HadCM3 Climate Simulation - IPCC emission scenario SRES-A1B with trace gases, ozone, sulphur emission and aerosol forcing all held constant at year 2000 levels.

The Hadley Centre Coupled Model Version 3 was developed from the earlier HadCM2 model. 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. Momentum fluxes are interpolated between atmosphere and ocean grids so are not conserved precisely, but this non-conservation is not thought to have a significant effect. 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. The HadCM3 model was used by the Hadley Centre to provide input for the IPCC Third Assessment Report. The SRESA1B-2000S simulation is a parallel simulation to the standard SRESA1B simulation, but in this case the forcings of green house gases (including methane), sulfur (direct and indirect forcing, sulphur chemistry without natural DMS and SO2 background emissions; anthropogenic SO2 emissions from surface and high level only) and tropospheric/stratospheric ozone are held constant at year 2000 levels throughout the simulation.