Acta Geographica Sinica ›› 2011, Vol. 66 ›› Issue (1): 25-37.doi: 10.11821/xb201101003

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Interdecadal Variations of East-Asian Summer Monsoon and Drought/Flood Distribution over Eastern China in Last 159 Years

LI Qian1,2, WEI Fengying2, LI Dongliang1   

  1. 1. Nanjing University of Information Science and Technology, Nanjing 210044, China;
    2. State Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China
  • Received:2010-07-14 Revised:2010-09-26 Online:2011-01-25 Published:2011-01-25
  • Supported by:

    National Natural Science Foundation of China, No.40890053; Special Scientific Fund for Non-profit Public Industry (Meteorology), No.GYHY200906016; No.GYHY201006038

Abstract: Based on the drought/flood grads of 90 meteorological stations over eastern China and summer average sea-level pressure (SLP) during 1850-2008, this paper analyzed the coupling relationship between the drought/flood grads and the East-Asian summer SLP using BPCCA statistical methods. The East-Asian summer monsoon index which is closely related with interdecadal variation of drought/flood distribution over eastern China was defined by using the key areas of SLP. Then, we studied the impact of the interdecadal variation of East-Asian summer monsoon on the drought/flood distribution over eastern China in the last 159 years. The results showed that there were four typical drought and flood spatial patterns in eastern China: the drought/flood distribution in South China was contrary to that of the other areas; the drought/flood distribution along the Huanghe-Huaihe river valleys was contrary to that of the Yangtze River valley and the areas south of it; the drought/flood distribution along the Huaihe River valley was contrary to that of the other areas; and the drought/flood distribution in the eastern areas was contrary to the western areas. The main distribution pattern of the SLP in summer was that the strength of SLP in Asian continent was opposite to that in Western Pacific. The interdecadal variation of drought/flood distribution patterns over eastern China had a close relationship with that of the East-Asian summer monsoon defined in this study, although their correlation was not stable and had a significant difference in interdecadal phase change. When the East-Asian summer monsoon was stronger (weaker), the northern regions of the Yangtze River valley were more susceptible to drought (flood), but the Yangtze River valley and its southern regions were more susceptible to flood (drought) before the 1920s; when the East-Asian summer monsoon was stronger (weaker), the northern regions of the Yangtze River valley were more prone to flood (drought), but the Yangtze River and its southern regions were prone to drought (flood) after the 1920s. It is indicated that by using the data of the longer period more results could be obtained than by using the data of the last 50-60 years. The interdecadal phase differences between the East-Asian summer monsoon and the drought/flood distribution in eastern China may relate to the nonlinear feedback of the East-Asian summer monsoon to the extrinsic forcing (e.g. solar activity).

Key words: eastern China, drought/flood distribution, East-Asian summer monsoon, interdecadal variation