[Met_help] help with copygb

[John Halley Gotway]

Hello Jeff,

You basically need to figure out what command line options to pass to
copygb to tell it how to regrid the data.  Hopefully, you have the "wgrib"
utility available on your system.

If not, it can be downloaded and built from here:
http://www.cpc.noaa.gov/products/wesley/wgrib.html

Try running this command on your WRFPRS file:
wgrib -V WRFPRS_d02.012_00

That will dump out, among other things, the definition of the grid on
which your WRF data resides.  Next, you'll need to take those values and
translate them into the correct arguments to copygb.

The arguments will differ somewhat depending on the type of projection
used for the WRFPRS data.  But it'll probably be on either a lat/lon,
polar stereographic, or lambert conformal grid.  Please look at slides 26,
27, and 28 of the WPP tutorial talk for examples of specifying these 3
types of grids:
http://www.mmm.ucar.edu/wrf/users/tutorial/200907/Basic/2009jul_wpp_joint_tutorial.pdf

One thing that's a little funny is that latitude and longitude are passed
into copygb as thousandths of a degree.  That keeps everything as integers
on the command line.  So, once you've figured out your copygb arguments,
you'd call copygb with something like this:

copygb -xg'255 0 201 201 25000 270000 128 45000 290000 100 100 64'
ST4.2008071918_01h ST4.2008071918_01h_wrf.grib

That'll use all of the default interpolation options and regrid to the
grid defined by that string beginning with 255.  Once you've done this,
double-check your work by running the copygb output through wgrib:
wgrib -V ST4.2008071918_01h_wrf.grib

And make sure the grid definition matches exactly the one from your WRFPRS
file.

If you get stuck, just send me the output of "wgrib -V WRFPRS_d02.012_00"
and I can tell you what copygb arguments you should use.

Hope that helps.

John

> Hello,
> I am trying to use the copygb utility included with the WPP software to
> regrid Stage IV precip data from its original grid to the same grid as my
> WRF model runs.  I have read the usage guide in copygb.doc, but it isn't
> helping me with what specifically I want to do.  I have GRIB files for
> both
> sources (ST4.2008071918_01h and WRFPRS_d02.012_00 are my GRIB files for
> the
> Stage IV data (left) and my WRF output (right)).  My issue is with the
> grid
> flag option "-g".  I want to copy the Stage IV data to be on the same grid
> as my WRFPRS file.  I figure that means I need to have the grid flag
> option
> set at "-4", but I get errors when trying to run it.  Here is the command
> line I'm using:
>
> * ./copygb.exe -g-4 -b WRFPRS_d02.012_00.idx -a ST4.2008071918.01h
> ST4.2008071918.01h.idx WRFPRS_d02.012_00*
>
>
> And I get this error:
> *copygb: unsupported output grid -4*
>
> I don't want to put in a positive number because that means copygb will
> try
> to copy the Stage IV data onto an AWIPS grid, and I don' want that.  How
> do
> I get it to copy to my WRF output grid?
>
> Thanks.
>
> Jeff Duda
>
> --
> Jeff Duda
> Iowa State University
> Meteorology Graduate Student
> 3134 Agronomy Hall
> www.meteor.iastate.edu/~jdduda
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