On the Formation of Elongated Cold Perturbations off the Dry Tortugas

Abstract

The life cycle of a cold perturbation on the boundary of the Loop Current in the Gulf of Mexico was studied over the period of 18 March to 22 May 1984, approximately a 60-day period. The study focused on the behavior of the surface and subsurface area of the cold perturbation as it moved along the boundary of the Loop Current. The area of the perturbation was defined by an alongflow-scale length, which is the scale length parallel to the unperturbed flow of the Loop Current, and the crossflow-scale length, which is the scale length perpendicular to the unperturbed flow of the Loop Current. The area of the perturbation remained relatively unchanged as the perturbation moved along the Loop Current boundary and reached the region off the Dry Tortugas; however, when the perturbation reached the Dry Tortugas, the orientation of the perturbation changed, suggesting a method whereby elongated cold perturbations form off the Dry Tortugas. Shortly thereafter, the area of the perturbation began to decrease, signaling the decay of the perturbation.