Variation of Sunshine Hours and Its Influence Factors in Last 50 Years in Fujian Province

The meteorological data including monthly sunshine hours and total cloud amount,low-level cloud amount,vapor pressure and relative humidity,from 64 observational stations in Fujian province from 1961 to 2008 was analyzed,based on climate tendency rate method.The results showed that annual sunshine hours decreased in Fujian province at the rate of 71.7 h/10y in last 50 years,in southern Fujian particularly.The sunshine hours in four seasons decreased at the rate between 13.8 h/10y to 26.5 h/10y,of which the maximum was in summer and the minimum was in autumn,in latest 30 years particularly.From decadal variation,four seasons had sufficient sunshine during 1960s to 1970s,with positive anomaly.But only summer sunshine hours had positive anomaly in 1980s,while negative anomaly for the other three seasons.In 1990s,three seasons had more sunshine except spring.The annual sunshine hours were extremely excessive in 1963 or 1971,but never extremely deficient.Annual and seasonal sunshine hours decreased with the increasing of low-level cloud amount,and the reduction of sunshine hours increased along with vapor pressure in winter.