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[IDV #XNA-384239]: IDV - Data from MM5 netCDF to IDV supported netCDF



Hi Mark-

> Attached is the MM5 data file(in the MM5 netCDF format) that I am trying to 
> use in IDV. IDV will allow me to use the Omni control, but I want to be able 
> to use the other tools IDV provides.

Thanks for the sample file.  What is the source of this file (who generates
these, etc).  We looked at this and found a couple of
reasons that the IDV does not like it.

The first is that we are looking for a grid_type_code variable which 
is part of the NUWG convention files we generate.  In looking through
the NUWG conventions online, it doesn't look like there was agreement
on this.  For this file, it looks like the type is defined in
the string grid_type, but since there is no "convention" on what
can go here, we're not sure how to handle this.  Do you have any
documentation on the navigation parameters for these NUWG files?

Secondly, the variables are all dimensioned with a Z variable, but they
appear to be 2D data.

One other issue (though it doesn't keep the IDV from reading the data
once the others are fixed) is that the units for relative humidity is
"meters".  There is a LAPS_units attribute which shows "PERCENT", but
event that is not a valid unit specification (should be percent).

The upshot is that one can overcome these issues by using an NcML
(netCDF Markup Language) file to wrap the file and get it into
the IDV.  If you put the attached NCML file in the same directory as the
fsf file and open that with the IDV, you can view the data.  You can
read more about NCML at:

http://www.unidata.ucar.edu/software/netcdf/ncml

This NCML file adds in variables for the grid_type_code and the Z
coordinate.

If you can get some documentation on the valid entries for
grid_type and the rest of the navigation parameters, we can try 
to add that in to our NUWG parser for a future release.

Don Murray


Ticket Details
===================
Ticket ID: XNA-384239
Department: Support IDV
Priority: Normal
Status: Open

Attachment: MM5.Mercator.nc.fsf.ncml
Description: Binary data