Raw data review (QA1): Difference between revisions

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== Raw data review ==
== Raw data review ==


The raw data review seeks to identify the Level 1 data that satisfies a range of quality control criteria.  Typical criteria used to identify possible bad data include:
The raw data review seeks to identify the Level 1 data that satisfies a range of quality control criteria.  These may involve comparison of data between beams, between bins and over time and be informed by data from other sensors e.g. meteorological, wave or CTD sensors. Typical criteria used to identify possible bad data include:


# Velocity limits
# Correlation  
## Check for values outside the nominal measurement range for the instrument configuration
## Check for evidence of phase wrapping (ambiguity velocity) issues
# Correlation coefficient
## minimum threshold
## minimum threshold
# Echo intensity  
# Echo intensity  
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## applies to measurement modes with in-instrument averaging across multiple pings per ensemble
## applies to measurement modes with in-instrument averaging across multiple pings per ensemble
# Orientation (heading, pitch, roll) and depth (if sensor installed)  
# Orientation (heading, pitch, roll) and depth (if sensor installed)  
## deployment as planned?
## resolve location of observations
## indentify specific changes or periodic motion  
## indentify factors affecting location and any periodic motion  
# Along beam velocity  
# Along beam velocity
## data return rate  
## variations in data return rate
## phase wrapping for pulse-pulse coherent observations  
## values outside the nominal measurement range for the instrument configuration
## evidence of phase wrapping (ambiguity velocity) in pulse-pulse coherent observations  
## periodicity indicating waves or oscillatory motion  
## periodicity indicating waves or oscillatory motion  
## distribution outliers  
## distribution outliers  
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## burst variance spatial and temporal trends  
## burst variance spatial and temporal trends  
## shear over observation range
## shear over observation range
is a comparison of data between beams, between bins and over time to determine possible anomalies. Note that consideration of spatial and temporal trends may be informed by data from other sensors e.g. meteorological, wave or CTD sensors. The following characteristics should be examined:


Return to [[ADCP structure function flow chart| ADCP Flow Chart front page]]
Return to [[ADCP structure function flow chart| ADCP Flow Chart front page]]

Revision as of 14:21, 9 November 2021

Raw data review

The raw data review seeks to identify the Level 1 data that satisfies a range of quality control criteria. These may involve comparison of data between beams, between bins and over time and be informed by data from other sensors e.g. meteorological, wave or CTD sensors. Typical criteria used to identify possible bad data include:

  1. Correlation
    1. minimum threshold
  2. Echo intensity
    1. false target / “fish” detection
  3. Percent good
    1. applies to measurement modes with in-instrument averaging across multiple pings per ensemble
  4. Orientation (heading, pitch, roll) and depth (if sensor installed)
    1. resolve location of observations
    2. indentify factors affecting location and any periodic motion
  5. Along beam velocity
    1. variations in data return rate
    2. values outside the nominal measurement range for the instrument configuration
    3. evidence of phase wrapping (ambiguity velocity) in pulse-pulse coherent observations
    4. periodicity indicating waves or oscillatory motion
    5. distribution outliers
    6. burst variance spatial and temporal trends
  6. Temperature and salinity (if sensors installed)
    1. indication of changes in local stratification and/or internal wave activity
  7. Earth coordinate velocity
    1. may need to be derived from along-beam velocity
    2. bin mapping if ADCP orientation isn’t vertical
    3. error velocity from 4-beam instruments
    4. comparison with ambiguity velocity to check for possible phase wrapping
    5. burst variance spatial and temporal trends
    6. shear over observation range

Return to ADCP Flow Chart front page