Variation of sunshine hour in recent 45 years in Aksu Prefecture

Sunshine hour is the most intuitionistic representation of radiation quantum.The change of sunshine hours affects the growth of plant,animal and the anthropogenic activity.In this paper,the series of annual sunshine hours in the Aksu Prefecture,Xinjiang,China,are developed using the sunshine hours data from 8 meteorological stations in the Aksu Prefecture during the period of 1961-2005.The basic features of sunshine hours are analyzed using the methods of 3-year moving average,linear regression,Mann-Kendall statistic,grey forecast,et al.The main results are as follows:(1) The annual sunshine hours in the area is increasing at the trend rate of 3.9 h/10 a.This kind of tendency appears mainly in spring and summer and the trend rates are 12.1 h/10 a and 3.1 h/10 a,respectively.However,the kind of tendency in autumn and winter is decreasing and the trend rates of them is-0.4 h/10 a and-11.0 h/10 a,respectively.(2) The annual sunshine hours in Aksu Prefecture can be classified into three stages and the years with the most and least sunshine hours occurred in 1985 and 2005,respectively.The fluctuation of spring and winter sunshine hours is not significant.However,the oscillation of summer and autumn ones is complex.May be it is because the summer rainless days have a downward trend.The downward trend of winter is probably due to dust-floating increasing in the atmosphere because large amount of coal has been consume by human being.(3) The predicted amount of sunshine hours from the established grey dynamic model indicates that there is an upward trend of the annual sunshine hours,but the trend is not significant.The sunshine hours changed abruptly in 1974,and then there is a relative less hours period,which is synchronous with temperature and precipitation trend at the same time.