Abstract: Based on the daily sunshine duration data observed at 23 weather stations in the Tianshan Mountains during the period of 1961-2008, the spatiotemporal distribution and variation features of sunshine duration in the Tianshan Mountains were analyzed using some statistical methods, such as the simple linear regression and Mann-Kendall test. The results are as follows: (1) There was an obvious regional difference in climatic distribution of sunshine duration, and the sunshine duration increased from the west to the east and from the north to the south in the Tianshan Mountains; (2) The regional average sunshine duration was in a decrease trend, especially in winter and summer; (3) There was an obvious decadal variation trend of seasonal sunshine duration except that in spring, and a sharp decrease of seasonal sunshine duration occurred in winter 1987, summer 1978 and autumn 1980; (4) The sharp decrease of sunshine duration in winter and summer was related to the serious air pollution and the increase of cloud cover in recent 20 years.

Key words: climate change, sunshine duration, spatiotemporal distribution, decadal change, seasonal variation, Tianshan Mountains, Xinjiang