The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments

Results are presented from a new version of the Hadley Centre coupled model (HadCM3) that does not require flux adjustments to prevent large climate d rifts in the simulation. The model has both an improved atmosphere and ocea n component. In particular, the ocean has a 1.25 degrees x 1.25 degrees deg ree horizontal resolution and leads to a considerably improved simulation o f ocean heat transports compared to earlier versions with a coarser resolut ion ocean component. The model does not have any spin up procedure prior to coupling and the simulation has been run for over 400 years starting from observed initial conditions. The sea surface temperature (SST) and sea ice simulation are shown to be stable and realistic. The trend in global mean S ST is less than 0.009 degrees C per century. In part, the improved simulati on is a consequence of a greater compatibility of the atmosphere and ocean model heat budgets. The atmospheric model surface heat and momentum budget are evaluated by comparing with climatological ship-based estimates. Simila rly the ocean model simulation of poleward heat transports is compared with direct ship-based observations for a number of sections across the globe. Despite the limitations of the observed datasets, it is shown that the coup led model is able to reproduce many aspects of the observed heat budget.