Hi Jonathan,
I wasn't very clear in the earlier mail. Actually, the quality flags
are different, but the attributes flag_values and flag_meanings are same
for all the flag variables. These attributes are being repeated within
each quality flag variable instead of perhaps having a single
"definition" of the flag_values and flag_meanings.
One solution we looked at is to have a "container variable" for flag
definitions which will be referred to by each of the flag variables,
something like this:
float temperature(z);
....................
temperature:ancillary_variables = "temperature_WODflag";
int temperature_WODflag(z);
....................
temperature:flag_definitions = "WOD_flag_definitions";
float salinity(z);
....................
salinity:ancillary_variables = "salinity_WODflag";
int salinity_WODflag(z);
....................
salinity:flag_definitions = "WOD_flag_definitions";
<similarly for other other variables>
int WOD_flag_definitions;
WOD_flag_definitions:flag_values = "0, 1, 2, 3, 4, 5, 6, 7, 8, 9" ;
WOD_flag_definitions:flag_meanings = "accepted_value range_outlier
failed_inversion_check failed_gradient_check
observed_level_bullseye_flag_and_zero_gradient_check combined_gradient
_and_inversion_checks failed_range_and_inversion_checks
failed_range_and_gradient_checks
failed_range_and_questionable_data_checks
failed_range_and_combined_gradient_and_inversion_checks" ;
Of course, flag_definitions is not a CF attribute and the above solution
wouldn't work with CF based software. Is there a way around within the
ambit of CF other than to repeat the flag definitions?
Upendra
On 11/1/2011 11:38 AM, Jonathan Gregory wrote:
Dear Upendra
On 11/1/2011 10:47 AM, Upendra Dadi wrote:
The same issue occurs with World Ocean Database which consists of
mainly profile data. Each profile typically consists of several
variables measured along the depth. The quality flags used for all
the variable are same.
On 10/31/2011 12:12 PM, Randy Horne wrote:
The current CF conventions dictate that quality flags are
attached to specific variables. The implication is that
comforming with CF conventions would require the same quality
flags to be stored multiple times in our NetCDF product files.
Quality flags are attached to variables using the ancillary_variables att of
the data variable. If several data variables had the same quality flags and
dimensions, they could all point to the same quality variable. Perhaps the
problem is that the different variables have different standard names, and
this means the quality variables would also have different standard names
(and therefore could not be the same variable)? If that is the problem, perhaps
we could find a way round it. Or have I missed the point?
Best wishes
Jonathan
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