Contribution of recycled moisture to precipitation and its influencing factors in the subalpine zone of Qilian Mountains

Recycled moisture, the part of precipitating vapor that comes from surface evapotranspiration, plays an important role in the hydrological process and the feedback of the land surface-atmosphere system. In this study, we use the delta H-2 and delta O-1(8) data of precipitation, plant water, and surface water systematically collected in the subalpine area of the Qilian Mountains from May to October, 2019, and assess the contribution of recycled moisture to precipitation based on the three-component isotopic mixing model. The results indicated that the main source of precipitating vapor comes from the advected vapor, and its contribution reaches up to 87.8 +/- 1.6%. The contribution of local recycled moisture is 12.2 +/- 1.6%, in which the proportion of transpiration and evaporation are 8.9 +/- 0.6% and 3.3 +/- 1.0%, respectively. In terms of the correlation between recycled moisture and its influencing factors, the temperature has a positive effect on evapotranspiration and promotes moisture recycling, while precipitation and humidity have a certain inhibition effect on evapotranspiration and reduce the contribution of recycled moisture.