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, Günther Lang Bundesanstalt für Wasserbau Abteilung Wasserbau im Küstenbereich Referat Ästuarsysteme II (K3) Wedeler Landstraße 157 22559 Hamburg, Germany phone +49 40 81908 360 mail [email protected]
test_compress_true_coord_var.cdl
Description: test_compress_true_coord_var.cdl
test_compress_true_coord_var.nc
Description: test_compress_true_coord_var.nc
test_compress_aux_coord_var.cdl
Description: test_compress_aux_coord_var.cdl
test_compress_aux_coord_var.nc
Description: test_compress_aux_coord_var.nc
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