Behavior of Gulf Stream Warm-Core Rings (WCRs) South of Georges Bank, 1993-1997}

Carol A. Alessi and Robert C. Beardsley

Using Warm Core Ring (WCR) center-positions estimated from the NOAA Gulf Stream Oceanographic Analysis Charts, and a dataset compiled by the Naval Oceanographic Office (NAVO), trajectories of WCRs which moved close to the southern flank of Georges Bank during the 1995 GLOBEC Stratification Study are presented. Figure 1 shows the observed WCR positions from NAVO analysis for 188 weeks, between October 1993 and May 1997. There were a total of 72 different WCRs observed during this time period. In general, roughly 20 WCRs are formed per year from about 75 W south of New England to the Grand Banks. During 1995, three WCRs moved close to the southern flank of Georges Bank. Rings 6, 8, and 12 are shown in Figures 2, 3, and 4, respectively. The green circles represent the center positions estimated from the NOAA Gulf Stream Analysis Charts, the dark blue circles represent the center positions determined by the NAVO analysis. The black ellipses indicate the size and orientation of the WCR also taken from the NAVO analysis. The calendar date of each ellipse is shown at the outer edge of the ellipse, and the year date is annotated at the center of each ellipse, which is shown in red.