Abstract:
Statistical analyses were done for data collected from three observational stations in Jingmen municipality from 1961 to 2017. The analyzed data include monthly sunshine duration, total cloud amount, low-level cloud amount, vapor pressure, relative humidity, and visibility. The results indicated that the sunshine duration of Jingmen station and Zhongxiang station was significantly reduced with time, with the greatest reduction rate occurring in summer when the sunshine duration was the most, followed by autumn and winter, and the lowest reduction rate in spring. The sunshine duration was abundant during the 60s and 70s. It started to decline during the 80s and decreased remarkably since the 90s. At Jingshan station, the decrease in sunshine duration was significant in summer but not significant in autumn and winter. For the spring, however, there was a slight (not significant) increase in sunshine duration. A significant decrease in visibility contributed mainly to the reduced annual/seasonal sunshine duration, while the increase of total cloud cover, relative humidity and water vapor pressure also partly explained the decrease of sunshine duration in individual seasons and stations. The lower decreasing rate of sunshine duration in Jingshan station compared to the Jingmen station and zhongxiang station was mainly attributed to the smaller decrease of visibility in Jinshan station which could be related to the geographical environment and the economic development model of Jingshan county.