Spatiotemporal changes in atmospheric total water content in Xizang from 1980 to 2024

The Second Scientific Expedition on the Qinghai-Xizang Plateau revealed the imbalance between the Asian Water Tower and the warming-wetting tendency of the plateau. Xizang is a critical region sensitive to climate and eco-environmental changes. Therefore, understanding spatiotemporal changes in atmospheric total water content is of great significance for the construction of ecological security barriers and the highland ecology of Xizang. Based on ERA5 reanalysis data from 1980 to 2024, this study investigates spatiotemporal changes in atmospheric total water content in Xizang using methods including regional averaging, EOF decomposition, the Mann-Kendall test, and linear trend analysis. The results indicate the following: (1) The spatial variation of the annual-mean atmospheric total water content in Xizang is significant, decreasing sharply from the maximum in southeastern Xizang (38.3 mm) to the minimum (2.0 mm) in northwestern Xizang, with the spatial variation in southeastern Xizang being the most intense. (2) According to the results of the EOF decomposition analysis, only the first modes of summer, autumn, and winter atmospheric total water content regional consistent change across Xizang, while. In contrast, the other modes exhibit a spatial inconsistent change. (3) In most regions of Xizang, the atmospheric total water content increases significantly in spring, summer, and autumn. In summer, this increase generally exceeds 0.3 mm per 10 years. (4) The spring-, summer-, autumn-, and annual-mean atmospheric total water contents significantly increase in years 2003, 2006, 2016, and 2006, respectively. These can be interpreted as abrupt climate changes.