EGU25-8009, updated on 14 Mar 2025
https://doi.org/10.5194/egusphere-egu25-8009
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under the Creative Commons Attribution 4.0 License.
Oral |
Thursday, 01 May, 09:05–09:15 (CEST) Room 1.61/62
AMOC sensitivity to air-sea fluxes parametrization
- LSCE, MERMAID, Gif-sur-Yvette, France (clement.dehondt@lsce.ipsl.fr)
The Atlantic Meridional Overturning Circulation (AMOC) is a large scale circulation of about 18 Sv and 1.2 PW at 26°N characterized by upper waters flowing northward, losing heat and becoming cold deep waters before flowing back southward. The Deep Water Formation (DWF) and the Subpolar gyre circulation are key aspects of AMOC intensity [1] but strongly depend on air-sea fluxes, thus the need to quantify their influence.
To do so, we compare 5 air-sea fluxes parametrizations within the IPSL General Circulation Model (GCM) [2] based on the new DYNAMICO atmospheric dynamical core [3] and the ocean engine NEMO [4]. We show that the spread in AMOC is more than 2 Sv, confirming the high sensitivity to air-sea fluxes. Furthermore, we manage to explain these discrepancies by assessing (i) winter time buoyancy fluxes in DWF area and (ii) subtropical and subpolar gyres intensity which drives the circulation. We also analyse the ocean-atmosphere feedbacks (mainly wind and sea surface temperature) that may be responsible for changes in AMOC, hence paving the way to a better representation in GCMs.
To do so, we compare 5 air-sea fluxes parametrizations within the IPSL General Circulation Model (GCM) [2] based on the new DYNAMICO atmospheric dynamical core [3] and the ocean engine NEMO [4]. We show that the spread in AMOC is more than 2 Sv, confirming the high sensitivity to air-sea fluxes. Furthermore, we manage to explain these discrepancies by assessing (i) winter time buoyancy fluxes in DWF area and (ii) subtropical and subpolar gyres intensity which drives the circulation. We also analyse the ocean-atmosphere feedbacks (mainly wind and sea surface temperature) that may be responsible for changes in AMOC, hence paving the way to a better representation in GCMs.
[1] Buckley, M. W. and J. Marshall (2016), Observations, inferences, and mechanisms of Atlantic Meridional Overturning Circulation variability: A review, Rev. Geophys., 54, 5–63, doi:10.1002/2015RG000493.
[2] Boucher O., Servonnat, J., Albright, A. L., Aumont, O., Balkanski, Y., Bastrikov, V., et al. (2020). Presentation and evaluation of the IPSL‐CM6A‐LR climate model. Journal of Advances in Modeling Earth Systems, 12, e2019MS002010. https://doi.org/10.1029/2019MS002010
[3] Dubos, T., Dubey, S., Tort, M., Mittal, R., Meurdesoif, Y., and Hourdin, F.: DYNAMICO-1.0, an icosahedral hydrostatic dynamical core designed for consistency and versatility, Geosci. Model Dev., 8, 3131–3150, https://doi.org/10.5194/gmd-8-3131-2015, 2015.
[4] “NEMO ocean engine”, Scientific Notes of Climate Modelling Center, 27 — ISSN 1288-1619, Institut PierreSimon Laplace (IPSL), doi:10.5281/zenodo.1464816
How to cite: Dehondt, C., Braconnot, P., Fromang, S., and Marti, O.: AMOC sensitivity to air-sea fluxes parametrization, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8009, https://doi.org/10.5194/egusphere-egu25-8009, 2025.
