Diurnal Impact of Below-Cloud Evaporation on Isotope Compositions of Precipitation on the Southern Slope of the Altai Mountains, Central Asia

Precipitation is an important natural resource relating to regional sustainability in arid central Asia, and the stable oxygen hydrogen isotopes provide useful tracers understand precipitation processes. In this study, we collected hourly meteorological data at several stations on southern slope of Altai Mountains from March 2017 June 2022, examined diurnal impact below-cloud evaporation isotope compositions precipitation. During nighttime, changes below cloud base are generally weak. The enhanced can be found after around 15:00, relatively strong afternoon, especially 18:00 22:00. Summer spring usually have a larger than autumn, winter not influenced by evaporation. On annual basis, differences evaporation-led between daytime nighttime 1.1‰ for compositions, 4.0‰ 4.7‰ deuterium excess. period 2:00 10:00 shows low sensitivity relative humidity, 14:00 22:00 impacts sensitive. Considering fluctuations does greatly modify seasonal environmental signals.