[Met_help] MODE inputs

John Halley Gotway johnhg at rap.ucar.edu
Wed Feb 18 16:08:43 MST 2009


Let me see if I understand your situation correctly.  You are running the
WRF-ARW model and are generating WRF NetCDF output files.  You're running
those NetCDF output files through the WRF Post-Processor (WPP) and
generating GRIB files.  Then you trying to use the PCP-Combine tool in MET
to combine the precipitation fields.

Please note that PCP-Combine currently only reads GRIB files.  So you'd
need to run your WRF output through WPP prior to running MET.

You say that you'd like to combine RAINC and RAINNC from the model.  Now
I'm not sure when you run your data through WPP, how does it write those
fields out?  Perhaps they're written as large scale precip (NCPCP) and
convective precip (ACPCP).

And your question is this: Is there a way to get PCP-Combine to add
together NCPCP and ACPCP?  The short answer is no, not currently.

But if I understand correctly, I'm wondering why don't you just use the
accumulated precipitation field, APCP (i.e. GRIB code 61)?  The StageIV
analysis, against which you're verifying, is accumulated precip (code 61).
 Is there a reason that you'd like to combine RAINC and RAINNC, rather
than just using accumulated precip directly?

If there is some reason why combining these two precip types makes sense,
we could probably add support for it to the PCP-Combine tool.

Do I understand the situation correctly?  Does verifying APCP accomplish
what you're trying to do?

John Halley Gotway
johnhg at ucar.edu

> Hi!
> I have been working with the MODE tool within MET off and on for a year
> now.  I have to tool properly configured as it will work with the canned
> data and some of my own data.  My main issue is that I am trying to
> compare 1 or 3 hour surface accumulations of rainfall from WRF output
> (convective and grid scale) and Stage IV observations.  I have
> successfully used copygb and pcp_combine to format the Stage IV obs. but
> with the modeled data, I haven't been able to: add the rainc and rainnc
> variables; get the proper accumulation period; and then write out a netcdf
> or GRIB file.  Is there a program available that will properly process my
> modeled data?
> Thank you!
> Shelley
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