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- Title
Presentation and Evaluation of the IPSL‐CM6A‐LR Ensemble of Extended Historical Simulations.
- Authors
Bonnet, Rémy; Boucher, Olivier; Deshayes, Julie; Gastineau, Guillaume; Hourdin, Frédéric; Mignot, Juliette; Servonnat, Jérôme; Swingedouw, Didier
- Abstract
The Institut Pierre‐Simon Laplace Climate Modeling Center has produced an ensemble of extended historical simulations using the IPSL‐CM6A‐LR climate model. This ensemble (referred to as IPSL‐EHS) is composed of 32 members over the 1850–2059 period that share the same external forcings but differ in their initial conditions. In this study, we assess the simulated decadal to multidecadal climate variability in the IPSL‐EHS. In particular, we examine the global temperature evolution and recent warming trends, and their consistency with ocean heat content and sea ice cover. The model exhibits a large low‐frequency internal climate variability. In particular, a quasi‐bicentennial mode of internal climate variability is present in the model and is associated with the Atlantic Meridional Overturning Circulation. Such variability modulates the global mean surface air temperature changes over the historical period by about ∼ 0.1K. This modulation is found to be linked to the phase present in the initial condition state of each member. This variability appears to decrease during the 1850–2018 period in response to external forcings. The analysis of the ocean heat content reveals furthermore an overestimation of the ocean stratification, which likely leads to an overestimation of the recent warming rate on average. Plain Language Summary: The Institut Pierre‐Simon Laplace (IPSL) developed an ensemble of 32 simulations over the 1850–2059 period using the IPSL‐CM6A‐LR climate model. Such a large ensemble allows a better sampling of the internally generated variability. Moreover, the ensemble averaging provides an estimation of the forced variability induced by the greenhouse gases and the aerosol concentration used as boundary conditions. In this study, we assess the simulated decadal to multidecadal climate variability in the IPSL ensemble. Relative to the large variability of the model, the evolution of observed surface temperature and sea ice cover is within the range of possibilities of the ensemble. The oceanic circulation and sea surface temperature over the North Atlantic are key players in the low‐frequency internal variability of the model. Key Points: A large part of the spread of temperature and sea ice trends in the IPSL ensemble is related to a large multicentennial internal variabilitySome members of the IPSL ensemble are consistent with the observed surface temperature, sea ice variations, and ocean heat content evolutionThe low‐frequency internal climate variability of IPSL‐CM6A‐LR decreases since the 2000s in response to external forcing
- Subjects
MERIDIONAL overturning circulation; OCEAN temperature; ENTHALPY; SEA ice; ATMOSPHERIC temperature; ATMOSPHERIC models
- Publication
Journal of Advances in Modeling Earth Systems, 2021, Vol 13, Issue 9, p1
- ISSN
1942-2466
- Publication type
Article
- DOI
10.1029/2021MS002565