Quantifying Climate-Induced Changes in the Tibetan Plateau's Hydrologic Cycle Through Atmospheric Moisture Depletion and Restoration Times

Abstract

This study examines the effects of atmospheric moisture dynamics on the Tibetan Plateau's hydrologic cycle, focusing on moisture depletion (${\tau }_P$, removal through precipitation) and restoration (${\tau }_E$, restoration through evaporation) times. We used a water budget approach within the Eulerian framework, utilizing ERA-Interim data and 20 CMIP6 models, to analyze spatiotemporal variations, trends, and abrupt changes in ${\tau }_P$ and ${\tau }_E$ for the periods 2026–2050, 2051–2070, and 2071–2100, relative to 1979–2019, under the SSP245 and SSP585 scenarios. Sensitivities to local warming are expressed as relative changes per degree Kelvin (K). Results show that as temperatures rise, atmospheric moisture content increases more rapidly than precipitation and evaporation, intensifying the hydrological cycle. This is reflected in moisture sensitivity, with stronger responses to temperature changes (7.49%, 7.34%, 7.52%/K) compared to precipitation (2.62%, 3.46%, 3.99%/K) and evaporation (2.73, 3.24, 3.40%/K) across near-, mid-, and long-term periods. Area-averaged ${\tau }_P$ and ${\tau }_E$ are 9.5 and 17.1 days, respectively, with a projected 15.7% and 18.8% increase by 2100. Sensitivities of ${\tau }_P$ and ${\tau }_E$ to warming are 4.66%, 3.46%, 2.90%/K and 4.55%, 3.69%, 3.48%/K over the near-, mid-, and long-term periods. Increased ${\tau }_E$ suggests slower moisture restoration due to reduced evaporation rates or limited surface moisture, while increased ${\tau }_P$ indicates slower moisture removal due to less frequent rainfall. These changes may lead to a drier atmosphere, reduced cloud formation, and increased vegetation water stress, potentially exacerbating drought conditions. This research enhances the understanding of moisture recycling in the Tibetan Plateau's hydrologic cycle and its climate-induced changes.