By projecting the XBTs into the same stream coordinate system
as used for the upperocean velocity, we obtain a matching thermal description of
the current. The ensembleaveraged depth of the 10° C isotherm is
shown in Figure 12(below).


This isotherm lies just below the reach of the
seasonal thermocline near the Gulf Stream such that salinity remains
invariant in time and essentially constant across the Gulf Stream.

It represents the sigma_{t} = 27.2 surface quite well.

The isotherm deepens
sharply from north to south across the current.

If we fit an
exponential to the initial deepening (y < 0), we obtain a scalewidth
of 19 km (dashed line), which agrees reasonably well with the
estimates from the velocity field.



Figure 12. Ensembleaveraged depth of the 10° isotherm as a
function of normal distance from the velocity maximum.
