Generation and Propagation of Annual Rossby Waves in the North Atlantic

Abstract

Results of a nonlinear quasi-geostrophic mode model on the ?-planewith topography and coastal geometry of the North Atlantic in thearea 10°?50°N, 10°?80°W are presented. Two modes are used inthis study. The baroclinic one is based on the mean density profilefrom the Levitus dated at 30°N. Mean and annual variations of thewind stress curl, which drive the model, were obtained from the Bunkerclimatic atlas. Annual Rossby waves emanating off the eastern coastare strongly influenced by the Mid-Atlantic Ridge. West of the MARa relative minimum of energy is observed. The waves are influencedand modified by variable bottom topography. In the western basintwo regions are identified where Rossby waves are generated: theGulf Stream and its extension towards the east and the southern flankof the subtropical gyre. Compared to the North Pacific, annual Rossbywaves seem to be less energetic in the North Atlantic.