广西冬季降水的低频特征及其与MJO的联系
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摘要
应用广西壮族自治区国家气象站降水,NCEP/NCAR逐日再分析资料,NOAA逐日向外长波辐射(OLR)等逐日资料,NOAA-CPC热带大气季节内振荡(MJO)指数等,使用经验正交函数分解方法分析了广西冬季降水的气候特征;用功率谱、带通滤波、相关分析和滞后线性回归等方法,以及定义MJO相关降水事件,研究了广西冬季降水异常偏多年的降水低频特征及其与MJO的联系。(1)广西冬季降水特征以全区一致型分布为主;冬季降水异常偏多年份的逐日降水具有14～26 d的低频周期。(2) MJO强对流在赤道印度洋东部发展并东传到西太平洋热带地区时,广西可出现冬季持续强降水。(3)当MJO异常对流在印度洋东部热带地区产生,中南半岛地区到华南地区上空为异常低频偏南和偏西南气流,有利于降水形成;当印度洋东部热带地区为MJO对流抑制区,华南地区上空为异常低频偏东气流控制,不利于降水产生。(4)华南地区上空大气环流的异常是由热带印度洋地区的MJO对流激发的Rossby波列造成。
Using daily precipitation records in Guangxi, NCEP/NCAR reanalysis dataset, outgoing long wave radiation(OLR) data, and the Madden-Julian Oscillation(MJO) index provided by NOAA-CPC, the climatic characteristics of wintertime rainfall in Guangxi are found through empirical orthogonal function analysis. By means of power spectrum analysis, bandpass filter, correlation analysis and lagged linear regression techniques, as well as the definition of the MJO-related rainfall events, the low-frequency features of wintertime rainfall and its connection with MJO are studied. The results are shown as follows. The chief distribution pattern of wintertime rainfall in Guangxi is uniform, with a 14～26 d low-frequency oscillation during the wintertimes with more precipitation. When the MJO convection develops in the eastern equatorial India Ocean and spreads to the tropical western Pacific, it would be a persistent rainfall period in wintertime. When the MJO anomalous convection occurs in the eastern tropical region of the India Ocean,the abnormal low-frequency south-west flow covers the Indochina Peninsula and southern China, which is beneficial to the formation of precipitation. On the contrary, when the MJO convection is suppressed over the tropical eastern India Ocean, the anomalous low-frequency easterly flow covers the southern China area,which is not favorable for rain. The anomalous atmospheric circulation over the south of China is caused by the Rossby wave train excited by the MJO convection in the tropical India Ocean region.
Using daily precipitation records in Guangxi, NCEP/NCAR reanalysis dataset, outgoing long wave radiation(OLR) data, and the Madden-Julian Oscillation(MJO) index provided by NOAA-CPC, the climatic characteristics of wintertime rainfall in Guangxi are found through empirical orthogonal function analysis. By means of power spectrum analysis, bandpass filter, correlation analysis and lagged linear regression techniques, as well as the definition of the MJO-related rainfall events, the low-frequency features of wintertime rainfall and its connection with MJO are studied. The results are shown as follows. The chief distribution pattern of wintertime rainfall in Guangxi is uniform, with a 14～26 d low-frequency oscillation during the wintertimes with more precipitation. When the MJO convection develops in the eastern equatorial India Ocean and spreads to the tropical western Pacific, it would be a persistent rainfall period in wintertime. When the MJO anomalous convection occurs in the eastern tropical region of the India Ocean,the abnormal low-frequency south-west flow covers the Indochina Peninsula and southern China, which is beneficial to the formation of precipitation. On the contrary, when the MJO convection is suppressed over the tropical eastern India Ocean, the anomalous low-frequency easterly flow covers the southern China area,which is not favorable for rain. The anomalous atmospheric circulation over the south of China is caused by the Rossby wave train excited by the MJO convection in the tropical India Ocean region.
引文
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[26] LO F,HENDON H H. Empirical extended-range prediction of the Madden-Julian oscillation[J]. Mon Wea Rev,2000,128(7):2 528-2 543.
[27]何洁琳,万齐林,管兆勇,等.亚洲-西太平洋夏半年ISO传播特征与热带天气尺度波动联系的观测事实研究[J].热带气象学报,2010,26(6):724-731.
[28]何洁琳,万齐林,管兆勇,等.亚洲-西太平洋夏半年季节内振荡:热带气旋活动强、弱年的对比[J].热带气象学报,2011,27(1):22-30.
[29]孙照渤,刘华,倪东鸿.中国华北地区冬季降水异常特征及其与大气环流和海温的关系[J].大气科学学报,2017,40(5):577-586.
[2]林爱兰,纪忠萍,谷德军,等.大气季节内振荡在华南降水预报中的应用[J].热带气象学报,2016,32(6):878-889.
[3]陈官军,魏凤英.基于低频振荡特征的夏季江淮持续性降水延伸期预报方法[J].大气科学,2012,36(3):633-644.
[4]李崇银,凌健,袁媛,等.大气MJO研究的几个前沿问题[J].热带气象学报,2016,32(6):797-816.
[5]魏蕾,房佳蓓,杨修群.华南夏季12-30d持续性强降水的低频特征分析[J].气象学报,2017,75(1):80-97.
[6]童金,徐海明.长江中下游旱涝急转年多尺度低频振荡特征及其对旱涝急转的影响[J].热带气象学报,2014,30(4):707-718.
[7]贾燕,王黎娟,张佳婷. SVD揭示的东亚地区低频振荡强度与中国夏季降水的联系[J].热带气象学报,2013,29(5):813-823.
[8] MADDEN R A,JULIAN P R. Detection of a 40—50 day oscillation in the zonal wind in the tropical Pacific[J]. J Atmos Sci,1971,28(5):702-708.
[9] MADDEN R A,JULIAN P R. Observations of the 40—50 day tropical oscillation-a review[J]. Mon Wea Rev,1994,122(5):814-837.
[10]李帅,陈莉,任玉玉. 1951/1952—2004/2005年中国冬季降水变化研究[J].热带气象学报,2008,24(2):94-98.
[11]王林,冯娟.我国冬季降水年际变化的主模态分析[J].大气科学,2011,35(6):1 105-1 116.
[12]马洁华,王会军,张颖.我国未来冬季降水会增加吗?北极夏季无海冰情景时的模拟试验[J].科学通报,2012,57(9):759-764.
[13]袁为,杨海军. Madden-Julian振荡对中国东南部冬季降水的调制[J].北京大学学报(自然科学版),2010,46(2):207-214.
[14]刘冬晴,杨修群.热带低频振荡影响中国东部冬季降水的机理[J].气象科学,2010,30(5):684-693.
[15]冯俊阳,肖子牛.热带大气低频振荡强度年际异常对中国东部冬季降水的影响[J].热带气象学报,2013,29(4):559-569.
[16] ZHANG C,DONG M. Seasonality in the Madden—Julian oscillation[J]. J Climate,2004,17(16):3 169-3 180.
[17]广西壮族自治区气候中心. 2016年广西气候公报[R].南宁:广西壮族自治区气象局, 2017:2-5.
[18] KALNAY E,COAUTHORS. The NCEP/NCAR 40 year reanalysis project[J]. Bull Amer Meteor Soc,1996,77(3):437-471.
[19]何洁琳,段安民,覃卫坚.热带大气季节内振荡与西北太平洋热带气旋活动的季节预测:统计事实研究[J].气候与环境研究,2013,18(1):101-110.
[20]魏凤英.现代气候统计诊断与预测技术[M].北京:气象出版社,1999:77-122.
[21] MURAKAMI T. Large-scale aspects of deep convective activity over the GATE area[J]. Mon Wea Rev,1979,107(8):994-1 013.
[22] KEMBALL-COOK S,WANG B. Equatorial waves and air-sea interaction in the boreal summer intraseasonal oscillation[J]. J Climate,2001,14(13):2 923-2 942.
[23] HSU H H,WENG C H. Northwestward Propagation of the Intraseasonal oscillation in the Western North Pacific during the boreal summer:structure and mechanism[J]. J Climate,2001,14(18):3 834-3 849.
[24] STRAUB K H,KILADIS G N. Interactions between the boreal summer intraseasonal oscillation and higher-frequency tropical wave activity[J]. Mon Wea Rev,2003,131(5):945-960.
[25]李崇银.大气季节内振荡研究的新进展[J].自然科学进展,2004,14(7):734-741.
[26] LO F,HENDON H H. Empirical extended-range prediction of the Madden-Julian oscillation[J]. Mon Wea Rev,2000,128(7):2 528-2 543.
[27]何洁琳,万齐林,管兆勇,等.亚洲-西太平洋夏半年ISO传播特征与热带天气尺度波动联系的观测事实研究[J].热带气象学报,2010,26(6):724-731.
[28]何洁琳,万齐林,管兆勇,等.亚洲-西太平洋夏半年季节内振荡:热带气旋活动强、弱年的对比[J].热带气象学报,2011,27(1):22-30.
[29]孙照渤,刘华,倪东鸿.中国华北地区冬季降水异常特征及其与大气环流和海温的关系[J].大气科学学报,2017,40(5):577-586.