Modelling water isotopologues ( 1 H 2 H 16 O, 1 H 2 17 O) in the coupled numerical climate model iLOVECLIM (version 1.1.5)

• Published in: Geoscientific Model Development
• Main Authors: Extier, Thomas, Caley, Thibaut, Roche, Didier M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2024
• Subjects: Arctic; Indian; Antarc*; Antarctica
• Online Access: https://research.vu.nl/en/publications/7ca01d49-5f41-4526-acb7-7e6dbcf35338; https://doi.org/10.5194/gmd-17-2117-2024; https://hdl.handle.net/1871.1/7ca01d49-5f41-4526-acb7-7e6dbcf35338; http://www.scopus.com/inward/record.url?scp=85187941873&partnerID=8YFLogxK; http://www.scopus.com/inward/citedby.url?scp=85187941873&partnerID=8YFLogxK

Stable water isotopes are used to infer changes in the hydrological cycle for different climate periods and various climatic archives. Following previous developments of δ 18 O in the coupled climate model of intermediate complexity, iLOVECLIM, we present here the implementation of the 1 H 2 H 16 O and 1 H 2 17 O water isotopes in the different components of this model and calculate the associated secondary markers deuterium excess (d-excess) and oxygen-17 excess ( 17 O-excess) in the atmosphere and ocean. So far, the latter has only been modelled by the atmospheric model LMDZ4. Results of a 5000-year equilibrium simulation under preindustrial conditions are analysed and compared to observations and several isotope-enabled models for the atmosphere and ocean components. In the atmospheric component, the model correctly reproduces the first-order global distribution of the δ 2 H and d-excess as observed in the data (R = 0.56 for δ 2 H and 0.36 for d-excess), even if local differences are observed. The model–data correlation is within the range of other water-isotope-enabled general circulation models. The main isotopic effects and the latitudinal gradient are properly modelled, similarly to previous water-isotope-enabled general circulation model simulations, despite a simplified atmospheric component in iLOVECLIM. One exception is observed in Antarctica where the model does not correctly estimate the water isotope composition, a consequence of the non-conservative behaviour of the advection scheme at a very low moisture content. The modelled 17 O-excess presents a too-important dispersion of the values in comparison to the observations and is not correctly reproduced in the model, mainly because of the complex processes involved in the 17 O-excess isotopic value. For the ocean, the model simulates an adequate isotopic ratio in comparison to the observations, except for local areas such as the surface of the Arabian Sea, a part of the Arctic and the western equatorial Indian Ocean. Data–model evaluation also ...