Atmospheric Water Vapor Budget and Its Long‐Term Trend Over the Tibetan Plateau. Issue 23 (26th November 2020)

• Record Type: Journal Article
• Authors: Yan, Hongru; Huang, Jianping; He, Yongli; Liu, Yuzhi; Wang, Tianhe; Li, Jiming
• Is Part Of: Journal of geophysical research. Volume 125:Issue 23(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-26
• Subjects: Water Vapor -- Tibetan Plateau -- Balance -- Trend; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2020JD033297
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: The rapid warming and consequent retreat of glaciers across the Tibetan Plateau (TP) have given rise to the debate on the ability of the atmospheric water supply to alleviate the depletion of surface water storage. We investigate long‐term changes in atmospheric water vapor balance across the TP using 40‐year fifth generation European Centre for Medium‐Range Weather Forecasts (ECMWF) (ERA5) reanalysis. Precipitation, water vapor convergence, and evaporation generally maintain an equilibrium but with different long‐term variation trends: 0.68, −0.18, and 0.69 mm/a, respectively. Results suggest the inability of the water vapor arriving from outside the TP to effectively replenish the surface water storage. Despite of huge changes in atmospheric water vapor balance during summer, the risk of water storage depletion is brought by other three seasons, especially the autumn. The climatology and long‐term trends of water vapor balance exhibit strong variation across the regions of TP. The surrounding areas of Yarlung Zangbo Grand Canyon experience sharp decrease in water vapor convergence, thus reducing precipitation. Moreover, increasing evaporation is expected to severely loss of surface water storage. For the Three Rivers Source Region with no significant changes in total precipitations, decrease in water transported from outside of TP overlaps increase in evaporation results in the possible depletion of surface water storage. Brahmaputra basin, inner TP, and Qilian Mountain exhibit significant wetting trends due to increases in both convergence of water vapor flux and evaporation. Above regional and seasonal characteristics of water vapor, balances across the TP are attributed by inhomogeneous variation of atmospheric heat source and complex changes of atmospheric circulations. Plain Language Summary: We aim to determine whether the increase in atmospheric water vapor is able to replenish the surface water storage depletion across the Tibetan Plateau (TP) by analyzing long‐term trends in precipitation, water vapor convergence, and evaporation. Results suggest that surface water storage will not be overall replenished by precipitation for the whole year, as despite the increase in water vapor from local evaporation, transportation from outside of the TP is reduced. Furthermore, long‐term trends in the water vapor balance and their impacts on surface water storage vary from place to place across the TP. Key Points: Despite that air of Tibetan Plateau is moistening, atmospheric water supply is not able to alleviate the depletion of the surface water storage Regions around Yarlung Zangbo Grand Canyon suffer severe loss of water storage due to the overwhelming decrease in water vapor convergence The surface water storage of the Three Rivers source region is also under risk of depletion