Analysis of the evolutionary patterns and drivers of Capturability of Atmospheric Water (CAW) on the Qinghai-Tibet Plateau

Abstract

The Qinghai-Tibet Plateau (QTP) is a climate-sensitive region with profound implications for the atmospheric water cycle in both Asia and the globe. While global warming has increased precipitation and atmospheric water-holding capacity, energy constraints prevent a proportional relationship between atmospheric water content and global mean precipitation changes. In this study, we utilized multi-source precipitation datasets (ERA5-Land, CPC, CRU, CMAP, GPCP) and atmospheric water flux data (ERA5) to investigate the conversion of atmospheric water to precipitation, a fundamental water cycle process, across the QTP and its surrounding regions from 1979 to 2020 using the Capturability of Atmospheric Water (CAW) index. Our findings reveal a dipole evolution pattern in CAW, with strengthening in the north and weakening in the south. The QTP, a positive mismatch region with limited atmospheric water but efficient precipitation conversion, is highly sensitive to climate change. The evolution of CAW is driven by meteorological factors, with cloud cover and actual evapotranspiration enhancing CAW in the northeastern QTP, while potential evapotranspiration weakens CAW in the southeastern QTP. On a larger scale, CAW evolution is modulated by large-scale atmospheric circulation patterns, where the East Asian summer monsoon enhances CAW in the northeast, while the South Asian summer monsoon weakens CAW in the southeast. Additionally, a qualitative assessment of atmospheric water resource potential, integrating CAW and water vapor transport flux, identifies four distinct development models. These findings provide critical insights for water resource management and climate adaptation strategies in the QTP.