[Met_help] [rt.rap.ucar.edu #74879] History for Question Concerning ascii2nc

[John Halley Gotway via RT]

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  Initial Request
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Hello, my name is Andrew, and I am working on doing some verifications with the MET system.
I have been using the MET system for quite some time, and I recently ran across the issue of verifying both 1- and 3-hourly precipitation values. For our model simulations, both values are interesting in terms of verification. As the model has a 1-hourly time resolution, it is not difficult to create either a 1- or 3-hourly precipitation field using the accumulated precipitation from the parent grib files and the pcp_combine tool.  

However, I am running into a problem when creating a netcdf observation file using the ascii2nc tool.  I have observation ascii files (in the correct format), with observations of both 1- and 3-hourly precipitation. I would like to create one netcdf from these observations using ascii2nc. However, it does not appear that I can save both of these fields into a resultant netcdf file, because there is only one grib code (61) for accumulated precipitation.  This means that I would need to generate a whole new observation netcdf each time I wanted to evaluate a new time resolution for precipitation accumulation.  This, of course, takes time with many observations, and is currently not optimal for what I would like to do.  Would you have suggestions / is there a possible work around to save both 1- and 3-hourly accumulated precipitation observations in the same ascii2nc output netcdf file?
Thank you in advance!
- Andrew


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  Complete Ticket History
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Subject: Question Concerning ascii2nc
From: John Halley Gotway
Time: Wed Jan 27 09:57:06 2016

Andrew,

I'm glad you've found MET to be useful in your work.  I see that
you're
asking how to store observations for both 1 and 3-hour accumulated
precipitation point observations in a single file.  I expect this to
be
very straight-forward, but if something doesn't work as expected,
please
let us know so we can troubleshoot.

Listed below is the generic 11-column ascii format expected by
ascii2nc, as
listed in the usage statement for that tool:

        The "met_point" ASCII format consists of 11 columns:
                Message_Type Station_ID Valid_Time(YYYYMMDD_HHMMSS)
                Lat(Deg North) Lon(Deg East) Elevation(msl)
                Grib_Code Level Height(msl or agl) QC_String
Observation_Value

                where   "Level" is the pressure level (hPa) or
accumulation
interval (HH[MMSS]).
                        "Height" is meters above sea level or above
ground
level for the observation (msl or agl).

Note that the "Level" column (#8) should either be a pressure level or
accumulation interval.  For observations of accumulated precipitation,
it
should obviously be an accumulation interval in HH or HHMMSS format.
You
should just be able to set that column to "01" for hourly and "03" for
3-hourly accumulated precip.  Both would use the GRIB code of 61 to
indicate that it's accumulated precip.

Next, when you use these observations to verify your model output with
Point-Stat, you need to make sure that only hourly observations are
used to
verify the hourly forecast and 3-hourly observations for the 3-hourly
forecast.  Run Point-Stat with the matched pair (MPR) output turned
on, and
inspect the output closely to make sure the correct observations are
being
used to verify the 1 and 3-hourly accumulations.

If there's any issue there, I'll ask you to send us some test data to
debug
it.

Hope that helps.

Thanks,
John Halley Gotway


On Wed, Jan 27, 2016 at 2:49 AM, Andrew J. via RT <met_help at ucar.edu>
wrote:

>
> Wed Jan 27 02:49:14 2016: Request 74879 was acted upon.
> Transaction: Ticket created by andrewwx at yahoo.com
>        Queue: met_help
>      Subject: Question Concerning ascii2nc
>        Owner: Nobody
>   Requestors: andrewwx at yahoo.com
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=74879 >
>
>
> Hello, my name is Andrew, and I am working on doing some
verifications
> with the MET system.
> I have been using the MET system for quite some time, and I recently
ran
> across the issue of verifying both 1- and 3-hourly precipitation
values.
> For our model simulations, both values are interesting in terms of
> verification. As the model has a 1-hourly time resolution, it is not
> difficult to create either a 1- or 3-hourly precipitation field
using the
> accumulated precipitation from the parent grib files and the
pcp_combine
> tool.
>
> However, I am running into a problem when creating a netcdf
observation
> file using the ascii2nc tool.  I have observation ascii files (in
the
> correct format), with observations of both 1- and 3-hourly
precipitation. I
> would like to create one netcdf from these observations using
ascii2nc.
> However, it does not appear that I can save both of these fields
into a
> resultant netcdf file, because there is only one grib code (61) for
> accumulated precipitation.  This means that I would need to generate
a
> whole new observation netcdf each time I wanted to evaluate a new
time
> resolution for precipitation accumulation.  This, of course, takes
time
> with many observations, and is currently not optimal for what I
would like
> to do.  Would you have suggestions / is there a possible work around
to
> save both 1- and 3-hourly accumulated precipitation observations in
the
> same ascii2nc output netcdf file?
> Thank you in advance!
> - Andrew
>
>

------------------------------------------------
Subject: Question Concerning ascii2nc
From: Andrew J.
Time: Thu Jan 28 01:31:25 2016

Okay, great!  Thank you for your detailed response. I have been
working with MET for awhile, not sure how I missed the 'accumulation
level' option in the observation file. I'll give it a try! Thanks!


    John Halley Gotway via RT <met_help at ucar.edu> schrieb am 17:57
Mittwoch, 27.Januar 2016:


 Andrew,

I'm glad you've found MET to be useful in your work.  I see that
you're
asking how to store observations for both 1 and 3-hour accumulated
precipitation point observations in a single file.  I expect this to
be
very straight-forward, but if something doesn't work as expected,
please
let us know so we can troubleshoot.

Listed below is the generic 11-column ascii format expected by
ascii2nc, as
listed in the usage statement for that tool:

        The "met_point" ASCII format consists of 11 columns:
                Message_Type Station_ID Valid_Time(YYYYMMDD_HHMMSS)
                Lat(Deg North) Lon(Deg East) Elevation(msl)
                Grib_Code Level Height(msl or agl) QC_String
Observation_Value

                where  "Level" is the pressure level (hPa) or
accumulation
interval (HH[MMSS]).
                        "Height" is meters above sea level or above
ground
level for the observation (msl or agl).

Note that the "Level" column (#8) should either be a pressure level or
accumulation interval.  For observations of accumulated precipitation,
it
should obviously be an accumulation interval in HH or HHMMSS format. 
You
should just be able to set that column to "01" for hourly and "03" for
3-hourly accumulated precip.  Both would use the GRIB code of 61 to
indicate that it's accumulated precip.

Next, when you use these observations to verify your model output with
Point-Stat, you need to make sure that only hourly observations are
used to
verify the hourly forecast and 3-hourly observations for the 3-hourly
forecast.  Run Point-Stat with the matched pair (MPR) output turned
on, and
inspect the output closely to make sure the correct observations are
being
used to verify the 1 and 3-hourly accumulations.

If there's any issue there, I'll ask you to send us some test data to
debug
it.

Hope that helps.

Thanks,
John Halley Gotway


On Wed, Jan 27, 2016 at 2:49 AM, Andrew J. via RT <met_help at ucar.edu>
wrote:

>
> Wed Jan 27 02:49:14 2016: Request 74879 was acted upon.
> Transaction: Ticket created by andrewwx at yahoo.com
>        Queue: met_help
>      Subject: Question Concerning ascii2nc
>        Owner: Nobody
>  Requestors: andrewwx at yahoo.com
>      Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=74879 >
>
>
> Hello, my name is Andrew, and I am working on doing some
verifications
> with the MET system.
> I have been using the MET system for quite some time, and I recently
ran
> across the issue of verifying both 1- and 3-hourly precipitation
values.
> For our model simulations, both values are interesting in terms of
> verification. As the model has a 1-hourly time resolution, it is not
> difficult to create either a 1- or 3-hourly precipitation field
using the
> accumulated precipitation from the parent grib files and the
pcp_combine
> tool.
>
> However, I am running into a problem when creating a netcdf
observation
> file using the ascii2nc tool.  I have observation ascii files (in
the
> correct format), with observations of both 1- and 3-hourly
precipitation. I
> would like to create one netcdf from these observations using
ascii2nc.
> However, it does not appear that I can save both of these fields
into a
> resultant netcdf file, because there is only one grib code (61) for
> accumulated precipitation.  This means that I would need to generate
a
> whole new observation netcdf each time I wanted to evaluate a new
time
> resolution for precipitation accumulation.  This, of course, takes
time
> with many observations, and is currently not optimal for what I
would like
> to do.  Would you have suggestions / is there a possible work around
to
> save both 1- and 3-hourly accumulated precipitation observations in
the
> same ascii2nc output netcdf file?
> Thank you in advance!
> - Andrew
>
>




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