The MRCS (Medium-Resolution Continental Shelf) model is a coupled hydrodynamic-ecosystem model, where the hydrodynamics are supplied by the Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS) developed at Proudman Oceanographic Laboratory (POL) and the ecosystem component is supplied by the European Regional Seas Ecosystem Model (ERSEM), developed at Plymouth Marine Laboratory (PML).

The model is located on north-west European continental shelf, ranging from 12° W to 13° E and 48° N to 62° N, as shown in the figure below. It has a 'moveable open boundary' which follows the 200 m depth contour around most of domain. The resolution is approximately 6 km in the horizontal and there are 18 S-coordinate levels in the vertical. Also shown in the figure are those sites at which the model is being validated against observational data.

View near real-time daily averaged output from the MRCS model.

More about validation of the MRCS model

The MRCS is a coupling of the POLCOMS baroclinic model with ERSEM, a complex ecosystem model, on a 6 km grid set up in a pre-operational system at the Met Office (Siddorn et al., submitted). Detailed descriptions of the MRCS implementation of the POLCOMS are given in Holt and James (2001) and Holt et al. (2004). It is a 3D baroclinic finite difference model which uses an Arakawa-B grid in the horizontal and hybrid S-coordinates in the vertical. This choice of grid, the decision not to model explicitly the horizontal diffusion and the use of a sophisticated horizontal advection scheme - the Piecewise Parabolic Method (James, 1996) - combine to give the model good frontal conserving properties.

The European Regional Seas Ecosystem Model (ERSEM) (Baretta et al., 1995) was conceived as a generic model, and is one of the most complex lower trophic-level marine ecosystem models currently in use. Its philosophy is to include all those processes which significantly influence ecosystem dynamics, and to resolve the ecosystem into sufficient functional groups so that those processes can be sensibly defined. It thus has one bacteria, four phytoplankton and three zooplankton functional groups, and has a fully resolved diurnal cycle, variable carbon to chlorophyll ratios and independent nutrient pools for carbon, nitrogen, phosphorous and silicate. The inclusion of an 'over-wintering' physiology for the mesozooplankton (Calanus-like) functional group has been included to act as a proxy for the egg and early nauplii stages, overcoming some of the problems associated with using the functional group based approach for the more complex and behavioural life-stages of these plankton. Coupled with this pelagic complexity is a benthic model, designed to give not only detailed process information of the benthic ecosystem (Ebenhöh et al., 1995), but also a well defined nutrient coupling between the benthic and pelagic systems. Blackford et al. (2004) give a full description of the ERSEM2004 model and parametrizations used.

Baretta, J.W., Ebenhöh, W. and Ruardij, P., 1995: The European regional Seas Ecosystem Model, a complex marine ecosystem model. Netherlands Journal of Sea Research, 33, 233-246.

Blackford, J.C., Allen, J.I. and Gilbert, F.J., 2004: Ecosystem dynamics at six contrasting sites: A generic modelling study. Journal of Marine Systems. 52, 191-215.

Ebenhöh, W., Kohlmeier C. and Radford, P.J., 1995: The benthic biological model in the European Regional Seas Ecosystem Model. Netherlands Journal of Sea Research, 38, 169-172.

Holt, J.T. and James, I.D., 2001: An s-coordinate density evolving model of the northwest European continental shelf Part 1 model description and density structure. Journal of Geophysical Research, 106, 14,015-14,034.

Holt, J.T., Proctor, R., Blackford, J.C., Allen, J.I. and Ashworth, M., 2004: Advective controls on primary production in the stratified western Irish Sea: an eddy-resolving model study. Journal of Geophysical Research, 109, C05024.

James, I.D., 1996: Advection schemes for shelf sea models. Journal of Marine Systems, 8, 237-254.

Siddorn, J.R., Allen, J.I., Blackford, J.C., Gilbert, F.J., Holt, J.T., Holt, M.W., Osborne, J.P., Proctor, R. and Mills, D.K. (submitted). Modelling the hydrodynamics and ecosystem of the north-west European continental shelf for operational oceanography. Journal of Marine Systems.