Sunshine Duration Variation and its Influence Factors in Shandong Province

The variation of annual and seasonal sunshine duration was analyzed by using of t-test method,based on monthly sunshine duration of 123 meteorological stations in Shandong province from 1970 to 2009.The spatial variation of meteorological factors,which affected sunshine duration,including cloud amount,low cloud amount,vapor pressure and precipitation,was analyzed.The results showed that mutation point of annual sunshine duration was in 1983 and 1997.The annual sunshine duration decreased from north to south in Shandong province.The total annual sunshine duration decreased significantly during last 40 years with a rate of 91.3h/10y(P0.01),particularly in southwest,west,northern coast and mountains of middle Shandong province.The decreasing trend of sunshine duration was obvious in summer and not obvious in spring,but the maximum total amount was in May.The reason of sunshine duration decreasing mainly because of vapor pressure increasing during 1970 to 2009 but the affect of cloud amount increasing was more after 1997.The results could provide references to sustainable development to adapt to climate change.