1954—2017年磴口县日照时数变化特征及突变分析

Variation Characteristics and Mutation Analysis of Sunshine Duration in Dengkou County during 1954-2017

为了解磴口县日照时数的变化规律,利用磴口县1954—2017年逐月日照时数资料,运用线性拟合、气候倾向率、Mann-Kendall检测法、Mann-Kendall突变分析、滑动t检验等方法,对磴口县四季和年日照时数的变化趋势和突变特征等进行了分析。结果表明,磴口县1954—2017年年平均日照时数呈现上升趋势,变化倾向率为14.2h/10年,远高于全国平均值-36.9h/10年。变化趋势通过了95%显著性检验。年日照时数在1974、1994年存在明显的突变,突变点通过0.05检验。磴口县春、夏、秋、冬四季的日照时数变化倾向率分别为11.58、4.06、-2.83、0.914h/10年,除秋季外,其他3季均呈现上升趋势,且春季变化趋势通过了99%显著性检验,说明春季日照时数增幅非常显著。磴口县四季的突变检验存在较大差异,春季日照时数的突变发生在2010年,该突变点通过了0.01显著性检验;夏季日照时数的突变发生在1975和1997年,该突变点通过了0.05显著性检验;秋季日照时数的突变发生在1994和2006年,该突变点通过了0.05显著性检验;冬季日照时数的突变发生在1993和2003年,该突变点通过了0.05显著性检验。磴口县1954—2017年各月日照时数变化呈现一峰一谷,其中5月份最多,2月份最少,年平均日照百分率为73%。磴口县各月日照时数变化与降水呈较强的负相关,相关系数为-0.858。

In order to learn the fluctuation rule of sunshine hours in Dengkou County, using the monthly sunshine hours data from 1954 to 2017 in Dengkou County, the variation trends and mutation characteristics of sunshine hours in four seasons and years were analyzed by using the methods of linear fitting, climatic tendency rate, Mann-Kendall detection method, Mann-Kendall mutation analysis and sliding t-test. The results showed that the annual average sunshine hours in Dengkou County from 1954 to 2017 showed an upward trend, with a change tendency rate of 14.2 h/10a, which was much higher than the national average of -36.9 h/10a. The change trend passed the 95% significance test. In 1974 and 1994, there were an obvious mutation in annual sunshine hours, and the mutation point had passed 0.05 test. The trend rates of sunshine hours in spring, summer, autumn and winter in Dengkou County were respectively 11.58, 4.06,-2.83 and 0.914 h/10a. Except autumn, the trend of sunshine hours in other three seasons showed an upward trend, and the change trend in spring passed 99% significance test, indicating that the increase rate in spring was very significant. There were great differences in mutation tests in the four seasons in Dengkou County. The mutation of spring sunshine hours occurred in 2010 and passed the 0.01 significance test;the mutation of summer sunshine hours occurred in 1975 and 1997 and passed the 0.05 significance test;the mutation of autumn sunshine hours occurred in 1994 and 2006 and passed the 0.05 significance test;the mutation of winter sunshine hours occurred in 1993 and 2003 and passed the 0.05 significance test. The change of sunshine hours from 1954 to 2017 in Dengkou County showed a peak-valley pattern, with the peak in May and the bottom in February, with an average annual sunshine percentage of 73%. The change of monthly sunshine hours in Dengkou County was negatively correlated with rain fall, and the correlation ratio was -0.858.