A Fast Ocean GCM without Flux Adjustments

Abstract

The Fast Met Office/U.K. Universities Simulator project (FAMOUS) aims to develop a fast GCM, possibly 10 times faster than the Third Hadley Centre Coupled Ocean?Atmosphere GCM (HadCM3). Such a model would allow long-term climate runs and/or large ensembles of runs to be carried out. It would also be suitable for use on computers other than a supercomputer. Modifications to the geometry of the North Atlantic (including removal of Iceland) and an increase in the ocean time step, allow the FAMOUS ocean model to run without the use of flux adjustments, and about 40 times quicker than the HadCM3 ocean component (HadOM3). Transient climate change simulations carried out using the new ocean component coupled to the HadCM3 atmospheric component (HadAM3) produce a similar climate sensitivity to the full HadCM3.