Hi John,
This kind of "note" just means that Ferret doesn't do any automatic
conversions with the given units, like it can with time units or
lat/lon. There isn't any problem with the units of sigma_level; Ferret
keeps the string for use on plots and in output files, but it needs the
user to tell it how to do any conversions to physical units (which you
might do with one of the ZAXREPLACE functions in Ferret).
Ansley
John Schattel wrote:
Hello All,
The Ferret User's Guide says that Ferret supports COARDS netCDF files
(see below).
As discussed in the Chapter, "Converting Data
to
NetCDF," (p. 247) Ferret expects netCDF files to adhere to the COARDS
conventions
(http://www.ferret.noaa.gov/noaa_coop/coop_cdf_profile.html).
And the COARDS profile says that "sigma_level" is an acceptable unit
name (see below).
This standard also refers
to version 1.7.1 of the udunits standard supported by Unidata. The
udunits package is available via anonymous ftp at ftp.unidata.ucar.edu.
Included in the udunits package is a file, udunits.dat, which lists
collections of unit names. The names given therein and their plural
forms will be regarded as acceptable unit names for this standard with
the following additions and deletions:
- "degrees" - deleted
- "level", "layer", "sigma_level" - added
Yet when I run Ferret with a COARDS complaint netCDF file, it complains
that it doesn't recognize "sigma_level" (see below). Am I interpreting
the diagnostic message correctly and if so should Ferret support units
of "sigma_level"?
! Define the dataset we will work with
use "http://localhost/cgi-bin/nph-dods/dgom/$1"
!-> SET DAT/FORM=CDF
"http://localhost/cgi-bin/nph-dods/dgom/hazmat.nc"
*** NOTE: Units on axis "sigma" are not recognized: sigma_level
*** NOTE: They will not be convertible:
Thanks for helping me understand what, if anything, needs to be done to
address this issue.
John
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