Trends in precipitation recycling over the Qinghai–Xizang Plateau in last decades

Abstract

Summary This study calculated the annual and inter-annual variations in the precipitation recycling ratio (PRR) on the Qinghai–Xizang Plateau (QXP); and by using water mass balance equation; we evaluated the estimated evaporation in the area. The results indicate that the estimated evaporation relate strongly to surface air temperature, relative humidity and wind speed. As temperatures on the QXP increase, the changes of PRR vary by regions within the plateau. Between 1979 and 2008, the PRR decreased in the western QXP, which is an arid area, but it increased in the other areas. The strongest increasing PRR trend is 3.1%/10 a in the northeastern QXP, but a decreasing trend, ranging downward to −2.5%/10 a, was observed in the western QXP. There is a significant seasonal change in precipitation recycling (PR) over QXP. The PR peak values occurred in July in all regions, and PR was very low (approaching 0.0) in winter half-year period. The monthly maximum PRR reached 0.62, which occurred in July over the southeastern QXP, where is a rich center of precipitation. These results imply that there is remarkable change of moisture resource of precipitation in last decades. On the QXP, large-scale moisture advances decrease with increased temperature, and the local moisture cycle is reinforced in wet regions.