[Met_help] MET/pcp_combine help

[John Halley Gotway]

Jeff,

Sorry for the delay in getting back to you.

Actually, the output of the PCP-Combine tool is a NetCDF file.  We use
NetCDF as our internal file format.  The other MET tools, like Grid-Stat,
Point-Stat, MODE, and Wavelet-Stat are all able to read GRIB files or the
NetCDF output of the PCP-Combine tool.

For the next release of MET, we're working on generalizing our support for
NetCDF so that we're able to read more flavors of NetCDF and not just the
output of the PCP-Combine tool.

Since the output is NetCDF, I'd suggest using the ncdump or ncview tools
to display/interrogate the data.  And let me refer to the MET User's Guide
(http://www.dtcenter.org/met/users/docs/users_guide/MET_Users_Guide_v2.0_rev2.pdf)
for more details.

Hope that helps.

John

> John,
> I was able to successfully run copygb with your help and now am looking to
> run pcp_combine, subtract, to get a one hour precip field from my WRF
> output
> files.  I have isolated the two files (and actually uploaded them to the
> server described in previous emails), and used the following command to
> run
> pcp_combine assuming the following:
>
>   "accum1" indicates the accumulation interval to be used from in_file1 in
> HH format (required).   -I set this as 12
>   "accum2" indicates the accumulation interval to be used from in_file2 in
> HH format (required).   -I set this as 11
>
> I got this:
>
> /bin/pcp_combine -subtract WRFPRS_d02.012_00 12 WRFPRS_d02.011_00 11
> difference.out
> Reading input file: WRFPRS_d02.012_00
> Reading input file: WRFPRS_d02.011_00
> Performing subtraction command.
> Writing output file: difference.out
>
> Figuring that pcp_combine took the difference between two GRIB files, the
> output should also be grip, no?  So I tried to convert it to view using
> Grads, but got an error when I ran grib2ctl.pl:
> "/grib2ctl.pl difference.out > difference_ctl.ctl
> found unidentified data
> Big problem:
>   either difference.out is missing or not a grib file
>   or wgrib is not on your path
>
> Please help.  Thank you very much for your help so far.
>
> Jeff Duda
>
> On Fri, Dec 18, 2009 at 3:45 PM, John Halley Gotway
> <johnhg at rap.ucar.edu>wrote:
>
>> Jeff,
>>
>> Well I'd first check to see what's actually in that GRIB file using the
>> "wgrib" command.  For example, try this:
>> wgrib WRFPRS_d02.012_00 | grep APCP
>>
>> That'll dump out the contents of that GRIB file, looking only for the
>> APCP
>> records (accumulated precip).  Look to see if that file really does
>> contain a record for 0-12 hour accumulated precip.
>>
>> If you have more questions about this, it'd probably be easier for you
>> to
>> just send me some sample data to take a look at.  If you'd like to do
>> that, you could post it to our anonymous ftp site in the following way:
>>
>> cd "the directory that contains the files you want to send"
>> ftp ftp.rap.ucar.edu
>> username = anonymous
>> password = "your email address"
>> cd incoming/irap/met_help
>> mkdir duda_data
>> cd duda_data
>> put WRFPRS_d02.012_00
>> put WRFPRS_d02.011_00
>> bye
>>
>> Hope that helps.
>>
>> John
>>
>> > John,
>> > I am Bill Gallus' student and I am trying to use MODE to verify a WRF
>> > model
>> > run using accumulated precip.  To do this, I need to match Stage_IV
>> data
>> > to
>> > my model grid.  To do that, though, I need to get a difference in
>> precip
>> > file to compare with Stage_IV data (which has 1 hourly accumulated
>> > precip).
>> > My WRF files use run total accumulated precip.  I have run WPP on the
>> > NetCDF
>> > output of the WRF files and now am trying to use pcp_combine -subtract
>> to
>> > basically subtract the total accumulated precip from one file from one
>> an
>> > hour before it (my NetCDF output interval is 15 minutes).  When I
>> tried
>> to
>> > run pcp_combine, though, I got an error.  Can you help me with this,
>> > please?  Thank you.
>> >
>> >
>> > Here's a screen grab of the command and error:
>> >
>> > -bash-3.2$ /usr/local/METv2.0/bin/pcp_combine -subtract
>> WRFPRS_d02.012_00
>> > 12
>> > WRFPRS_d02.011_00 11 20080719_18-17_precipdiff
>> > Reading input file: WRFPRS_d02.012_00
>> >
>> >
>> > ERROR: get_field() -> can't find grib code 61 with accumulation of 12
>> > hours
>> > in grib file: WRFPRS_d02.012_00
>> >
>> > Jeff Duda
>> > --
>> > Jeff Duda
>> > Iowa State University
>> > Meteorology Graduate Student
>> > 3134 Agronomy Hall
>> > www.meteor.iastate.edu/~jdduda
>> <http://www.meteor.iastate.edu/%7Ejdduda>
>> >
>>
>>
>>
>
>
> --
> Jeff Duda
> Iowa State University
> Meteorology Graduate Student
> 3134 Agronomy Hall
> www.meteor.iastate.edu/~jdduda
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