An Acoustic Doppler and Electromagnetic Velocity Profiler

Sanford, Thomas B.; Driver, Robert G.; Dunlap, John H.

doi:10.1175/1520-0426(1985)002<0110:aadaev>2.0.co;2

Cited by 53 publications

(18 citation statements)

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“…The velocity sensor operates on the same principles of motional induction applied on the Absolute Velocity Profiler (Sanford et al, 1985) and the Expendable Current Profiler (Sanford et al, 1982). The electric field sensing electrodes are located on the top end of the floats (Fig.…”

Section: Em-apex Floatsmentioning

confidence: 99%

Autonomous microstructure EM-APEX floats

Sanford

Lien

Dunlap

et al. 2016

Methods in Oceanography

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Fast responding FP-07 thermistors have been incorporated on autonomous profiling EM-APEX floats to measure microscale ocean temperature fluctuations produced by turbulence. In this implementation, the FP-07 thermistor generates an electrical signal corresponding to ocean temperature fluctuations, which is conditioned by an analog circuit board, and digitized and recorded on a custom data acquisition and storage board. The raw and processed temperature observations are stored on a microSD card. Results from eight microstructure EM-APEX floats deployed in the Sargasso Sea are presented here. The slow profiling speed of EM-APEX floats enables them to resolve the higher wavenumber regime of the microscale temperature gradient spectrum, beyond the roll-off wavenumber. The temperature variance dissipation rate  is computed directly by integrating the observed temperature gradient spectrum over the turbulence wavenumber region without the need to fit the observed temperature gradient spectrum to the empirical spectral form. The accuracy of estimated from microstructure EM-APEX floats is confirmed by the agreement, within a factor of 2, between the temperature diffusivity K T computed from our estimates of  and estimates of diapcynal diffusivity computed from simultaneous tracer measurements. The observed temperature gradient spectra averaged over many realizations resemble the Batchelor spectral form, though individual spectra often do not fit the empirical prediction. Estimates of from different floats have similar temporal fluctuations and vertical profiles, further supporting measurement quality. Estimates of  exhibit a lognormal distribution, as expected for statistically homogeneous isotropic turbulence. Turbulence measurements derived from FP-07 sensors on autonomous profiling floats are of comparable quality to those on conventional free-fall microstructure profilers.

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Section: Em-apex Floatsmentioning

confidence: 99%

Autonomous microstructure EM-APEX floats

Sanford

Lien

Dunlap

et al. 2016

Methods in Oceanography

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“…Turbulent kinetic-energy dissipation rate ε and diapycnal diffusivity K , obtained across French Frigate Shoals over the depth range of 400 to 600 m (upper left panel; note the logarithmic axes). These measurements were made with four unique turbulence vehicles: AMP, AVP (28), and Chameleon are vertical profilers, and Marlin (8) is a towed vehicle. The solid line indicates the mean value of all of the data in 20-km lateral bins.…”

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confidence: 99%

From Tides to Mixing Along the Hawaiian Ridge

Rudnick

Boyd

Brainard

et al. 2003

Science

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312

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The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 meters occur on the ridge. Internal-wave energy is enhanced, and turbulent dissipation in the region near the ridge is 10 times larger than open-ocean values. Given these major elements in the tides-to-turbulence cascade, an energy budget approaches closure.

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“…The ratio of sediment conductance to water column conductance ðlÞ is typically small (0-0.2) in the open ocean, as seen in both models (Chave and Luther, 1990;Flosadó ttir et al, 1997;Tyler et al, 1997) and observations (Sanford et al, 1985;Sanford, 1986;Chave and Luther, 1990;Szuts, 2004). In the Newfoundland Basin in water deeper than 4000 m, the sediment is only a few kilometers thick (Tucholke, 1986;Laske and Masters, 1997) and its homogeneity and small conductivity are relatively easy to parameterize for our purposes (Flosadó ttir et al, 1997).…”

Section: Theory Of Motional Inductionmentioning

confidence: 93%