Spin‐up and breakdown of source‐driven deep North Atlantic flow over realistic bottom topography

In this study we examine the time dependent behaviour of the deep North Atlantic dynamics. We use a 1½‐layer, nonlinear, shallow water model with realistic topography and high‐spatial resolution. It is driven by an inflow of deep water from a northern source and by parameterized density exchange processes at the interface. The evolving circulation pattern is complex. The Mid‐Atlantic Ridge with the Charlie Gibbs Fracture Zone has a fundamental influence on the large‐scale flow field. A reduction of the inflow causes a temporary reversal of the interior currents. The perturbation travels along the geostrophic contours. The response times of the currents for the spin‐up and breakdown experiments are of the order of years. They differ for different areas of the North Atlantic Ocean. The area which is affected last by the perturbation is the northwesternmost interior corner, which is close to the position of the source.