Lohmann, G., Gerdes, R., and Chen, D., 1996 a,
Climate Dynamics 12, 403-416.
We analyze the sensitivity of the oceanic thermohaline circulation (THC)
regarding perturbations in fresh water flux for a range of coupled oceanic
general circulation - atmospheric energy balance models. The energy balance
model (EBM) predicts surface air temperature and fresh water flux and contains
the feedbacks due to meridional transports of sensible and latent heat. In the
coupled system we examine a negative perturbation in run-off into the
southern ocean and analyze the role of changed atmospheric heat transports
and fresh water flux.
With mixed boundary conditions (fixed air temperature and fixed surface
fresh water fluxes) the response is characterised by a completely different
oceanic heat transport than in the reference case. On the other hand, the
heat flux remains roughly constant when the air temperature can adjust in a
model where no anomalous atmospheric transports are allowed. This gives an
artificially stable system with nearly unchanged oceanic heat transport.
However, if meridional heat transports in the atmosphere are included, the
sensitivity of the system lies between the two extreme cases. We find that
changes in fresh water flux are unimportant for the THC in the coupled system.
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