An Autumn Instability Event in the Gasp&aacute: Current

Abstract

The Gaspé Current is a buoyant jet driven primarily by the freshwater discharge from the St. Lawrence estuary. Previously, many incidents of unstable wave development in the3 Gaspé Current have been reported under summer, high runoff, conditions. Here we present satellite infrared images and discuss the occurrence and evolution of an autumn episode of current instability; in the fall, runoff is lower. This event is notable in that the pattern observed differs considerably from that of summer events, apparently due to the offshore shift that of the core of the jet in early autumn. A stability analysis suggests that the Gaspé Current instabilities may grow slightly faster in autumn conditions. The possible role of wind forcing in triggering wave growth is discussed.