Acta Geographica Sinica ›› 2003, Vol. 58 ›› Issue (4): 569-576.doi: 10.11821/xb200304011

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Interdecadal Variability of East-Asian Summer Monsoon and Its Impact on the Climate of China

GUO Qiyun1, CAI Jingning2, SHAO Xuemei1, SHA Wanying1   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. Department of Atmospheric Sciences, School of Physics, Peking University, Beijing 100871, China
  • Received:2002-11-13 Revised:2002-12-27 Online:2003-07-25 Published:2003-07-25
  • Supported by:

    Knowledge Innovation Project of CAS, No. KZCX2-314


Interdecadal variabilities of East-Asian summer monsoon are studied according to the sum of sea level pressure gradient which is ≤-5 hPa between the land (110oE) and sea (160oE) from 10oN to 50oN. The sum for each year from 1951 to 2000 is divided by the mean sum averaged for the total 50 years, to form a series of Summer Monsoon Index (SMI). It shows a systematic reduction during the period of 1951-2000. Strong monsoon (SMI ≥1.0) was predominated during the first half of the studied period. SMI was less than 1.0 since 1976. Association of the climate in China to the SMI is examined based on the calculation of correlation coefficients between monthly mean temperatures and precipitations in each of 160 stations covered the whole land area of Chinese territory. It indicates that summer (June to August) precipitation increased in North China and decreased along the lower reaches of the Changjiang River when summer monsoon was stronger than the normal, and vice versa. Summer temperatures were higher along the Huaihe and Changjiang rivers when summer monsoon was stronger than the normal.

Key words: East Asian summer monsoon, interdecadal variability, climate of China