[Met_help] [rt.rap.ucar.edu #38806] History for problem running pcp combine for 5 minute radar data

RAL HelpDesk {for John Halley Gotway} met_help at ucar.edu
Mon Jul 12 11:38:02 MDT 2010

  Initial Request



I'm using MET to verify WRF accumulated precipitation files with radar
images. Problem is that the radar files come in 5 minute resolution,
while WRF output is one hourly cumulative precipitation. I tried to use
pcp-combine in MET, but I get the following error:


ERROR: check_file_time() -> time range indicator of  not currently
supported.  Time range indicator must be accumulation (Grib Code 4)


The command I'm trying to run is this:


/cm/shared/apps/met/2.0/METv2.0/bin/pcp_combine \

   -sum ${year}${month}${day}_060000 1/12 ${year}${month}${day}_070000 1

{day}06_24A.nc \



You find the input files in the attachments.


I hope you can help to sum the 5 minute radar data.



Marlous Jonker




  Marlous Jonker

  Meteorological Researcher

  Meteo Consult BV - A MeteoGroup Company

  Wageningen - The Netherlands

  Tel: +31 (0)317 399800

  Email: M.Jonker at weer.nl

  www: research.meteogroup.com




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  Complete Ticket History

Subject: problem running pcp combine for 5 minute radar data
From: John Halley Gotway
Time: Fri Jun 25 11:33:21 2010


I see what you're trying to do here.  You'd like to sum up 12 files,
each containing 5 minutes of precipitation data, into a 1 hour total
of precipitation.

As you can probably guess, pcp_combine was written with the assumption
that we'd be handling precipitation in chunks no finer than 1 hour.
But it would not be very difficult to extend it to allow it to be used
on sub-hourly accumulations.

However, the problem in the radar data you sent me is a more
fundamental problem.  In the GRIB files you sent me, the precipitation
is stored as an instantaneous value - not as an accumulation interval.
Typically, there is an accumulation interval defined for each record
of precipitation, e.g. accumulations of 1, 3, 6, and 12 hours are

Generally speaking, pcp_combine needs to check to make sure that it's
grabbing the correct accumulation intervals.  A lot of model output
files contain multiple accumulation intervals for precip, and we need
to be sure we're using the one the user wants.

I haven't used this type of precip data from radar in the past and
don't know how much control you have over the formatting of the GRIB
file.  From my perspective, the best solution would be for me to
modify pcp_combine to handle 5-minute data well and for you to modify
the GRIB files to correctly list the 5-minute accumulation interval.

Does that sound like a possibility?

John Halley Gotway
met_help at ucar.edu


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