ON THE MERIDIONAL SURFACE PROFILE OF THE GULF-STREAM AT 55-DEGREES-W

Nine-month records from nine inverted echo sounders (IESs) are analyze d to describe the mean baroclinic Gulf Stream at 55 degrees W. IES aco ustic travel times are converted to thermocline depth which is optimal ly interpolated. Kinematic and dynamic parameters (Gulf Stream meridio nal position, velocity, and vorticity) are calculated. Primary Gulf St ream variability is attributed to meandering and changes in direction. A mean, stream-coordinate (relative to Gulf Stream instantaneous posi tion and direction) meridional profile is derived and compared with re sults presented by other investigators. The mean velocity is estimated at 0.84 m s(-1) directed 14 degrees to the right of eastward, and the thermocline (12 degrees C) drops 657 m (north to south), correspondin g to a baroclinic rise of the surface of 0.87 m. The effect of Gulf St ream curvature on temporal mean profiles is found to be unimportant an d of minimal importance overall. The derived, downstream current profi le is well represented by a Gaussian function and is about 190 km wide where it crosses zero. Surface baroclinic transport is estimated to b e 8.5 x 10(4) m(2) s(-1), and maximum shear (flanking the maximum) is 1.2 x 10(-5) s(-1). Results compare well with other in situ observatio nal results from the same time period. On the other hand, analyses (by others) of concurrent satellite altimetry (Geosat) suggest a consider ably narrower, more intense mean Gulf Stream.