| 夏季逐月东亚高空急流异常对我国降水的影响 |
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| 引用本文： | 宣守丽,张庆云,孙淑清,石春林.夏季逐月东亚高空急流异常对我国降水的影响[J].气候与环境研究,2013,18(6):781-792. |
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| 作者姓名： | 宣守丽 张庆云 孙淑清 石春林 |
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| 作者单位： | 江苏省农业科学院/农业部长江下游平原农业环境重点实验室, 南京210014;中国气象局河南省农业气象保障与应用技术重点开放实验室, 郑州450000;中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室, 北京100029;中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室, 北京100029;中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室, 北京100029;江苏省农业科学院/农业部长江下游平原农业环境重点实验室, 南京210014 |
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| 基金项目： | 江苏省农业科技自主创新资金项目CX(12)5059;中国气象局/河南省农业气象保障与应用技术重点开放实验室开放研究基金课题AMF201201;公益性行业(农业)科研专项201203032;公益性行业(气象)科研专项GYHY201306035;江苏省科技支撑计划—农业部分BE2012391 |
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| 摘 要： | 根据1981～2010年NCEP/DOE再分析资料与中国160站降水资料,利用统计学、物理量诊断等方法,探讨夏季东亚季风环流系统重要成员——东亚高空西风急流位置、强度逐月变化与我国降水的关系。分析表明:6～8月东亚高空西风急流比各自气候态位置偏南(北)时,易造成6月华南、江南地区降水、7月江淮流域降水以及8月长江中上游地区降水偏多(少)。本文重点分析2010年6月、2007年7月及2006年8月东亚高空西风急流位置异常时东亚高、低纬度环流特征及其对我国降水影响的物理成因。研究发现:2010年6月东亚高空西风急流稳定在35°N以南。急流轴南侧(北侧)为强辐散(辐合)距平,相应低层辐合(辐散),造成江南、华南地区从低层至高层的强上升运动,配合整层偏西水汽通量距平,为该地区持续性降水提供了有利的动力和水汽条件;2007年7月东亚高空急流位置偏南、强度偏弱,急流月内尺度扰动偏强,使得东亚中高纬度冷空气活动频繁,造成淮河流域出现持续性暴雨;2006年8月东亚高空西风急流位置持续偏北、强度偏强,有利西太平洋副高西伸、北抬,我国四川—重庆地区受副高控制,出现了极端高温干旱天气。
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| 关 键 词： | 西风急流 降水 月际变化 扰动 |
| 收稿时间： | 2012/11/16 0:00:00 |
| 修稿时间： | 2013/5/27 0:00:00 |
Influence of the Monthly Variation of the East Asia Westerly Jet on Summer Rainfall in China |
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| XUAN Shouli,ZHANG Qingyun,SUN Shuqing and SHI Chunlin.Influence of the Monthly Variation of the East Asia Westerly Jet on Summer Rainfall in China[J].Climatic and Environmental Research,2013,18(6):781-792. |
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| Authors: | XUAN Shouli ZHANG Qingyun SUN Shuqing and SHI Chunlin |
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| Institution: | Jiangsu Academy of Agricultural Sciences/Key Laboratory of Agricultural Environment in Lower Valley of the Yangtze River of Chinese Agriculture Ministry, Nanjing 210014;Henan Key Laboratory of Agrometeorological Support and Applied Technique, China Meteorological Administration, Zhengzhou 450000;State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Chinese Academy of Sciences, Beijing 100029;State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Chinese Academy of Sciences, Beijing 100029;State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Chinese Academy of Sciences, Beijing 100029;Jiangsu Academy of Agricultural Sciences/Key Laboratory of Agricultural Environment in Lower Valley of the Yangtze River of Chinese Agriculture Ministry, Nanjing 210014 |
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| Abstract: | The East Asian westerly jet (EAWJ) is one of the most important circulation systems in East Asia, linking the high and low latitude circulations of East Asia. Based on NCEP/DOE reanalysis data and monthly rainfall data at 160 meteorological stations in China during 1981-2010, the monthly relationship between the position and intensity variation of the EAWJ and summer rainfall in China was analyzed by using the statistical diagnosis method. It was found that a southward-moving EAWJ favors Jiangnan-Huanan rainfall in June, the Yangtze River-Huaihe River valley rainfall in July, and rainfall in the middle-upper reaches of the Yangtze River valley in August. Analyses of the high-low latitude circulation characteristics associated with the abnormal EAWJ of June 2010, July 2007, and August 2006 as well as the physical process of the influences of the EAWJ on rainfall were emphasized in this study. The results showed that in June 2010, the EAWJ moved southward to 35°N where an anomalous upper-level divergence (convergence) and a low-level convergence (divergence) occurred south (north) of the EAWJ, and which induced significant ascending (descending) motion. The anomalous vertical motion together with west vertically integrated water vapor transportation offered favorable dynamic and vapor conditions for persistent precipitation over the Jiangnan-Huanan region. During July 2007, the EAWJ was weaker and located south of its mean climatic position. In addition, the perturbation of the EAWJ was stronger than normal. In this case, the stationary rainy band over the Huaihe River valley was mainly caused by the strong cold air activities in the middle-high latitudes of East Asia which were due to the strong perturbation of the EAWJ. However, during August 2006 the EAWJ was stronger and located abnormally northward, favoring the westward and northward motions of the western Pacific subtropical high. In this case, weather conditions in the Sichuan-Chongqing region of southwestern China were controlled by subtropical high pressure, resulting in severe drought and heat waves. |
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| Keywords: | Westerly jet Rainfall Monthly variation Perturbation |
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