[Met_help] [rt.rap.ucar.edu #70294] History for nam rainfall forecast

[John Halley Gotway via RT]

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  Initial Request
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Dear MET help,

I want to produce NAM rainfall forecast skill score with MET (comparing with stage IV observation).
Is there a way of doing so?
NAM data are downloaded from here:
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/nam/prod/
They are in GRIB format, however, in order to get their three hourly rainfall, we need an additional post processing step.  
Do you know if there are any softwares that we can use to preprocess NAM for MET?

Thanks,
Di


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  Complete Ticket History
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Subject: nam rainfall forecast
From: John Halley Gotway
Time: Wed Jan 07 13:34:33 2015

Hello Di,

You should definitely be able to use MET to compare NAM to StageIV
observations.  Since you're comparing a gridded forecast to a gridded
observation, you'd use the MET grid_stat tool.  Here are the steps I'd
suggest:
(1) Decide the grid over which you'd like to compute that statistics -
either NAM grid or the 4km StageIV grid.
(2) Decide what rainfall accumulation interval you'd like to evaluate
-
sound like you're interested in 3-hourly accumulations.
(3) Use copygb to either regrid the NAM to the StageIV domain or vice
versa.  Examples of running copygb are included in the MET online
tutorial:

http://www.dtcenter.org/met/users/support/online_tutorial/METv5.0/copygb/index.php
(4) Now that you have the forecast and observations on a common grid,
run
the MET pcp_combine tool to put the precipitation into 3-hourly bins.
StageIV is available in 1, 6, and 24 hourly chunks.  To get 3 hourly,
you
could add up 3 1-hourly files (e.g. pcp_combine -add).  NAM
precipitation
may already be available in 3-hourly chunks.  If so, no additional
work is
required.  If not, you may need to run pcp_combine to get it into 3-
hourly
bins.
(5) Copy over and setup a configuration file for the grid_stat tool.
Specify the geographic regions over which you want to compute
statistics,
the precipitation thresholds you'd like to use, and the statistical
output
types you'd like to see (usually contingency table counts (CTC) and
contingency table statistics (CTS), but maybe continuous statistics
(CNT)
too).
(6) Run grid_stat once for each 3-hourly accumulation you'd like to
evaluate.

I'd suggest putting these steps together into a script that you'd run
once
for each forecast to be evaluated.

As for the statistics MET computes, please refer to appendix C of the
MET
user's guide:
   http://www.dtcenter.org/met/users/docs/overview.php

As for skill scores, the CTS line type includes the Gilbert Skill
Score and
Heidke Skill Score, along with several other statistics.

Hope that helps get you going.

Thanks,
John Halley Gotway
met_help at ucar.edu

On Wed, Jan 7, 2015 at 12:25 PM, Wu, Di[SCIENCE SYSTEMS APPLICATIONS]
via
RT <met_help at ucar.edu> wrote:

>
> Wed Jan 07 12:25:43 2015: Request 70294 was acted upon.
> Transaction: Ticket created by di.wu at nasa.gov
>        Queue: met_help
>      Subject: nam rainfall forecast
>        Owner: Nobody
>   Requestors: di.wu at nasa.gov
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=70294 >
>
>
> Dear MET help,
>
> I want to produce NAM rainfall forecast skill score with MET
(comparing
> with stage IV observation).
> Is there a way of doing so?
> NAM data are downloaded from here:
> ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/nam/prod/
> They are in GRIB format, however, in order to get their three hourly
> rainfall, we need an additional post processing step.
> Do you know if there are any softwares that we can use to preprocess
NAM
> for MET?
>
> Thanks,
> Di
>
>

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