The Hadley Centre Hadley Centre Coupled Model Version 3 was developed from the earlier HadCM2 model in the period 1997-2000. Various improvements were applied to the 19 level atmosphere model and the 20 level ocean model and as a result the model requires no artificial flux adjustments to prevent excessive climate drift. The atmosphere and ocean exchange information once per day, heat and water fluxes being conserved exactly. The main differences from the previous HadCM2 model are a significantly more sophisticated radiation scheme; the inclusion of the direct impact of convection on momentum; and the inclusion of a new land surface scheme that includes a better representation of evaporation, freezing and melting of soil moisture. It improved on the resolution available from previous Hadley Centre models and included support for interactive couplings between the atmosphere and ocean and the biosphere, atmospheric chemistry, the sulphur cycle and atmospheric aerosols. The HadCM3 model was used by the Hadley Centre to provide input for the IPCC Third Assessment Report.