Impact of sub-cloud evaporation on precipitation isotopes with climate change in the Zhangye

Abstract

Based on the precipitation isotopic data of Zhangye station, as well as daily meteorological data, the sub-cloud evaporation variations and their influence on precipitation isotopes with climate change were analyzed. The slope of the Local Meteoric Water Line at ground is lower than that under clouds, and the precipitation is affected by sub-cloud evaporation. Sub-cloud evaporation is most influenced by relative humidity with a negative influence, followed by precipitation amount (negative influence) and air temperature (positive influence). It is higher in the period of 2004–2020 relative to the period of 1986–2003, resulting in richer precipitation isotopes at ground in 2004–2020.