The seasonal cycle in coupled ocean-atmosphere general circulation models

• Published in: Climate Dynamics
• Main Authors: Covey, C., Abe-Ouchi, A., Boer, G. J., Boville, B. A., Cubasch, U., Fairhead, L., Flato, G. M., Gordon, H., Guilyardi, E., Jiang, X., Johns, T. C., Le Treut, H., Madec, G., Meehl, G. A., Miller, R., Noda, A., Power, S. B., Roeckner, E., Russell, G., Schneider, E. K., Stouffer, J. R., Terray, L., von Storch, J.-S.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer 2000
• Subjects: surface air-temperature; spatial variability; climate sensitivity; CO2; increase; project; layer; Southern Ocean
• Online Access: https://research.usq.edu.au/item/q6wyq/the-seasonal-cycle-in-coupled-ocean-atmosphere-general-circulation-models; https://doi.org/10.1007/s003820000081

We examine the seasonal cycle of near-surface air temperature simulated by 17 coupled ocean-atmosphere general circulation models participating in the Coupled Model Intercomparison Project (CMIP). Nine of the models use ad hoc 'flux adjustment' at the ocean surface to bring model simulations close to observations of the present-day climate. We group flux-adjusted and non-flux-adjusted models separately and examine the behavior of each class. When averaged over all of the flux-adjusted model simulations, near-surface air temperature falls within 2 K of observed values over the oceans. The corresponding average over non-flux-adjusted models shows errors up to 6 K in extensive ocean areas. Flux adjustments are not directly applied over land, and near-surface land temperature errors are substantial in the average over flux-adjusted models, which systematically underestimates (by 5 K) temperature in areas of elevated terrain. The corresponding average over non-flux-adjusted models forms a similar error pattern (with somewhat increased amplitude) over land. We use the temperature difference between July and January to measure seasonal cycle amplitude. Zonal means of this quantity from the individual flux-adjusted models form a fairly tight cluster (all within 30% of the mean) centered on the observed values. The non-flux-adjusted models perform nearly as well at most latitudes. In Southern Ocean mid-latitudes, however, the non-flux-adjusted models overestimate the magnitude of January-minus-July temperature differences by 5 K due to an overestimate of summer (January) near-surface temperature. This error is common to five of the eight non-flux-adjusted models. Also, over Northern Hemisphere mid-latitude land areas, zonal mean differences between July and January temperatures simulated by the non-flux-adjusted models show a greater spread (positive and negative) about observed values than results from the flux-adjusted models. Elsewhere, differences between the two classes of models are less obvious. At no latitude is ...