Analysis on Variation Characteristics of the Sunshine Duration of Recent 50 Years in Heilongjiang Province

In order to make good use of meteorology resources for agriculture,using the statistical date of sunshine duration from 77 meteorological stations in Heilongjiang,the annual,seasonal and monthly variation features of sunshine duration in Heilongjiang were analyzed by the methods of linear trend estimation and accumulative anomaly.It was found that the annual sunshine duration showed a significant decreasing tendency during the recent 50 years with a decreasing rate of 26.7 h per 10 a.The average sunshine duration in 1960s was the most,1990s was the least;Annual average sunshine duration were the highest in 1967,and the lowest in 2003;Four seasons sunshine duration showed a decreasing tendency,especially in spring,followed by winter and summer,the smallest in autumn;except for August and September,sunshine duration in each month went down,especially June;The transition time of sunshine duration happened around the early of 1980s.