HadGEM1 - Thermohaline Circulation Simulation

The Hadley Centre Global Environmental Model version 1 was developed from the Met Office Unified Model New Dynamics in the period 2000-2004. 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 HadGEM1 model was used by the Hadley Centre to provide input for the IPCC Fourth Assessment Report. The Control Run simulation contained in this dataset were used to initialise transient coupled model simulations using HadGEM1 for a variety of scenarios. This run uses fixed 1860 forcing levels for greenhouse gases, ozone, sulfur, and other aerosol precursor emissions and land surface boundaries. The control run was initialised and spun up as defined in Stott et al. (2006) The Thermohaline Circulation (THC) simulation output contained in this dataset was used to investigate the response of the Atlantic THC and the climate to increased freshwater fluxes of 0.1 Sv (1 Sv=10**6 m**3 s*-1) and 1.0 Sv for a period of 100 years. The increased freshwater fluxes were then stopped to determine if the decline in THC would reverse. All other forcing and bounday conditions were as for the HadGEM1 control simulation. These simulation data were intercompared with equivalent outputs from other climate models as an activity of the World Climate Research program (WCRP) Coupled Model InterComparison Project (CMIP).