一次西北地区东部大暴雨的物理机制分析
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摘要
利用探空、地面加密自动气象站、卫星云图以及1°×1°NCEP再分析资料,从大气环流、水汽来源、湿斜压矢量、涡度转换、大气非平衡强迫等方面对2010年7月23日发生在西北地区东部的大暴雨过程进行了诊断分析。结果表明,低涡切变线在中、低层形成强辐合,对流层高层南亚高压东部北风急流出口区左侧形成强辐散,这样高层辐散、低层辐合的环流配置在暴雨区上空易形成强大的上升运动。在台风"灿都"和副热带高压的作用下,偏南风低空气流源源不断地向西北地区东部输送水汽。暴雨期间,大气降水率与暴雨不同阶段的雨强变化一致,暴雨最强时段降水率达到50 mm·h-1以上。鞍型流场引导干冷空气和暖湿空气在低涡切变线处汇集,总变形大值区与等相当位温线密集带一致,有利于低涡湿斜压性增强。低涡快速发展期,500 h Pa垂直涡度的增长绝大部分来源于扭转项的贡献,即水平涡度向垂直涡度的转换,且出现最大值比垂直涡度超前6 h,对暴雨预报有一定的指示意义。850h Pa大气非平衡强迫负值中心值越小,雨强越强,在出现极端强降水的区域大气非平衡强迫中心值小于-10.0×10-9s-2。
By using the data of sounding and surface intensive AWS,the satellite cloud images and the reanalysis data of NCEP 1° × 1°,the forming mechanism of a rainstorm occurred on 23 July 2010 in the eastern part of Northwest China are analyzed. The results showthat the eastern part of Northwest China is at the left side of exit zone of the upper level north jet and convergence region of the lowvortex and shear-line in the lowlevel,so the coupling of the upper and lowlevel system is easy to form strong ascend movement. The lowlevel southerly air current formed by interaction of typhoon ‘Chanthu'and the subtropical high continuously transports water vapor to the eastern region of Northwest china. During the rainstorm,precipitation rate and rainfall intensity is consistent and the precipitation rate is over 50 mm ·h-1in the strongest period of rainstorm. Under the background of the saddle pattern flowfield,the cold and warm air converge in shear lines of the lowvortex. The great total deformation zones coincide with the dense belt of equivalent potential temperature isoline,it is conducive to enhance the wet baroclinicity of the lowvortex. During the rapid development of the vortex,the vertical vorticity growth mostly come from the twisting term on 500 h Pa. The twisting term maximum ahead of vertical vorticity maximum appears,which has the very good instruction significance for rainstorm forecast. The smaller the negative center value of non-equilibrium force of atmospheric motion on 850 h Pa is,the stronger the raininess will be. The negative center value of non-equilibrium force of atmospheric motion in the extreme precipitation region is below-10. 0 × 10-9s-2.
By using the data of sounding and surface intensive AWS,the satellite cloud images and the reanalysis data of NCEP 1° × 1°,the forming mechanism of a rainstorm occurred on 23 July 2010 in the eastern part of Northwest China are analyzed. The results showthat the eastern part of Northwest China is at the left side of exit zone of the upper level north jet and convergence region of the lowvortex and shear-line in the lowlevel,so the coupling of the upper and lowlevel system is easy to form strong ascend movement. The lowlevel southerly air current formed by interaction of typhoon ‘Chanthu'and the subtropical high continuously transports water vapor to the eastern region of Northwest china. During the rainstorm,precipitation rate and rainfall intensity is consistent and the precipitation rate is over 50 mm ·h-1in the strongest period of rainstorm. Under the background of the saddle pattern flowfield,the cold and warm air converge in shear lines of the lowvortex. The great total deformation zones coincide with the dense belt of equivalent potential temperature isoline,it is conducive to enhance the wet baroclinicity of the lowvortex. During the rapid development of the vortex,the vertical vorticity growth mostly come from the twisting term on 500 h Pa. The twisting term maximum ahead of vertical vorticity maximum appears,which has the very good instruction significance for rainstorm forecast. The smaller the negative center value of non-equilibrium force of atmospheric motion on 850 h Pa is,the stronger the raininess will be. The negative center value of non-equilibrium force of atmospheric motion in the extreme precipitation region is below-10. 0 × 10-9s-2.
引文
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[10]王伏村,许东蓓,王宝鉴,等.敦煌致洪暴雨的广义湿位涡分析[J].高原气象,2013,32(1):145-155,doi:10.7522/j.issn.1000-0534.2013.00015.
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[20]陈忠明,高文良,闵文彬,等.湿位涡、热力学参数CD与涡度、散度演化[J].高原气象,2006,25(6):983-988.
[21]陈忠明.湿斜压大气中暴雨中尺度系统发展的一种可能机制[J].高原气象,2007,26(2):233-239.
[22]姜勇强,王元,吕梅,等.2010年6月中下旬南方暴雨过程变形场作用分析[J].气象科学,2013,33(2):168-177.
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[24]冉令坤,楚艳丽.等熵面和湿等熵面倾斜发展的诊断分析[J].大气科学,2007,31(4):655-665.
[25]李明,高维英,侯建忠,等.一次西南涡东北移对川陕大暴雨影响的分析[J].高原气象,2013,32(1):133-144,doi:10.7522/j.issn.1000-0534.2013.00014.
[26]姜勇强,王元.地形对1998年7月鄂东特大暴雨鞍型场的影响[J].高原气象,2010,29(2):297-308.
[27]Jiang Yongqiang,Wang Yuan.Numerical simulation on the formation of mesoscale vortex in col field[J].Acta M eteor Sinica,2012,26(1):112-128.
[28]赵桂香,范卫东,刘志斌,等.“8.18-19”山西中南部暴雨天气特征分析[J].高原气象,2012,31(5):1309-1319.
[29]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(5):475-490.
[30]顾清源,周春花,青泉,等.一次西南低涡特大暴雨过程的中尺度特征分析[J].气象,2008,34(4):39-47.
[31]伍红雨,杨康权.应用新型散度方程诊断暴雨的触发和增幅机理[J].气象学报,2011,69(2):234-248.
[2]慕建利,李泽椿,李耀辉.高原东侧特大暴雨过程中秦岭山脉的作用[J].高原气象,2009,28(6):1282-1290.
[3]李生辰,巩远发,王田寿.青藏高原东北部一次强暴雨过程环流特征分析[J].高原气象,2010,29(2):278-285.
[4]赵玉春,王叶红.高原涡诱生西南涡特大暴雨成因的个例研究[J].高原气象,2010,29(4):819-831.
[5]宋雯雯,李国平.一次高原低涡过程的数值模拟与结构特征分析[J].高原气象,2011,30(2):267-276.
[6]郁淑华,高文良,彭骏.青藏高原低涡活动对降水影响的统计分析[J].高原气象,2012,31(3):592-604.
[7]钟水新,王东海,张人禾,等.一次冷涡发展阶段大暴雨过程的中尺度对流系统研究[J].高原气象,2013,32(2):435-445,doi:10.7522/j.issn.1000-0534.2012.00042.
[8]杨康权,张琳,肖递祥,等.四川盆地西部一次大暴雨过程的中尺度特征分析[J].高原气象,2013,32(2):357-367,doi:10.7522/j.issn.1000-0534.2012.00035.
[9]白涛,李崇银,王铁,等.干侵入对陕西“2008.07.21”暴雨过程的影响分析[J].高原气象,2013,32(2):345-356,doi:10.7522/j.issn.1000-0534.2012.00034.
[10]王伏村,许东蓓,王宝鉴,等.敦煌致洪暴雨的广义湿位涡分析[J].高原气象,2013,32(1):145-155,doi:10.7522/j.issn.1000-0534.2013.00015.
[11]Rasmussen E N,Wilhelmson R B.Relationship between storm characteristics and 1200 GM S hodographs,low-level shear and stability[R].13thConf.on Severe Local Storms,Amer M eteor Soc,Tulsa,1983.
[12]Rasmussen E N,Blanchard D O.A baseline climatology of sounding-derived supercell and tornado forecast parameters[J].Wea Forecasting,1998,13:1148-1164.
[13]吴国雄,蔡雅萍,唐晓菁.湿位涡和倾斜涡度发展[J].气象学报,1995,53(4):387-404.
[14]吴国雄,刘还珠.全型垂直涡度倾向方程和倾斜涡度发展[J].气象学报,1999,57(1):1-15.
[15]孙淑清.低层风场在暴雨发生中的动力作用[J].大气科学,1982,6(2):394-404.
[16]孙淑清.散度变化在中尺度对流系统分析预报中之应用[J].气象,1989,15(1):3-8.
[17]陈忠明.大气内部非平衡强迫激发暴雨的动力诊断[J].科学通报,1992,37(14):1342-1343.
[18]陈忠明,闵文彬,高文良,等.大气运动非平衡强迫与“98.7”突发性特大暴雨诊断分析[J].气象,2003,29(12):3-9.
[19]陈忠明,闵文彬,徐茂良,等.大气运动非平衡强迫与“98.7”暴雨云团的中尺度特征[J].气象学报,2004,62(3):375-383.
[20]陈忠明,高文良,闵文彬,等.湿位涡、热力学参数CD与涡度、散度演化[J].高原气象,2006,25(6):983-988.
[21]陈忠明.湿斜压大气中暴雨中尺度系统发展的一种可能机制[J].高原气象,2007,26(2):233-239.
[22]姜勇强,王元,吕梅,等.2010年6月中下旬南方暴雨过程变形场作用分析[J].气象科学,2013,33(2):168-177.
[23]刘式适,刘式达.大气动力学[M].北京:北京大学出版社,1999:50-67.
[24]冉令坤,楚艳丽.等熵面和湿等熵面倾斜发展的诊断分析[J].大气科学,2007,31(4):655-665.
[25]李明,高维英,侯建忠,等.一次西南涡东北移对川陕大暴雨影响的分析[J].高原气象,2013,32(1):133-144,doi:10.7522/j.issn.1000-0534.2013.00014.
[26]姜勇强,王元.地形对1998年7月鄂东特大暴雨鞍型场的影响[J].高原气象,2010,29(2):297-308.
[27]Jiang Yongqiang,Wang Yuan.Numerical simulation on the formation of mesoscale vortex in col field[J].Acta M eteor Sinica,2012,26(1):112-128.
[28]赵桂香,范卫东,刘志斌,等.“8.18-19”山西中南部暴雨天气特征分析[J].高原气象,2012,31(5):1309-1319.
[29]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(5):475-490.
[30]顾清源,周春花,青泉,等.一次西南低涡特大暴雨过程的中尺度特征分析[J].气象,2008,34(4):39-47.
[31]伍红雨,杨康权.应用新型散度方程诊断暴雨的触发和增幅机理[J].气象学报,2011,69(2):234-248.