From the QARTOD meetings I attended and the vocabularies in our repository, I'm confident the oceanographic community uses a lot more QC flag approaches than listed so far. So it is safe to say that there is no single approach.
Still, the approaches from Randy and Roy certainly are accepted by a whole lot of folks. If that meets your definition of "the generally accepted approach", you're good to go.
John
On Aug 24, 2012, at 00:27, andrew walsh wrote:
> Randy,
>
> The oceanographic community uses a set of integer QC flags (0 to 9)
> See document http://www.nodc.noaa.gov/GTSPP/document/qcmans/MG22rev1.pdf
> and section 2 'Quality Flagging'.
>
> One of the flags is for a 'missing value' = 9. Would that suit your fill value case?
>
> A netCDF sample in CDL is:
>
> double TEMP(TIME, DEPTH, LATITUDE, LONGITUDE) ;
> TEMP:standard_name = "sea_water_temperature" ;
> TEMP:units = "Celsius" ;
> TEMP:_FillValue = -99.99 ;
> TEMP:valid_min = -2. ;
> TEMP:valid_max = 40. ;
> TEMP:quality_control_set = 1. ;
> TEMP:ancillary_variables = "TEMP_quality_control" ;
> byte TEMP_quality_control(TIME, DEPTH, LATITUDE, LONGITUDE) ;
> TEMP_quality_control:long_name = "quality control flag for temperature" ;
> TEMP_quality_control:standard_name = "sea_water_temperature status_flag" ;
> TEMP_quality_control:quality_control_convention = "IMOS standard using IODE flags" ;
> TEMP_quality_control:_FillValue = -9b ;
> TEMP_quality_control:valid_min = 0 ;
> TEMP_quality_control:valid_max = 9 ;
> TEMP_quality_control:flag_values = 0b, 1b, 2b, 3b, 4b, 5b, 6b, 7b, 8b, 9b ;
> TEMP_quality_control:flag_meanings = "no_qc_performed good_data probably_good_data bad_data_that_are_potentially_correctable bad_data value_changed not_used not_used interpolated_values missing_values" ;
>
> HTH,
>
> Andrew Walsh
>
> ----- Original Message ----- From: "Randy Horne" <rhorne at excaliburlabs.com>
> To: <cf-metadata at cgd.ucar.edu>
> Cc: <aschut01 at harris.com>; <rhorne99 at harris.com>; <ekennell at aer.com>
> Sent: Friday, August 24, 2012 4:37 AM
> Subject: [CF-metadata] Quality flag values for missing data
>
>
>>
>> What is the "generally accepted" approach for how a specific quality flag value should be assigned for a corresponding data value (in the corresponding data variable) that has a _FillValue ?
>>
>> Is it sufficient that, because the data variable value is _FillValue, the corresponding quality flag value can be undefined ?
>>
>>
>>
>> ..............End of Message ...............................-->
>>
>>
>>
>>
>>
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----------------
John Graybeal <mailto:jgraybeal at ucsd.edu> phone: 858-534-2162
Product Manager
Ocean Observatories Initiative Cyberinfrastructure Project:
http://ci.oceanobservatories.org
Marine Metadata Interoperability Project:
http://marinemetadata.org
Received on Fri Aug 24 2012 - 02:04:04 BST
