Rs. Pickart et Ss. Lindstrom, A COMPARISON OF TECHNIQUES FOR REFERENCING GEOSTROPHIC VELOCITIES, Journal of atmospheric and oceanic technology, 11(3), 1994, pp. 814-824
A geostrophic velocity section across the Gulf Stream and deep western
boundary current near 35-degrees-N is referenced four different ways:
using a POGO float (acoustically tracked transport float), shipboard
acoustic Doppler current profiler (ADCP), and bottom current meters, a
nd by assuming an isotherm level of no motion. The comparison between
the first two techniques is emphasized because they are most easily ap
plied. In general, reference velocities calculated using the float dat
a agree well with those obtained from the ADCP data. However, there is
disagreement at locations where the ADCP velocity is not in thermal w
ind balance, in which case the POGO value is deemed more accurate beca
use the float samples deeper into the subsurface geostrophic flow. Dis
agreement is also caused by insufficient cross-stream POGO spacing (al
though this could be avoided). The isotherm- and current meter-referen
ced sections, while similar to each other, both show unrealistic featu
res. It is argued that the POGO method is preferable to the shipboard
ADCP for a deep-water hydrographic experiment.