The characteristics of water vapor transport during the Tibetan Plateau summer monsoon in 1980-2020

The Tibetan Plateau summer monsoon is an important component of the Asian monsoon system, significantly influencing the energy and moisture cycles in the plateau and its surrounding regions. This study uses JRA-55 monthly reanalysis data from 1980 to 2020 and GPCC monthly precipitation data, combined with the Tibetan Plateau Monsoon Index.  This paper focuses on the impact of the summer monsoon over theTibetan Plateau on water transport, such as precipitation, atmospheric circulation, and water budget. The results show that: (1) When the Tibetan Plateau summer monsoon is strong (weak), precipitation in the central and eastern parts of the plateau increases (decreases). (2) From the perspective of water vapor transport, when the summer monsoon over the plateau is stronger, there is an anomalous anticyclonic circulation over central India, an anomalous westerly airflow to the south of the plateau, and the water vapor transport over the plateau is primarily dominated by the westerly water vapor transport channel.(3) Analysed in terms of moisture budget, when the Tibetan Plateau summer monsoon is strong (weak), moisture inflow at the southern and western boundaries of the plateau increases (decreases), while moisture inflow at the northern boundary decreases (increases), resulting in an increase (decrease) in regional net moisture budget. (4) The impact of the Tibetan Plateau summer monsoon on moisture convergence/divergence is mainly driven by the contribution of the wind’s dynamic component, while the thermal component from moisture advection is relatively small.