Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations
- 1Italy (dorotea.iovino@cmcc.it)
- 2Met Office, Exeter EX1 3PB, U.K
- 3European Centre for Medium Range Weather Forecasting (ECMWF), Reading, U.K.
- 4Istituto di Scienze dell’Atmosfera e del Clima (CNR-ISAC), Bologna, Italy
- 5Rossby Centre, Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden
- 6Barcelona Supercomputing Center – Centro Nacional de Supercomputación (BSC), Barcelona, Spain
- 7National Oceanography Centre, Southampton, U. K.
- 8 Koninklijk Nederlands Meteorologisch Instituut (KNMI), De Bilt, The Netherlands
- 9Max Planck Gesellschaft zur Foerderung der Wissenschaften E.V. (MPI-M), Hamburg, Germany
- 10National Centre for Atmospheric Science (NCAS), University of Reading, Reading, U.K.
- 11CECI, Université de Toulouse, CERFACS/CNRS, Toulouse, France
- 12Center for Ocean-Atmospheric Prediction Studies (COAPS)/FSU, Tallahassee, USA
- *A full list of authors appears at the end of the abstract
The Atlantic Meridional Overturning Circulation (AMOC) is a key component of the three-dimensional ocean circulation that transports warm and salty water northward, and exports cold and dense water from the Arctic southward.
The simulated AMOC in Coupled Model Intercomparison Project models (both coupled and ocean-only) has been studied extensively. However, correctly simulating the AMOC with these models remains a challenge for the climate modelling community. One model aspect that can affect the AMOC representation is the model resolution (i.e. grid spacing).
Here, we examine key aspects of the North Atlantic Ocean circulation using a multi-model, multi-resolution ensemble based on the CMIP6 HighResMIP coupled experiments. The AMOC and associated heat transport tend to become stronger as model resolution increases, particularly when the ocean resolution changes from non-eddying to eddy-present and eddy-rich. However, the circulation remains too shallow compared to observations for most models, and this, together with temperature biases, cause the northward heat transport to be too low for a given overturning strength.
In the period 2015-2050, the overturning circulation tends to decline more rapidly in the higher resolution models by more than 20% compared to the control state, which is related to both themean state and to the subpolar gyre contribution to deep water formation. The main part of the decline comes from the Florida Current component of the circulation.
Qiuying Zhang, Ping Chang, Stephen G. Yeager, Frederic S. Castruccio, Shaoqing Zhang, Lixin Wu
How to cite: Iovino, D., Roberts, M. J., Jackson, L. C., Roberts, C. D., Meccia, V., Docquier, D., Koenigk, T., Ortega, P., Moreno-Chamarro, E., Bellucci, A., Coward, A., Drijfhout, S., Exarchou, E., Gutjahr, O., Hewitt, H., Lohmann, K., Schiemann, R., Seddon, J., Terray, L., and Xu, X. and the iHESP group members: Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18216, https://doi.org/10.5194/egusphere-egu2020-18216, 2020.
