Experience with an Expendable Temperature and Velocity Profiler

The performance of an expendable temperature and velocity profiler (XTVP) against several independent velocity profilers is discussed. The XTVP operates on the principles of motional induction resulting from the movement of sea water through the earth´s magnetic field. The induced electric currents are interpreted in terms of the generating velocity distribution. Profile intercomparisons have shown the XTVP capable of measuring ocean velocity (relative to an unknown, depth independent offset velocity) to within an uncertainty of 1 cm/s with 6 m vertical averaging for both the east and north velocity components. White noise density of about 3.5 (cm/s) /cpm limits vertical resolution to about 10 m. The probe falls at about 4.5 m/s, requiring about 200 s to complete a profile to 900 m (3000 ft), and has a dynamic range of ±400 cm/s. Profiles and comparison results are presented demonstrating the achievement of the development goal of velocity uncertainties of 1 cm/s rms at a vertical resolution of 10 m.