Abstract:

On the basis of the monthly sunshine duration data for the period 1961～2007 collected from 68 meteorological observation stations over Tibetan Plateau (TP) and by the methods of statistics analysis,the characteristics of interdecadal variation of the annual sunshine duration over TP were analyzed. The results of our research may lead to the following conclusions:The condition of annual sunshine duration over eastern and southern region of TP was in a poor state and the annual sunshine duration was abundant in western of TP.The variation trend of the annual sunshine duration over TP displayed a remarkable regional difference. The annual sunshine duration obviously decreased over southeastern,southwestern and central regions of TP and north of Qinghai Province,but obviously increased over western and central regions of TP and the southern of Qinghai Province.The interdecadal variation of the annual sunshine duration over TP is also remarkable.The annual sunshine duration increase region and decrease region appeared the remarkable period of 12.1a and 21.1a periodic oscillations,respectively.The annual sunshine duration of increase region raised from 1960s to 1980s then descended from 1990s to the beginning of the 21st century.The annual sunshine duration decrease region raised in 1960s and 1970s then descended in 1990s,and it reached to the bottom in the early 21st century.The spatial differences of annual sunshine duration over TP between each decade are also obvious.

Key words: Tibetan Plateau/annual sunshine duration/ interdecadal variation