The interaction of an ocean eddy with an ice edge ocean jet in a marginal ice zone

Abstract

Remotely sensed images in the East Greenland Current marginal ice zone region indicate a variety of mesoscale motions. These range from isolated monopoles and dipoles to multiple eddy fields. Recent observations indicate that many of the eddies may be advected into the region from the West Spitsbergen Current region. They then interact with the East Greenland Current marginal ice zone and its associated along‐ice‐edge jet. In this paper we illustrate how the ice floe fields can evolve during the interaction of an ocean eddy with an along‐ice‐edge ocean jet. The effects of eddy sense of rotation, flow strength, and bottom topography are considered in barotropic and baroclinic, two‐layer numerical experiments. Initially, barotropic experiments involve the combined effects of flat‐bottom eddy‐jet interactions and eddy‐topography interactions. Over a flat bottom, anticyclones interact with the cyclonically sheared side of the jet and move seaward, exporting ice away from the ice edge in a dipolar distribution. Cyclones move toward the jet and are advected downstream. A second dipole formation mechanism is associated with eddy‐topography interaction and is a consequence of the shallow pycnocline depth of the region. Rapid topographic Rossby wave radiation in the lower layer spreads energy along slope and upslope (downslope) for cyclones (anticyclones). The upper ocean response to this process is a dipole which propagates parallel to the ice edge with shallow water to the left (topographic eastward). Jet‐induced and topography‐induced eddy propagation tendencies combine to enhance cyclone‐jet interaction and limit anticyclone‐jet interactions. The dipole formation associated with eddy‐topography interaction is weakened by the presence of the jet but not eliminated. Eddy‐induced distortions in the ice edge are suppressed by the stabilizing effect of topography on the jet. Sensitivity of the initially barotropic results to variation in the Rossby number and degree of topographic slope illustrates that eddies are more efficient in producing ice edge distortions for stronger flows and weaker topographic slopes. For initially baroclinic simulations over topography, results are comparable to flat‐bottom cases. Strong upper layer eddy‐jet interactions can occur independent of topographic effects which are constrained to the lower layer.