Temporal and Spatial Variations of Total Cloud Amount and Their Possible Relationships with Temperature and Water Vapor over China during 1960 to 2012

This study investigates temporal and spatial variations of total cloud cover (TCC) in China during 1960 to 2012 and further analyzes their relationships with temperature and relative humidity based on the dataset of observations from 543 surface meteorological stations in China. Basic statistical methods, including the empirical orthogonal function (EOF) and climate tendency and linear trend analysis, are used here. It is found that TCC is higher in South China than in North China with the maximum value occurring in Sichuan Basin (82%). The climate tendency of TCC in China is -0.8%(10a)^-1 in the recent 53 years and the trend coefficient is -0.68. The variation of the TCC in China demonstrates remarkable seasonal change, which is the largest in the summer and smallest in the winter. It exhibits a clear declining trend in all seasons except the winter. In addition, the first two dominant EOF modes of TCC display a uniform declining variation and apparent regional differences. Meanwhile, variations of temperature and relative humidity are consistent with the variations of TCC with respect to the trend, regional differences and temporal evolution, implying a close relationship between the variations of TCC and these two variables.