A primary factor limiting the accuracy of shipboard Acoustic Doppler Current Profiler (ADCP) measurements is uncertainty in the ship's heading as measured by the gyrocompass. ADCP has become a powerful tool for measuring undersea currents from moving research vessels. Using carrier phase measurements of the Global Positioning System satellites with an array of antennas, the ability to routinely measure ship's heading, pitch, and roll with an accuracy of order 0.1 degrees will be investigated. The study will include analysis of algorithms and error sources, and the development of software for recording and postprocessing the carrier phase measurements to yield the attitude of the antenna array. The prototype system will be tested at sea on short cruises, and will be used to improve ADCP accuracy on the first three WOCE Hydrographic Project cruises in the Pacific.
