Variety Trend Analysis of Sunshine Hours in Guinan County in Recent 50 Years

Based on the data of sunshine hours in Guinan County of Hainan,Qinghai Province in recent 50 years(1961-2009),using linear trend estimate,correlation analysis,sliding t test and other methods,the annual,seasonal and monthly change characteristics of sunshine hours in Guinan County in recent 50 years and its relationship with precipitation,cloud amount were analyzed.The results showed that the annual sunshine hours in Guinan County in the past 50 years showed not significant upward trend.In 49 years,the sunshine hours increased 67.2 h and there was the largest number of sunshine hours in 1990s,In 1970s and 1980s,the age changes in amplitude was larger than the sunshine hours interannual variability of sunshine hours by a big margin of 484.2 h.In spring,autumn and winter,the sunshine hours each quarter after quarter showed an upward trend,but the number of sunshine hours showed decreasing trend in summer.In June,August,December,the sunshine hours showed a decreasing trend while increasing tend in other months.Years and seasons' sunshine hours showed negative correlation with the same period the total of clouds,precipitation.Annual sunshine hours in 1976 and 1993 showed the phenomenon of significant mutations.In the vicinity of 1976 showed a sharp reduction in sunshine,but after 1993,showed an upward trend.In the spring of 1976 and the winter of 1977,there are also mutations.