Understanding the North Sea System

Twenty years since the discovery of tidal mixing fronts there are still few convincing observations of the velocity field associated with these structures. Simple models of shelf sea fronts predict strong along-front jets, weaker convergent circulations and instabilities. During the North Sea Project a series of studies of the Flamborough frontal system has used a new approach based upon novel combinations of modern instrumentation (hf radar, acoustic Doppler current profiler, Decca-Argos drifting buoys and towed undulating ctd) and have provided one of the first directly observed pictures of shelf sea frontal circulation. Observational confirmation of jet-like along-front flow has been found together with evidence of cross-frontal convergence. A new generation of eddy-resolving models will help to focus the next phase of frontal circulation studies in relation to questions concerning baroclinic instability and eddy generation.