ye,et al.Caused by central asian vortex in the west of south Xinjiang[J].Journal of Arid Meteorology,2016,34(2):297-304.]
[10]HOSKINS B J,MCINTYRE M E,ROBERTSON A W.On the use and significance of isentropic potential vorticity maps[J].Quart J Roy Meteor Soc,1985,111(470):877-946.
[11]寿绍文,李耀辉,范可.暴雨中尺度气旋发展的等熵面位涡分析[J].气象学报,2001,59(5):560-568.[SHOU Shaowen,LI Yaohui,FAN Ke.Isentropic potential vorticity analysis of the mesoscale cyclone development in a heavy rain process[J].Acta Meteorologica Sinica,2001,59(5):560-568.]
[12]徐晶,王东生,杨克明.2003年7月4~7日淮河流域特大暴雨等熵位涡分析[J].气象,2004,30(1):33-37.[XU Jing,Wang Dongsheng,YANG Keming.Isentropic potential vorticity analysis of heavy rain in the Huaihe River Valley during 4-7 July 2003[J].Meteorological Monthly,2004,30(1):33-37.]
[13]程鹏,赵庆云,李江萍,等.西北地区东部一次连阴雨过程等熵位涡分析[J].干旱气象,2007,25(1):58-62.[CHENG Peng,ZHAO Qingyun,LI Jiangping,et al.Analysis of isentropic potential vorticity of a continuous rain process in the east of northwest China[J].Journal of Arid Meteorology,2007,25(1):58-62.]
[14]吴蓁,范学峰,郑世林,等.台风外围偏东气流中的暴雨及其等熵位涡特征[J].高原气象,2008,27(3):584-595.[WU Zhen,FAN Xuefeng,ZHENG Shilin,et al.Rainstorm in the east airflow of typhoon periphery and its isentropic potential vorticity character[J].Plateau Meteorology,2008,27(3):584-595.]
[15]黎惠金,李江南,肖辉,等.2008年初中国南方低温雨雪冰冻事件的等熵位涡分析[J].高原气象,2010,29(5):1196-1207.[LI Huijin,LI Jiangnan,XIAO Hui,et al.Isentropic potential vorticity analysis on the events of low temperature freezing rain and snow in southern China in early 2008[J].Plateau Meteorology,2010,29(5):1196-1207.]
[16]周秋林,闵锦忠,梅士龙.浙北地区一次大暴雨过程的等熵位涡分析[J].气象科学,2010,30(4):475-480.[ZHOU Qiulin,MIN Jinzhong,MEI Shilong.Analysis of isentropic potential vorticity for a heavy rain event in north of Zhejiang[J].Journal of the Meteorological Sciences,2010,30(4):475-480.]
[17]葛晶晶,陆汉城,张群,等.强烈发展的中尺度涡旋影响下持续性暴雨的位涡诊断[J].高原气象,2012,31(4):952-962.[GE Jingjing,LU Hancheng,ZHANG Qun,et al.Vorticity diagnosis of continuous rainstorm under the influence of strong developing mesoscale vortex[J].Plateau Meteorology,2012,31(4):952-962.]
[18]田秀霞,何丽华,陈笑娟.一次西南涡暴雨的等熵位涡特征分析[J].气象与环境学报,2014,30(6):25-30.[TIAN Xiuxia,HE Lihua,CHEN Xiaojuan.Analysis of isentropic potential vorticity for a heavy rain caused by a southwestern low vortex[J].Journal of Meteorology and Environment,2014,30(6):25-30.]
[19]邱静雅,李国平,郝丽萍.高原涡与西南涡相互作用引发四川暴雨的位涡诊断[J].高原气象,2015,34(6):1556-1565.[QIU Jingya,LI Guoping,HAO Liping.Diagnostic analysis of potential vorticity on a heavy rain in Sichuan Basin under interaction between plateau vortex and southwest vortex[J].Plateau Meteorology,2015,34(6):1556-1565.]
[20]陈铁,罗爱文,徐为根,等.一次大范围暴雨过程的诊断分析[J].气象科学,2015,35(3):362-369.[CHEN Tie,LUO Aiwen,XU Weigen,et al.Diagnostic analysis on a wide range rainstorm process[J].Journal of the Meteorological Sciences,2015,35(3):362-369.]
[2]陈春艳,赵克明,阿不力米提江·阿布力克木,等.暖湿背景下新疆逐时降水变化特征研究[J].干旱区地理,2015,38(4):692-702.[CHEN Chunyan,ZHAO Keming,ABLIKM Ablimitijan,et al.Temporal and spatial distributions of hourly rain intensity under the warm background in Xinjiang[J].2015,38(4):692-702.]
[3]王江,周雅蔓,王昀,等.2014年夏初南疆一次持续性强降雨过程的水汽和动力条件分析[J].干旱区地理,2015,38(6):1103-1111.[WANG Jiang,ZHOU Yaman,WANG Yun,et al.Water vapour and dynamic conditions of a continuity heavy rainfall over southern Xinjiang in early summer 2014[J].2015,38(6):1103-1111.]
[4]赵战成,丁国峰,艾尔肯.塔克拉玛干沙漠东部边缘降雨日变化[J].干旱区地理,2016,39(6):1182-1185.[ZHAO Zhancheng,DING Guofeng,Arken.Eastern edge of the Taklimakan Desert rainfall diurnal variation[J].2016,39(6):1182-1185.]
[5]周成龙,钟昕洁,杨兴华,等.新疆巴州地区降水量、可降水量及降水转化率计算解析[J].干旱区地理,2016,39(6):1204-1211.[ZHOU Chenglong,ZHONG Xinjie,YANG Xinghua,et al.Calculation of precipitation,precipitable water and precipitation conversion efficiency of Bayingolin Prefecture in Xinjiang[J].2016,39(6):1204-1211.]
[6]赵战成.库尔勒一次强对流大暴雨天气特征分析[J].干旱区地理,2016,39(5):1070-1077.[ZHAO Zhancheng.Characteristics of a strong onvective weather and heavy rainstorm in Korla City,Xinjiang[J].2016,39(5):1070-1077.]
[7]李如琦,孙鸣婧,李桉孛,等.南疆西部暴雨的动力热力特征分析[J].沙漠与绿洲气象,2017,11(2):1-7.[LI Ruqi,SUN Mingjing,LI Anbei,et al.Analysis of dynamic and thermal characteristics on rainstorm in west of southern Xinjiang[J].Desert and Oasis Meteorology,2017,11(2):1-7.]
[8]曾勇,杨莲梅.中亚低涡背景下新疆连续短时强降水特征分析[J].沙漠与绿洲气象,2016,10(4):67-73.[ZENG Yong,YANG Lianmei.Characteristic analysis of continuous heavy shorttime rainfall under the background of central asian vortex in Xinjiang[J].Desert and Oasis Meteorology,2016,10(4):67-73.]
[9]李如琦,李建刚,唐冶,等.中亚低涡引发的两次南疆西部暴雨中尺度特征对比分析[J].干旱气象,2016,34(2):297-304.[LI Ruqi,LI Jiangang,TANG Ye,et al.Caused by central asian vortex in the west of south Xinjiang[J].Journal of Arid Meteorology,2016,34(2):297-304.]
[10]HOSKINS B J,MCINTYRE M E,ROBERTSON A W.On the use and significance of isentropic potential vorticity maps[J].Quart J Roy Meteor Soc,1985,111(470):877-946.
[11]寿绍文,李耀辉,范可.暴雨中尺度气旋发展的等熵面位涡分析[J].气象学报,2001,59(5):560-568.[SHOU Shaowen,LI Yaohui,FAN Ke.Isentropic potential vorticity analysis of the mesoscale cyclone development in a heavy rain process[J].Acta Meteorologica Sinica,2001,59(5):560-568.]
[12]徐晶,王东生,杨克明.2003年7月4~7日淮河流域特大暴雨等熵位涡分析[J].气象,2004,30(1):33-37.[XU Jing,Wang Dongsheng,YANG Keming.Isentropic potential vorticity analysis of heavy rain in the Huaihe River Valley during 4-7 July 2003[J].Meteorological Monthly,2004,30(1):33-37.]
[13]程鹏,赵庆云,李江萍,等.西北地区东部一次连阴雨过程等熵位涡分析[J].干旱气象,2007,25(1):58-62.[CHENG Peng,ZHAO Qingyun,LI Jiangping,et al.Analysis of isentropic potential vorticity of a continuous rain process in the east of northwest China[J].Journal of Arid Meteorology,2007,25(1):58-62.]
[14]吴蓁,范学峰,郑世林,等.台风外围偏东气流中的暴雨及其等熵位涡特征[J].高原气象,2008,27(3):584-595.[WU Zhen,FAN Xuefeng,ZHENG Shilin,et al.Rainstorm in the east airflow of typhoon periphery and its isentropic potential vorticity character[J].Plateau Meteorology,2008,27(3):584-595.]
[15]黎惠金,李江南,肖辉,等.2008年初中国南方低温雨雪冰冻事件的等熵位涡分析[J].高原气象,2010,29(5):1196-1207.[LI Huijin,LI Jiangnan,XIAO Hui,et al.Isentropic potential vorticity analysis on the events of low temperature freezing rain and snow in southern China in early 2008[J].Plateau Meteorology,2010,29(5):1196-1207.]
[16]周秋林,闵锦忠,梅士龙.浙北地区一次大暴雨过程的等熵位涡分析[J].气象科学,2010,30(4):475-480.[ZHOU Qiulin,MIN Jinzhong,MEI Shilong.Analysis of isentropic potential vorticity for a heavy rain event in north of Zhejiang[J].Journal of the Meteorological Sciences,2010,30(4):475-480.]
[17]葛晶晶,陆汉城,张群,等.强烈发展的中尺度涡旋影响下持续性暴雨的位涡诊断[J].高原气象,2012,31(4):952-962.[GE Jingjing,LU Hancheng,ZHANG Qun,et al.Vorticity diagnosis of continuous rainstorm under the influence of strong developing mesoscale vortex[J].Plateau Meteorology,2012,31(4):952-962.]
[18]田秀霞,何丽华,陈笑娟.一次西南涡暴雨的等熵位涡特征分析[J].气象与环境学报,2014,30(6):25-30.[TIAN Xiuxia,HE Lihua,CHEN Xiaojuan.Analysis of isentropic potential vorticity for a heavy rain caused by a southwestern low vortex[J].Journal of Meteorology and Environment,2014,30(6):25-30.]
[19]邱静雅,李国平,郝丽萍.高原涡与西南涡相互作用引发四川暴雨的位涡诊断[J].高原气象,2015,34(6):1556-1565.[QIU Jingya,LI Guoping,HAO Liping.Diagnostic analysis of potential vorticity on a heavy rain in Sichuan Basin under interaction between plateau vortex and southwest vortex[J].Plateau Meteorology,2015,34(6):1556-1565.]
[20]陈铁,罗爱文,徐为根,等.一次大范围暴雨过程的诊断分析[J].气象科学,2015,35(3):362-369.[CHEN Tie,LUO Aiwen,XU Weigen,et al.Diagnostic analysis on a wide range rainstorm process[J].Journal of the Meteorological Sciences,2015,35(3):362-369.]