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  • Author or Editor: Richard L. Koehler x
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Raymond W. Schmit
,
John M. Toole
,
Richard L. Koehler
,
Edward C. Mellinger
, and
Kenneth W. Doherty

Abstract

A new freely-falling ocean profiler for measuring finescale variations in temperature, salinity and horizontal velocity and microscale variations in temperature, conductivity, velocity and refractive index has been constructed. The High Resolution Profiler (HRP) features: full ocean depth capability, a microcomputer to control sampling, data storage and operations, solid state mass storage, and commercially available sensors. A special handling rig facilitates deployment and recovery at sea. Because the data are transferred electronically to a microcomputer for archiving, the instrument can be redeployed after use without opening the pressure case. Twenty to forty drops can be made before the battery needs to be replaced. Several different sensor configurations are possible, depending on the type of small-scale mixing process of interest. By observing both finestructure and microstructure with one instrument, it is possible to study the relationship between the finescale driving forces and the small-scale mixing events.

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Albert J. Williams 3rd
,
John S. Tochko
,
Richard L. Koehler
,
William D. Grant
,
Thomas F. Gross
, and
Christopher V. R. Dunn

Abstract

A vertical array of acoustic current meters measures the vector flow field in the lowest 5 m of the oceanic boundary layer. By resolving the velocity to 0.03 cm s−1 over 15 cm paths, it samples the dominant turbulent eddies responsible for Reynolds stress to within 50 cm of the bottom. Profiles through the inner boundary layer, from six sensor pods, of velocity, turbulent kinetic energy, and Reynolds stress can be recorded for up 10 four months with a 2 Hz sample rate and 20 min averaging interval. We can study flow structure and spectra from as many as four event-triggered recordings of unaveraged samples, each lasting one hour, during periods of intense sediment transport. Acoustic transducer multiplexing permits 24 axes to be interfaced to a single receiving circuit. Electrical reversal of transducers in each axis eliminates zero drift. A deep-sea tripod supports the sensor array rigidly with minimum flow disturbance, yet releases on command for free vehicle recovery.

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