Spatial-temporal variation of precipitation recycling over the Tibetan Plateau under climate warming

Abstract

In this study, the precipitation recycling ratio (ρ) on the Tibetan Plateau (TP) was calculated based on the improved two-dimensional precipitation recycling model, and the contribution of internal and external cycling precipitation to the changes in total precipitation in the plateau was quantified. From 1979 to 2018, the annual average ρ of the TP was approximately 12.2%, with the highest being 26.3% in summer, approximately 9% in spring and autumn, and only 4.3% in winter. Moreover, ρ tended to increase, and such an increasing trend was more noticeable in summer. Spatially, ρ showed an up-climbing tendency over most areas of the TP, among which the central and eastern regions had more notable success as the recycling process over most areas of the TP strengthened. However, ρ in some western regions showed a weak decreasing trend, indicating that the recycling process was weakened. As the external cycling precipitation (Po) contributed by advection moisture was much greater than the internal recycling precipitation (Pw) contributed by evapotranspiration, the changes in TP total precipitation were mainly dominated by Po changes. Quantitatively, the TP annual precipitation showed a significant increasing trend in the nearly 40 year period, to which the increase in Po contributed 68.4% and the increase in Pw contributed approximately 31.6%.