SENSITIVITY OF A COARSE RESOLUTION OCEAN GENERAL-CIRCULATION MODEL UNDER CLIMATE-CHANGE FORCING

Tunable parameters in an ocean general circulation model are assessed as modifiers to the model response to several climate change scenarios . For the current climate scenario ii is found that vertical diffusivi ty plays a dominant role as expected. An analysis of the horizontal di ffusivity variation suggests that use of the peak value of the overtur ning streamfunction is a misleading indicator of model Bow strength. F or the warming and cooling scenarios vertical and horizontal diffusivi ty variations dominated the equilibria response. However, these tunabl e parameters are of minor significance in the transient response in th e cooling scenarios. The diffusively dominant warming scenarios, in co ntrast, very much depend on the magnitude of the vertical diffusivity. This has important implications for the use of coarse resolution mode ls in coupled atmosphere-ocean model climate change simulations.