A salt-stratified tank for measuring the dynamic response of conductivity probes

Gregg, Michael C.; Meagher, T.; Aagaard, E.; Hess, William C.

doi:10.1109/joe.1981.1145499

Cited by 13 publications

(3 citation statements)

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“…Early experimental work on the dynamic response of a two-electrode conductivity probe suggested that roughly 99% of the CV is contained within a sphere equal to the electrode spacing (Gregg et al 1981). In that case the electrode diameter was 1 3 10 24 m. Hill and Woods (1988) presented a theoretical approach in an effort to determine the spatial response of a two-electrode conductivity probe.…”

Section: A Theoretical Estimatementioning

confidence: 99%

A Conductivity Sensor for Nearbed Sediment Concentration Profiling

Puleo

Faries

Davidson

et al. 2010

Journal of Atmospheric and Oceanic Technology

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A new sensor that measures the vertical profile of nearbed sediment concentration is described. The conductivity-based sensor is composed of eight electrode pairs separated in the vertical by 2.5 3 10 23 m. Electrode pairs are sampled at 16 Hz, with higher rates achievable. Each electrode pair response is linear over the range of conductivity tested from 0.2 to 0.65 mS cm 21 that exceeds the range of conductivity values corresponding to sediment-water mixtures from clear water to the packed bed limit of 0.65 m 3 m 23 . A laboratory test over a planar sloping beach indicates the capability of the sensor to simultaneously quantify sediment concentration profiles from roughly 0.01 m below to 0.1 m above the at-rest bed. The data indicate that the upper few millimeters of the bed are highly mobile and that bed dilation and sediment mobility vary considerably over a swash cycle.

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Section: A Theoretical Estimatementioning

confidence: 99%

A Conductivity Sensor for Nearbed Sediment Concentration Profiling

Puleo

Faries

Davidson

et al. 2010

Journal of Atmospheric and Oceanic Technology

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“…One body of work that systematically studied the response characteristics of conductivity cells was performed in a salt-stratified tank, in which a sharp interface was maintained between two mixed layers by the turbulence generated by oscillating grids (Gregg et al, 1981(Gregg et al, , 1982Gregg and Hess, 1985). However, these tests failed to detect the substantial thermal mass problems of one conductivity cell (Lueck and Picklo, 1990;Lueck, 1990), since there was little or no temperature difference across the salt interface in most of the trials.…”

Section: Introductionmentioning

confidence: 99%

A double-diffusive interface tank for dynamic-response studies

Schmitt¹,

Millard²,

Toole³

et al. 2005

J Mar Res

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A large tank capable of long-term maintenance of a sharp temperature-salinity interface has been developed and applied to measurements of the dynamical response of oceanographic sensors. A two-layer salt-stratified system is heated from below and cooled from above to provide two convectively mixed layers with a thin double-diffusive interface separating them. A temperature jump exceeding 10°C can be maintained over 1-2 cm (a vertical temperature gradient of order 10 3°C /m) for several weeks. A variable speed-lowering system allows testing of the dynamic response of conductivity and temperature sensors in full-size oceanographic instruments. An acoustic echo sounder and shadowgraph system provide nondisruptive monitoring of the interface and layer microstructure. Tests of several sensor systems show how data from the facility is used to determine sensor response times using several fitting techniques and the speed dependence of thermometer time constants is illustrated. The linearity of the conductivity-temperature relationship across the interface is proposed as a figure of merit for design of lag-correction filters to accurately match temperature and conductivity sensors for the computation of salinity. The effects of finite interface thickness, slow sensor sampling rates and the thermal mass of the conductivity cell are treated. Sensor response characterization is especially important for autonomous instruments where data processing and compression must be performed in-situ, but is also helpful in the development of new sensors and in assuring accurate salinity records from traditional wire-lowered and towed systems.

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“…and the sampling time which corresponds to the ordinate of the ith data value ti= to I In xi (20) a I orm eij= ti-…”

mentioning

confidence: 99%