Acta Geographica Sinica ›› 2011, Vol. 66 ›› Issue (7): 885-894.doi: 10.11821/xb201107002

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Climatic Change in Cold and Warm Winter over Tibet during 1961-2010

DU Jun1,2, YANG Zhigang2, SHI Lei2, MAPengfei2   

  1. 1. Institute of Plateau Meteorology, China Meteorological Administration, Chengdu 610071, China;
    2. Tibet Climatic Centre, Lhasa 850001, China
  • Received:2011-03-26 Revised:2011-05-18 Online:2011-07-20 Published:2011-07-20
  • Supported by:

    National Natural Science Foundation of China, No.40865008; The Key Project of Tibet's Science and Technology Bureau, No.2010KJGX01-19

Abstract: According to the China national standard, the warm winter is classified into two groups by space and intensity grades. In the space group the warm winter is divided into two spatial grades as single station warm winter, and regional warm winter. In the intensity group, there are two grades as weak warm winter (warm winter) and strong warm winter. Average winter air temperature is divided into three probability categories to define the threshold of warm winter for single station and its warm winter intensity. Then the division criteria for regional winter warm intensity are calculated according to percentile rank of warm winter stations. In accordance with this standard, the grade of single station and regional cold winter are determined. On the basis of the division method for cold and warm winter, the characteristics of cold and warm winter from 1961 to 2010 over Tibet are analyzed. The results show that the mean temperature in winter has increased over Tibet with a rate of (0.29-1.04) oC/10a in recent half century, and the maximum value is in Bangoin. Especially in recent 20 years (1991-2010), the warming amplitude becomes stronger with a rate of (0.73-2.36) oC/10a. Regional warm winter index has an obvious rising trend at a decadal rate of 16%, which is higher than that in Northeast China, North China and Northwest China. Frequency of single station warm winter is 32%-52% with 6%-26% of strong warm winters. There are 21 regional warm winter years over the 50 years with 10 strong warm winters, and there are more occurrences of warm winter in the 2000s, while the most extensive and strongest of regional warm winter occurred in 2006 and 2009. The results also show that the frequency of single station cold winter is 18%-40% with 2%-20% of strong cold winters, and that regional cold winter index has a decreasing trend at a decadal rate of 12%. There are 16 regional cold winter years over the 50 years with 8 strong cold winters, and more occurrences of cold winter was observed in the 1960s. Additionally, the year 1962 witnessed the most extensive and strongest regional cold winter, followed by 1968 and 1983.

Key words: warm winter, cold winter, Tibet