Analysis on the change law and meteorological factor of sunshine duration in Dalian City in recent 60 years.

Based on the statistical data of sunshine duration from base station in Dalian City from 1951 to 2009,the annual,seasonal,and monthly variation of sunshine duration in recent 60 years were analyzed,as well as its meteorological factor,and sunshine duration was detected by means of climate mutation theory.The results revealed that annual sunshine duration in Dalian in recent 60 years showed decrease trend on the whole,and its climatic variation rate was-3.31 h/a,with larger annual variation,namely the difference between maximum value(1978) and minimum value(2003) reached 681 h;there was obvious seasonal variation in sunshine duration,with the order of autumnsummerwinterspring,and their climatic variation rate were-1.18、-1.15、-0.91、-0.62 h/a;except for March,sunshine duration in each month went down,especially October,while there was slight increase trend in March;sunshine percentage had inverse correlation relationship with total cloudiness,relative humidity and heavy fog days;annual sunshine duration reduced suddenly around 1983.