高空急流对青藏高原切变线影响的数值试验与动力诊断
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摘要
利用NCEP 1°×1°FNL分析资料和中尺度数值模式WRF对一次青藏高原(简称高原)切变线过程进行了数值试验,主要研究高空急流强度对高原切变线的影响,并结合ω方程分析了影响高原切变线上垂直上升运动的若干因子。研究得出高空急流的强度对低层风场有重要影响,急流增强会使高原切变线上的风切变增大,切变线变长,同时高空急流强度的增强也有利于高原切变线上水汽的辐合。高空急流可通过影响高层辐散、低层辐合的散度场垂直配置对高原切变线上的正涡度柱与辐合上升运动产生作用。ω方程的诊断分析表明,温度平流的拉普拉斯项对高原切变线上的垂直上升运动起主导作用,低层暖平流有利于切变线上产生上升运动。高空急流强度的变化对差动涡度平流项的影响要大于温度平流拉普拉斯项,高空急流强度的增强会放大差动涡度平流项和温度平流项的正贡献,从而更加有利于上升运动及高原切变线的维持。
Using the NCEP 1°×1°FNL analysis data and the mesoscale model WRF,numerical experiments have been conducted to simulate a Tibetan Plateau shear line process.The study focuses on the impact of the upper-level jet stream intensity on the Tibetan Plateau shear line.In combination with theωequation,factors affecting the ascending motion in the Tibetan Plateau shear line are also analyzed.The results show that the intensity of the upper-level jet stream has an important influence on low-level wind fields.The increases in jet stream will intensify the wind shear along the Tibetan Plateau shear line,and the shear line will become longer.Meanwhile,the enhancement of the upper-level jet intensity is also favorable for the convergence of water vapor along the Tibetan Plateau shear line.The upper jet can affect positive vorticity,convergence and ascending motion along the Tibetan Plateau shear line by influencing the vertical configuration of lower-level convergence and upper-level divergence.The diagnostic analysis of theωequation shows that the Laplace term of temperature advection plays a dominant role in the ascending motion along the Tibetan Plateau shear line,and the low-level warm advection is favorable for the development of ascending motion along the shear line.The influence of the variation of upper-level jet stream intensity on the differential term of the vorticity advection is greater than that of the Laplace term of temperature advection,and the enhancement of the upper-level jet intensity will enlarge the positive contributions of the differential vorticity advection term and the temperature advection term,which is more favorable for the development of ascending motion and the maintenance of the Tibetan Plateau shear line.
Using the NCEP 1°×1°FNL analysis data and the mesoscale model WRF,numerical experiments have been conducted to simulate a Tibetan Plateau shear line process.The study focuses on the impact of the upper-level jet stream intensity on the Tibetan Plateau shear line.In combination with theωequation,factors affecting the ascending motion in the Tibetan Plateau shear line are also analyzed.The results show that the intensity of the upper-level jet stream has an important influence on low-level wind fields.The increases in jet stream will intensify the wind shear along the Tibetan Plateau shear line,and the shear line will become longer.Meanwhile,the enhancement of the upper-level jet intensity is also favorable for the convergence of water vapor along the Tibetan Plateau shear line.The upper jet can affect positive vorticity,convergence and ascending motion along the Tibetan Plateau shear line by influencing the vertical configuration of lower-level convergence and upper-level divergence.The diagnostic analysis of theωequation shows that the Laplace term of temperature advection plays a dominant role in the ascending motion along the Tibetan Plateau shear line,and the low-level warm advection is favorable for the development of ascending motion along the shear line.The influence of the variation of upper-level jet stream intensity on the differential term of the vorticity advection is greater than that of the Laplace term of temperature advection,and the enhancement of the upper-level jet intensity will enlarge the positive contributions of the differential vorticity advection term and the temperature advection term,which is more favorable for the development of ascending motion and the maintenance of the Tibetan Plateau shear line.
引文
程正泉,陈联寿,李英.2012.登陆热带气旋海马(0421)变性加强的诊断研究.气象学报,70(4):628-641.Cheng Z Q,Chen LS,Li Y.2012.Diagnosis of the extra-tropical transition of landfalling tropical cyclone Haima(2004).Acta Meteor Sinica,70(4):628-641(in Chinese)
高守亭,孙淑清.1984.次天气尺度低空急流的形成.大气科学,8(2):178-188.Gao S T,Sun S Q.1984.The forming of subsynoptic scale low-level jet stream.Chinese J Atmos Sci,8(2):178-188(in Chinese)
高文良,郁淑华.2007.高原低涡东移出高原的平均环流场分析.高原气象,26(1):206-212.Gao W L,Yu S H.2007.Analyses on mean circulation field of the plateau low vortex moving out of Tibetan Plateau.Plateau Meteor,26(1):206-212(in Chinese)
何光碧,师锐.2011.夏季青藏高原不同类型切变线的动力、热力特征分析.高原气象,30(3):568-575.He G B,Shi R.2011.Studies on dynamic and thermal characteristics of different shear lines over Tibetan Plateau in summer.Plateau Meteor,30(3):568-575(in Chinese)
何光碧,师锐.2014.三次高原切变线过程演变特征及其对降水的影响.高原气象,33(3):615-625.He G B,Shi R.2014.A-nalysis on evolution characteristics of three plateau shear lines and their effect on precipitation.Plateau Meteor,33(3):615-625(in Chinese)
江志红,卢尧,丁裕国.2013.基于时空结构指标的中国融合降水资料质量评估.气象学报,71(5):891-900.Jiang Z H,Lu Y,Ding Y G.2013.Analysis of the high-resolution merged precipitation products over China based on the temporal and spatial structure score indices.Acta Meteor Sinica,71(5):891-900(in Chinese)
李国平.2014.新编动力气象学.2版.北京:气象出版社,131-132.Li G P.2014.The Dynamic Meteorology Newly Organized.2nd ed.Beijing:China Meteorological Press,131-132(in Chinese)
李山山,李国平.2017a.一次高原低涡与高原切变线演变过程与机理分析.大气科学,41(4):713-726.Li S S,Li G P.2017a.E-volution and mechanism analysis of a plateau vortex and plateau shear line.Chinese J Atmos Sci,41(4):713-726(in Chinese)
李山山,李国平.2017b.一次鞍型场环流背景下高原东部切变线降水的湿Q矢量诊断分析.高原气象,36(2):317-329.Li S S,Li G P.2017b.Diagnostic analysis based on wet Q-vector of a shear line with rain on the east side of Qinghai-Tibetan Plateau under the saddle pattern circulation background Field.Plateau Meteor,36(2):317-329(in Chinese)
廖移山,冯新,石燕等.2011.2008年“7.22”襄樊特大暴雨的天气学机理分析及地形的影响.气象学报,69(6):945-955.Liao YS,Feng X,Shi Y,et al.2011.Analysis of the mechanism for“2008.7.22”excessive rain event in Xiangfan with a focus on the terrain effect.Acta Meteor Sinica,69(6):945-955(in Chinese)
林毅,刘铭,刘爱鸣.2006.高低空急流在闽西北大暴雨过程中的作用及数值模拟.气象科学,26(4):449-455.Lin Y,Liu M,Liu A M.2006.Numreical study and action of high and low level jet stream in"2002.6"torrential rainstorm of northwest Fujian.Scientia Meteor Sinica,26(4):449-455(in Chinese)
师锐,何光碧.2011.移出与未移出高原的高原切变线背景环流对比分析.高原气象,30(6):1453-1461.Shi R,He G B.2011.Contrast analysis on background circulation of plateau shear line moving out and not moving out of the Tibetan Plateau.Plateau Meteor,30(6):1453-1461(in Chinese)
斯公望.1989.论东亚梅雨锋的大尺度环流及其次天气尺度扰动.气象学报,47(3):312-323.Si G W.1989.On the large-scale circulation of Mei-Yu system over East Asia.Acta Meteor Sinica,47(3):312-323(in Chinese)
屠妮妮,何光碧.2010.两次高原切变线诱发低涡活动的个例分析.高原气象,29(1):90-98.Tu N N,He G B.2010.Case analysis on two low vortexes induced by Tibetan Plateau shear line.Plateau Meteor,29(1):90-98(in Chinese)
徐建芬,陶健红,夏建平.2000.青藏高原切变线暴雪中尺度分析及其涡源研究.高原气象,19(2):187-197.Xu J F,Tao J H,Xia J P.2000.A meso-scale analysis of Qinghai-Xizang Plateau snow storm and its vortex source study.Plateau Meteor,19(2):187-197(in Chinese)
姚秀萍,孙建元,康岚等.2014.高原切变线研究的若干进展.高原气象,33(1):294-300.Yao X P,Sun J Y,Kang L,et al.2014.Advances on research of shear convergence line over Qinghai-Xizang Plateau.Plateau Meteor,33(1):294-300(in Chinese)
郁淑华,高文良,顾清源.2007.近年来影响我国东部洪涝的高原东移涡环流场特征分析.高原气象,26(3):466-475.Yu S H,Gao W L,Gu Q Y.2007.The middle-upper circulation analyses of the plateau vortex moving out of Plateau and influencing flood in east China in recent years.Plateau Meteor,26(3):466-475(in Chinese)
郁淑华,何光碧.2003.水汽图像在高原天气预报中应用的初步分析.高原气象,22(S1):75-82.Yu S H,He G B.2003.Analysis on application of statellite vapour image to weather prediction over Plateau.Plateau Meteor,22(S1):75-82(in Chinese)
郁淑华,何光碧,滕家谟.1997.青藏高原切变线对四川盆地西部突发性暴雨影响的数值试验.高原气象,16(3):306-311.Yu SH,He G B,Teng J M.1997.The numerical experiments of influence of shear line over Qinhai-Xizang Plateau on a sharp heavy rain in west Sichuan basin.Plateau Meteor,16(3):306-311(in Chinese)
郑淋淋,孙建华.2016.风切变对中尺度对流系统强度和组织结构影响的数值试验.大气科学,40(2):324-340.Zheng L L,Sun J H.2016.The impact of vertical wind shear on the intensity and organizational mode of mesoscale convective systems using numerical experiments.Chinese J Atmos Sci,40(2):324-340(in Chinese)
周兵,韩桂荣,何金海.2003.高空西风急流对长江中下游暴雨影响的数值试验.南京气象学院学报,26(5):595-604.Zhou B,Han G R,He J H.2003.Numerical experiment of effects of the upper level westerly jet on a torrential rain over the middlelower reaches of the Yangtze river.J Nanjing Inst Meteor,26(5):595-604(in Chinese)
朱禾,王秀明.2016.影响气温直减率变化的物理过程讨论.气象科技进展,6(5):51-54.Zhu H,Wang X M.2016.A discussion about the physical process of environmental temperature lapse rate tendency.Adv Meteor Sci Technol,6(5):51-54(in Chinese)
朱乾根,林锦瑞,寿绍文等.2000.天气学原理和方法.3版.北京:气象出版社,120-122.Zhu Q G,Lin J R,Shou S W,et al.2000.The Principle and Method of Weather.3rd ed.Beijing:China Meteorological Press,120-122(in Chinese)
Brill K F,Uccellini L W,Burkhart R P,et al.1985.Numerical simulations of a transverse indirect circulation and low-level jet in the exit region of an upper-level jet.J Atmos Sci,42(12):1306-1320
Prezerakos N G,Flocas H A,Brikas D.2006.The role of the interaction between polar and subtropical jet in a case of depression rejuvenation over the eastern Mediterranean.Meteor Atmos Phys,92(1-2):139-151
Tao S Y,Chen L.1987.A review of recent research on the East A-sian summer monsoon in China∥Chang C P,Krishnamurti TN.Monsoon Meteorology.Oxford:Oxford University Press,60-92
Whitney L F Jr.2009.Relationship of the subtropical jet stream to severe local storms.Mon Wea Rev,105(4):398-412
高守亭,孙淑清.1984.次天气尺度低空急流的形成.大气科学,8(2):178-188.Gao S T,Sun S Q.1984.The forming of subsynoptic scale low-level jet stream.Chinese J Atmos Sci,8(2):178-188(in Chinese)
高文良,郁淑华.2007.高原低涡东移出高原的平均环流场分析.高原气象,26(1):206-212.Gao W L,Yu S H.2007.Analyses on mean circulation field of the plateau low vortex moving out of Tibetan Plateau.Plateau Meteor,26(1):206-212(in Chinese)
何光碧,师锐.2011.夏季青藏高原不同类型切变线的动力、热力特征分析.高原气象,30(3):568-575.He G B,Shi R.2011.Studies on dynamic and thermal characteristics of different shear lines over Tibetan Plateau in summer.Plateau Meteor,30(3):568-575(in Chinese)
何光碧,师锐.2014.三次高原切变线过程演变特征及其对降水的影响.高原气象,33(3):615-625.He G B,Shi R.2014.A-nalysis on evolution characteristics of three plateau shear lines and their effect on precipitation.Plateau Meteor,33(3):615-625(in Chinese)
江志红,卢尧,丁裕国.2013.基于时空结构指标的中国融合降水资料质量评估.气象学报,71(5):891-900.Jiang Z H,Lu Y,Ding Y G.2013.Analysis of the high-resolution merged precipitation products over China based on the temporal and spatial structure score indices.Acta Meteor Sinica,71(5):891-900(in Chinese)
李国平.2014.新编动力气象学.2版.北京:气象出版社,131-132.Li G P.2014.The Dynamic Meteorology Newly Organized.2nd ed.Beijing:China Meteorological Press,131-132(in Chinese)
李山山,李国平.2017a.一次高原低涡与高原切变线演变过程与机理分析.大气科学,41(4):713-726.Li S S,Li G P.2017a.E-volution and mechanism analysis of a plateau vortex and plateau shear line.Chinese J Atmos Sci,41(4):713-726(in Chinese)
李山山,李国平.2017b.一次鞍型场环流背景下高原东部切变线降水的湿Q矢量诊断分析.高原气象,36(2):317-329.Li S S,Li G P.2017b.Diagnostic analysis based on wet Q-vector of a shear line with rain on the east side of Qinghai-Tibetan Plateau under the saddle pattern circulation background Field.Plateau Meteor,36(2):317-329(in Chinese)
廖移山,冯新,石燕等.2011.2008年“7.22”襄樊特大暴雨的天气学机理分析及地形的影响.气象学报,69(6):945-955.Liao YS,Feng X,Shi Y,et al.2011.Analysis of the mechanism for“2008.7.22”excessive rain event in Xiangfan with a focus on the terrain effect.Acta Meteor Sinica,69(6):945-955(in Chinese)
林毅,刘铭,刘爱鸣.2006.高低空急流在闽西北大暴雨过程中的作用及数值模拟.气象科学,26(4):449-455.Lin Y,Liu M,Liu A M.2006.Numreical study and action of high and low level jet stream in"2002.6"torrential rainstorm of northwest Fujian.Scientia Meteor Sinica,26(4):449-455(in Chinese)
师锐,何光碧.2011.移出与未移出高原的高原切变线背景环流对比分析.高原气象,30(6):1453-1461.Shi R,He G B.2011.Contrast analysis on background circulation of plateau shear line moving out and not moving out of the Tibetan Plateau.Plateau Meteor,30(6):1453-1461(in Chinese)
斯公望.1989.论东亚梅雨锋的大尺度环流及其次天气尺度扰动.气象学报,47(3):312-323.Si G W.1989.On the large-scale circulation of Mei-Yu system over East Asia.Acta Meteor Sinica,47(3):312-323(in Chinese)
屠妮妮,何光碧.2010.两次高原切变线诱发低涡活动的个例分析.高原气象,29(1):90-98.Tu N N,He G B.2010.Case analysis on two low vortexes induced by Tibetan Plateau shear line.Plateau Meteor,29(1):90-98(in Chinese)
徐建芬,陶健红,夏建平.2000.青藏高原切变线暴雪中尺度分析及其涡源研究.高原气象,19(2):187-197.Xu J F,Tao J H,Xia J P.2000.A meso-scale analysis of Qinghai-Xizang Plateau snow storm and its vortex source study.Plateau Meteor,19(2):187-197(in Chinese)
姚秀萍,孙建元,康岚等.2014.高原切变线研究的若干进展.高原气象,33(1):294-300.Yao X P,Sun J Y,Kang L,et al.2014.Advances on research of shear convergence line over Qinghai-Xizang Plateau.Plateau Meteor,33(1):294-300(in Chinese)
郁淑华,高文良,顾清源.2007.近年来影响我国东部洪涝的高原东移涡环流场特征分析.高原气象,26(3):466-475.Yu S H,Gao W L,Gu Q Y.2007.The middle-upper circulation analyses of the plateau vortex moving out of Plateau and influencing flood in east China in recent years.Plateau Meteor,26(3):466-475(in Chinese)
郁淑华,何光碧.2003.水汽图像在高原天气预报中应用的初步分析.高原气象,22(S1):75-82.Yu S H,He G B.2003.Analysis on application of statellite vapour image to weather prediction over Plateau.Plateau Meteor,22(S1):75-82(in Chinese)
郁淑华,何光碧,滕家谟.1997.青藏高原切变线对四川盆地西部突发性暴雨影响的数值试验.高原气象,16(3):306-311.Yu SH,He G B,Teng J M.1997.The numerical experiments of influence of shear line over Qinhai-Xizang Plateau on a sharp heavy rain in west Sichuan basin.Plateau Meteor,16(3):306-311(in Chinese)
郑淋淋,孙建华.2016.风切变对中尺度对流系统强度和组织结构影响的数值试验.大气科学,40(2):324-340.Zheng L L,Sun J H.2016.The impact of vertical wind shear on the intensity and organizational mode of mesoscale convective systems using numerical experiments.Chinese J Atmos Sci,40(2):324-340(in Chinese)
周兵,韩桂荣,何金海.2003.高空西风急流对长江中下游暴雨影响的数值试验.南京气象学院学报,26(5):595-604.Zhou B,Han G R,He J H.2003.Numerical experiment of effects of the upper level westerly jet on a torrential rain over the middlelower reaches of the Yangtze river.J Nanjing Inst Meteor,26(5):595-604(in Chinese)
朱禾,王秀明.2016.影响气温直减率变化的物理过程讨论.气象科技进展,6(5):51-54.Zhu H,Wang X M.2016.A discussion about the physical process of environmental temperature lapse rate tendency.Adv Meteor Sci Technol,6(5):51-54(in Chinese)
朱乾根,林锦瑞,寿绍文等.2000.天气学原理和方法.3版.北京:气象出版社,120-122.Zhu Q G,Lin J R,Shou S W,et al.2000.The Principle and Method of Weather.3rd ed.Beijing:China Meteorological Press,120-122(in Chinese)
Brill K F,Uccellini L W,Burkhart R P,et al.1985.Numerical simulations of a transverse indirect circulation and low-level jet in the exit region of an upper-level jet.J Atmos Sci,42(12):1306-1320
Prezerakos N G,Flocas H A,Brikas D.2006.The role of the interaction between polar and subtropical jet in a case of depression rejuvenation over the eastern Mediterranean.Meteor Atmos Phys,92(1-2):139-151
Tao S Y,Chen L.1987.A review of recent research on the East A-sian summer monsoon in China∥Chang C P,Krishnamurti TN.Monsoon Meteorology.Oxford:Oxford University Press,60-92
Whitney L F Jr.2009.Relationship of the subtropical jet stream to severe local storms.Mon Wea Rev,105(4):398-412