Modelling the water isotope distribution in the Mediterranean Sea using a high-resolution oceanic model (NEMO-MED12-watiso v1.0): evaluation of model results against in situ observations

• Published in: Geoscientific Model Development
• Main Authors: Ayache, Mohamed, Dutay, Jean-Claude, Mouchet, Anne, Tachikawa, Kazuyo, Risi, Camille, Ramstein, Gilles
• Format: Text
• Language: English
• Published: 2024
• Subjects: Western Basin; Planktonic foraminifera
• Online Access: https://doi.org/10.5194/gmd-17-6627-2024; https://gmd.copernicus.org/articles/17/6627/2024/

Stable water isotopes ( δ 18 O w and δ D w ) have been successfully implemented for the first time in a high-resolution model of the Mediterranean Sea (NEMO-MED12). In this numerical study, model results are compared with available in situ observations to evaluate the model performance of the present-day distribution of stable water isotopes and their relationship with salinity on a sub-basin scale. There is good agreement between the modelled and observed distributions of δ 18 O w in the surface water. The model successfully simulates the observed east–west gradient of δ 18 O w characterising surface, intermediate, and deep waters. The results also show good agreement between the simulated δ D w and the in situ data. The δ D w shows a strong linear relationship with δ 18 O w ( r 2 =0.98 ) and salinity ( r 2 =0.94 ) for the whole Mediterranean Sea. Moreover, the modelled relationships between δ 18 O w and salinity agree well with observations, with a weaker slope in the eastern basin than in the western basin. We investigate the relationship of the isotopic signature of the planktonic foraminifera shells ( δ 18 O c ) with temperature and the influence of seasonality. Our results suggest a more quantitative use of δ 18 O records, combining reconstruction with modelling approaches.