Raw data review (QA1): Difference between revisions
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Raw data review | |||
The objective of the raw data review is to ensure that the velocity data used for the calculation of the structure functions are of good quality before proceeding with the turbulence analysis. Bad data are typically identified from the velocity data themselves and other ancillary data (e.g. correlations). It is recommended that velocity data should be flagged if the following are observed: | The objective of the raw data review is to ensure that the velocity data used for the calculation of the structure functions are of good quality before proceeding with the turbulence analysis. Bad data are typically identified from the velocity data themselves and other ancillary data (e.g. correlations). It is recommended that velocity data should be flagged if the following are observed: | ||
= Data quality is poor = | |||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* Low correlation values | #* Low correlation values | ||
#* Echo intensity anomalies | #* Echo intensity anomalies | ||
#* Low percent good values | #* Low percent good values | ||
#* Data return rate varies | #* Data return rate varies | ||
</div> | |||
= Unrealistic velocity values = | |||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* Evidence of phase wrapping | #* Evidence of phase wrapping | ||
#* Velocities outside nominal measurement range | #* Velocities outside nominal measurement range | ||
#* Velocities outside expected distribution | #* Velocities outside expected distribution | ||
</div> | |||
= Significant instrument motion and orientation = | |||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* High variability in pitch, heading and roll | #* High variability in pitch, heading and roll | ||
#* Orientation deviates from expected values | #* Orientation deviates from expected values | ||
</div> | |||
= There is wave or periodic motion = | |||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* Periodic motion at wave frequencies observed in velocity data | #* Periodic motion at wave frequencies observed in velocity data | ||
</div> | |||
= Velocity shear is too large = | |||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* earth velocities indicate significant horizontal shear | #* earth velocities indicate significant horizontal shear | ||
</div> | |||
#* variance of velocity bursts shows spatial or temporal trends | = Stationary assumption may be violated = | ||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* variance of velocity bursts shows spatial or temporal trends | |||
</div> | |||
= Stratification is too large = | |||
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand variables"> | |||
#* Temperature and salinity (if available) indicate local stratification | #* Temperature and salinity (if available) indicate local stratification | ||
</div> | |||
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Next step: [[ ]]<br></br> | Next step: [[ ]]<br></br> | ||
Revision as of 14:34, 15 November 2021
Raw data review
The objective of the raw data review is to ensure that the velocity data used for the calculation of the structure functions are of good quality before proceeding with the turbulence analysis. Bad data are typically identified from the velocity data themselves and other ancillary data (e.g. correlations). It is recommended that velocity data should be flagged if the following are observed:
Data quality is poor
- Low correlation values
- Echo intensity anomalies
- Low percent good values
- Data return rate varies
Unrealistic velocity values
- Evidence of phase wrapping
- Velocities outside nominal measurement range
- Velocities outside expected distribution
Significant instrument motion and orientation
- High variability in pitch, heading and roll
- Orientation deviates from expected values
There is wave or periodic motion
- Periodic motion at wave frequencies observed in velocity data
Velocity shear is too large
- earth velocities indicate significant horizontal shear
Stationary assumption may be violated
- variance of velocity bursts shows spatial or temporal trends
Stratification is too large
- Temperature and salinity (if available) indicate local stratification
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