Free-sinking temperature and salinity profiler for ocean microstructure studies

Williams, Antony J.

doi:10.1109/oceans.1974.1161414

Cited by 16 publications

(3 citation statements)

References 6 publications

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“…The instrument used in this work is a freely sinking vehicle containing the optical imaging system described above, a con= ductivity=temperature=pressure recorder, and a velocity shearmeter [Williams, 1974a]. This instrument, Scimp (serf contained imaging microprofiler), sinks at 12 cm/s, its buoy= ancy adjusted by acoustic commands from the surface vessel which cause it to jettison heavy or light fluid as required.…”

Section: Instrumentationmentioning

confidence: 98%

The role of double diffusion in a Gulf Stream frontal intrusion

Williams¹

1981

J. Geophys. Res.

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Double diffusive convection is possible where large vertical gradients in temperature and salinity tend to compensate in density. Frontal intrusions have these large gradients and can provide the possibility for a salt finger interface at one boundary and a diffusive interface at the other. But large vertical gradients of velocity are present at the boundaries of intrusions, which cause mechanical stirring and turbulent mixing as well. In the exceptionally active intrusions at the Gulf Stream Front near 38°N 69°W, a convective process resulting from incomplete mechanical mixing was observed photographically on both intrusive boundaries.

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Section: Instrumentationmentioning

confidence: 98%

The role of double diffusion in a Gulf Stream frontal intrusion

Williams¹

1981

J. Geophys. Res.

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“…Furthermore, Styles (2006) found that the LISST detected the scattering from the small-scale refractive index changes caused by the density gradient as particles > 100 μm, corresponding to scattering between 0.05°and 0.25°for the LISST-100C (LISST-100 user's guide). Williams (1974) used this principle to take pictures of optical inhomogeneities created by salinity and temperature microstructures in the ocean. Such optical inhomogeinities are known as schlieren and are akin to the light distortion caused by heat rising from a hot pavement.…”

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confidence: 99%

The influence of schlieren on in situ optical measurements used for particle characterization

Mikkelsen

Milligan

Hill

et al. 2008

Limnology & Ocean Methods

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In pycnoclines, the density differences can cause light scattering -schlieren -even though only few particulate scatterers may be present. This may pose problems for the interpretation of results obtained with instruments relying on light scattering and transmission, for example the LISST (Laser In Situ Scattering and Transmissometry) particle sizer, and various cameras. Here, the influence of schlieren on in situ forward light scattering, beam attenuation and image analysis is evaluated using a LISST-100 and a digital floc camera. Automated image analysis routines detect schlieren as particles, causing an apparent increase in particle size and volume. Re-analysis omitting schlieren-affected parts of the images reveals no increase. LISST beam attenuation and Volume Scattering Function (VSF) measurements indicate that schlieren can cause increases in beam attenuation due to a marked increase in the VSF at angles smaller than ~1.5°-2°, and falsely indicate accumulation of suspended particles in the pycnocline. Light scattering caused by density differences can also cause multiple scattering, which produces an apparent decrease in particle size derived from the LISST. Schlieren is visible in images when the buoyancy frequency exceeds ~0.12 s -1

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“…The instrument used in this work is a freely sinking vehicle containing the optical imaging system described above, a conductivity-temperature-pressure recorder, and a velocity shearmeter [Williams, 1974a]. This instrument, Scimp (self contained imaging microprofiler), sinks at 12 cm/s, its buoyancy adjusted by acoustic commands from the surface vessel which cause it to jettison heavy or light fluid as required.…”

Section: Instrumentationmentioning

confidence: 99%

The role of double diffusion in a Gulf Stream frontal intrusion

Williams¹

1981

View full text Add to dashboard Cite

Free-sinking temperature and salinity profiler for ocean microstructure studies

Cited by 16 publications

References 6 publications

The role of double diffusion in a Gulf Stream frontal intrusion

The role of double diffusion in a Gulf Stream frontal intrusion

The influence of schlieren on in situ optical measurements used for particle characterization

The role of double diffusion in a Gulf Stream frontal intrusion

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