Modelling water isotopologues (<sup>1</sup>H<sup>2</sup>H<sup>16</sup>O, <sup>1</sup>H<sub>2</sub><sup>17</sup>O) in the coupled numerical climate model iLOVECLIM (version 1.1.5)
<p>Stable water isotopes are used to infer changes in the hydrological cycle for different climate periods and various climatic archives. Following previous developments of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O in the coupled c...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-03-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/17/2117/2024/gmd-17-2117-2024.pdf |
| Summary: | <p>Stable water isotopes are used to infer changes in the hydrological cycle for different climate periods and various climatic archives. Following previous developments of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O in the coupled climate model of intermediate complexity, iLOVECLIM, we present here the implementation of the <span class="inline-formula"><sup>1</sup></span>H<span class="inline-formula"><sup>2</sup></span>H<span class="inline-formula"><sup>16</sup></span>O and <span class="inline-formula"><sup>1</sup></span>H<span class="inline-formula"><sub>2</sub></span><span class="inline-formula"><sup>17</sup></span>O water isotopes in the different components of this model and calculate the associated secondary markers deuterium excess (d-excess) and oxygen-17 excess (<span class="inline-formula"><sup>17</sup></span>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.</p>
<p>In the atmospheric component, the model correctly reproduces the first-order global distribution of the <span class="inline-formula"><i>δ</i><sup>2</sup></span>H and d-excess as observed in the data (<span class="inline-formula"><i>R</i>=0.56</span> for <span class="inline-formula"><i>δ</i><sup>2</sup></span>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 <span class="inline-formula"><sup>17</sup></span>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 <span class="inline-formula"><sup>17</sup></span>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 presents a good match for the <span class="inline-formula"><i>δ</i><sup>2</sup></span>H over the entire water column in the Atlantic Ocean, reflecting the influence of the different water masses.</p> |
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| ISSN: | 1991-959X 1991-9603 |