Evaporation measurement and modelling of an alpine saline lake influenced by freeze–thaw on the Qinghai–Tibet Plateau

Abstract. Saline lakes on the Qinghai–Tibet Plateau (QTP) profoundly affect the regional climate and water cycle through loss of water (E, evaporation under ice–free (IF) and sublimation under ice–covered (IC) conditions). Due to the observation difficulty over lakes, E and its underlying driving forces are seldom studied targeting saline lakes on the QTP, particularly during the IC. In this study, E of Qinghai Lake (QHL) and its influencing factors during the IF and IC were first quantified based on six years of observations. Subsequently, two models were chosen and applied in simulating E and its response to climate variation during the IF and IC from 2003 to 2017. The annual E sum of QHL is 768.58 ± 28.73 mm, and E sum during the IC reaches 175.22 ± 45.98 mm, accounting for 23 % of the annual E sum. The E is mainly controlled by the wind speed, vapor pressure difference, and air pressure during the IF, but driven by the net radiation, the difference between the air and lake surface temperatures, wind speed, and ice coverage during the IC. The mass transfer model simulates lake E well during the IF, and the model based on energy achieves a good simulation during the IC. Moreover, wind speed weakening results in an 11.14 % decrease in E during the IC of 2003–2017. Our results highlight the importance of E in IC, provide new insights into saline lake E in alpine regions, and can be used as a reference to further improve hydrological models of alpine lakes.