Acta Geographica Sinica ›› 2006, Vol. 61 ›› Issue (7): 675-686.doi: 10.11821/xb200607001

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Northerly Advancement Characteristics of the East Asian Summer Monsoon with Its Interdecadal Variations

JIANG Zhihong1, HE Jinhai1, LI Jianping2, YANG Jinhu1, WANG Ji1   

  1. 1. Key Laboratory of Meteorological Disaster of Jiangsu Province, Department of Geography, Nanjing University of Information Science & Technology, Nanjing 210044, China;
    2. Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Beijing 100029, China
  • Received:2005-08-20 Revised:2006-03-16 Online:2006-07-25 Published:2006-07-25
  • Supported by:

    National Natural Science Foundation of China, No.40375032

Abstract:

In the context of 1951-2001 NCEP daily re-analyses and the 1957-2000 daily precipitation from 366 stations over eastern China, a quantitative index is proposed to study the interdecadal variation of the northerly advancement of East Asian Summer Monsoon (EASM). The results show that drawing the isoline of standardized rainfall index of 1.5 that is better indicative of the meridional shifting of the summer rainband in eastern China, and its phased and abrupt change in its northward march. The northerly march of EASM displays conspicuous interdecadal variations. The position indices of the EASM jump in the mid-1960s, however the jump of the intensity indices occurs in the end of the 1970s. Before the mid-1960s, the onset of the South China Sea monsoon is later, but the northward advance is quicker, the time of arrival in North China is earlier, which maintains a longer time in North China, its north edge lies north to the normal position, and thus the North China rainy season and Huaihe River Valley (HRV) Mei-yu are distinct. In recent 20 years, the onset is earlier, the intensity is obviously weaker, and therefore precipitation mainly concentrates in the Yangtze River Valley (YRV) and areas south of the Yangtze River, and the North China rainy season is not evident.

Key words: East Asia, summer monsoon, interdecadal variation, summer rainfall, eastern China