UKMO Coupled General Circulation Model Dynamical Model
United Kingdom Met Office
Exeter, United Kingdom
Long-range dynamical forecast products are based on the output from a coupled ocean-atmosphere General Circulation Model (GCM). The GCM, known as the GloSea (Global Seasonal) model, is similar to the HadCM3 climate version of the Met Office Unified Model (UM), with a number of enhancements for seasonal forecasting purposes. Details of the model physics and discussion of HadCM3 can be found in Gordon et al, Climate Dynamics (2000). The seasonal forecast performance of the GloSea coupled GCM, including comparison to that of an equivalent uncoupled GCM, is described in Graham et al., Tellus (2005).
The atmospheric component is version HadAM3 (see Pope et al, Climate Dynamics (2000) for a description), with a horizontal resolution of 3.75° east-west and 2.5° north-south, and 19 vertical levels. The oceanic component has 40 vertical levels (compared to 20 in HadCM3), zonal grid spacing at 1.25° and meridional grid spacing of 0.3° near the equator increasing to 1.25° poleward of the mid-latitudes (compared to 1.25° resolution east-west and north-south in HadCM3). A coastal tiling scheme has been included, to enable specifications of the land-sea mask at the ocean resolution. Like HadCM3, the GloSea coupled GCM contains no flux corrections or relaxations to climatology.
Seasonal forecasts to six months ahead are produced each month, using a 41 member ensemble with initial conditions for the first day of the month. The ensemble is generated using oceanic perturbations. Forecast maps with global coverage, issued in the second half of the month, are available at
Browse descriptive and explanatory information about the model, including verifications.
View the model's current ENSO forecast plumes.
Contact: enquiries@metoffice.gov.uk
References:
Gordon, C., C. Cooper, C. A. Senior, H. Banks, J. M. Gregory, T. C. Johns, J. F. B. Mitchell, and R. A. Wood, 2000: The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments. Clim. Dynam., 16, 147-168.
Graham. R., M. Gordon, P.J. McLean, S. Ineson, M.R. Huddleston, M.K. Davey, A. Brookshaw, R.T.H. Barnes, 2005: A performance comparison of coupled and uncoupled versions of the Met Office seasonal prediction general circulation model. Tellus, 57A, 320-339.
Pope, V. D., M. L. Gallani, P. R. Rowntree and R. A. Stratton, 2000: The impact of new physical parametrizations in the Hadley Centre climate model - HadAM3. Clim. Dyn., 16, 123-146.