干侵入对陕西“2008.07.21”暴雨过程的影响分析
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摘要
利用NCEP/NCAR再分析资料,分析了2008年7月21日发生在陕西西南部一次暴雨过程的大尺度环流背景和水汽条件,运用相对湿度、风矢量、湿位涡和垂直涡度等多种物理量场,研究了该暴雨过程中干侵入的机制和特征,以及对暴雨发生、发展和维持的影响。结果表明,此次强降水过程是在高空槽和低空气旋的有利形势下产生的。水汽主要来源于孟加拉湾,持续的高层辐散、低层辐合的环流配置保证了低层源源不断的水汽辐合并抬升凝结,有利于转化为降水。受高空低槽发展东移的影响,干侵入在垂直层次上表现为由对流层中高层向低层的注入,水平方向上主要表现为由西向东的侵入,其中在103°E以西地区存在较强的下沉运动是干侵入的载体。应用湿位涡与倾斜涡度发展理论分析表明,当对流层中高层具有高值位涡的干空气侵入到低层时,由于湿位涡守恒特性,引起倾斜涡度发展,进而导致低层垂直涡度的急剧发展,有利于上升运动将水汽向上层输送,冷暖空气相遇,产生此次暴雨过程。
Based on the NCEP/NCAR reanalysis datasets,the large-scale circulation and water vapor conditions of the rainstorm process on 21 July 2008 occurred in southwest of Shaanxi have been analyzed.By employing multiple variations(such as relative humidity,vector wind,moisture potential vorticity,and vertical vorticity),the characteristics and mechanisms of the dry intrusion,as well as its impacts on the formation,development and maintenance of the rainstorm are explored.It is founded that the development of the upper-level trough and low-level cyclone are helpful to the occurrence of rainstorm event.The water vapor mainly comes from the Bay of Bengal,The circulation configuration of sustained high-level divergence and low-level convergence is in favor of plenty of low-level water vapor convergence,ascent and condensation motion,which can provide an advantageous condition for the conversion of precipitation.Influenced on moving eastward and development of the upper-level trough,dry intrusion can be mainly observed in two patterns,in the vertical direction,the dry air from the mid-upper troposphere can be extended into the lower troposphere;in the horizontal direction,the dry air can intrude from west to east.The stronger descending motion exists to the west of 103°E,which could be recognized as the carrier of the dry intrusion.The analysis of moisture potential vorticity and slantwise vorticity theory shows that,when the dry air along with high potential vorticity from mid-upper troposphere intrude into lower troposphere,the slantwise vorticity and low-level vertical vorticity develops due to the conservation of moisture potential vorticity,which facilitates ascend motion brings water vapor upward.When cold air and warm air interacts,the rainstorm event happens.
Based on the NCEP/NCAR reanalysis datasets,the large-scale circulation and water vapor conditions of the rainstorm process on 21 July 2008 occurred in southwest of Shaanxi have been analyzed.By employing multiple variations(such as relative humidity,vector wind,moisture potential vorticity,and vertical vorticity),the characteristics and mechanisms of the dry intrusion,as well as its impacts on the formation,development and maintenance of the rainstorm are explored.It is founded that the development of the upper-level trough and low-level cyclone are helpful to the occurrence of rainstorm event.The water vapor mainly comes from the Bay of Bengal,The circulation configuration of sustained high-level divergence and low-level convergence is in favor of plenty of low-level water vapor convergence,ascent and condensation motion,which can provide an advantageous condition for the conversion of precipitation.Influenced on moving eastward and development of the upper-level trough,dry intrusion can be mainly observed in two patterns,in the vertical direction,the dry air from the mid-upper troposphere can be extended into the lower troposphere;in the horizontal direction,the dry air can intrude from west to east.The stronger descending motion exists to the west of 103°E,which could be recognized as the carrier of the dry intrusion.The analysis of moisture potential vorticity and slantwise vorticity theory shows that,when the dry air along with high potential vorticity from mid-upper troposphere intrude into lower troposphere,the slantwise vorticity and low-level vertical vorticity develops due to the conservation of moisture potential vorticity,which facilitates ascend motion brings water vapor upward.When cold air and warm air interacts,the rainstorm event happens.
引文
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[3]刘会荣,李崇银,周育锋.山东地区一次台风降水事件中的干侵入特征分析[J].气候与环境研究,2011,16(3):289-300.
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[7]Spencer P L,Stensurd D J.Simulating flash flood events:im-portance of subgrid representation of convection[J].Mon WeaRev,1998,126:2884-2192.
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[13]James R P,Clark J H E.The diagnosis of vertical motionwithin dry in intrusions[J].Wea Forecasting,2003,18(5):825-835.
[14]于玉斌,姚秀萍.干侵入的研究及其应用进展[J].气象学报,2003,61(6):769-778.
[15]姚秀萍,于玉斌.2003年梅雨期干空气的活动及其对梅雨降水的作用[J].大气科学,2005,29(6):973-985.
[16]王东海,杨帅.一个干侵入参数及其应用[J].气象学报,2009,67(4):522-529.
[17]刘会荣,李崇银.干侵入对济南“7.18”暴雨的作用[J].大气科学,2008,34(2):374-386.
[18]郭大梅,慕建利,刘瑞芳,等.陕西暴雨个例倾斜涡度发展和干侵入分析[J].陕西气象,2009(6):5-8.
[19]侯建忠,袁媛,胡皓,等.2008年陕西盛夏一次区域性大暴雨的综合分析[C].第26届中国气象学会年会论文集.北京:中国气象学会,2009:149-150.
[20]徐国强,朱乾根,薛纪善,等.1998年中国区域降水低频变化的传播机制的初步分析[J].大气科学,2004,28(5):736-746.
[21]高守亭,雷霆,周玉淑.强暴雨系统中湿位涡异常的诊断分析[J].应用气象学报,2002,13(6):662-669.
[22]矫梅燕,毕宝贵,鲍媛媛,等.2003年7月3-4日淮河流域大暴雨结构和维持机制分析[J].大气科学,2006,30(3):475-490.
[23]任余龙,寿绍文,李耀辉.西北地区东部一次大暴雨过程的湿位涡诊断与数值模拟[J].高原气象,2007,26(2):344-352.
[24]毕宝贵,鲍媛媛,李泽椿.“02.6”陕南大暴雨结构及成因分析[J].高原气象,2006,25(1):34-44.
[25]杨贵名,毛冬艳,姚秀萍.“强降水和黄河气旋”中的干侵入分析[J].高原气象,2006,25(1):16-28.
[26]Cho Hanru,Chan Donglas.Meso-β-scale potential vorticity a-nomalies and rainbands,PartⅡ:Moist model simulation[J].JAtmos Sci,1991,48(2):331-341.
[27]王淑云.干侵入在环渤海地区秋季暴雨中的作用[D].南京:南京信息工程大学,2005:25-29.
[28]陶诗言等著.中国之暴雨[M].北京:科学出版社,1980:25-34.
[29]寿绍文,励申申,姚秀萍.中尺度气象学[M].北京:气象出版社,2003:235-239,276-285.
[30]吴国雄,蔡雅萍,唐晓箐.湿位涡和倾斜涡度发展[J].气象学报,1995,53(4):387-404.
[31]于玉斌,姚秀萍.华北一次特大台风暴雨过程的位涡诊断分析[J].高原气象,2000,19(1):111-121.
[32]黄彬,陈涛,康志明,等.诱发渤海风暴潮的黄河气旋动力学诊断和机制分析[J].高原气象,2011,30(4):901-912.
[33]吴蓁,范雪峰,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.
[2]姚秀萍,吴国雄,赵兵科,等.与梅雨锋上低涡降水相伴的干侵入研究[J].中国科学(D辑),2007,37(3):417-428.
[3]刘会荣,李崇银,周育锋.山东地区一次台风降水事件中的干侵入特征分析[J].气候与环境研究,2011,16(3):289-300.
[4]Danislsen E F.Project Springfield Report[R].Washington DC:Defense Atomic Support Agency,1964:99.
[5]Young M V.Extratropical cyclones-A forecaster's perspec-tive[J].Meteor Appl,1997,4:293-300.
[6]Young M V,Monk G A,Browning K A.Interpretation ofsatellite imagery of a rapidly deepening cyclones[J].Quart JRoy Meteor Soc,1987,111:1089-1115.
[7]Spencer P L,Stensurd D J.Simulating flash flood events:im-portance of subgrid representation of convection[J].Mon WeaRev,1998,126:2884-2192.
[8]Browning K A,Roberts N M.Variation of frontal and precipi-tation structure along a cold front[J].Quart J Roy MeteorSoc,1996,122(536):1845-1872.
[9]Kreitzberg C W.The mesoscale wind field in an occlusion[J].J Appl Meteor,1968,7:53-67.
[10]Hobbs P V,Houze R A Jr,Matejka T J.The dynamical andmicrophical structure of an occluded frontal system and itsmodification by orography[J].J Atmos Sci,1975,32:1542-1562.
[11]Neiman P J,Shapiro M A,Fdor L S.The life cycle of an ex-tratropical marine cyclone.PartⅡ.Mesoscale structure and di-agnostics[J].Mon Wea Rev,1993,121:2177-2199.
[12]Browning K A,Clough S A,Davitt C S A,et al.Observationof the mesoscale sub-structure in the cold air of a developingfrontal cyclone[J].Quart J Roy Meteor Soc,1995,121:1229-1254.
[13]James R P,Clark J H E.The diagnosis of vertical motionwithin dry in intrusions[J].Wea Forecasting,2003,18(5):825-835.
[14]于玉斌,姚秀萍.干侵入的研究及其应用进展[J].气象学报,2003,61(6):769-778.
[15]姚秀萍,于玉斌.2003年梅雨期干空气的活动及其对梅雨降水的作用[J].大气科学,2005,29(6):973-985.
[16]王东海,杨帅.一个干侵入参数及其应用[J].气象学报,2009,67(4):522-529.
[17]刘会荣,李崇银.干侵入对济南“7.18”暴雨的作用[J].大气科学,2008,34(2):374-386.
[18]郭大梅,慕建利,刘瑞芳,等.陕西暴雨个例倾斜涡度发展和干侵入分析[J].陕西气象,2009(6):5-8.
[19]侯建忠,袁媛,胡皓,等.2008年陕西盛夏一次区域性大暴雨的综合分析[C].第26届中国气象学会年会论文集.北京:中国气象学会,2009:149-150.
[20]徐国强,朱乾根,薛纪善,等.1998年中国区域降水低频变化的传播机制的初步分析[J].大气科学,2004,28(5):736-746.
[21]高守亭,雷霆,周玉淑.强暴雨系统中湿位涡异常的诊断分析[J].应用气象学报,2002,13(6):662-669.
[22]矫梅燕,毕宝贵,鲍媛媛,等.2003年7月3-4日淮河流域大暴雨结构和维持机制分析[J].大气科学,2006,30(3):475-490.
[23]任余龙,寿绍文,李耀辉.西北地区东部一次大暴雨过程的湿位涡诊断与数值模拟[J].高原气象,2007,26(2):344-352.
[24]毕宝贵,鲍媛媛,李泽椿.“02.6”陕南大暴雨结构及成因分析[J].高原气象,2006,25(1):34-44.
[25]杨贵名,毛冬艳,姚秀萍.“强降水和黄河气旋”中的干侵入分析[J].高原气象,2006,25(1):16-28.
[26]Cho Hanru,Chan Donglas.Meso-β-scale potential vorticity a-nomalies and rainbands,PartⅡ:Moist model simulation[J].JAtmos Sci,1991,48(2):331-341.
[27]王淑云.干侵入在环渤海地区秋季暴雨中的作用[D].南京:南京信息工程大学,2005:25-29.
[28]陶诗言等著.中国之暴雨[M].北京:科学出版社,1980:25-34.
[29]寿绍文,励申申,姚秀萍.中尺度气象学[M].北京:气象出版社,2003:235-239,276-285.
[30]吴国雄,蔡雅萍,唐晓箐.湿位涡和倾斜涡度发展[J].气象学报,1995,53(4):387-404.
[31]于玉斌,姚秀萍.华北一次特大台风暴雨过程的位涡诊断分析[J].高原气象,2000,19(1):111-121.
[32]黄彬,陈涛,康志明,等.诱发渤海风暴潮的黄河气旋动力学诊断和机制分析[J].高原气象,2011,30(4):901-912.
[33]吴蓁,范雪峰,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.