Climatic Variation Characteristics over Qilian Mountain Area during the Last 40 Years

Using the temperature and precipitation data of 30 meteorological stations in the period 1960-2000 over Qilian mountain area, the temporal and spatial variational characteristics of temperature and precipitation are analyzed with EOF and REOF methods. The results show temperature spatial variations have high consistency, the variance ratio contribution of the first principal component is about 75%. The consistency in summer is lower than other seasons. The first three rotated loading vector fields represent the principal characteristic of temperature variations: Hexi corridor, Qilian mountain and plateau, east of Qilian mountain. It is obvious that the temperature is getting warming from the middle of 1980′s over Qilian mountain, same as over the majority region of China, except east of Qilian mountain warming from later of 1990′s. The consistency of precipitation is not better than temperature, the variance ratio contribution of the first is about 30%, and higher than other seasons in the spring and autumn, about 50%. The precipitation spatial characteristic is divided into three parts: west of Hexi corridor, east of Qilian mountain, middle of Qilian mountain and Hexi corridor. The sectors are distinct in different seasons. The annual precipitation increased in 1980′s and 1990′s over the majority region of Qilian mountain,which is different from east of Northwest China, the increasement was obvious in summer. The trend was reserved in autumn.

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