Thirty-six XBT temperature profiles have been used in a parametric mod
el introduced by Hendry to model the Gulf Stream's thermal structure a
t 65 degrees W between 200 and 1200 dbar, with an rms residual error o
f 0.56 degrees C. Velocity has been computed geostrophically relative
to 1200 dbar, and has been included in calculating potential vorticity
analytically from the model. The resulting potential vorticity sectio
n for 65 degrees W has been compared with the analogous result from He
ndry's parametric model at 59 degrees W, as well as observed potential
vorticity sections from 68 degrees to 55 degrees W. There is a signif
icant feature in the potential vorticity structure at 65 degrees W not
found at 59 degrees W-namely, a relative minimum in potential vortici
ty along isopycnals, centered at the Gulf Stream's axis and 350 dbar.
The modeled potential vorticity sections are consistent with the obser
vations, including the downstream disappearance of this feature. The d
ynamical implications of these results are briefly discussed.