Model configuration

The MIT primitive equation model was developed by Marshall et al. (1997), in its free-surface, hydrostatic version. The model is run on a 1x1 deg. grid with 23 vertical levels (figure 1). The mixing coefficients for temperature (T), salinity (S) and momentum are constant in space and time. Atmospheric forcing fields are daily heat and fresh water fluxes and twice-daily wind stress fields from the NCEP-Reanalysis .

 

Figure 1: Model bathymetry (upper) and velocity and temperature fields at the southern boundary (lower).

A relatively simple scheme has been adopted to deal with the open boundaries located at the south of the domain, at the Strait of Gilbratar, on the north, east of Greenland, and on the north of Scandinavia. It relies on the advection of tracers and horizontal velocity from prescribed values at the open boundaries. A parallel optimization experiment over the years 1992-97, at the global scale and on a 2x2 deg. horizontal grid (Stammer et al., 1999) provides monthly fields which are used as initial estimates at the open-boundaries.