[Met_help] [rt.rap.ucar.edu #98514] History for How to add pressure level as a filter in PB2NC config

[John Halley Gotway via RT]

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  Initial Request
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Hello,

I am wondering is there a way to add the height pressure level as a filter
inside of PB2NC config file? I know there is elevation_range and
level_category as shown below, but if I only want to get a certain pressure
level, say 825mb, how to do that?

elevation_range = {
   beg =  -1000;
   end = 100000;
}
  level_ category = [ ]

Thank you.
Binyu


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  Complete Ticket History
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Subject: How to add pressure level as a filter in PB2NC config
From: John Halley Gotway
Time: Wed Feb 03 09:27:17 2021

Binyu,

No, I do not think there's a way to set up pb2nc to filter
observations by
pressure level. The data isn't stored in a way that would make it
convenient to do so. The closest option is filtering by the
"level_range".
PrepBUFR messages contain up to 255 levels of output. For the ADPUPA
message type, one of those levels would presumably correspond to
825mb. For
other message types, those levels may correspond to meters above
ground, or
cm below ground. But I'm really not sure if the index of the level for
825mb would remain constant across the ADPUPA messages. And frankly
it's
never really come up before.

Even if you could, I wouldn't recommend filtering by pressure level in
PB2NC. The PB2NC tool is first and foremost just a reformatting tool.
I've
always found it much better to pass through most, if not all, of the
observations to the output file. And then specify options in point-
stat or
ensemble-stat to specify exactly which pressure levels you'd like to
use.

One exception to this advice is filtering obs spatially. If you're
using
global (GDAS) PrepBUFR data to verify a limited area model, you could
certainly only retain obs which actually overlap your model domain.
And
that's done using the "mask" dictionary in the PB2NC config file.

Thanks,
John Halley Gotway

On Wed, Feb 3, 2021 at 5:33 AM George McCabe via RT
<met_help at ucar.edu>
wrote:

>
> Wed Feb 03 05:33:42 2021: Request 98514 was acted upon.
> Transaction: Given to johnhg (John Halley Gotway) by mccabe
>        Queue: met_help
>      Subject: How to add pressure level as a filter in PB2NC config
>        Owner: johnhg
>   Requestors: binyu.wang at noaa.gov
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=98514 >
>
>
> This transaction appears to have no content
>

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Subject: How to add pressure level as a filter in PB2NC config
From: binyu.wang at noaa.gov
Time: Wed Feb 03 09:44:48 2021

Thank you for your explanation, it makes sense.
Binyu

On Wed, Feb 3, 2021 at 11:27 AM John Halley Gotway via RT
<met_help at ucar.edu>
wrote:

> Binyu,
>
> No, I do not think there's a way to set up pb2nc to filter
observations by
> pressure level. The data isn't stored in a way that would make it
> convenient to do so. The closest option is filtering by the
"level_range".
> PrepBUFR messages contain up to 255 levels of output. For the ADPUPA
> message type, one of those levels would presumably correspond to
825mb. For
> other message types, those levels may correspond to meters above
ground, or
> cm below ground. But I'm really not sure if the index of the level
for
> 825mb would remain constant across the ADPUPA messages. And frankly
it's
> never really come up before.
>
> Even if you could, I wouldn't recommend filtering by pressure level
in
> PB2NC. The PB2NC tool is first and foremost just a reformatting
tool. I've
> always found it much better to pass through most, if not all, of the
> observations to the output file. And then specify options in point-
stat or
> ensemble-stat to specify exactly which pressure levels you'd like to
use.
>
> One exception to this advice is filtering obs spatially. If you're
using
> global (GDAS) PrepBUFR data to verify a limited area model, you
could
> certainly only retain obs which actually overlap your model domain.
And
> that's done using the "mask" dictionary in the PB2NC config file.
>
> Thanks,
> John Halley Gotway
>
> On Wed, Feb 3, 2021 at 5:33 AM George McCabe via RT
<met_help at ucar.edu>
> wrote:
>
> >
> > Wed Feb 03 05:33:42 2021: Request 98514 was acted upon.
> > Transaction: Given to johnhg (John Halley Gotway) by mccabe
> >        Queue: met_help
> >      Subject: How to add pressure level as a filter in PB2NC
config
> >        Owner: johnhg
> >   Requestors: binyu.wang at noaa.gov
> >       Status: new
> >  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=98514 >
> >
> >
> > This transaction appears to have no content
> >
>
>

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