Model simulation of the Skagerrak circulation and hydrography during Skagex

A 3-dimensional barotropic/baroclinic numerical circulation/transport model system is set up and run for an extended North Sea area in the period October 1989 to August 1990. The model system consists of a “large scale” model with a 20 × 20 km2 horizontal resolution, coupled to a finer scale (4 × 4 Km2 similar model set up for the Skagerrak/Kattegat area. The performance of this model system is evaluated against the Skagex-90 data set containing several drifting buoy tracks, transport estimates from moored current meters, ship-mounted ADCP current velocities, and 10 synoptic hydrographical field data over most of the area obtained every third day in May/June 1990. The Skagex data set also contains chemical (nutrients) and biological (chlorophyll concentration, primary production etc.) data which later will be used for evaluation of this physical model system coupled to a primary production model. The model system is forced with realistic wind and atmospheric pressure fields. Although some of the outputs (after more than half a year prognostic running) still are questionable, the results so far are very promising both with respect to the simulated vertical and horizontal structure and magnitude of the circulation and the salinity distribution.