Focus on Quality Control and Real time data collected in-situ
What is real-time data?
Is the definition up to the user?
OCSD- within hours
What is Quality Control? Portion after the data is collected
Requires an activity which checks the parameters
Methods of collection
 Profiling from ship
 Moored
 Profiling floats
 Fixed platforms
 Gliders/AUVs…potential for RT with telemetry
 Expendables
Parameters- define required for QC
 Primary Sensors
 Conductivity
 Temperature
 Pressure
 Oxygen
 Other optical sensors
 Position
 Date/Time/Time reference
 Derived
 Depth
 Salinity
 Density
Metadata
 Time
 Position
 Time reference
 Bottom depth/Station depth…is this a parameter? Part of QA or QC?
Parameter: Conductivity
Category
Range Test (Gross)
Criteria
REQUIRED
Absolute number
RECOMMENDED (if applicable)
Range Test (Climatology
+/- (n) SD
profile)
Compare w/ Temperature
Gradient Tests
Nearest Neighbors
Spike Tests
Determined by data
provider
Descent Rate
Parameter: Temperature
Category
Criteria
Range Tests
Range Test
(Climatology
profile)
Spike Tests
Flag
REQUIRED
Criteria
Absolute num
+/- (n) SD
RECOMMENDED (if applicable)
Gradient tests
Compare w/
Conductivity
Density Inversions
Freezing Point
Nearest Neighbor
TSP relationships
(?)
Dual Sensors
Flag
Parameter: Pressure
Category
Range Tests (Gross)
Range Test
(Climatology profile)
Gradient Test
Spike Tests
Compare with surface
pressure
Dual Sensors
Density Inversions
Freezing Point
Criteria
Notes
REQUIRED
Absolute
numbers
RECOMMENDED (if applicable)
Required for profile data
QA or QC?
Requires temp, sal, and pressure for
calculation
Definitions:
Climatology- The observed geographic or temporal distribution of
observations over a specified period of time.
Range tests (gross) – Gross bounds on the parameter; removes gross errors.
Range tests (climatology) - Bounds determined for specific zones or time
periods at specific sampling range, eg. depth.
Spike tests- Check for transient variation (outlier) in parameter value.
Gradient tests- Bounds on rate of change in sequential measured
observations: spatial and temporal.
Nearest neighbors- Observations lying within a specified spatial or temporal
range/zone of a selected observation.
Dual sensors- More than one sensor in the immediate vicinity which measures
the same parameter with similar accuracy and resolution.
Freezing point- Using the measured temperature, salinity, pressure to
calculate the point at which water changes from liquid to solid.
References:
WOCE manuals- see http://cchdo.ucsd.edu/manuals.htm
JGOFS
GTSPP- see http://nodc.noaa.gov/GTSPP/
Ocean climate laboratory tables
Next Steps:
 Follow-up meeting to tackle the remaining primary parameters – DO,
optional sensors, position, date/time/time reference
 Look over salinity report before tackling derived parameters
 Identify other participants
Other items discussed:
Ways to verify data collected:
No brainer tests:
 Range tests: storm options,
 Climatology tests: consider specific area and seasonality
 Gradient test
 Spiking routines- 3 point test, running std of data
 Comparison with other parameters: correlation of std and compared
to other sensors
Further tests, additional methods:
 Dual sensors
 Descent rate- specific to profiles
 Ensure derived parameters are within boundaries- eg. Increasing
density with depth
 Freezing point test
 Comparison between adjacent sensors- vertical and horizontal
Nearest neighbors
 Discrete samples or additional data from sensors- not real-time, QA?
 TSP relationships/ water mass characteristics


Comparison with models- real-time?
Stuck/Frozen sensor- David Castell
Consider what is required, recommended, etc…
Words of Caution:
 Flag instead of throwing out data
Does one remove data or flag?
 Know instrument problem: recover or remove?
 Allow for user to determine whether they want flagged data
Who’s responsibility is it?
Problems and how to QC:

Stuck sensor- see constant
Approaches to QC
 Automated QC versus human checking
Ordering for NOAA:
 Tests on location and identification of a station/date/time
 Stage two- spikes, etc.
 Stage three- climate
 Stage four- visual inspection