Deep Velocity Profiling with Self-contained ADCPs

Fischer, Jürgen and Visbeck, Martin (1993) Deep Velocity Profiling with Self-contained ADCPs Journal of Atmospheric and Oceanic Technology, 10 (5). pp. 764-773. DOI 10.1175/1520-0426(1993)010<0764:DVPWSC>2.0.CO;2.

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Ocean deep velocity profiles were obtained by lowering a self-contained 153.6-kHz acoustic Doppler current profiler (ADCP) attached to a CTD-rosette sampler. The data were sampled during two Meteor cruises in the western tropical Atlantic.
The ADCP depth was determined by integration of the vertical velocity measurements, and the maximum depth of the cast was in good agreement with the CTD depth. Vertical shears were calculated for individual ADCP velocity profiles of 140-300-m range to eliminate the unknown horizontal motion of the instrument package. Subsequent raw shear profiles were then averaged with respect to depth to obtain a mean shear profile and its statistics. Typically, the shear standard deviations were about 10(-3) s-1 when using up and down traces simultaneously.

The shear profiles were then vertically integrated to get relative velocity profiles. Different methods were tested to transform the relative velocities into absolute velocity profiles, and the results were compared with Pegasus dropsonde measurements. The best results were obtained by integrating the raw velocities and relative velocities over the duration of the cast and correcting for the ship drift determined from the Global Positioning System.
Below 1000-m depth a reduction of the measurement range was observed, which results either from a lack of scatterers or instrumental problems at higher pressures.

Document Type: Article
Keywords: Physical Oceanography; Acoustic Doppler Current Profiler; ADCP
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
DOI etc.: 10.1175/1520-0426(1993)010<0764:DVPWSC>2.0.CO;2
ISSN: 0739-0572
Date Deposited: 18 Feb 2008 17:27
Last Modified: 25 Jan 2017 12:11

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