4.6 Article

A Lagrangian Perspective on Stable Water Isotopes During the West African Monsoon

期刊

出版社

AMER GEOPHYSICAL UNION
DOI: 10.1029/2021JD034895

关键词

stable water isotopes; Lagrangian trajectories; West African Monsoon; air mass mixing; rain interaction

资金

  1. Deutsche Forschungsgemeinschaft (DFG) [290612604/GZ:SCHN1126/2-1]
  2. Swiss National Science Foundation (SNSF) [164721]
  3. TEDDY (DFG) [416767181/GZ:SCHN1126/5-1]
  4. European Space Agency
  5. PIRE funding scheme via the SNSF [177996]
  6. Ministry of Science, Research and the Arts Baden-Wuerttemberg
  7. German Federal Ministry of Education and Research
  8. Projekt DEAL

向作者/读者索取更多资源

The Lagrangian framework presented in this study is used to identify mechanisms controlling the isotopic composition of mid-tropospheric water vapor during the West African Monsoon in the Sahel region in 2016. By analyzing air mass mixing, convective processes, and microphysical processes along different transport pathways, the study reveals that isotopic changes in water vapor are determined by contributions from different processes such as air mass mixing, condensation during convection, and microphysical processes depleting the vapor beyond the Rayleigh prediction.
We present a Lagrangian framework for identifying mechanisms that control the isotopic composition of mid-tropospheric water vapor in the Sahel region during the West African Monsoon 2016. In this region mixing between contrasting air masses, strong convective activity, as well as surface and rain evaporation lead to high variability in the distribution of stable water isotopologues. Using backward trajectories based on high-resolution isotope-enabled model data, we obtain information not only about the source regions of Sahelian air masses, but also about the evolution of H2O and its isotopologue HDO (expressed as delta D) along the pathways of individual air parcels. We sort the full trajectory ensemble into groups with similar transport pathways and hydro-meteorological properties, such as precipitation and relative humidity, and investigate the evolution of the corresponding paired {H2O, delta D} distributions. The use of idealized process curves in the {H2O, delta D} phase space allows us to attribute isotopic changes to contributions from (a) air mass mixing, (b) Rayleigh condensation during convection, and (c) microphysical processes depleting the vapor beyond the Rayleigh prediction, i.e., partial rain evaporation in unsaturated and isotopic equilibration in saturated conditions. Different combinations of these processes along the trajectory ensembles are found to determine the final isotopic composition in the Sahelian troposphere during the monsoon. The presented Lagrangian framework is a powerful tool for interpreting tropospheric water vapor distributions. In the future, it will be applied to satellite observations of {H2O, delta D} over Africa and other regions in order to better quantify characteristics of the hydrological cycle.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.6
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据