[IDV #XYH-126534]: multiple file display

["Unidata IDV Support" <support-idv@xxxxxxxxxxxxxxxx>]

Hi-

> I have 24 netcdf files containing each hour of WRF
> output. I have no problem loading the datasets into
> IDV, however, I want to display a single variable
> (e.g., 2 meter temperature) for all hours w/o loading
> each hour manually. Is there a convenient way to do
> this?

Right now, we don't have an easy way to aggregate the
separate files on the fly.  For GRIB products, there is
a Data Source Type that will aggregate the individual
timesteps into a single data source.  However, this does
not work for the netCDF files because the time dimension
has a different name.

So, one option would be to write an NcML file that would
aggregate the individual files into one dataset.  You 
would then open that file.  The problem would be that you
would need a different NcML file for each different set
of files.  The NcML file would look like:

<?xml version="1.0" encoding="UTF-8"?>
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>

  <aggregation dimName="Time" type="joinExisting">
      <netcdf location="wrfout-d01-2006070100"/>
      <netcdf location="wrfout-d01-2006070103"/>
  </aggregation>


</netcdf>

(also attached).  you could add as many:

      <netcdf location=""/>

lines as you have files.  Depending how you store the data,
you might be able to use the scan feature like:

    <scan location="/data/model/" suffix=".nc" />

See the documentation on NcML for the scan options:

http://www.unidata.ucar.edu/software/netcdf/ncml/v2.2/Aggregation.html

Alternatively, if you are using IDV 2.4 or higher, you can use the
Formula "Miscellaneous->Make a time sequence from single time grids/images"
which would allow you to select each individual timestep and
create a loop.  That can be tedious for many timesteps and the
NcML approach would be easier at this point.

Don Murray


Ticket Details
===================
Ticket ID: XYH-126534
Department: Support IDV
Priority: Normal
Status: Open

Attachment: wrf.ncml
Description: Binary data