Shear probes quality control metrics: Difference between revisions

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Spikes in epsilon estimates arise from a number of causes such as collisions of sensor tips with suspended particles (e.g. detritus, plankton, jelly fish, seaweed), electronic noise due to other sensors, or mechanical platform vibrations. This section describes quality control measures and its coding.  
Shear-probe data can be corrupted or compromised in several different ways. These include but are not limited to (''i'') collision with plankton and other materials, (''ii'') unremovable vibrational contamination. (''iii'') electronic noise, and (''iv'') interference from other instrumentation on a platform that carries the shear probes. This section describes the quality control metrics and the coding used to [[Quality control coding|identify]] them. Quality-control metrics that are currently identified include;


In a ''first step'', epsilon estimates are flagged based on quality control matric and disagreement between dissipation estimates from redundant sensors.  
:* [[figure of merit (FOM)]]
:* [[fraction of shear-probe data altered by the de-spiking routine]]
:* number of [[iterations]] of the de-spiking routine required to clean the data
:* [[agreement between dissipation estimates]] from redundant sensors (i.e. two or more shear probes)


# Quality-control metrics (see also Processing Steps section V) that accompanied dissipation estimates are used to flag individual estimates. In particular, quality control thresholds for
The numerical threshold for these metrics should depend, as much as possible, on the known statistical properties of a turbulence shear measurement. The numerical values of the QC codes (or flags) is found in [[Quality control coding|QC-flags]].
#:* FM (figure of merit)
#:* fraction of shear-probe data altered by the de-spiking routine
#:* number of iterations of the de-spiking routine required to clean the data
#:* (more to be discussed)
# Agreement between dissipation estimates from redundant sensors (i.e. two or more shear probes) does not exist.


Flagged data will receive a quality control coding 4
Please note that most choices made must be included in a data set, as described in the [[Netcdf meta data (shear probes)|list of meta data]].


In a ''second step'' of quality control, a review of ensembles that have been flagged is performed. Individual shear spectra, associated tilt and acceleration data and microstructure thermistor data/spectra are visually examined for consistency. Previously flagged data that appears to be good data will receive quality control coding 2.
 
 
 
 
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[[Category:Shear probes]]

Latest revision as of 18:21, 6 June 2024

Shear-probe data can be corrupted or compromised in several different ways. These include but are not limited to (i) collision with plankton and other materials, (ii) unremovable vibrational contamination. (iii) electronic noise, and (iv) interference from other instrumentation on a platform that carries the shear probes. This section describes the quality control metrics and the coding used to identify them. Quality-control metrics that are currently identified include;

The numerical threshold for these metrics should depend, as much as possible, on the known statistical properties of a turbulence shear measurement. The numerical values of the QC codes (or flags) is found in QC-flags.

Please note that most choices made must be included in a data set, as described in the list of meta data.



return to Flow chart for shear probes

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