[Met_help] [rt.rap.ucar.edu #40061] History for 2 quick ascii2nc format questions

[RAL HelpDesk {for John Halley Gotway}]

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  Initial Request
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Hello,

I am writing a program to convert madis observations to the ascii file
format required by the "ascii2nc" program. I have 2 brief questions:

1) How do I write an entries for 2m-temperature or 10m-wind surface
observations where the station pressure is unknown/un-reported. Looking at
the ascii2nc documentation it appears as though the "Elev" & "Hgt" columns
are not used (ie -9999). Furthermore, the "Lvl" column expects only pressure
or accumulation intervals, but not height. Without a way to include 2m or
10m above ground heights, is there any way to distinguish a difference in
these observations? Without an observation pressure can I set "Lvl" to -9999
without point_stat rejecting these?

2) If I do not have a WMO id for an observation, can I set this field to
-999 without the observation being rejected?

I would greatly appreciate advice on how to proceed with these two issues.

Thanks,
Scott


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  Complete Ticket History
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Subject: Re: [rt.rap.ucar.edu #40061] 2 quick ascii2nc format questions
From: John Halley Gotway
Time: Fri Aug 13 10:31:25 2010

Scott,

Good questions.

I'll answer the second one first.

(2) You're welcome to put in any text string you'd like in the station
name column.  Personally, I'd think a string like "NA" or "MISSING"
would make more sense.  Point-Stat shouldn't reject
observations based on the station name unless you use the "mask_sid"
option in the Point-Stat config file to list out the names of the
stations you want.  But as long as you're just looking over an
area, using a masking grid or polyline, it'll behave as you expect.

And now to the first question.

(1) I see that you want to verify 2-m tmp and 10-m winds.  Point-Stat
treats these surface observations in a special way we've inherited
from the NCEP verification software upon which MET was
initially based.  When verifying surface variables, the actual
pressure or level values of the observation are NOT used.  Instead,
the matching is only done using message types.  Specifically,
observations with message types of "ADPSFC" or "SFCSHP" are used to
verify surface variables.  So in your reformatting step, be sure to
encode 2-m tmp and 10-m winds with the "ADPSFC" message type.

Just let us know if more questions arise in your use of MET.

Thanks,
John Halley Gotway
met_help at ucar.edu

RAL HelpDesk {for Scott Rabenhorst} wrote:
> Fri Aug 13 09:55:53 2010: Request 40061 was acted upon.
> Transaction: Ticket created by scott.rabenhorst at gmail.com
>        Queue: met_help
>      Subject: 2 quick ascii2nc format questions
>        Owner: Nobody
>   Requestors: scott.rabenhorst at gmail.com
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=40061 >
>
>
> Hello,
>
> I am writing a program to convert madis observations to the ascii
file
> format required by the "ascii2nc" program. I have 2 brief questions:
>
> 1) How do I write an entries for 2m-temperature or 10m-wind surface
> observations where the station pressure is unknown/un-reported.
Looking at
> the ascii2nc documentation it appears as though the "Elev" & "Hgt"
columns
> are not used (ie -9999). Furthermore, the "Lvl" column expects only
pressure
> or accumulation intervals, but not height. Without a way to include
2m or
> 10m above ground heights, is there any way to distinguish a
difference in
> these observations? Without an observation pressure can I set "Lvl"
to -9999
> without point_stat rejecting these?
>
> 2) If I do not have a WMO id for an observation, can I set this
field to
> -999 without the observation being rejected?
>
> I would greatly appreciate advice on how to proceed with these two
issues.
>
> Thanks,
> Scott

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