两次华北冷涡降水成因及预报偏差对比分析
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摘要
利用多种常规及非常规观测资料、美国国家环境预报中心全球模式业务系统分析资料(NCEP/FNL)以及三家全球确定性模式产品对2017年两次华北冷涡降水过程成因及模式预报偏差进行了对比分析。结果表明;个例1(6月22日)降水回波为层-积混合型,对流发展高度低,小时雨强小,先后经历了持续的稳定降水和弱对流降水两个阶段;个例2(7月6日)降水以积云状对流回波为主,对流发展高度高,短历时强降水特点明显。二者对应的环境场差异较大,前者冷涡处在成熟期,副热带高压位置偏南,前期暖区对流冷池降温明显,对流能量及水汽条件一般;后者冷涡为发展期,副热带高压位置偏北,中低纬相互作用明显,水汽与能量充沛。两次过程北京均出现了暴雨及以上量级降水,对应的中尺度对流系统(MCS)特征、对流触发机制以及对流不稳定能量重建过程存在明显差异。前者为层状云中发展的γ中尺度MCS,边界层偏东风增强为MCS提供了触发机制,中低层偏东风暖湿输送以及对流层高层干冷平流有利于对流不稳定能量重建;后者为组织化的β中尺度MCS,列车效应明显,偏南低空急流及其气旋式切变配合地形为MCS发展提供了抬升条件,对流不稳定能量建立与中低层偏南低空急流强暖湿输送有关。各家数值模式对不同类型冷涡降水的预报偏差特征一致,即对冷涡成熟期的降水,因对动力条件预报过强导致空报降水;而对冷涡发展期的降水,由于对槽前暖区辐合及其对流性降水预报不足导致强降水出现漏报。
By using the conventional observation, and the radiosonde, satellite, radar, wind profile,NCEP-FNL analysis data as well as the data of three deterministic global forecast systems, causes of rainfall and forecast biases of two cold vortex rainfall events in 2017 over North China are comparatively studied. The results show that the event that occurred on 22 June 2017 is characterized by persistent and steady rainfall with weak rainfall intensity and lower convective height. The rainfall echo is of convectivestratiform mixed type. However, the rainfall on 6 July is short-time severe rainfall and the height of convective echo top is very high. The background conditions are quite different between these two cases. For the 22 June event, cold vortex is at its mature stage and subtropical high is far south. Moreover, a warm section convection occurred on the previous day, and its cold pool is quite strong, leading to the release of convective energy, thus the convective energy and water vapor are normal for the first case. Comparatively, for the second case the cold vortex is at its developing phase and subtropical high is located more northward.The interaction between low and middle latitude atmospheres is remarkable, bringing a plenty of energy and water vapor. During the severe rainfall periods for both cases in Beijing, the features of mesoscale convective system(MCS), triggering mechanism and building of convective energy have significant differences. For the first case, meso-γ MCSs are the main rainfall systems which developed in the stratiform cloud. Easterly wind not only supplies the lifting condition but also brings the warm and wet flow, working together with the upper-level dry and cold air intrusion, which finally causes the re-building of energy. However, for the second case, MCSs are featured by the well-developed meso-β systems and the trainecho pattern is quite clear. The increase of energy is due to warm and wet flow transported by southerly low-level jet. The low-level jet and the cyclonic shear, accompanied by the appropriate terrain are the main triggering of the MCS. As regard to the precipitation forecast of models, biases are completely different for these two cold vortex rainfall cases. For the matured cold vortex case, because of much stronger forecasted dynamic conditions and the grid-scale rainfall, the rainfall is over-forecast. Instead, for the developing cold vortex one, model underestimates the convergence of warm shear and its convective rainfall, which results in the under-forecast rainfall.
By using the conventional observation, and the radiosonde, satellite, radar, wind profile,NCEP-FNL analysis data as well as the data of three deterministic global forecast systems, causes of rainfall and forecast biases of two cold vortex rainfall events in 2017 over North China are comparatively studied. The results show that the event that occurred on 22 June 2017 is characterized by persistent and steady rainfall with weak rainfall intensity and lower convective height. The rainfall echo is of convectivestratiform mixed type. However, the rainfall on 6 July is short-time severe rainfall and the height of convective echo top is very high. The background conditions are quite different between these two cases. For the 22 June event, cold vortex is at its mature stage and subtropical high is far south. Moreover, a warm section convection occurred on the previous day, and its cold pool is quite strong, leading to the release of convective energy, thus the convective energy and water vapor are normal for the first case. Comparatively, for the second case the cold vortex is at its developing phase and subtropical high is located more northward.The interaction between low and middle latitude atmospheres is remarkable, bringing a plenty of energy and water vapor. During the severe rainfall periods for both cases in Beijing, the features of mesoscale convective system(MCS), triggering mechanism and building of convective energy have significant differences. For the first case, meso-γ MCSs are the main rainfall systems which developed in the stratiform cloud. Easterly wind not only supplies the lifting condition but also brings the warm and wet flow, working together with the upper-level dry and cold air intrusion, which finally causes the re-building of energy. However, for the second case, MCSs are featured by the well-developed meso-β systems and the trainecho pattern is quite clear. The increase of energy is due to warm and wet flow transported by southerly low-level jet. The low-level jet and the cyclonic shear, accompanied by the appropriate terrain are the main triggering of the MCS. As regard to the precipitation forecast of models, biases are completely different for these two cold vortex rainfall cases. For the matured cold vortex case, because of much stronger forecasted dynamic conditions and the grid-scale rainfall, the rainfall is over-forecast. Instead, for the developing cold vortex one, model underestimates the convergence of warm shear and its convective rainfall, which results in the under-forecast rainfall.
引文
白人海,孙永罡,1997.东北冷涡中尺度天气的背景分析[J].黑龙江气象,1997(3):6-12.Bai R H,Sun Y G,1997. The background analysis of mesoscale weather of the cold vortex in Northeast China[J]. Heilongjiang Meteor,1997(3):6-12(in Chinese).
陈力强,张立祥,周小珊,2008.东北冷涡不稳定能量分布特征及其与降水落区的关系[J].高原气象,27(2):339-348. Chen L Q,Zhang L X,Zhuo X S,2008. Characteristic of instable energy distribution in cold vortex over Northeastern China and its relation to precipitation area[J]. Plateau Meteor,27(2):339-348(in Chinese).
郜彦娜,2013.华北和东蒙冷涡的天气学特征及其中尺度对流系统发生发展研究[D].南京:南京信息工程大学.Gao Y N,2013.The synoptic characteristics of cold vortex over North China and East Mongolia and the development reseach of mesoscale convective systems[D]. Nanjing:Nanjing University of Information Science and Technology(in Chinese).
姜学恭,李彰俊,宫春宁,等,2010.蒙贝低涡类环北京暴雨过程分型研究[J].大气科学学报,33(4):412-419. Jiang X G,Li Z J,Gong CN,et al, 2010. A classification-based research on rainstorm processes around Beijing caused by Mongolia-Baikal low[J].Trans Atmos Sci,33(4):412-419(in Chinese).
华北暴雨编写组,1992.华北暴雨[M].北京:气象出版社,55-57.Book Writing Team of North China Heavy Rainfall, 1992. Heavy Rainfall in North China[M]. Beijing:China Meteorological Press:55-57(in Chinese).
李江波,王宗敏,王福侠,等,2011.华北冷涡连续降雹的特征与预报[J].高原气象,30(4):1119-1131. Li J B,Wang Z M,Wang F X,et al, 2011. Characteristic and forecasting of continuous hail shooting processes caused by the North China cold vortex[J].Plateau Meteor,30(4):1119-1131(in Chinese).
李茜,2013.华北冷涡暴雨及雷达预报追踪的应用研究[D].南京:南京信息工程大学. Li Q,2013. Analysis of rainstorm and application about forecast and trace of Doppler radar during a cold cyclone on North China[D]. Nanjing:Nanjing University of Information Science and Technology(in Chinese).
李爽,丁治英,戴萍,等,2016.东北冷涡的最新研究进展[J].干旱气象,34(1):13-19.Li S,Ding Z Y,Dai P,et al,2016.Recent advances in research on Northeast China cold vortex[J]. J Arid Meteor,34(1):13-19(in Chinese).
梁钰,张一平,董俊玲,等,2014.郑州地区3次冷涡型强对流天气对比分析[J].气象与环境科学,37(3):1-7. Liang Y,Zhang Y P,Dong J L,et al,2014. Contractive analysis of three severe convective weather processes under cold eddy synoptic situation in Zhengzhou[J]. Meteor Environ Sci,37(3):1-7(in Chinese).
刘英,王东海,张中锋,等,2012.东北冷涡的结构及其演变特征的个例综合分析[J].气象学报,70(3):354-370. Liu Y,Wang D H,Zhang Z F,et al,2012. A comprehensive analysis of the structure of a northeast China-cold-vortex and its characteristics of evolution[J]. Acta Meteor Sin,70(3):354-370(in Chinese).
闵晶晶,刘还珠,曹晓钟,等,2011.天津“6. 25”大冰雹过程的中尺度特征及成因[J].应用气象学报,22(5):525-536. Min J J,Liu H Z,Cao X Z,et al,2011. The mesoscale characteristics and causes of a severe hail event in Tianjin[J]. J Appl Meteor Sci,22(5):525-536(in Chinese).
孙力,王琪,唐晓玲,1995.暴雨类冷涡与非暴雨类冷涡的合成对比分析[J].气象,21(3):7-10. Sun L,Wang Q,Tang X L,1995. A composite diagnostic analysis of cold vortex of storm-rainfall andnon-storm rainfall types[J]. Meteor Mon, 21(3):7-10(in Chinese).
孙力,王晓明,秦元明,等,2000.嫩江、松花江流域暴雨的中尺度系统和过程分析[J].黑龙江气象,2000(S1):27-36. Sun L,Wang X M,Qin Y M et al,2000. The analysis on mesoscale systems of heavy rainfall over Songhua and Nenjiang River Basin[J]. Heilongjiang Meteor,2000(S1):27-36(in Chinese).
寿亦萱,许健民,2007.“05. 6”东北暴雨中尺度对流系统研究I:常规资料和卫星资料分析.[J]气象学报,65(2):160-170. Shou Y X,Xu J M,2007. The rainstorm and mesoscale convective systems over Northeast China in June 2005. I:a synthetic analysis of MCS by conventional observations and satellite data[J]. Acta Meteor Sin,65(2):160-170(in Chinese).
王东海,钟水新,刘英,等,2007.东北暴雨的研究[J].地球科学进展,22(6):549-560. Wang D H,Zhong S X,Liu Y,et al,2007. Advances in the study of rainstorm in Northeast China[J]. Adv Earth Sci,22(6):549-560(in Chinese).
王黎黎,巍婷婷,2014.近50年来东北冷涡暴雨过程动力条件诊断和水汽条件分析[J].气象灾害防御,4:10-13. Wang L L, Wei T T,2014. The diagnostic analysis on the kinematic and humidity conditions of rainstorm caused by Northeast China cold vortex in recent 50 years[J]. Meteor Disarster Prevention,4:10-13(in Chinese).
王宗敏,李江波,王福侠,等,2015.东北冷涡暴雨的特点及其非对称结构特征[J].高原气象,34(6):1721-1731. Wang Z M,Li J B,Wang F X,et al,2015. Asymmetric characteristics of the Northeast cold vortex and its effects on heavy rain[J]. Plateau Meteor,34(6):1721-1731(in Chinese).
应爽,袁大宇,李尚锋,2014.一次东北冷涡不同阶段强对流天气特征对比分析[J].气象与环境学报,30(4):9-18. Ying S,Yuan D Y,Li S F,2014. Comparative analysis of severe convective weather characteristics in different stages of Northeast China cold vortex[J]. J Meteor Environ,30(4):9-18(in Chinese).
郁珍艳,何立富,范广洲,等,2011.华北冷涡背景下强对流天气的基本特征分析[J].热带气象学报,27(1):89-94. Yu Z Y,He L F,Fan G Z,et al,2011. The basic features of the severe convective at the background of cold vortex over North China[J]. J TropMeteor,27(1):89-94(in Chinese).
张立祥,李泽椿,2009.东北冷涡研究概述[J].气候与环境研究,14(2):218-228. Zhang L X,Li Z C,2009. A summary of research on cold vortex over Northeast China[J]. Climat Environ Res,14(2):218-228(in Chinese).
张文龙,崔晓鹏,王迎春,等,2013.对流层低层偏东风对北京局地暴雨的作用[J].大气科学,37(4):829-840. Zhang W L,Cui X P,Wang Y C,et al,2013. Roles of low-level easterly winds in the local torrential rains of Beijing[J]. Chin J Atmos Sci, 37(4):829-840(in Chinese).
张云,雷恒池,钱贞成,2008.一次东北冷涡衰退阶段暴雨成因分析[J].大气科学,32(3):481-498. Zhang Y,Lei H C,Qian Z C,2008. Analyses of formation mechanisms of a rainstorm during the declining phase of a Northeast cold vortex[J]. Chin J Atmos Sci,32(3):481-498(in Chinese).
郑秀雅,张延治,白人海,1992.东北暴雨[M].北京:气象出版社:19-43. Zheng X Y,Zhang Y Z,Bai R H,1992. Rainstorm in Northeast China[M]. Beijing:China Meteorological Press:19-43(in Chinese).
钟水新,王东海,张人禾,等,2011.一次东北冷涡降水过程的结构特征与影响因子分析[J].高原气象,30(4):951-960. Zhong S X,Wang D H,Zhang R H,et al, 2011. Analyses on the structure characteristic and formation mechanism of the rainstorm related to a cold vortex system over Northeast China[J]. Plateau Meteor,30(4):951-960(in Chinese).
钟水新,王东海,张人禾,等,2013.一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,32(2):435-445. Zhong S X,Wang D H,Zhang R H,et al,2013. Study of mesoscale convective system in heavuy rainstorm process at a cold vortex development stage[J]. Plateau Meteor,32(2):435-445(in Chinese).
Ebert E E,McBride J L,2000. Verification of precipitation in weather systems:determination of systematic errors[J]. J Hydro, 239:179-202.
Zhang D L,Lin Y H,Zhao P,et al,2013. The Beijing extreme rainfall of 21 July 2012:"Right results"but for wrong reasons[J]. Geophy Res Lett,40:1426-1431. DOI:10. 1002/grl. 50304.
陈力强,张立祥,周小珊,2008.东北冷涡不稳定能量分布特征及其与降水落区的关系[J].高原气象,27(2):339-348. Chen L Q,Zhang L X,Zhuo X S,2008. Characteristic of instable energy distribution in cold vortex over Northeastern China and its relation to precipitation area[J]. Plateau Meteor,27(2):339-348(in Chinese).
郜彦娜,2013.华北和东蒙冷涡的天气学特征及其中尺度对流系统发生发展研究[D].南京:南京信息工程大学.Gao Y N,2013.The synoptic characteristics of cold vortex over North China and East Mongolia and the development reseach of mesoscale convective systems[D]. Nanjing:Nanjing University of Information Science and Technology(in Chinese).
姜学恭,李彰俊,宫春宁,等,2010.蒙贝低涡类环北京暴雨过程分型研究[J].大气科学学报,33(4):412-419. Jiang X G,Li Z J,Gong CN,et al, 2010. A classification-based research on rainstorm processes around Beijing caused by Mongolia-Baikal low[J].Trans Atmos Sci,33(4):412-419(in Chinese).
华北暴雨编写组,1992.华北暴雨[M].北京:气象出版社,55-57.Book Writing Team of North China Heavy Rainfall, 1992. Heavy Rainfall in North China[M]. Beijing:China Meteorological Press:55-57(in Chinese).
李江波,王宗敏,王福侠,等,2011.华北冷涡连续降雹的特征与预报[J].高原气象,30(4):1119-1131. Li J B,Wang Z M,Wang F X,et al, 2011. Characteristic and forecasting of continuous hail shooting processes caused by the North China cold vortex[J].Plateau Meteor,30(4):1119-1131(in Chinese).
李茜,2013.华北冷涡暴雨及雷达预报追踪的应用研究[D].南京:南京信息工程大学. Li Q,2013. Analysis of rainstorm and application about forecast and trace of Doppler radar during a cold cyclone on North China[D]. Nanjing:Nanjing University of Information Science and Technology(in Chinese).
李爽,丁治英,戴萍,等,2016.东北冷涡的最新研究进展[J].干旱气象,34(1):13-19.Li S,Ding Z Y,Dai P,et al,2016.Recent advances in research on Northeast China cold vortex[J]. J Arid Meteor,34(1):13-19(in Chinese).
梁钰,张一平,董俊玲,等,2014.郑州地区3次冷涡型强对流天气对比分析[J].气象与环境科学,37(3):1-7. Liang Y,Zhang Y P,Dong J L,et al,2014. Contractive analysis of three severe convective weather processes under cold eddy synoptic situation in Zhengzhou[J]. Meteor Environ Sci,37(3):1-7(in Chinese).
刘英,王东海,张中锋,等,2012.东北冷涡的结构及其演变特征的个例综合分析[J].气象学报,70(3):354-370. Liu Y,Wang D H,Zhang Z F,et al,2012. A comprehensive analysis of the structure of a northeast China-cold-vortex and its characteristics of evolution[J]. Acta Meteor Sin,70(3):354-370(in Chinese).
闵晶晶,刘还珠,曹晓钟,等,2011.天津“6. 25”大冰雹过程的中尺度特征及成因[J].应用气象学报,22(5):525-536. Min J J,Liu H Z,Cao X Z,et al,2011. The mesoscale characteristics and causes of a severe hail event in Tianjin[J]. J Appl Meteor Sci,22(5):525-536(in Chinese).
孙力,王琪,唐晓玲,1995.暴雨类冷涡与非暴雨类冷涡的合成对比分析[J].气象,21(3):7-10. Sun L,Wang Q,Tang X L,1995. A composite diagnostic analysis of cold vortex of storm-rainfall andnon-storm rainfall types[J]. Meteor Mon, 21(3):7-10(in Chinese).
孙力,王晓明,秦元明,等,2000.嫩江、松花江流域暴雨的中尺度系统和过程分析[J].黑龙江气象,2000(S1):27-36. Sun L,Wang X M,Qin Y M et al,2000. The analysis on mesoscale systems of heavy rainfall over Songhua and Nenjiang River Basin[J]. Heilongjiang Meteor,2000(S1):27-36(in Chinese).
寿亦萱,许健民,2007.“05. 6”东北暴雨中尺度对流系统研究I:常规资料和卫星资料分析.[J]气象学报,65(2):160-170. Shou Y X,Xu J M,2007. The rainstorm and mesoscale convective systems over Northeast China in June 2005. I:a synthetic analysis of MCS by conventional observations and satellite data[J]. Acta Meteor Sin,65(2):160-170(in Chinese).
王东海,钟水新,刘英,等,2007.东北暴雨的研究[J].地球科学进展,22(6):549-560. Wang D H,Zhong S X,Liu Y,et al,2007. Advances in the study of rainstorm in Northeast China[J]. Adv Earth Sci,22(6):549-560(in Chinese).
王黎黎,巍婷婷,2014.近50年来东北冷涡暴雨过程动力条件诊断和水汽条件分析[J].气象灾害防御,4:10-13. Wang L L, Wei T T,2014. The diagnostic analysis on the kinematic and humidity conditions of rainstorm caused by Northeast China cold vortex in recent 50 years[J]. Meteor Disarster Prevention,4:10-13(in Chinese).
王宗敏,李江波,王福侠,等,2015.东北冷涡暴雨的特点及其非对称结构特征[J].高原气象,34(6):1721-1731. Wang Z M,Li J B,Wang F X,et al,2015. Asymmetric characteristics of the Northeast cold vortex and its effects on heavy rain[J]. Plateau Meteor,34(6):1721-1731(in Chinese).
应爽,袁大宇,李尚锋,2014.一次东北冷涡不同阶段强对流天气特征对比分析[J].气象与环境学报,30(4):9-18. Ying S,Yuan D Y,Li S F,2014. Comparative analysis of severe convective weather characteristics in different stages of Northeast China cold vortex[J]. J Meteor Environ,30(4):9-18(in Chinese).
郁珍艳,何立富,范广洲,等,2011.华北冷涡背景下强对流天气的基本特征分析[J].热带气象学报,27(1):89-94. Yu Z Y,He L F,Fan G Z,et al,2011. The basic features of the severe convective at the background of cold vortex over North China[J]. J TropMeteor,27(1):89-94(in Chinese).
张立祥,李泽椿,2009.东北冷涡研究概述[J].气候与环境研究,14(2):218-228. Zhang L X,Li Z C,2009. A summary of research on cold vortex over Northeast China[J]. Climat Environ Res,14(2):218-228(in Chinese).
张文龙,崔晓鹏,王迎春,等,2013.对流层低层偏东风对北京局地暴雨的作用[J].大气科学,37(4):829-840. Zhang W L,Cui X P,Wang Y C,et al,2013. Roles of low-level easterly winds in the local torrential rains of Beijing[J]. Chin J Atmos Sci, 37(4):829-840(in Chinese).
张云,雷恒池,钱贞成,2008.一次东北冷涡衰退阶段暴雨成因分析[J].大气科学,32(3):481-498. Zhang Y,Lei H C,Qian Z C,2008. Analyses of formation mechanisms of a rainstorm during the declining phase of a Northeast cold vortex[J]. Chin J Atmos Sci,32(3):481-498(in Chinese).
郑秀雅,张延治,白人海,1992.东北暴雨[M].北京:气象出版社:19-43. Zheng X Y,Zhang Y Z,Bai R H,1992. Rainstorm in Northeast China[M]. Beijing:China Meteorological Press:19-43(in Chinese).
钟水新,王东海,张人禾,等,2011.一次东北冷涡降水过程的结构特征与影响因子分析[J].高原气象,30(4):951-960. Zhong S X,Wang D H,Zhang R H,et al, 2011. Analyses on the structure characteristic and formation mechanism of the rainstorm related to a cold vortex system over Northeast China[J]. Plateau Meteor,30(4):951-960(in Chinese).
钟水新,王东海,张人禾,等,2013.一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,32(2):435-445. Zhong S X,Wang D H,Zhang R H,et al,2013. Study of mesoscale convective system in heavuy rainstorm process at a cold vortex development stage[J]. Plateau Meteor,32(2):435-445(in Chinese).
Ebert E E,McBride J L,2000. Verification of precipitation in weather systems:determination of systematic errors[J]. J Hydro, 239:179-202.
Zhang D L,Lin Y H,Zhao P,et al,2013. The Beijing extreme rainfall of 21 July 2012:"Right results"but for wrong reasons[J]. Geophy Res Lett,40:1426-1431. DOI:10. 1002/grl. 50304.