All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 201 62 1
PDF Downloads 52 18 1

Using 3DF GPS Heading for Improving Underway ADCP Data

Gwyn GriffithsJames Rennell Centre for ocean Circulation, Southampton, United Kingdom

Search for other papers by Gwyn Griffiths in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

Systematic error in the cross-track velocity measured under way from shipboard acoustic Doppler current profilers (ADCPs) can be attributed to error in measuring the ship's heading with a gyrocompass. Drift- and direction-dependent errors in marine gyrocompasses may amount to 2°–3°, yet they can be difficult to observe. A new system for obtaining attitude information using differential carrier phase measurements on signals from Global Positioning System (GPS) navigation satellites can provide a heading accuracy of 0.05°. This paper proposes a method of using these GPS heading measurements as a reference, with the gyrocompass as an interpolation device, to reduce the cross-track velocity error from a shipboard ADCP. The practical application of the method is illustrated by a long north-south section dominated by latitude-induced gyrocompass error, and a small-scale survey where heading-dependent errors in the gyrocompass dominated.

Abstract

Systematic error in the cross-track velocity measured under way from shipboard acoustic Doppler current profilers (ADCPs) can be attributed to error in measuring the ship's heading with a gyrocompass. Drift- and direction-dependent errors in marine gyrocompasses may amount to 2°–3°, yet they can be difficult to observe. A new system for obtaining attitude information using differential carrier phase measurements on signals from Global Positioning System (GPS) navigation satellites can provide a heading accuracy of 0.05°. This paper proposes a method of using these GPS heading measurements as a reference, with the gyrocompass as an interpolation device, to reduce the cross-track velocity error from a shipboard ADCP. The practical application of the method is illustrated by a long north-south section dominated by latitude-induced gyrocompass error, and a small-scale survey where heading-dependent errors in the gyrocompass dominated.

Save