Observations of a near-surface Gulf Stream eddy and of changes in the surface-subsurface frontal separation

During August 1981, five survey flights on alternating days mapped the surface and subsurface fronts of the Gulf Stream from about 58 to 52 degree W. The horizontal separation between the surface and subsurface fronts was quite variable. In contrast to earlier observations, the separation did not tend to vary with current curvature. Of greatest interest was the observation of a near-surface eddy that connected regions of greatly dissimilar separation between the fronts. West of the eddy the surface front was anomalously to the right (looking downstream) of the subsurface front. Between surveys the anomalous section of the surface front moved downstream at a speed of about 50 cm s super(-1). The anomaly in separation was not confined to the mixed layer, but decayed with depth beneath the mixed layer in accordance with the scale fL/N.