三江源果洛地区日照时数变化特征及影响因子分析

Variation of Sunshine Duration and Its Impact Factor in Guoluo Region of Sanjiangyuan

利用三江源果洛地区6个站1980—2019年的日照资料,分析了该地区日照时数的变化特征及其影响因子。结果表明:三江源果洛地区日照时数的空间分布呈现从西北向东南逐渐减少的趋势;近40年的日照时数以-40.2 h/(10 a)的趋势显著减少;日照时数在春、夏、秋、冬四季均呈减少趋势,变化率分别为-11.4 h/(10 a)、-8.2 h/(10 a)、-11.8 h/(10 a)、-8.2 h/(10 a);月平均日照时数的分布呈“三峰三谷”型,4月为全年日照时间最多的月份;根据Hurst指数的H值判断,日照时数变化与过去一致,呈较强的减少趋势,四季以及各站日照时数的变化趋势亦与过去一致;日照时数的变化与总云量、低云量、降水量存在显著的负相关关系,其中低云量对日照时数的影响最大,其次是总云量、降水量。

Based on the sunshine data of 6 stations in Guoluo region of Sanjiangyuan from 1980 to 2019,the variation characteristics of sunshine duration and its impact factors were analyzed.The results show that the spatial distribution of sunshine duration in Guoluo region shows a decreasing trend from northwest to southeast.Meanwhile,the sunshine duration decreases significantly at the rate of-40.2 h/(10 a)in recent 40 years.The decreasing trend is found in four seasons of spring,summer,autumn and winter,with a changing rate of-11.4 h/(10 a),-8.2 h/(10 a),-11.8 h/(10 a)and-8.2 h/(10 a),respectively.The distribution of monthly average sunshine duration presents a pattern of“three peaks and three valleys”,and April is the month with the most sunshine duration.Judging by H value of Hurst index,the variation of sunshine duration is consistent with the past,showing a strong decreasing trend,and the variation trend of sunshine duration in four seasons and at all stations is also consistent with the past.There is a significant negative correlation between sunshine duration and total cloud cover,low cloud cover and precipitation.Low cloud cover has the greatest influence on sunshine duration,followed by total cloud cover and precipitation.