I'm in agreement with Jonathan!
On 5/6/15 1:09 PM, Jonathan Gregory wrote:
Dear Kristian
In these case the feature type is a trajectory, so
the latitude and longitude are auxiliary coordinates.
You said that for auxiliary coordinates it could be ok, Would this mean
that it could be added to the CF conventions?
I don't think any change would be needed to the CF convention. CF allows a
given netCDF variable to serve as both a data variable in its own right and
an aux coord var of another data variable. An example of where this might be
useful is for an ocean model on density levels, in which depth as a function
of density is of interest as a data variable, but could also be an auxiliary
coordinate variable for other data variables. Therefore I think it would be
legal for your aux coord vars to have ancillary vars. Since the lat and lon
along a trajectory are actually dependent data variables, this feels quite
reasonable to me for your case. I wonder what others think.
Cheers
Jonathan
On 5 May 2015 at 18:58, Jonathan Gregory <[email protected]> wrote:
Dear Kristian
Ancillary variables are only for data variables in the current convention.
It wouldn't be illegal to use the attribute on coord variables, but CF
doesn't define what that would mean. (CF always permits any
non-standardised
attributes.)
I wonder whether these are 1D coord variables (in the Unidata sense) or
aux coord vars (named by the coordinates attribute)? In the latter case, it
could be OK, because other data variables could be named as aux coord vars.
Best wishes
Jonathan
----- Forwarded message from Kristian Sebasti??n <[email protected]>
-----
Date: Thu, 30 Apr 2015 08:43:54 +0200
From: Kristian Sebasti??n <[email protected]>
To: [email protected]
Subject: [CF-metadata] Ancillary variables in coordinate variables
(latitude,
longitude, ...)
Dear CF community,
We have some dataset with quality controls applied to the coordinate
variables, such as latitude and longitude coordinate. The result are
quality control variables that we associate as ancillary variables of the
coordinate variables with the ancillary_variables attribute. For example,
the LAT coordinate variable has the ancillary variable QC_LAT. The
dataset
http://thredds.socib.es/thredds/dodsC/drifter/surface_drifter/drifter_svp052-ime_svp017/L1/2014/dep0001_drifter-svp052_ime-svp017_L1_2014-05-25.nc
The cf-conventions clarifies the use of the ancillary_variables attribute
for data variables but not for coordinate variables. My question is, Is
the
ancillary_variables attribute in coordinates variables compliant with the
cf-conventions?
Best regards,
Kristian
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SOS Division: Data Center Technical
Tel: 971439860 - Fax: 971439979
E-mail: [email protected]
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Tel: 971439860 - Fax: 971439979
E-mail: [email protected]
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