Atmospheric Water Transport to the Endorheic Tibetan Plateau and Its Effect on the Hydrological Status in the Region

The endorheic Tibetan Plateau (ETP), which consists of all the endorheic basins of the Tibetan Plateau (TP), has exhibited an overall mass gain in recent decades. However, the role played by atmospheric water (AW) transport on the hydrological status over the ETP is poorly understood. In this study, the AW source to the ETP was tracked with the Water Accounting Model-2 layers (WAM-2) and AW transport to the ETP through its boundaries was quantified, with three reanalysis products (ERA-I, MERRA-2, and JRA-55) during 1979/1980-2015. It is found that total AW input to the ETP is about 13-25%, 59-71%, 10-13%, and 3-7% of mean annual totals in spring, summer, autumn, and winter, respectively. At annual scales, the AW source from land (52-54%) dominates the AW contribution to the ETP, while local recycling of AW over the ETP accounts for about 17-22% of the mean annual total AW contribution. Increased precipitation over the ETP during 1979-2015 was mostly attributed to the significantly increased AW contribution from the Indian Ocean, especially from increased AW inputs transported from the western and southern boundaries in summer. Comparisons between the AW budget and terrestrial water storage changes indicate that the AW budget change over the ETP modulated the variations of terrestrial water storage change during 2002-2014 and annual lake mass change during 1989-2015.