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Improved High-Resolution Global and Regionalized Isoscapes of δ18O, δ2H, and d-Excess in Precipitation
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  • Stefan Terzer-Wassmuth,
  • Leonard Wassenaar,
  • Jeff Welker,
  • Luis Araguás
Stefan Terzer-Wassmuth
International Atomic Energy Agency Department of Nuclear Sciences and Applications
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Leonard Wassenaar
International Atomic Energy Agency Department of Nuclear Sciences and Applications
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Jeff Welker
University of Alaska Anchorage
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Luis Araguás
International Atomic Energy Agency Department of Nuclear Sciences and Applications
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Abstract

Patterns of δ18O and δ2H in Earth’s precipitation provide essential scientific data for use in hydrological, climatological, ecological and forensic research. Insufficient global spatial data coverage promulgated the use of gridded datasets employing geostatistical techniques (isoscapes) for spatiotemporally coherent isotope predictions. Cluster-based isoscape regionalization combines the advantages of local or regional prediction calibrations into a global framework. Here we present a revision of a Regionalized Cluster-Based Water Isotope Prediction model (RCWIP2) incorporating new isotope data having extensive spatial coverage and a wider array of predictor variables combined with high-resolution gridded climatic data. We introduced coupling of δ18O and δ2H (e.g. d-excess constrained) in the model predictions to prevent runaway isoscapes when each isotope is modelled separately. We validated RCWIP2 isoscape performance by cross-checking observed versus modelled d-excess values. We improved model error quantification by adopting full uncertainty propagation in all calculations. RCWIP2 improved the RMSE over previous isoscape models by ca. 0.6 ‰ for δ18O and 5 ‰ for δ2H with an uncertainty <1.0 ‰ for δ18O and <8 ‰ for δ2H for most regions of the world. The improved RCWIP2 isoscape grids and maps (season, monthly, annual, regional) are available for download at https://isotopehydrologynetwork.iaea.org.

Peer review status:ACCEPTED

30 Oct 2020Submitted to Hydrological Processes
31 Oct 2020Submission Checks Completed
31 Oct 2020Assigned to Editor
31 Oct 2020Reviewer(s) Assigned
15 Dec 2020Review(s) Completed, Editorial Evaluation Pending
16 Dec 2020Editorial Decision: Revise Major
29 Mar 20211st Revision Received
30 Mar 2021Submission Checks Completed
30 Mar 2021Assigned to Editor
30 Mar 2021Reviewer(s) Assigned
03 May 2021Review(s) Completed, Editorial Evaluation Pending
05 May 2021Editorial Decision: Revise Minor
17 May 20212nd Revision Received
17 May 2021Reviewer(s) Assigned
17 May 2021Submission Checks Completed
17 May 2021Assigned to Editor
18 May 2021Review(s) Completed, Editorial Evaluation Pending
18 May 2021Editorial Decision: Accept