Isotopic variation of precipitation over eastern Mongolia and its implication for the atmospheric water cycle
Isotopic variation of precipitation over eastern Mongolia and its implication for the atmospheric water cycle
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DOI：
10.1016/j.jhydrol.2006.07.022
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发表时间：
2007-01
影响因子：
6.4
通讯作者：
T. Yamanaka;M. Tsujimura;D. Oyunbaatar;G. Davaa
中科院分区：
文献类型：
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作者：
T. Yamanaka;M. Tsujimura;D. Oyunbaatar;G. Davaa
为了研究蒙古东部及周边地区的大气水循环，建立了稳定的降水氢、氧同位素监测网络。2002年10月至2003年9月，在6个站点采集了66个月样本，2003年4月至9月，在7个站点采集了204个日样本。观测到的同位素组成在空间上显示出相当大的一致性，其特点是与气温有很强的相关性（与降水的相关性较弱）。涉及温度和降水量的瑞利模式成功地再现了观测值的逐日变化，δD和δ18O的均方根误差分别为30‰和2.7‰。这种良好的重现性表明，降水的同位素变化可以用单个蒸汽源水库输送过程中的降雨历史来解释。水库条件与副热带海洋大气条件基本一致，表明大陆再循环对降水同位素的时间变化影响较小。然而，7月份观测到的δ值远低于预测值。考虑到大气环流型及其与同位素资料的关系，推测低δ附加水汽可能来自南方地区（如东南稻田）。瞬态涡旋在将水汽输送到蒙古东部的过程中发挥了重要作用。
To investigate the atmospheric water cycle over eastern Mongolia and its surrounding regions, a monitoring network for stable hydrogen and oxygen isotopes in precipitation has been established. We obtained 66 monthly samples at six stations for a year from October 2002 to September 2003 and 204 daily samples at seven stations during the warm period from April to September of 2003. The observed isotopic composition showed considerable coherence in space and was characterized by a strong correlation with air temperatures (and a weak correlation with precipitation). A Rayleigh-type model involving the temperature and amount of precipitation successfully reproduced day-to-day variations in the observations with root mean square errors of 30‰ for δD and 2.7‰ for δ18O. This good reproducibility demonstrates that isotopic variation of precipitation can be explained by rainout history during transportation from a single vapor-source reservoir. The conditions of the reservoirs generally corresponded with those for a subtropical marine atmosphere, indicating that continental recycling generally has a minor effect at least on the temporal variability of isotopes in the precipitation. In July, however, observed δ values were very much lower than predicted. Considering the atmospheric circulation pattern and its relationship to isotopic data, it is inferred that the additive water vapor with low δ might be supplied from regions in the south (e.g., rice paddy fields in southeast China). Transient eddies can play an important role in transporting such water vapor to eastern Mongolia.