Advances in Earth Science ›› 2007, Vol. 22 ›› Issue (5): 456-467. doi: 10.11867/j.issn.1001-8166.2007.05.0456

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Diagnostic and Modeling Study of the Two Basic Modes of Surface Air Temperature and Its Variation in China

PU Bing 1, WEN Xin-yu 1, WANG Shao-wu 1, ZHU Jin-hong 1, 2   

  1. 1.Department of Atmospheric Sciences, School of Physics, Peking University, Beijing 100871, China;2.Illinois State Water Survey, University of Illinois at Urbana-Champaign, Illinois, USA
  • Received:2006-11-21 Revised:2007-03-28 Online:2007-05-10 Published:2007-05-10

PU Bing, WEN Xin-yu, WANG Shao-wu, ZHU Jin-hong. Diagnostic and Modeling Study of the Two Basic Modes of Surface Air Temperature and Its Variation in China[J]. Advances in Earth Science, 2007, 22(5): 456-467.

Because of its particular geographical condition, the climate of China vary from one region to another. Thus, studies of the spatial patterns of temperature variance in the context of global warming in the past one hundred years are very meaningful. Using the constructed and observational data, we obtained a series of surface temperature anomaly over Eastern China in four seasons during the period of 1880-2004. EOF analysis was applied on this sequence, and it is found that two basic spatial patterns, which are independent of seasonal cycle, dominate the variation of surface temperature in China. The two leading EOF eigenvectors are: (1) Eastern China experiences a consistent change; (2) Northeastern China exhibits an opposite change compared with the rest parts of China. Moreover, detailed analysis shows that the warming since the 1980s in China is chiefly caused by the persistently increasing in positive phase of EOF-1 mode since 1976. The warming during the period of the 1920s-1940s can be mainly attributed to the positive phase of EOF-2 mode.
Besides the diagnostic analysis, the results from an ensemble numerical simulation were also examined, using the same methods and approaches as above. It should be noted that the first mode can be captured by an Atmospheric General Circulation Model forced by observational sea surface temperature and sea ice data. However, this model failed to present the second mode except for boreal winter (DJF).
Furthermore, because of the relatively steady performance of the two modes in winter, the circulation patterns in 500 hPa level for these two modes were investigated by composite analysis on both the observational and modeled data. The results from the two kinds of data show conformably that the positive phase of the first mode corresponds to the enhanced zonal circulation in winter, which leads to the warming in eastern China, while the negative phase corresponds to the circulation structure that the East Asia trough is deepening, which leads to the coherent cold in Eastern China. The second mode is affected by the large scale of high level anomaly centers. The positive phase corresponds to the situation that from northern East Asia to Aleutian is controlled by negative geopotential height anomaly and from East Asia to northern Pacific Ocean in middle latitude is covered by positive anomaly, resulting in the cold anomaly on surface in northeast and warm anomaly in the rest parts. The circulation pattern of the negative phase is almost in the opposite condition.

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