欧亚遥相关型对印度夏季风与华北夏季降水间关系的影响
投稿时间:2019-01-02  修订日期:2019-02-24  点此下载全文
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作者单位E-mail
杨洁凡 南京信息工程大学 492246351@qq.com 
郭品文 南京信息工程大学 guo@nuist.edu.cn 
中文摘要:利用国家气候中心160站月平均降水资料、印度热带气象研究所的全印度月平均降水资料和NCEP/NCAR的再分析资料,从年际和年代际角度分别研究了欧亚遥相关型(EU)对印度夏季风与华北夏季降水关系的影响,并探究其物理机制。结果表明,EU与印度夏季风之间的相关系数只有-0.078,二者相互独立。印度夏季风与华北夏季降水有正相关关系(ISM-NCSR关系),且在正EU位相时,ISM-NCSR关系较弱;负EU位相时,ISM-NCSR关系较强。这是由于EU负位相时,贝加尔湖右侧存在反气旋环流,有利于北风及冷空气南下。因此,强印度季风时北上的暖湿气流在华北地区与偏北风相遇形成锋面,有利于华北降水;弱印度季风时华北地区完全被强北风控制,水汽输送通道被阻断,十分不利于降水,从而导致ISM-NCSR关系强。正EU位相时与此相反,相关关系弱。
中文关键词:欧亚遥相关型  印度夏季风  华北夏季降水
 
Effect on the relationship between Indian summer monsoon and North China summer rainfall by Eurasian teleconnection
Abstract:Based on the 160 stations monthly rainfall data provided by National Climate Center of China Meteorological Administration, the all-India monthly rainfall data provided by Indian Institute of Tropical Meteorology and the NCEP/NCAR reanalysis data, this study is made to investigate the summer Eurasian teleconnection (EU) effect on the relationship between the Indian summer monsoon (ISM) and North China summer rainfall (NCSR) from interannual and interdecadal scales respectively, as well as the associated mechanism. The results show that the EU and ISM independent of each other because of the -0.078 correlation coefficient. The ISM and NCSR have a positive correlation, and this relationship becomes weak when it comes to the positive EU phase, but strong in the negative EU phase. The possible mechanism is clarified, that when in negative EU phase, an anti-cyclonic circulation appears over Lake Baikal area that extremely conducive to the northerly wind in the southeast of Lake Baikal area, so that the circulation over North China is controlled by strong anomaly northerly wind. Therefore, when in strong ISM the southwest warm moist air flow encounters the northerly wind at North China and form a front, which is conducive to the North China rainfall. However when in weak ISM, circulation over North China is completely dominated by strong northerly wind, and the water vapor transport channel is blocked entirely, which is not conducive to the rainfall. As a result of the negative EU phase, the ISM-NCSR relationship is strong. Conversely, the ISMR-NCSR relationship is weak in positive EU phase.
keywords:Eurasian teleconnection  Indian summer monsoon  North China summer rainfall
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