[ferret_users] inconsistent data grids: File needs axis attributes on coordinate variables indicating correct direction

[Patrick Brockmann <patrick.brockmann@xxxxxxxxxxxx>]

Hi ferreters,

A colleague has encountered a strange problem as he was trying to

nicely respect the netCDF CF conventions to describe a curvilinear grid (NEMO configuration).

ferret complains about some inconsistent data grid and missing axis attributes.

use notok.nc 
          *** NOTE: 
          *** NOTE: Could not adjust grid for variable mask_T 
**ERROR: inconsistent data grids: File needs axis attributes on coordinate variables indicating correct directions

Stranger, if I change the name of the dimension, then the file

is read. I have not been able to fix this by adding a direction attribute as requested.

The file is simple as:

$ ncdump notok.nc
netcdf notok { 
dimensions: 
       y_grid_T = 1 ; 
       x_grid_T = 1 ; 
       nvertex_grid_T = 4 ; 
variables: 
       double bounds_lat_grid_T(y_grid_T, x_grid_T, nvertex_grid_T) ; 
       double bounds_lon_grid_T(y_grid_T, x_grid_T, nvertex_grid_T) ; 
       byte mask_T(y_grid_T, x_grid_T) ; 
               mask_T:cell_measures = "area: area_grid_T" ; 
               mask_T:coordinates = "nav_lat_grid_T nav_lon_grid_T" ; 
       double nav_lat_grid_T(y_grid_T, x_grid_T) ; 
               nav_lat_grid_T:standard_name = "latitude" ; 
               nav_lat_grid_T:long_name = "Latitude" ; 
               nav_lat_grid_T:units = "degrees_north" ; 
               nav_lat_grid_T:bounds = "bounds_lat_grid_T" ; 
       double nav_lon_grid_T(y_grid_T, x_grid_T) ; 
               nav_lon_grid_T:standard_name = "longitude" ; 
               nav_lon_grid_T:long_name = "Longitude" ; 
               nav_lon_grid_T:units = "degrees_east" ; 
               nav_lon_grid_T:bounds = "bounds_lon_grid_T" ; 
data: 
bounds_lat_grid_T = 
 -29.5895932339965, -29.5895932339965, -27.835621888657, -27.835621888657 ; 
bounds_lon_grid_T = 
 156.999148343641, 158.999201071309, 158.999201071309, 156.999148343641 ; 
mask_T = 
 1 ; 
nav_lat_grid_T = 
 -28.7162844516478 ; 
nav_lon_grid_T = 
 157.999608915878 ; 
}

If I remove _grid_T suffix then the file is read correctly.
$ ncgen -o notok.nc notok.cdl
$ sed -e 's/_grid_T//g' notok.cdl > ok.cdl
$ ncgen -o ok.nc ok.cdl


Any idea on why there is the unexpected behaviour (test on names of dimensions) ?

Patrick

--
Data Analytics and Visualization Engineer / Project Manager
LSCE/IPSL, CEA-CNRS-UVSQ laboratory
LSCE - Climate and Environment Sciences Laboratory
IPSL - Institut Pierre Simon Laplace
--sed -e 's/_grid_T//g' tyty.cdl > tyty1.cdl

Attachment: notok.nc
Description: Cdf file