近50年青州市日照时数变化特征

Change Characteristics of Sunshine Hours in Qingzhou City in Recent 50 Years

利用1961—2010年青州市日照观测资料,采用线性回归方法、Mann-Kendall方法、滑动t检验等,对近50年青州市日照时数的变化特征进行分析。结果表明,近50年青州市平均日照时数为2 517.3 h,总体呈显著减少趋势,减幅为61.1 h/10 a,其年际变化振幅较大,并呈现出阶段性变化。20世纪60年代日照时数最多,70年代次之,80—90年代接近常年平均值略偏低,21世纪以来日照时数大幅减少。春、夏、秋、冬四季日照时数与年日照时数变化趋势相同,均呈减少趋势;夏季日照时数年际变化最大,秋季次之,冬季和春季日照时数减少缓慢,四季变化差异很明显。近50年青州市逐月日照时数变化趋势为双峰型,年内最高峰出现在5月,从6月开始雨量、云量增多,日照时数逐渐减少,7—8月降水日数最多,12月日照时数最少。

Using the sunshine observation data of Qingzhou City from 1961 to 2010 ,the change characteristics of sunshine hours in Qingzhou City in the past 50 years were analyzed by the linear regression method, the Mann-Kendall method and the sliding t test. The results showed that the average sunshine hours of Qingzhou City was 2 517.3 h in the past 50 years,the overall trend showed a significant decrease,and the decrease was 61.1 h/10 a,the amplitude of interannual variation was large and showed a phased change. In the 1960s ,the sunshine hours was the highest ,fol- lowed by the 1970s,the sunshine hours from 1980s to 1990s was close to the annual average and slightly lower, the sunshine hours in the 21st cen- tury was greatly reduced. The trend of sunshine hours in spring, summer, autumn and winter was the same as that of annual sunshine hours, and showed a decreasing trend. The annual variation of sunshine hours in sununer was the largest, followed by autumn, and the sunshine hours in winter and spring were slow, and the variation of the four seasons was obvious. In the past 50 years,the monthly trend of sunshine hours in Qingzhou City was double peak type. The peak of the year was in May, the rainfall was increasing and the amount of cloud was increasing from June, the sunshine hours was decreasing, and the precipitation days was the most in July and August, the sunshine hours in December was the least.