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" <rho...@excaliburlabs.com>
To: <cf-metadata@cgd.ucar.edu>
Cc: <aschu...@harris.com>; <rhorn...@harris.com>; <ekenn...@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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