  The performance of coastal altimetry over a wide continental shelf is
assessed using multiple-year ocean current observations by moored Acoustic
Doppler Current Profilers (ADCP) and high frequency (HF) radar on the West
Florida Shelf. Across track, surface geostrophic velocity anomalies, derived
from the XTRACK along-track sea level anomalies are compared with the near
surface current vector components from moored ADCP observations at mid shelf.
The altimeter derived velocity anomalies are also directly compared with the HF
radar surface current vector radial components that are aligned perpendicular
to the satellite track. Preliminary results indicate the potential usefulness
of the along-track altimetry data in contributing to descriptions of the
surface circulation on the West Florida Shelf and the challenges of such
applications. On subtidal time scales, the root mean square difference (rmsd)
between the estimated and the observed near surface velocity component
anomalies is 8 11 cms-1, which is about the same magnitude as the standard
deviations of the velocity components themselves. Adding a wind-driven Ekman
velocity component generally helps to reduce the rmsd values.
