两次陕北暴雨过程热力动力机制诊断
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摘要
利用常规气象观测资料、NCEP FNL分析资料(水平分辨率为1°×1°,时间分辨率为6 h),对2013年7月21—22日和2014年7月8—9日两次陕北暴雨过程成因进行热力动力诊断,结果表明:两次陕北暴雨与高低空急流关系密切,暴雨带位于低空急流左侧的水汽辐合区,"0721"过程低空急流更强,在高低空急流耦合的强上升运动区(延安)出现大暴雨。降水前期,两次过程大气均存在对流不稳定,切变线触发对流,产生强降水,而其释放的凝结潜热加热形成中低层大气的热力不连续面,湿斜压性及锋生增强,造成整层饱和大气的抬升,维持强降水。"0721"过程前期对流降水的潜热释放更大,由此反馈的低空急流及锋生更强,出现大暴雨天气。广义对流涡度矢量垂直分量很好地描述了两次暴雨过程高低空急流耦合作用以及凝结潜热释放增强的锋生作用,其变化趋势能够反映降水的发展和减弱过程。暴雨出现在湿热力平流参数垂直积分大值中心及南侧的高梯度区,大值中心出现后约6h会产生强降水,这对于强降水落区的预报有一定指示意义。
Based on the conventional meteorological observations and 6 h 1°X1° NCEP FNL analysis data,two heavy rain processes occurred on 21 — 22 July 2013 and 8 — 9 July 2014 in northern Shaanxi are diagnosed with synoptic method and dynamic diagnosis method.It shows that both processes can be attributed to the intersection of the warm moist air flow along the edge of subtropical high at 500 hPa and the cold air brought from plateau troughs.Low-level jet plays an important role,as it provides adequate water vapor and water vapor convergence lifts on the left side of the shear line.The vertical secondary circulation produced by the coupling of upper-and low-level jet is an important triggering factor.Heavy rainfall in "0721" process occurs mainly at Yan'an where strong coupling of upper-level jet and low-level jet is located.There is strong convective instability in the atmosphere in the initial stage of precipitation during both rainstorm processes.Convergence lifting from the low-level shear line triggers convection energy,resulting in strong precipitation.The latent heat of condensation released by the precipitation extends downward to the middle atmosphere,and leads to thermal discontinuity of the middle and lower atmosphere.Atmospheric wet baroclinicity and frontogenesis significantly enhances,causing the uplift of whole layer saturated atmosphere and strong precipitation,finally producing heavy rainfall process.Because the convective precipitation is stronger and latent heat released is greater in "0721" rainstorm process,the feedback of the lowlevel jet and the middle atmosphere frontogenesis is stronger,and therefore the precipitation is heavier.The vertical component of generalized convective vorticity vector describes the enhancing of vertical wind shear very well,and describes the frontogenesis which is increased by condensation latent heat that released by water vapor phase transition in the middle and lower layers very well.Therefore,the changing trend of generalized convective vorticity vector can reflect the development and decrease of precipitation.The large value center and high gradient area on the south side of the vertically integrated moist thermodynamic advection parameters is consistent with rainstorm fall area,and it appears about 6 hours before the precipitation,indicating it can be used to effectively forecast regional precipitation.
Based on the conventional meteorological observations and 6 h 1°X1° NCEP FNL analysis data,two heavy rain processes occurred on 21 — 22 July 2013 and 8 — 9 July 2014 in northern Shaanxi are diagnosed with synoptic method and dynamic diagnosis method.It shows that both processes can be attributed to the intersection of the warm moist air flow along the edge of subtropical high at 500 hPa and the cold air brought from plateau troughs.Low-level jet plays an important role,as it provides adequate water vapor and water vapor convergence lifts on the left side of the shear line.The vertical secondary circulation produced by the coupling of upper-and low-level jet is an important triggering factor.Heavy rainfall in "0721" process occurs mainly at Yan'an where strong coupling of upper-level jet and low-level jet is located.There is strong convective instability in the atmosphere in the initial stage of precipitation during both rainstorm processes.Convergence lifting from the low-level shear line triggers convection energy,resulting in strong precipitation.The latent heat of condensation released by the precipitation extends downward to the middle atmosphere,and leads to thermal discontinuity of the middle and lower atmosphere.Atmospheric wet baroclinicity and frontogenesis significantly enhances,causing the uplift of whole layer saturated atmosphere and strong precipitation,finally producing heavy rainfall process.Because the convective precipitation is stronger and latent heat released is greater in "0721" rainstorm process,the feedback of the lowlevel jet and the middle atmosphere frontogenesis is stronger,and therefore the precipitation is heavier.The vertical component of generalized convective vorticity vector describes the enhancing of vertical wind shear very well,and describes the frontogenesis which is increased by condensation latent heat that released by water vapor phase transition in the middle and lower layers very well.Therefore,the changing trend of generalized convective vorticity vector can reflect the development and decrease of precipitation.The large value center and high gradient area on the south side of the vertically integrated moist thermodynamic advection parameters is consistent with rainstorm fall area,and it appears about 6 hours before the precipitation,indicating it can be used to effectively forecast regional precipitation.
引文
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[3]廖移山,李武阶,闵爱荣,等.“6.29”淮河暴雨过程β中尺度系统结构特征的数值模拟分析.应用气象学报,2006,17(4):421-430.
[4]朱乾根,周伟灿,张海霞.高低空急流耦合对长江中游强暴雨形成的机理研究.南京气象学院学报,2001,24(3):308-314.
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[8]廖移山,冯新,石燕,等.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,2011,69(6):945-955.
[9]王瑾,蒋建莹,江吉喜.“7·18”济南突发性大暴雨特征.应用气象学报,2009,20(3):295-302.
[10]全美兰,刘海文,朱玉祥,等.高空急流在北京“7.21”暴雨中的动力作用.气象学报,2013,71(6):1012-1019.
[11]庆涛,沈新勇,黄文彦,等.2011年梅汛期一次暴雨过程的对流涡度矢量方程诊断分析.高原气象,2015,34(2):401-412.
[12]王成鑫,高守亭,梁莉,等.动力因子对地形影响下的四川暴雨落区的诊断分析.大气科学,2013,37(5):1099-1110.
[13]李琴,杨帅,崔晓鹏,等.四川暴雨过程动力因子指示意义与预报意义研究.大气科学,2016,40(2):341-356.
[14]冉令坤,齐彦斌,郝寿昌,等.“7.21”暴雨过程动力因子分析和预报研究.大气科学,2014,38(1):83-100.
[15]冉令坤,周玉淑,杨文霞.强对流降水过程动力因子分析和预报研究.物理学报,2011,60(9):099201-1-099201-11.
[16]肖文俊,陈秋士.高空和低空急流与暴雨关系的实例分析.大气科学,1984,8(1):83-88.
[17]朱乾根.低空急流与暴雨.气象科技,1975.2(4):12-18.
[18]朱乾根,林锦瑞,寿绍文.等.天气学原理和方法.北京:气象出版社,2000.
[19]陈久康。丁治英.高低空急流与台风环流耦合下的中尺度暴雨系统.应用气象学报.2000,11(3):271-281.
[20]何立富,周庆亮,陈涛.“05.6”华南暴雨中低纬度系统活动及相互作用.应用气象学报,2010,21(4):385-394.
[21]Gao S T,Wang X R,Zhou Y S.Generation of generalized moist potential vorticity in a frictionless and moist adiabatic flow.Geophys Res Lett,2004,1(12):L12113.
[22]沈如金,张宝严.凝结潜热加热对台风降水分布的影响.大气科学,1982,6(3):249-257.
[23]Kuo H L.On formation and intensification of tropical cyclones through latent heat release by cumulus convection.J Atmos Sci,1965,22,40-63.
[24]丁一汇.高等天气学.北京:气象出版社,2005.
[25]王建捷,陶诗言.1998梅雨锋的结构特征及形成与维持.应用气象学报,2002。13(5):526-534.
[26]Wu Xiandu,Ran Lingkun.Chu Yanli.Diagnosis of a moist thermodynamic advection parameter in heavy-rainfall events.Adv Atmos Sci,2011,28(4):957-972.
[27]谈哲敏,赵思雄.中国南方β中尺度强对流系统结构与机理.北京:气象出版社,2013.
[28]王成鑫,高守亭,梁钊明,等.湿热力平流参数在一次华北暴雨模拟诊断中的应用研究.气候与环境研究,2014,19(6):753-762.
[29]高守亭.冉令坤,李娜,等.集合动力因子暴雨预报方法研究.暴雨灾害,2013,32(4):289-302.
[30]Gao S T,Wang X R.Zhou Y S.Generation of generalized moist potential vorticity in a frictionless and moist adiabatic flow.Geophys Res Lett,2004,31(12):L12113.
[31]Gao S T.Li X F,Tao W K,et al.Convective and moist vorticity vectors associated with tropical oceanic convection:A three-dimensional cloud-resolving model simulation.J Geophys Res,2007,112:D01105.
[32]高守亭.大气中尺度运动的动力学基础及预报方法.北京:气象出版社,2007.
[33]林青.台风莫拉克的动力诊断分析与数值模拟.南京:南京信息工程大学,2011.
[34]高守亭,刘璐,李娜.近几年中尺度动力学研究进展.大气科学,2013,37(2):319-330.
[2]徐海明,何金海,周兵.“倾斜”高空急流轴在大暴雨过程中的作用.南京气象学院学报,2001,24(2):155-161.
[3]廖移山,李武阶,闵爱荣,等.“6.29”淮河暴雨过程β中尺度系统结构特征的数值模拟分析.应用气象学报,2006,17(4):421-430.
[4]朱乾根,周伟灿,张海霞.高低空急流耦合对长江中游强暴雨形成的机理研究.南京气象学院学报,2001,24(3):308-314.
[5]程正泉,陈联寿,李英.登陆热带气旋与夏季风相互作用对暴雨的影响.应用气象学报,2012,23(6):660-671.
[6]叶成志,潘志祥,刘志雄,等.“03.7”湘西北特大致洪暴雨的触发机制数值研究.应用气象学报,2007,18(4):468-478.
[7]张维桓,董佩明.沈桐立.一次大暴雨过程中急流次级环流的激发及作用.大气科学,2000,24(1):47-57.
[8]廖移山,冯新,石燕,等.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,2011,69(6):945-955.
[9]王瑾,蒋建莹,江吉喜.“7·18”济南突发性大暴雨特征.应用气象学报,2009,20(3):295-302.
[10]全美兰,刘海文,朱玉祥,等.高空急流在北京“7.21”暴雨中的动力作用.气象学报,2013,71(6):1012-1019.
[11]庆涛,沈新勇,黄文彦,等.2011年梅汛期一次暴雨过程的对流涡度矢量方程诊断分析.高原气象,2015,34(2):401-412.
[12]王成鑫,高守亭,梁莉,等.动力因子对地形影响下的四川暴雨落区的诊断分析.大气科学,2013,37(5):1099-1110.
[13]李琴,杨帅,崔晓鹏,等.四川暴雨过程动力因子指示意义与预报意义研究.大气科学,2016,40(2):341-356.
[14]冉令坤,齐彦斌,郝寿昌,等.“7.21”暴雨过程动力因子分析和预报研究.大气科学,2014,38(1):83-100.
[15]冉令坤,周玉淑,杨文霞.强对流降水过程动力因子分析和预报研究.物理学报,2011,60(9):099201-1-099201-11.
[16]肖文俊,陈秋士.高空和低空急流与暴雨关系的实例分析.大气科学,1984,8(1):83-88.
[17]朱乾根.低空急流与暴雨.气象科技,1975.2(4):12-18.
[18]朱乾根,林锦瑞,寿绍文.等.天气学原理和方法.北京:气象出版社,2000.
[19]陈久康。丁治英.高低空急流与台风环流耦合下的中尺度暴雨系统.应用气象学报.2000,11(3):271-281.
[20]何立富,周庆亮,陈涛.“05.6”华南暴雨中低纬度系统活动及相互作用.应用气象学报,2010,21(4):385-394.
[21]Gao S T,Wang X R,Zhou Y S.Generation of generalized moist potential vorticity in a frictionless and moist adiabatic flow.Geophys Res Lett,2004,1(12):L12113.
[22]沈如金,张宝严.凝结潜热加热对台风降水分布的影响.大气科学,1982,6(3):249-257.
[23]Kuo H L.On formation and intensification of tropical cyclones through latent heat release by cumulus convection.J Atmos Sci,1965,22,40-63.
[24]丁一汇.高等天气学.北京:气象出版社,2005.
[25]王建捷,陶诗言.1998梅雨锋的结构特征及形成与维持.应用气象学报,2002。13(5):526-534.
[26]Wu Xiandu,Ran Lingkun.Chu Yanli.Diagnosis of a moist thermodynamic advection parameter in heavy-rainfall events.Adv Atmos Sci,2011,28(4):957-972.
[27]谈哲敏,赵思雄.中国南方β中尺度强对流系统结构与机理.北京:气象出版社,2013.
[28]王成鑫,高守亭,梁钊明,等.湿热力平流参数在一次华北暴雨模拟诊断中的应用研究.气候与环境研究,2014,19(6):753-762.
[29]高守亭.冉令坤,李娜,等.集合动力因子暴雨预报方法研究.暴雨灾害,2013,32(4):289-302.
[30]Gao S T,Wang X R.Zhou Y S.Generation of generalized moist potential vorticity in a frictionless and moist adiabatic flow.Geophys Res Lett,2004,31(12):L12113.
[31]Gao S T.Li X F,Tao W K,et al.Convective and moist vorticity vectors associated with tropical oceanic convection:A three-dimensional cloud-resolving model simulation.J Geophys Res,2007,112:D01105.
[32]高守亭.大气中尺度运动的动力学基础及预报方法.北京:气象出版社,2007.
[33]林青.台风莫拉克的动力诊断分析与数值模拟.南京:南京信息工程大学,2011.
[34]高守亭,刘璐,李娜.近几年中尺度动力学研究进展.大气科学,2013,37(2):319-330.