Abstract
We have recorded time series of ship GPS (global positioning system) positions at about 10-s intervals under favorable satellite conditions. Errors are less than 10 m rms, as demonstrated by comparing the GPS acoustic-source positions with Doppler-inferred positions from a receiver site 9200 km away. Offsets from a steady course held for 20 miles are of the order of 100 m, and could be the result of orbital surface velocities associated with internal waves. We suggest that such GPS measurements, taken routinely while under way, might produce useful data concerning small-scale oceanographic processes.
