title: Variations in stable hydrogen and oxygen isotopes in atmospheric water vapor in the marine boundary layer across a wide latitude range.
abstract: The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of δ(18)O and δ(2)H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature (Tair), with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial-temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world.
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: liujingfeng7732@126.com.
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; Chinese Academy of Meteorological Sciences, Beijing 100081, China.
authors.forename: Cunde
authors.initials: C
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; Chinese Academy of Meteorological Sciences, Beijing 100081, China.
authors.forename: Minghu
authors.initials: M
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
authors.forename: Jiawen
authors.initials: J
authors.lastname: Ren
mesh_terms: D000864:Antarctic Regions; D001272:Atmosphere; D002138:Calibration; D006813:Humidity; D006859:Hydrogen / Q000032:analysis*; D007700:Kinetics; D010103:Oxygen Isotopes / Q000032:analysis*
chemical_list: D010103:Oxygen Isotopes; D006859:Hydrogen
keywords: Atmospheric vapor isotope; CHINREN; Isotope fractionation; Water cycle