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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Hi Don- Don Morton wrote:
Hi, I'm pretty new to IDV and am just exploring the capabilities. I've loved the idea that I can take my WRF output files (netCDF or GRIB) and rapidly view the differentfields.
Glad this is working for you.
What I'm looking for - and I've found no indication that this is possible - is to open multiple WRF output files (one per timestep) and sequence through them - here's an example: My current WRF output is set up to come out in netCDF files at 3-hour intervals - one file for every three forecast hours (this is necessary so that I can produce GRIB data for NWS AWIPS in a real-time manner). What I'd "like" to be able to do, after the WRF run is completed, is to start up IDV, open all of the WRF output files as input, then sequence in time through a specified field (e.g. 500mb heights) with a common perspective.
The only possible way to do this is to use an netCDF Markup Language (NcML) file. However, I would need some sample files to be able to create the NcML file. Could you place 3 files from one run on an FTP server? Or, if you are daring, look at the docs at: http://www.unidata.ucar.edu/software/netcdf/ncml/v2.2/Aggregation.html and try to construct an NcML file using the JoinExisting option.
If I had all of my output data in a single file, this would be a no-brainer, but I don't see an intuitive way to do this with IDV, unless I'm willing to concatenate all my files into a single one, then run IDV. I'm guessing that's what I'm going to have to do, but if I've missed something and there's a better way, I'd sure appreciate hearing about it.
One of the projects on the netCDF for Java development plate is to do aggregations of multiple grib files since that is how many people are storing their WRF output. For now, the only solution is to concatenate the grib files together. There is one caveat with that though. If you always use the same file name for the concatenated file, you'll need to delete the index file that is created. This index is in your home directory under the .metapps/DefaultIdv/tmp/nj22 directory. It will have a name that looks like the filepath to the concatentated file with a .gbx extension. Currently, using NcML to aggregate the grib files might not work. Don ************************************************************* Don Murray UCAR Unidata Program dmurray@xxxxxxxxxxxxxxxx P.O. Box 3000 (303) 497-8628 Boulder, CO 80307 http://www.unidata.ucar.edu/staff/donm *************************************************************
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