乌海近60年日照时数变化特征

Variation Characteristics of Sunshine Hours in Wuhai During Recent 60 Years

利用乌海近60年(1961—2010)逐月日照时数资料,分析了乌海市年代际、年际及各月的日照时数变化特征。结果表明:(1)从年代际来看,日照时数逐年代大体呈减少趋势,20世纪80年代是日照时数变化的转折期,四季日照时数年代际极值除冬季外均与年极值出现年代相同,均为70年代日照时数最少,80年代日照时数最多;日照时数夏季最多,春季第二,秋季第三,冬季最少,夏季的日照时数变化趋势对全年日照时数变化趋势的影响最大。春季与夏季的日照时数变化是影响全年日照时数距平的主要因素。(2)日照时数年距平序列和秋季、冬季距平序列的变化趋势一元线性回归方程日照倾向率均<0,春季、夏季距平序列的变化趋势一元线性回归方程日照倾向率均>0,但只有秋季、冬季逐年日照时数距平序列通过0.05水平的显著性检验,两者均呈直线下降趋势;日照时数年和四季距平5年滑动平均二次拟合曲线春季、秋季和冬季通过0.05水平的显著性检验;以年及四季距平5年滑动平均序列作为趋势线,均表现出20世纪70年代末期之前日照时数呈下降趋势,80年代呈上升趋势,80年代末又呈下降趋势,且下降速率低于70年代末期之前。(3)日照时数年内分布规律为单峰型,5月最大,其次为6月,12月最小。

Based on the data of monthly sunshine duration in Recent 60 years(1961-2010)in Wuhai city,the decadal,annual and monthly variation characteristics of sunshine duration in Wuhai city were analyzed.The results showed that:(1)from the decadal perspective,the sunshine duration showed a decreasing trend year by year.1980s was the turning point of sunshine duration,and the decadal extreme values of sunshine duration in four seasons were the same as the annual extreme values except winter,with the lowest sunshine duration in 1970s and the highest sunshine duration in 1980s.The sunshine duration is the highest in summer,the second in spring,the third in autumn and the least in winter.The trend of sunshine duration in summer has the greatest influence on the trend of sunshine duration throughout the year.The variation of sunshine duration in spring and summer is the main factor affecting the annual sunshine duration anomaly.(2)the sunshine duration in analyzed the sequence and the change trend of autumn and winter anomaly sequence unary linear regression equation of rizhao tendency rate<0,the change trend of spring and summer departure sequence unary linear regression equation of sunshine tendency rate>0,but only the fall,winter sunshine time year by year by 0.05 level of significance test,analyzed the sequence both straight downward trend;The quadratic fitting curve of 5-year moving average of sunshine duration and seasonal anomaly passed the significance test at 0.05 level in spring,autumn and winter.Taking the 5-year moving average series of annual and seasonal anomalies as the trend line,the sunshine duration showed a downward trend before the end of 1970s,an upward trend in the 1980s,and a downward trend again at the end of 1980s,and the decreasing rate was lower than the end of 1970s.(3)The distribution pattern of sunshine duration in several years is single-peak type,which is maximum in May,followed by June and minimum in December.