1961—2020年青海高原日照时数时空变化特征

太阳辐射是地球系统的主要能源，与人类的生活密切相关。通过选取青海高原50个气象观测站点1961—2020年逐月日照时数数据，分析了青海高原整体、不同纬度地区、不同海拔高度地区日照时数时空变化特征。结果表明：（1）1961—2020年青海高原年日照时数呈显著降低趋势，且在2004年发生突变降低。从空间分布来看，除南部个别站点日照时数持平或略微增加外，其余地区年日照时数均呈显著降低趋势，其中柴达木地区和东部农业区降低趋势最显著。（2）青海高原高纬度地区年日照时数降低趋势显著大于低纬度地区。春季不同纬度地区日照时数变化趋势均较小，夏季和冬季纬度相对较高地区日照时数减少趋势显著大于纬度较低地区，秋季纬度较低和纬度较高地区日照时数减少趋势显著大于中纬度地区。（3）青海高原海拔相对较低地区年日照时数降低趋势显著大于海拔相对较高地区。春季不同海拔高度地区日照时数变化趋势均较小，基本持平或略微减少，夏季和冬季海拔相对较低地区日照时数减少趋势显著大于海拔较高地区，秋季不同海拔高度日照时数均呈减少趋势，但是减少趋势显著性状况差异较大。

Spatiotemporal variation characteristics of sunshine hours in Qinghai Plateau from 1961 to 2020

Solar radiation is the primary energy source of the earth’s system and is closely related to human life. By selecting the monthly sunshine hour data of 50 meteorological observation stations in the Qinghai Plateau of China from 1961 to 2020, the spatiotemporal variation characteristics of sunshine hours in the Qinghai Plateau as a whole, different latitudes, and different altitudes were analyzed. The results are as follows: (1) The annual sunshine hours in the Qinghai Plateau exhibit a significant downward trend from 1961 to 2020, and a sudden decrease occurred in 2004. From the perspective of spatial distribution, the annual sunshine hours in other regions showed a significant decreasing trend except that the sunshine hours in some southern stations is flat or slightly increased. And the decreasing trend is most significant in Qaidam area and eastern agricultural area. (2) The decreasing trend of sunshine hours in high-latitude areas is significantly greater than that in low-latitude areas of the Qinghai Plateau. The variation trend of sunshine hours at different latitudes in spring is small. In summer and winter, the decreasing trend of sunshine hours at relatively high latitudes is significantly greater than that at low latitudes, and in autumn, the decreasing trend of sunshine hours at low and high latitudes is significantly greater than that at middle latitudes. (3) The decreasing trend of annual sunshine hours in relatively low-altitude areas of the Qinghai Plateau is significantly greater than that in relatively high-altitude areas. The change trend of sunshine hours at different altitudes in spring is small, flat, or slightly reduced. The decreasing trend of sunshine hours at relatively low altitudes is significantly greater than that at higher altitudes in summer and winter. The sunshine hours at different altitudes in autumn exhibit a decreasing trend, but there is a significant difference in the decreasing trend.