Numerical investigation of baroclinic instability in the Gaspe Current using a frontal geostrophic model

The Gaspe Current, situated in the western Gulf of St. Lawrence, is an inte nse, buoyancy-driven jet, which is fed by freshwater runoff from the St. La wrence River. This coastal current is known to exhibit frequent episodes of instability, culminating in backward breaking waves as well as filaments a nd eddies. We investigate the observed mesoscale variability in a series of numerical simulations, employing a two-layer frontal geostrophic model tha t focuses on baroclinic dynamics. Unlike previous studies, we allow for lar ge-amplitude variations of the interface depth, with the possibility of out croppings, as well as two-way coupling of the dynamic pressures in each lay er. It is found that the growth rates and length scales associated with the early evolution of disturbances compare favorably with those observed. Mor eover, the mesoscale features resulting from highly nonlinear interactions closely resemble those seen in satellite data.