How Does the Evapotranspiration Over the Tibetan Plateau Affect the Precipitation in Itself and Low Reaches?

Through land-atmosphere interaction, the Tibetan Plateau (TP) directly or indirectly affect the weather and climate globally, nevertheless the majority regions of China. To investigate the influence of the terrestrial evapotranspiration over the TP on precipitation over its own and downstream, the water vapor tracer (WAT) method coupled with the Weather Research and Forecasting (WRF) are used in this study. According to the landing location of precipitation, the termination of the evaporative moisture over the TP could be apart into inside or outside the TP. The process in the former was named as recycling precipitation and the other was named as moving-out precipitation. The recycling precipitation was found dominate the termination of the ET, which showed a decrease gradient from eastern to western TP. The moving-out precipitation mainly spreads to the east with a few to the south. Seasonal variations suggested that more recycling precipitation occurs in summer and winter, and more the moving-out precipitation occurs in spring and autumn. The trade-off between convection and advection results in different reaches of moving-out precipitation in two seasons: the strong convection and diabatic heating plus a relative weak large-scale advection result in short reaches outside the TP in summer, while relative weak convection and strong advection result in far-reaches in autumn. This study is beneficial for the understanding of the water cycle over the TP as well as the TP direct impacts mechanism on the precipitation in central and eastern China.