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A Lagrangian perspective on stable water isotopes during the West African Monsoon

Diekmann, Christopher J. 1; Schneider, Matthias 1; Knippertz, Peter ORCID iD icon 1; Vries, Andries J.; Pfahl, Stephan; Aemisegger, Franziska; Dahinden, Fabienne; Ertl, Benjamin 1,2; Khosrawi, Farahnaz 1; Wernli, Heini; Braesicke, Peter 1
1 Institut für Meteorologie und Klimaforschung (IMK), Karlsruher Institut für Technologie (KIT)
2 Scientific Computing Center (SCC), Karlsruher Institut für Technologie (KIT)


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 E H$_{2}$O and its isotopologue HDO (expressed as E$\delta$D) along the pathways of individual air parcels. We sort the full trajectory ensemble into groups with similar transport pathways and h dro-meteorological properties, such as precipitation and relative humidity, and investigate the evolution of the corresponding paired {E EH$_{2}$O, $\delta$D} distributions. The use of idealized process curves in the {E EH$_{2}$O, $\delta$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. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000138281
Veröffentlicht am 24.03.2022
DOI: 10.1029/2021JD034895
Zitationen: 12
Web of Science
Zitationen: 11
Zitationen: 10
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Atmosphärische Spurenstoffe und Fernerkundung (IMK-ASF)
Institut für Meteorologie und Klimaforschung Troposphärenforschung (IMKTRO)
Scientific Computing Center (SCC)
Universität Karlsruhe (TH) – Zentrale Einrichtungen (Zentrale Einrichtungen)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 16.10.2021
Sprache Englisch
Identifikator ISSN: 2169-897X, 2169-8996
KITopen-ID: 1000138281
HGF-Programm 12.11.34 (POF IV, LK 01) Improved predictions from weather to climate scales
Weitere HGF-Programme 46.21.01 (POF IV, LK 01) Domain-Specific Simulation & SDLs and Research Groups
Erschienen in Journal of geophysical research / D
Verlag John Wiley and Sons
Band 126
Heft 19
Seiten e2021JD034895
Vorab online veröffentlicht am 23.09.2021
Nachgewiesen in Dimensions
Web of Science
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