定西市1961—2020年日照时数变化特征分析

为分析定西市日照的变化特征，利用1961—2020年定西市安定区日照、降水、相对湿度、云量和水汽压等资料，采用线性趋势分析、Mann-Kendall检验和通径分析等方法，对定西市安定区1961—2020年日照时数的年代际、年际、季、月的变化特征进行分析，探讨了影响区域日照变化的主要气象因子。结果表明：1961—2020年，定西市年日照时数呈现明显的年代际变化特征，20世纪80年代和21世纪00年代日照显著偏少(P<0.05)，日照总体呈现波动减少趋势，线性倾向率为-10.7 h/10 a (P>0.05)，年日照时数最大值出现在1963年，为2790.2 h，最小值出现在1988年，为2159.7 h，极差810.5 h，年日照在1967年和1993年出现了突变；日照时数存在明显的季节变化特征，春季日照增多，线性倾向率为5.1 h/10 a，夏季、秋季和冬季一致减少，其中夏季减少幅度最大(-8.9 h/10 a)；月日照时数变化趋势存在差异，6月日照显著下降(P<0.05)，其他月份增加或下降趋势不明显(P>0.05)，降水、相对湿度、云量和水汽压与日照显著负相...

Variation Characteristics of Sunshine Duration from 1961 to 2020 in Dingxi

To analyze the variation characteristics of sunshine duration in Dingxi City, the data of Dingxi Meteorological Observation Station from 1961 to 2020 was used, and the involved elements were: sunshine duration, precipitation, relative humidity, cloud amount and water vapor pressure. The interdecadal, interannual, seasonal and monthly variation characteristics of sunshine duration were analyzed by using the linear trend analysis, Mann-Kendall test and path analysis. In addition, the main meteorological factors affecting the variation of sunshine duration were discussed. The results showed that: the annual sunshine duration in Dingxi City had obvious interdecadal variation characteristics from 1961 to 2020, and the sunshine duration significantly decreased in the 1980s and 2000s (P<0.05) and its fluctuating trend also decreased with a linear tendency rate of -10.7 h/10 a (P<0.05). The maximum value of annual sunshine duration was 2790.2 h, which appeared in 1963, the minimum value of annual sunshine duration was 2159.7 h, which appeared in 1988, and the range was 810.5 h. The annual sunshine duration had abrupt change in 1967 and 1993. The sunshine duration showed obvious seasonal variation characteristics, which increased in spring with a linear tendency rate of 5.1 h/10 a, but decreased in summer, autumn and winter, and the decrease rate in summer was the largest (-8.9 h/10 a). There were differences in the variation trend of monthly sunshine duration, it decreased significantly in June (P<0.05), but not obvious (P>0.05) in other months. Sunshine duration had extremely obvious negative correlation with precipitation, relative humidity, cloud amount and water vapor pressure, and the main meteorological factors affecting sunshine hours were different in different seasons. The most obvious effect of meteorological factors on sunshine duration was found in autumn (R=0.862), and that in spring came the second. Relative humidity made the greatest contribution to the change of spring and annual sunshine duration variation, but it was the total cloud amount that mostly affected the sunshine duration change in summer, autumn and winter. This study can provide important reference for the efficient utilization of climate resources under the background of climate warming.