Coupled ocean-atmosphere models with flux correction

Abstract

A method is proposed for removing the drift of coupled atmosphere-ocean models, which in the past has often hindered the application of coupled models in climate response and sensitivity experiments. The ocean-atmosphere flux fields exhibit inconsistencies when evaluated separately for the individual subsystems in independent, uncoupled mode equilibrium climate computations. In order to balance these inconsistencies a constant ocean-atmosphere flux correction field is introduced in the boundary conditions coupling the two subsystems together. The method ensures that the coupled model operates at the reference climate state for which the individual model subsystems were designed without affecting the dynamical response of the coupled system in climate variability experiments. The method is illustrated for a simple two component box model and an ocean general circulation model coupled to a two layer diagnostic atmospheric model.

The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO<sub>2</sub> forcing

“…However, if one replaces AOGCM ocean surface fluxes with real-world estimates or with fluxes diagnosed from another model, a large climate drift will result, because they will not be consistent with the AOGCM's own surface climate. Therefore the FAFMIP experiments instead impose perturbations, added to the surface fluxes that are computed within the AOGCM from the state of the system (Lowe and Gregory, 2006;Bouttes and Gregory, 2014), technically like the flux adjustment that was formerly used in AOGCMs (Sausen et al, 1988) but with a different purpose.…”

Current and future latitudinal gradients in stream macroinvertebrate richness across North America

“…The horizontal resolution was essentially dictated by the computing facilities available at the time, considering that multicentury runs were required for climate change work. In order to minimize climate drift, the method of flux adjustments (Sausen et al 1988) was employed. This model was successfully used in a transient climate change experiment to 2xCO2, and is described in some detail in Gordon and O'Farrell (1997).…”

Comparison of the last interglacial climate simulated by a coupled global model of intermediate complexity and an AOGCM

“…In order to minimize a climate drift of the coupled system away from the climatologies simulated by the uncoupled models, a correction (Sausen et al 1988) is applied to the heat, freshwater and momentum¯uxes entering the ocean. The correction is constant in time except for the seasonal cycle.…”