Gulf Stream warm rings: a statistical study of their behavior

A 10 year series of NOAA polar-orbiter satellite infrared-based determinations of Gulf Stream warm-core ring (WCR) locations, is used to derive mean loci, lifetime and size, and movement statistics in the Slope water region off the northeast United States east coast. This time series, produced by the NOAA/NMFS Atlantic Environmental Group, is validated against precision observations of WCR frontal loci by investigators at the Universities of Miami and Rhode Island: an r.m.s. error of ± 15 km in latitude and longitude between the two sets is determined. We find that the ensemble of WCR lifetime is bi-modal with the split at 140 days. Rings are formed with a semi-major axis of ≈75 km. Longer-lived rings show a reduction in size over their lifetime to ≈35 km, shorter-lived rings do not. Ring movement shows some dependence on location, but mean motions are never <1.6 cm s−1; averaged translation speed is 6.5 cm s−1. Longer-lived rings tend to be located farther away from the climatological Gulf Stream north wall than shorter-lived rings east of 66°W. The mean loci are compared with Warm Core Ring Experiment results for 82B. We find similar changes in track corresponding to topographic variation, similar translation speed, size, decrease in size over time, etc., leading us to conclude that the kinematics observed for 82B are representative of those for a long-lived warm-core ring.

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