Aj. Weaver et Tmc. Hughes, ON THE INCOMPATIBILITY OF OCEAN AND ATMOSPHERE MODELS AND THE NEED FOR FLUX ADJUSTMENTS, Climate dynamics, 12(3), 1996, pp. 141-170
The surface heat and freshwater fluxes from equilibrium ocean (OGCM) a
nd atmospheric (AGCM) general circulation model climates are examined
in order to determine the minimum flux adjustment required to prevent
climate drift upon coupling. This is accomplished by integrating an OG
CM with specified surface fluxes. It is shown that a dramatic climate
drift of the coupled system is inevitable unless ocean meridional heat
and freshwater (salt) transports are used as constraints for tuning t
he AGCM present day climatology. It is further shown that the magnitud
e of the mismatch between OGCM and AGCM fluxes is not as important for
climate drift as the difference in OGCM and implied AGCM meridional h
eat and freshwater (salt) transports. Hence a minimum flux adjustment
is proposed, which is zonally-uniform in each basin and of small magni
tude compared to present flux adjustments. This minimum flux adjustmen
t acts only to correct the AGCM implied oceanic meridional transports
of heat and freshwater (salt). A slight extension is also proposed to
overcome the drift in the surface waters when the minimum flux adjustm
ent is used. Finally, it is suggested that the flux adjustments which
arise from current methods used to determine them are all very similar
, leading to adjustment fields which are significantly larger than bot
h AGCM and climatological fields over large regions.