On Gulf Stream variability and meanders over the Blake Plateau at 30°N

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Abstract
Current and temperature variability of the Gulf Stream at 30°N was observed with a subsurface array of current meter moorings from August 1980 to October 1981. Energetic current fluctuations in the 2–14 day period band accounted for 45–70% of the total observed variability. Flow perturbations in the cyclonic shear zone tended to have a cyclonic sense of rotation and were 180° out of phase from anticyclonic flow perturbations within the anticyclonic shear region. These fluctuations appear to result from northward propagating wave‐like meanders of the Gulf Stream axis. The fluctuations do not appear to be directly related to local wind forcing. Observations of near‐bottom flow on the Blake Plateau east of the Gulf Stream showed periods of prolonged southward currents lasting up to 40 days with speeds in excess of 30 cm s−1. The mean flow was also southward due to these strong events. The source of the southward flow is unknown. It may be connected to cold‐core eddies that are not detectable in the surface with remote sensing or possibly a remnant of the southward undercurrent that has been observed beneath the Gulf Stream off Cape Hatteras and on the deep slope of the Blake Escarpment.