Impact of the quasi-biweekly oscillation over the western North Pacific on East Asian subtropical monsoon during early summer

被引:82
作者
Jia, Xiaolong [1 ]
Yang, Song [2 ]
机构
[1] China Meteorol Adm, Natl Climate Ctr, Beijing, Peoples R China
[2] Sun Yat Sen Univ, Dept Atmospher Sci, Guangzhou 510275, Guangdong, Peoples R China
基金
中国国家自然科学基金;
关键词
intraseasonal oscillation; subtropical monsoon; MADDEN-JULIAN OSCILLATION; SOUTH CHINA SEA; INTRASEASONAL OSCILLATIONS; MOISTURE CONVERGENCE; SURFACE TEMPERATURE; POWER SPECTRUM; LIFE-CYCLE; LATE; 1970S; CIRCULATION; CONVECTION;
D O I
10.1002/jgrd.50422
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
The impact of quasi-biweekly oscillation (QBWO) over the western North Pacific on East Asian summer monsoon (EASM) is investigated. The life cycle of QBWO is divided into eight phases defined by the two leading principal components (PC1 and PC2) of an empirical orthogonal function analysis. Subtropical rainfall shows significant changes, with a northwestward propagation of convection from equatorial regions to the South China Sea (SCS). The most significant variations occur in QBWO phases 3 and 4 (enhanced convection over SCS) and phases 7 and 8 (reduced convection over SCS). The East Asia Mei-yu significantly decreases in QBWO phases 3 and 4 but increases in phases 7 and 8. The QBWO influences EASM through modulating the subtropical monsoon flow and extratropical circulation. The response of lower tropospheric atmosphere to QBWO shows a northwestward propagation and a downstream wave train that extends northward into the western North Pacific, modulating the SCS monsoon trough and the EASM flow associated with moisture transportation. The mid-tropospheric extratropical circulation and the western Pacific subtropical high also show obvious changes accompanying QBWO evolution, resulting in circulation patterns associated with cold air activity. Moreover, changes with QBWO are found in the upper tropospheric East Asian westerly jet stream and the South Asian high, and these changes contribute to upper level divergence over subtropical East Asia.
引用
收藏
页码:4421 / 4434
页数:14
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