Hi TIm:
The IDV/CDM software doesnt handle CF compressed indices. As you have
discovered, no one else does either, and there has been a suggestion to
deprecate this feature, since netcdf4 compression might work just as well, in a
way that would be transparent to applications. Would you like to try that?
John
Tim Cera wrote:
> I finally sat down to try and output to NetCDF from the Environmental
> Fluid Dynamics Code (EFDC) that we use for estuarine modeling.
>
> EFDC already handles all computation in a gather compression mode so
> that would seem to be a good fit to have, plus only about 10% of the
> cells are wet cells which would make a big impact on file size if I kept
> the blank cells about.
>
> EFDC uses a ordered, boundary-fitted, curvilinear, 4-sided cell grid
> with sigma-stretched layers in the vertical. That is a mouthful.
>
> We use UTM for the coordinates so the NetCDF needs to have projection
> information.
>
> It seems like I have tried everything and I can't get any NetCDF tool to
> bring in this dataset. I have tried IDV, Panoply, ncview (doesn't
> really support projection data), ncBrowse, and maybe some others.
>
> IDV does the best, at least putting the projected coordinates near the
> right spot in the 'Region' map, but IDV thinks that the WSElevation data
> is (3013, 3013) instead of (259, 121).
>
> I have 4 warnings when using the CF Compliance checker:
>
>
> WARNING (7.1): Data for variable y lies outside cell boundaries
> WARNING (7.1): Data for variable x lies outside cell boundaries
> ...
> ------------------
> Checking variable: rgrid
> ------------------
> WARNING (3): No standard_name or long_name attribute specified
> WARNING (3.1): units attribute should be present
>
>
> The first two I can fix because it must be related to the algorithm to
> calculate the cell corners. I have checked the last few cells and they
> are correct. The 'rgrid' variable is my gather compression variable and
> it shouldn't have units, nor could I find a reasonable standard name.
>
> Here is the CDL:
>
>
> netcdf efdcout {
> dimensions:
> IC = 259 ;
> JC = 121 ;
> rgrid = 3013 ;
> nv = 4 ;
> time = UNLIMITED ; // (2 currently)
> variables:
> int transverse_mercator ;
> transverse_mercator:grid_mapping_name =
> "transverse_mercator" ;
> transverse_mercator:latitude_of_projection_origin = 0. ;
> transverse_mercator:longitude_of_central_meridian = -81. ;
> transverse_mercator:false_easting = 500000. ;
> transverse_mercator:false_northing = 0. ;
> transverse_mercator:scale_factor_at_central_meridian =
> 0.9996 ;
> int rgrid(rgrid) ;
> rgrid:compress = "IC JC" ;
> float WSElevation(time, rgrid) ;
> WSElevation:standard_name =
> "height_above_reference_ellipsoid" ;
> WSElevation:units = "m" ;
> WSElevation:coordinates = "x y" ;
> WSElevation:grid_mapping = "transverse_mercator" ;
> float x(rgrid) ;
> x:standard_name = "projection_x_coordinate" ;
> x:units = "m" ;
> x:bounds = "x_bnds" ;
> float y(rgrid) ;
> y:standard_name = "projection_y_coordinate" ;
> y:units = "m" ;
> y:bounds = "y_bnds" ;
> float x_bnds(rgrid, nv) ;
> float y_bnds(rgrid, nv) ;
> double time(time) ;
> time:standard_name = "time" ;
> time:units = "days since 1995-1-1 0:0:0" ;
>
> // global attributes:
> :Conventions = "CF-1.0" ;
> }
>
> Any ideas on what I am doing wrong?
>
> Kindest regards,
> Tim Cera
>
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