Dear CF metadata discussion group.
Salinity data given at several arbitrarily spaced locations in different depth layers shall
be stored in a NetCDF file using a compressed dimension (datapoint) to remove permanently
missing data from the data record.
In order to get used to this style of data storage I have prepared two example CDL sets.
With NCGEN the respective NetCDF data files were generated from the CDL files and
verified using checker program
http://puma.nerc.ac.uk/cgi-bin/cf-checker.pl .
Example 1 - compression by gathering using true coordinate variables:
* see attached files test_compress_true_coord_var.cdl | .nc .
* checker says: ok, CF compliant .
Example 2 - compression by gathering using auxiliary coordinate variables for the horizontal:
* see attached files test_compress_aux_coord_var.cdl | .nc .
* checker says: not ok, due to
* ERROR (5): Dimensions of node_lon must be a subset of dimensions of salinity_3d
* ERROR (5): Dimensions of node_lat must be a subset of dimensions of salinity_3d
>From my understanding the dimensions of the auxiliary coordinate variables NODE_LON
and NODE_LAT are a true subset of the (uncompressed) dimensions of salinity_3d, similar
to the above example 1.
Due to the fact that the only difference lies in the use of auxiliary coordinates
for the horizontal domain, my question is whether within example 2 there is a
true error concerning the CF compliant description of this data set or whether
it is not possible at all to store data like example 2 in a CF compliant compressed
NetCDF file.
Any helpful remarks welcome.
Yours sincerely,
G?nther Lang
Bundesanstalt f?r Wasserbau
Abteilung Wasserbau im K?stenbereich
Referat ?stuarsysteme II (K3)
Wedeler Landstra?e 157
22559 Hamburg, Germany
phone +49 40 81908 360
mail guenther.lang at baw.de
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Received on Thu Apr 28 2011 - 08:49:14 BST
