Observations of Gulf Stream ring 83‐E and their interpretation using feature models

Abstract

Analysis techniques were developed to track and estimate the propagation velocity, size, shape, orientation, and swirl velocity of Gulf Stream warm core rings. The methods involve fitting idealized warm core ring feature models to observed surface fronts in the satellite imagery, to expendable bathythermograph survey data, and to satellite‐tracked drifting buoy data. The ring feature models are analytic structure functions with adjustable parameters. In this case the ring is modeled as an isolated translating elliptic paraboloid with a swirl velocity that increases linearly with distance from the center. Use of the feature models is illustrated with data collected from warm core ring 83‐E. Gradient currents based on the bathythermograph survey of ring 83‐E and the feature model agree well with currents measured by expendable current profilers. A comparison of the time series of ring 83‐E feature model parameters indicates that not only is the feature model analysis of the buoy track an effective method for tracking and monitoring the evolution of Gulf Stream rings, it also provides useful forecasts of ring locations based simply on a persisted propagation velocity. These techniques were used to provide real time support for exploratory deepwater drilling operations off the U.S. east coast.