Key features of the IPSL ocean atmosphere model and its sensitivity to atmospheric resolution

• Published in: Climate Dynamics
• Main Authors: Marti, Olivier, Braconnot, Pascale, Dufresne, Jean-Louis, Bellier, Jacques, Benshila, Rachid, Bony, Sandrine, Brockmann, Patrick, Cadule, Patricia, Caubel, Arnaud, Codron, Francis, de Noblet, Nathalie, Denvil, Sébastien, Fairhead, Laurent, Fichefet, Thierry, Foujols, Marie-Alice, Friedlingstein, Pierre, Goosse, Hugues, Grandpeix, Jean-Yves, Guilyardi, Éric, Hourdin, Frédéric, Idelkadi, Abderrahmane, Kageyama, Masa, Krinner, Gerhard, Lévy, Claire, Madec, Gurvan, Mignot, Juliette, Musat, Ionela, Swingedouw, Didier, Talandier, Claude
• Other Authors: Contribution to the European project ENSEMBLES (Project no. GOCE-CT-2003-505539) and to the French project MissTerre (LEFE-EVE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: Coupling; Resolution; Circulation; El Niño/Southern oscillation; Climate; Simulations; Ocean; Atmosphere; North-Atlantic oscillation; Storm-tracks; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; North Atlantic; North Atlantic oscillation
• Online Access: https://insu.hal.science/insu-00498320; https://doi.org/10.1007/s00382-009-0640-6

International audience This paper presents the major characteristics of the Institut Pierre Simon Laplace (IPSL) coupled ocean-atmosphere general circulation model. The model components and the coupling methodology are described, as well as the main characteristics of the climatology and interannual variability. The model results of the standard version used for IPCC climate projections, and for intercomparison projects like the Paleoclimate Modeling Intercomparison Project (PMIP 2) are compared to those with a higher resolution in the atmosphere. A focus on the North Atlantic and on the tropics is used to address the impact of the atmosphere resolution on processes and feedbacks. In the North Atlantic, the resolution change leads to an improved representation of the storm-tracks and the North Atlantic oscillation. The better representation of the wind structure increases the northward salt transports, the deep-water formation and the Atlantic meridional overturning circulation. In the tropics, the ocean-atmosphere dynamical coupling, or Bjerknes feedback, improves with the resolution. The amplitude of ENSO (El Niño-Southern oscillation) consequently increases, as the damping processes are left unchanged.