高原周边环流主模态变化特征及其对我国冬季气候的影响  

Variation Characteristics of Major Modes of Circulation around the Tibetan Plateau and Its Influence on the Winter Climate in China

作　　者：李超 夏昕 LI Chao;XIA Xin(Shenzhen Meteorological Service/Shenzhen National Climate Observatory,Shenzhen 518040,China)

机构地区：[1]广东省深圳市气象局/深圳市国家气候观象台,深圳518040

出　　处：《高原山地气象研究》2025年第1期39-49,共11页Plateau and Mountain Meteorology Research

基　　金：广东省气象科技项目(GRMC2024M52-Z);深圳市科技计划可持续发展专项(KCXFZ20240903094007010)。

摘　　要：本文利用经验正交分解(EOF)对冬季1月高原周边范围700 hPa高度场进行分析,探讨青藏高原周边环流主要模态变化特征及其区域气候影响。结果表明:年际变化时间尺度上,第一主模态(EOF1)表现为高原周边高度场一致变化,第二主模态(EOF2)表现为高原西北侧与东南侧区域高度场反相变化,两个主模态能分别解释年际变化总方差的42.9%和24.2%。EOF1空间模态对应于乌拉尔山高压和南支槽强度反相变化;正位相时乌拉尔山高压加强和南支槽减弱,上游西亚高空急流加强,东亚高空急流减弱,影响我国的冷空气活动加强,南风输送水汽减弱,我国东部地区温度偏低且降水减少;负位相时乌拉尔山高压减弱和南支槽加强,西亚高空急流和入侵我国的冷空气减弱,东南沿海地区温度偏高,华北南部到长江中下游地区温度偏低而降水增多。EOF2空间模态对应于乌拉尔山高压和南支槽强度同相变化;正位相时乌拉尔山高压和南支槽同时加强,东亚高空急流位置偏北,冷空气和西南暖湿气流均明显加强,我国东部地区气温偏低,南方地区降水明显增加;负位相时乌拉尔山高压和南支槽同时减弱,东亚高空急流位置偏南,我国东部地区气温偏高,降水增多主要分布在西南地区。前期海温对高原周边环流主模态变化有一定指示意义,北大西洋暖海温时高原上游天气瞬变扰动增强,有利于乌拉尔山高压加强和EOF1正位相维持;赤道西太平洋暖海温及印度洋冷海温时,高原南北两侧Eady最大增长率异常呈“负-正”偶极子型分布,有利于南支槽加深及EOF2正位相维持。The major modes of 700 hPa geopotential height around Tibetan Plateau are investigated by using the Empirical Orthogonal Function(EOF)method,and the main mode variation characteristics of the circulation around the Tibetan Plateau and its regional climate influence are discussed.The results show that on the time scale of interannual variation,the first main mode(EOF1)shows the consistent change of the height field around the plateau,and the second main mode(EOF2)shows the opposite change of the height field in the northwest and southeast of the plateau.The two main modes can explain 42.9%and 24.2%of the total variance of interannual variation,respectively.The EOF1 corresponds to the out-of-phase variation in the strength of the Ural high and the southern trough.The enhanced Ural high and the attenuated southern trough with the positive phase of EOF1 contributes the reinforced cold air activity and weakened southerly winds which result in low temperature and less precipitation over eastern parts of China.In the negative phase,the Ural high weakens and the southern trough strengthens,the West Asian upper-level jet and the cold air invading China weaken,the temperature in the southeast coastal area is high,and the temperature from the south of North China to the middle and lower reaches of the Yangtze River is low and the precipitation increases.The in-phase relationship of the strength of the Ural high and the southern trough is found in EOF2.Both the Ural high and the southern trough are enhanced with northward shift of East Asian jet(EAJ)during the positive phase of EOF2,the cold air and the southwest warm and humid air flow are obviously strengthened,the temperature in the eastern part of China is low,and the precipitation in the southern region is significantly increased.In the negative phase,the Ural high and the southern trough weaken at the same time,and the East Asian upper-level jet stream is positioned further south.The temperature in eastern China is high,and the increased precipitation is mainly distrib

关 键 词：经验正交分解 乌拉尔山高压 南支槽 海表面温度 天气瞬变扰动 

分 类 号：P461[天文地球—大气科学及气象学]