Interannual Variability of Precipitation Recycle Ratio over the Tibetan Plateau

Abstract:

The water cycle over the Tibetan Plateau (TP) is vital to the regional and downstream climate and ecosystem. Clarifying the water cycle process and its interannual variability mechanism over TP is important for the climate change adaptation activities. However, our current knowledge about the precipitation recycle ratio over TP remains inconclusive. Using the advanced reanalysis data ERA5 of the high resolution and a bulk model method, the water cycle over the TP is estimated in terms of the climatology and interannual variability. The climatic precipitation recycle ratio over TP in summer is 23%. The reason for the contradictory conclusions of previous studies is analyzed and found to be related to the different definitions of the precipitation recycle ratio associated with the atmospheric water vapor mixture. The interannual variability of the precipitation recycle ratio over TP in summer is significantly and negatively related with the Niño 3.4 index in the preceding winter (r= -0.38, p<0.05). The precipitation recycle ratio decreases 5.4% due to the more moisture inflow in the El Niño decay summer. The change of the recycle ratio induced by the preceding El Niño events explains 61% of its interannual variability. The response of precipitation recycle ratio over TP in summer to the preceding El Niño and La Niña events is asymmetric. The precipitation recycle ratio increases 2.2% insignificantly due to the less moisture inflow in La Niña decay summer. Our study is conductive to reach the consensus on the climatic precipitation recycle ratio over TP and advance our knowledge about its interannual variability mechanism.