Abstract:
Acoustic doppler velocities are combined with velocity profiles generated from XBT
measurements to produce estimates of the flow field between Bermuda and the eastern
coast of the United States. Repeated shipboard measurements along an ascending
GEOSAT subtrack between Bermuda and Cape Cod allow study of rapid Gulf Stream
Variability along the track, and comparison of sea surface and velocity measurements with
those computed from the GEOSAT altimeter. The shipboard data were taken during two
separate cruises on the R/V Oceanus in April and December, 1989. Using mass
conservation constraints and inverse techniques, the transport across the Cape Cod Bermuda
track has been balanced with transport across additional ship tracks between
Bermuda and Cape Hatteras, and between Bermuda and Nova Scotia. The shipboard
results show evidence of a rapid barotropic mode which caused changes in transport along
the Cape Cod-Bermuda track on the order of 8 Sverdrups in a week period. Comparisons
of sea surface velocity and dynamic height determined from the ship's data with
measurements made from the GEOSAT altimeter showed a consistent picture of the Gulf
Stream location and were also consistent in showing smaller scale variations in flow. The
dynamic height difference across the Gulf Stream was approximately 10% higher for the
GEOSAT measurements than for the shipboard measurements, which is within the
expected errors of the analysis techniques.
