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Quantification of moisture recycling in the river basins of China and its controlling factors

Ma, Qian, Zhang, Mingjun, Wang, Liwei, Che, Yanjun
Environmental earth sciences 2019 v.78 no.14 pp. 392
air, evaporation rate, fate and transport models, monsoon season, summer, watersheds, wind, winter, China, Yangtze River, Yellow River
By using 243 event-based precipitation samples from April 2011 to March 2012 and 289 long-term monthly average values from the GNIP stations, this study discussed the contribution rate of recycled moisture in The Yangtze River and The Yellow River in China and its controlling factors. The contribution rate of recycled moisture in The Yellow River is higher than the values in The Yangtze River basin during a whole year. The average proportion of recycled moisture, 5.52%, in the Yellow River basin is greater than the value of 1.97% in the Yangtze River basin in summer monsoon and 4.72% higher than 3.67% in winter monsoon. Distinct moisture sources may be a factor to influence the extent of recycled moisture. The Hybrid Single Particle Lagrangian Integrated Trajectory Model was applied to simulate the moisture sources in the study area. The air mass trajectories were controlled by distinct wind regimes during different time. The fraction of recycled moisture increases when the study region is under the control of the westerly air mass. Moreover, the influence of d-excess values should also be taken into consideration. Sub-cloud evaporation exists in the study area and has an impact on the recycled moisture. The evaporation rate in the Yellow River basin is significantly higher than the proportion in the Yangtze River over a year. It can be found that the study region which has a relatively higher evaporation rate always has a higher proportion in recycled moisture.