Denny Kirwan
University of Delaware
Scheduled to present on December 2, 2005


"The short life and violent death of Eddy Fourchon"


It is widely believed that Loop Current rings, LCRs, pinch off from the Loop Current, gently drift across the Gulf of Mexico basin, only to suffer a slow death in the “eddy graveyard” along the western slope. However, in a reanalysis of 16 LCRs from 1993-2001 using a data-assimilating model, Kantha et al (2005) could only track one, Eddy Millennium, to the eddy graveyard. They were unable to track the remaining LCRs west of 93W. In contrast, with data assimilation turned off, they routinely tracked LCRs to the western slope.

Which is wrong, data-assimilating models or GoM circulation orthodoxy? To shed some light on this question we reanalyzed three rings from the Kantha et al. reanalysis using Lagrangian geometric methods. These methods are illustrated for eddies Juggernaut, Millennium and Fourchon. Then a detailed analysis of Fourchon is presented as it breaks up near 93W. The presentation concludes with some heretical comments about the orthodox view of LCRs.