Baroclinic instability and the mesoscale eddy field around the Lofoten Basin

Abstract

The vigorous mesoscale eddy field around the Lofoten Basin west of northern Norway is thought to be related to eddy shedding from the Norwegian Atlantic Current flowing along the Norwegian coast. Here we study baroclinic instability in the current with a particular focus on the influence of topography. The flow over the steepest part of the continental slope is found to be the most unstable. The growth characteristics cannot be understood from Eady theory alone but require the consideration of interior potential vorticity gradients. A study of the fully developed macroturbulent field shows that eddy kinetic energy is advected away from the generation regions and that nonlinear effects likely draw the eddy statistics away from the linear growth regime. Key Points: Baroclinic stability analysis of the Norwegian Atlantic Current Growth rates are highest over steep continental slope Modified Eady theory fail to explain instability characteristics