Spatiotemporal variability of sunshine duration and influential climatic factors in mainland China during 1959–2017

Abstract Sunshine duration (SD) is a key index with which to quantitatively measure the intensity and duration of solar radiation. The exploration of spatiotemporal characteristics and potential influential factors for SD could help us better understand solar radiation variability. In this study, we first explore the spatiotemporal variability of SD across mainland China during 1959–2017, then identify the predominant influential climatic factors and detect their relative influence of temporal dynamic on SD, and finally discuss the relative influential rates of climatic factors and detect the dominating climatic factor on a spatial scale. The results show that: Firstly, the annual and seasonal SD gradually decreased from the northwest to southeast across mainland China; a significant decreasing trend ( p < .05) was detected for annual SD at a rate of −2.7 h⋅a –1 , a turning point significantly occurred in 1986 ( p < .05) in the year SD series, and oscillation periods of 2.4–3.8 years existed in mainland China and most sub‐regions. Secondly, the significant ( p < .05) decrease of wind speed (Win), increase of precipitation (Pre), and increase of vapour pressure (Vp) were responsible for the decreasing trend of SD with relative influential rates of 39.9, 30.6, and 29.5%, respectively. Thirdly, temporally, the relative influential rate of each climatic variable changed over time; spatially, Win dominated most areas of mainland China (55.9%) during 1959–2017, followed by Pre (24.9%) and Vp (19.2%).