冬半年青藏高原绕流与中国降水和气温的关系  

The Relationship between the Flow Around the Qinghai-Xizang Plateau and the Precipitation and Temperature in China in Winter Half-year

作　　者：张永莉 左洪超[1] 高晓清 吕世华 陈伯龙[1] 董龙翔 李立程[1] ZHANG Yongli;ZUO Hongchao;GAO Xiaoqing;LÜShihua;CHEN Bolong;DONG Longxiang;LI Licheng(College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000,Gansu,China;Northwest Institute of Ecological Environment and Resources,Chinese Academy of Sciences/Key Laboratory of Land Surface Process and Climate Change in the Cold and Arid Region of the Chinese Academy of Sciences,Lanzhou 730000,Gansu,China;College of Atmospheric Sciences,Chengdu University of Information Technology/Sichuan Key Laboratory of Plateau Atmosphere and Environment/Joint Laboratory of Climate and Environment Change,Chengdu 610225,Sichuan,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]兰州大学大气科学学院,甘肃兰州730000 [2]中国科学院西北生态环境资源研究院/中国科学院寒旱区陆面过程与气候变化重点实验室,甘肃兰州730000 [3]成都信息工程大学大气科学学院/高原大气与环境四川省重点实验室/气候与环境变化联合实验室,四川成都610225 [4]中国科学院大学,北京100049

出　　处：《高原气象》2023年第3期529-542,共14页Plateau Meteorology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0103);国家自然科学基金项目(42075019,42075081)。

摘　　要：冬半年中纬度西风带在青藏高原地区产生南北两支绕流,即动力性的南支槽和北支脊,这样的绕流对其周边及下游天气气候有重要影响。本文先分别用600 hPa动力性的南支槽和北支脊各自所在的关键区域的平均涡度与多年平均涡度的差异,表示南支槽和北支脊的强度,然后直观地将南支槽和北支脊强度之差定义为高原绕流强度指数,利用相关分析和合成分析等方法,讨论高原绕流在冬半年平均(10月至次年4月)、秋季、冬季和春季的演变与中国降水和气温的关系。结果表明:高原绕流在冬半年10月至次年4月期间定常的存在,年际变化明显,冬季最强。全球变暖背景下,各时间段绕流强度的变化与中国西北、西南和华南部分地区的降水和气温的关系明显,特别是在冬季。降水关联性最好的是中国西南地区和华南地区,与西北、西南和东北地区的气温变化关系明显。探讨各时间段各层的大尺度大气环流和水汽通量散度、垂直速度等物理量的异常场,亚洲大部分地区自下而上的正压性特征显著,可以很好地解释各时间段高原绕流的异常与中国降水和气温关系。绕流的异常也可能是引发中国冬半年期间高影响天气的原因之一。A dynamic southern branch trough(SBT)and a dynamic northern branch ridge(NBR),two flows around the Tibetan Plateau(FQXP)generated by the mid-latitude westerlies in the winter half-year(October-April),have an important influence on the weather and climate of their vicinity and downstream.In this paper,differences between the mean vorticity and the multi-year mean vorticity of two key regions-where the SBT and the NBR are located in 600 hPa are used to represent the intensity of the SBT and the NBR separately.Then the difference between the strength of SBT and NBR is defined visually as the intensity index of FQXP.The relationship between the precipitation and temperature in China and the evolution of FQXP's average in winter half-year and that in autumn,winter and spring is discussed,using correlation analysis and composite analysis.The results show that the FQXP is constant in the winter half-year(October-April),with significant interannual variations,and the strongest in winter.In the context of global warming,variations in the intensity of FQXP at each period is closely related to the precipitation and temperature in Northwest,Southwest and South China,especially in winter.FQXP has a significant relationship with the temperature changes in northwest,southwest and northeast China,and its best precipitation correlations are found in southwest and south China.Analysis of anomalous large-scale atmospheric circulation and physical quantity fields,such as water vapor flux dispersion and vertical velocity,at each layer in each time period leads to the conclusion that the bottom-up positive pressure characteristic is significant in most of Asia,which well explains the relationship between FQXP anomalies and precipitation and temperature in China at each time period.FQXP anomalies may also be one cause for high-impact weather in China during winter half-year.

关 键 词：青藏高原绕流 北支脊 南支槽 中国降水和气温 大气环流 

分 类 号：P466[天文地球—大气科学及气象学]