Influence of Sub-Cloud Secondary Evaporation Effects on the Stable Isotopes in Precipitation of Urumqi Glacier No.1,Eastern Tianshan  

作　　者：Mengyuan Song Zhongqin Li Feiteng Wang Xin Zhang 

机构地区：[1]State Key Laboratory of Cryospheric Sciences,Northwest Institute of Eco-Environment and Resources,Tianshan Glaciological Station,Chinese Academy of Sciences,Lanzhou 730000,China [2]College of Geography and Environmental Science,Northwest Normal University,Lanzhou 730000,China [3]College of Sciences,Shihezi University,Shihezi 832000,China

出　　处：《Journal of Earth Science》2024年第1期177-189,共13页地球科学学刊（英文版）

基　　金：funded by The Second Tibetan Plateau Scientific Expedition and Research(No.2019QZKK0201);the Strategic Priority Research Program of Chinese Academy of Sciences(Class A)(Nos.XDA20060201,XDA20020102);the National Natural Science Foundation of China(Nos.41761134093,41471058);The SKLCS founding(No.SKLCS-ZZ-2020)。

摘　　要：In arid regions,the stable hydrogen and oxygen isotopic composition in raindrops is often modified by sub-cloud secondary evaporation when they descend from cloud base to ground through the unsaturated air.As a result of kinetic fractionation,the slope and intercept of the δ^(2)H-δ^(18)O correlation equation decrease.The variation of deuterium excess from cloud base to the ground is often used to quantitatively evaluate the influence of secondary evaporation effect on isotopes in precipitation.Based on the event-based precipitation samples collected at Urumqi Glacier No.1,eastern Tianshan during four-year observation,the existence and impact of secondary evaporation effects were analyzed by the methods of isotope-evaporation model.Under high air temperature,small raindrop diameter and precipitation amount,and low relative humidity conditions,the remaining rate of raindrops is small and the change of deuterium excess is large relatively,and the slope and intercept of δ^(2)H-δ^(18)O correlation equation are much lower than those of Global Meteoric Water Line,which mean that the influence secondary evaporation on precipitation enhanced.While on the conditions of low air temperature,high relative humidity,heavy rainfall,and large raindrop diameter,the change of deuterium excess is small relatively and the remaining rate of raindrops is large,and the slope and intercept of δ^(2)H-δ^(18)O correlation equation increase,the secondary evaporation is weakened.The isotope-evaporation model described a good linear correlation between changes of deuterium excess and evaporation proportion with the slope of 0.90‰/%,which indicated that an increase of 1%in evaporation may result in a decrease of deuterium excess about 0.90‰.

关 键 词：stable isotopes meteoric water line deuterium excess sub-cloud secondary evaporation effect PRECIPITATION glaciers 

分 类 号：P343.6[天文地球—水文科学] P597[天文地球—地球物理学]