The Correction for Thermal-Lag Effects in Sea-Bird CTD Data

Morison, James H.; Andersen, R.; Larson, Nordeen; D’Asaro, Eric A.; Boyd, Tim

doi:10.1175/1520-0426(1994)011<1151:tcftle>2.0.co;2

Cited by 88 publications

(89 citation statements)

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“…To solve this inconsistency, two approaches can be followed-either estimating the conductivity that would have been measured outside the conductivity cell (without thermal mass inertia), or estimating the temperature that would have been measured inside the conductivity cell. Both approaches use the scheme described in Morison et al (1994) and Mensah et al (2009).…”

Section: A New Methodologymentioning

confidence: 99%

“…This approach offers an advantage over the first one, because it does not rely on the estimated sensitivity g, and it is also computationally more efficient because g does not need to be computed. Morison et al (1994) showed that there is a relation between the correction parameters a and t and the flow speed through the conductivity cell. In the case of pumped CTDs, the flow speed is either known or, at worst, can be estimated by observing the misalignment between the sensors' signals.…”

Section: A New Methodologymentioning

confidence: 99%

“…The approach in this paper proposes a generalization of the method developed by Morison et al (1994), where the relation between a and t and the flow speed is computed throughout the profile, so that the assumption of constant flow speed is no longer required. Following Morison et al (1994), the relation between the correction parameters and the flow speed is…”

Section: A New Methodologymentioning

confidence: 99%

“…Lueck and Picklo (1990) proposed a numerical model for the thermal inertia of Sea-Bird conductivity cells. By analyzing a temperature-salinity (T-S) diagram, Morison et al (1994) evaluated the correction to the thermal lag error.…”

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confidence: 99%

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Thermal Lag Correction on Slocum CTD Glider Data

Garau

Ruiz

Zhang

et al. 2011

Journal of Atmospheric and Oceanic Technology

163

137

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In this work a new methodology is proposed to correct the thermal lag error in data from unpumped CTD sensors installed on Slocum gliders. The advantage of the new approach is twofold: first, it takes into account the variable speed of the glider; and second, it can be applied to CTD profiles from an autonomous platform either with or without a reference cast. The proposed methodology finds values for four correction parameters that minimize the area between two temperature-salinity curves given by two CTD profiles. A field experiment with a Slocum glider and a standard CTD was conducted to test the method. Thermal lag-induced salinity error of about 0.3 psu was found and successfully corrected.

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Section: A New Methodologymentioning

confidence: 99%

Section: A New Methodologymentioning

confidence: 99%

Section: A New Methodologymentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Thermal Lag Correction on Slocum CTD Glider Data

Garau

Ruiz

Zhang

et al. 2011

Journal of Atmospheric and Oceanic Technology

163

137

View full text Add to dashboard Cite

show abstract

“…7) only and with a fractional lag of the conductivity relative to temperature plus the thermal mass correction, with the weights a and b chosen by inspection. Morison et al (1994) show that minimizing the salinity differences between rapid repeat up and down CTD casts is a practical way to optimize the selection of the weights when the appropriate field data are available. They also find that the form of the velocity dependence of the factors determining the weights is as expected, and suggest a more efficient implementation based on the estimated temperature of the water in the cell, rather than a corrected conductivity.…”

Section: Application Of Sensor Response Correctionmentioning

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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Extension of an Ice Shelf Water plume model beneath sea ice with application in McMurdo Sound, Antarctica

et al. 2014

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A one-dimensional, frazil-laden plume model predicts the properties of Ice Shelf Water (ISW) as it evolves beneath sea ice beyond the ice shelf edge. An idealized background ocean circulation, which moves parallel to the plume, imitates forcings other than the plume's own buoyancy. The size distribution and concentration of the plume's suspended frazil ice crystals are affected by the background circulation velocity, the root-mean square tidal velocity, the drag coefficient, and the efficiency of secondary nucleation. Consequently, these variables are the key physical controls on the survival of supercooled water with distance from the ice shelf, which is predicted using several realistic parameter choices. Starting at 65 m thick, the in situ supercooled layer thins to 11 6 5 and 4 6 3 m at distances of 50 and 100 km, respectively. We apply the extended model in McMurdo Sound, Antarctica, along the expected path of the coldest water. Three late-winter oceanographic stations along this path, in conjunction with historical data, provide initial conditions and evaluation of the simulations. Near the ice shelf in the western Sound, the water column consisted entirely of ISW, and the subice platelet layer thickness exceeded 5 m with platelet crystals dominating the sea ice structure suggesting that ISW persisted throughout winter. Presuming a constant ISW flux, the model predicts that the plume increases thermodynamic growth of sea ice by approximately 0.1 m yr 21 ($5% of the average growth rate) even as far as 100 km beyond the ice shelf edge.

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The Correction for Thermal-Lag Effects in Sea-Bird CTD Data

Cited by 88 publications

References 0 publications

Thermal Lag Correction on Slocum CTD Glider Data

Thermal Lag Correction on Slocum CTD Glider Data

A double-diffusive interface tank for dynamic-response studies

Extension of an Ice Shelf Water plume model beneath sea ice with application in McMurdo Sound, Antarctica

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