[Met_help] [rt.rap.ucar.edu #79110] History for about the definition of the observation variable wind vs ugrd or vgrd
John Halley Gotway via RT
met_help at ucar.edu
Mon Jan 9 14:32:48 MST 2017
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Initial Request
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Dear Mr. or Mrs.,
In the file like
:point_stat_namrr_hi_impnest_F06_ADPUPA_060000L_20151031_000000V.stat,
for the line type CNT,
in the observation var part,
there could be string WINDS or UGRD(VGRD..
For the former case, as in
^^
V5.2 namrr_hi_impnest 060000 20151031_000000 20151031_000000 000000
20151030_234500 20151031_001500 WIND P400 WIND P400 ADPUPA
FULL BILIN 4 NA NA NA 0.01 CNT
7 26.44202 18.12604 34.758 NA NA
5.93458 3.37537 17.68397 NA NA 33.09483 20.46217
45.7275 NA NA 9.0
VV
For the latter case as in
^^
V5.2 namrr_hi_impnest 060000 20151031_000000 20151031_000000 000000
20151030_234500 20151031_001500 UGRD P700 UGRD P700 ADPUPA
FULL BILIN 4 NA NA NA 0.01 CNT
7 8.65087 1.71962 15.58212 NA NA
4.94639 2.81333 14.73934 NA NA 8.91429 0.37783
17.4
VV
What are the obs corresponding to "WINDS" and "UGRD/VGRDS" respectively.
Your clarification is appreciated.
Best Regards,
Ting
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Complete Ticket History
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Subject: about the definition of the observation variable wind vs ugrd or vgrd
From: John Halley Gotway
Time: Mon Jan 09 14:18:54 2017
Hello Ting,
I see that you have a question about the variable names used for the
verification output of wind.
First, those strings, WIND, UGRD, and VGRD are GRIB code
abbreviations,
defined here:
http://www.nco.ncep.noaa.gov/pmb/docs/on388/table2.html
UGRD and VGRD are the U (east-west) and V (north-south) components of
the
wind which are GRIB codes 33 and 34.
WIND is GRIB code 32 and is the wind speed.
Here's how the logic works in MET. Observed U and V wind components
are
assumed to be defined relative to the earth. However, for most models
the
U and V wind components are defined relative to the grid. When the
user
requests that UGRD and VGRD be evaluated, MET reads in the gridded
data
fields and checks to see if they are defined relative to the grid. If
so,
MET rotates them from grid-relative to earth-relative before comparing
them
to the observations. If you turn up the verbosity level of point_stat
high
enough (-v 4 or -v 5), you'll see log messages about wind rotations.
For WIND, MET first checks to see if a wind speed GRIB record exists
in the
input file. If so, it uses it as-is. If not (which is often the
case), it
reads in the corresponding UGRD and VGRD records and derives wind
speed on
the fly. Then it compares the derived values to the observations.
This
logic works for both GRIB1 and GRIB2 files, but no other gridded file
formats.
Hope that helps clarify.
Thanks,
John Halley Gotway
On Mon, Jan 9, 2017 at 2:05 PM, Ting Lei - NOAA Affiliate via RT <
met_help at ucar.edu> wrote:
>
> Mon Jan 09 14:05:30 2017: Request 79110 was acted upon.
> Transaction: Ticket created by ting.lei at noaa.gov
> Queue: met_help
> Subject: about the definition of the observation variable wind
vs
> ugrd or vgrd
> Owner: Nobody
> Requestors: ting.lei at noaa.gov
> Status: new
> Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=79110 >
>
>
> Dear Mr. or Mrs.,
>
> In the file like
>
:point_stat_namrr_hi_impnest_F06_ADPUPA_060000L_20151031_000000V.stat,
> for the line type CNT,
> in the observation var part,
> there could be string WINDS or UGRD(VGRD..
> For the former case, as in
> ^^
> V5.2 namrr_hi_impnest 060000 20151031_000000 20151031_000000
000000
> 20151030_234500 20151031_001500 WIND P400 WIND P400
ADPUPA
> FULL BILIN 4 NA NA NA
0.01 CNT
> 7 26.44202 18.12604 34.758 NA
NA
> 5.93458 3.37537 17.68397 NA NA 33.09483
20.46217
> 45.7275 NA NA 9.0
>
> VV
> For the latter case as in
> ^^
> V5.2 namrr_hi_impnest 060000 20151031_000000 20151031_000000
000000
> 20151030_234500 20151031_001500 UGRD P700 UGRD P700
ADPUPA
> FULL BILIN 4 NA NA NA
0.01 CNT
> 7 8.65087 1.71962 15.58212 NA
NA
> 4.94639 2.81333 14.73934 NA NA 8.91429
0.37783
> 17.4
>
> VV
>
> What are the obs corresponding to "WINDS" and "UGRD/VGRDS"
respectively.
>
> Your clarification is appreciated.
> Best Regards,
> Ting
>
>
------------------------------------------------
Subject: about the definition of the observation variable wind vs ugrd or vgrd
From: Ting Lei - NOAA Affiliate
Time: Mon Jan 09 14:30:04 2017
Hi, John,
Thanks a lot for your perfect clarifications as always.
I got it.
Best Regards,
Ting
On Mon, Jan 9, 2017 at 4:18 PM, John Halley Gotway via RT
<met_help at ucar.edu
> wrote:
> Hello Ting,
>
> I see that you have a question about the variable names used for the
> verification output of wind.
>
> First, those strings, WIND, UGRD, and VGRD are GRIB code
abbreviations,
> defined here:
> http://www.nco.ncep.noaa.gov/pmb/docs/on388/table2.html
>
> UGRD and VGRD are the U (east-west) and V (north-south) components
of the
> wind which are GRIB codes 33 and 34.
> WIND is GRIB code 32 and is the wind speed.
>
> Here's how the logic works in MET. Observed U and V wind components
are
> assumed to be defined relative to the earth. However, for most
models the
> U and V wind components are defined relative to the grid. When the
user
> requests that UGRD and VGRD be evaluated, MET reads in the gridded
data
> fields and checks to see if they are defined relative to the grid.
If so,
> MET rotates them from grid-relative to earth-relative before
comparing them
> to the observations. If you turn up the verbosity level of
point_stat high
> enough (-v 4 or -v 5), you'll see log messages about wind rotations.
>
> For WIND, MET first checks to see if a wind speed GRIB record exists
in the
> input file. If so, it uses it as-is. If not (which is often the
case), it
> reads in the corresponding UGRD and VGRD records and derives wind
speed on
> the fly. Then it compares the derived values to the observations.
This
> logic works for both GRIB1 and GRIB2 files, but no other gridded
file
> formats.
>
> Hope that helps clarify.
>
> Thanks,
> John Halley Gotway
>
> On Mon, Jan 9, 2017 at 2:05 PM, Ting Lei - NOAA Affiliate via RT <
> met_help at ucar.edu> wrote:
>
> >
> > Mon Jan 09 14:05:30 2017: Request 79110 was acted upon.
> > Transaction: Ticket created by ting.lei at noaa.gov
> > Queue: met_help
> > Subject: about the definition of the observation variable
wind vs
> > ugrd or vgrd
> > Owner: Nobody
> > Requestors: ting.lei at noaa.gov
> > Status: new
> > Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=79110 >
> >
> >
> > Dear Mr. or Mrs.,
> >
> > In the file like
> >
:point_stat_namrr_hi_impnest_F06_ADPUPA_060000L_20151031_000000V.stat,
> > for the line type CNT,
> > in the observation var part,
> > there could be string WINDS or UGRD(VGRD..
> > For the former case, as in
> > ^^
> > V5.2 namrr_hi_impnest 060000 20151031_000000 20151031_000000
000000
> > 20151030_234500 20151031_001500 WIND P400 WIND P400
ADPUPA
> > FULL BILIN 4 NA NA NA
0.01
> CNT
> > 7 26.44202 18.12604 34.758 NA
NA
> > 5.93458 3.37537 17.68397 NA NA 33.09483
20.46217
> > 45.7275 NA NA 9.0
> >
> > VV
> > For the latter case as in
> > ^^
> > V5.2 namrr_hi_impnest 060000 20151031_000000 20151031_000000
000000
> > 20151030_234500 20151031_001500 UGRD P700 UGRD P700
ADPUPA
> > FULL BILIN 4 NA NA NA
0.01
> CNT
> > 7 8.65087 1.71962 15.58212 NA
NA
> > 4.94639 2.81333 14.73934 NA NA 8.91429
0.37783
> > 17.4
> >
> > VV
> >
> > What are the obs corresponding to "WINDS" and "UGRD/VGRDS"
respectively.
> >
> > Your clarification is appreciated.
> > Best Regards,
> > Ting
> >
> >
>
>
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