[ncl-talk] Confusion on GFS files in GRIB2
Dennis Shea
shea at ucar.edu
Mon Mar 8 14:18:58 MST 2021
[1] Please: Always include the version of NCL you are using.
%> ncl -V
The most recent version is 6.6.2
[2] Before processing, you can examine a GRIB file's contents via:
%> *ncl_filedump* gfs.t00z.pgrb2.0p25.f001.grb | less
Do you see a variable named "TMP_P0_L102_GLL0" ?
[3]
grib_file = "gfs.t00z.pgrb2.0p25.f001" + ".grb"
fin = addfile(grib_file, "r")
varnames = getfilevarnames(fin)
print(varnames)
The output you included shows only vertical dimension variables: lv_*
(0) lv_DBLL14_l1
(1) lv_DBLL14_l0
(2) lv_ISBL13
......SNIP ......
(15) lv_HTGL2
(16) lv_AMSL1
(17) lv_ISBL0
Then, NCL tells you that the variable *TMP_P0_L102_GLL0* *is not in the
grib file *
On Mon, Mar 8, 2021 at 1:35 PM dr.hieronymus--- via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:
> Hi,
>
> Regarding the GFS files, I have written to NCEP. Thanks, that was a good
> idea.
>
> When using following code:
>
> ;;; load ncl scripts/files
> load "/usr/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "/usr/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "/usr/lib/ncarg/nclscripts/csm/contributed.ncl"
>
> begin
>
> ;;; read data from grib file
> grib_file = "gfs.t00z.pgrb2.0p25.f001"
> fin = addfile(grib_file, "r")
> varnames = getfilevarnames(fin)
>
> print(varnames)
> printVarSummary(fin->TMP_P0_L102_GLL0)
>
> ;;; get variables: level, variable, longitude, latitude
> ;t2m = fin->TMP_P0_L102_GLL0(:,:)
> ;lon = fin->lon
> ;lat = fin->lat
>
> ;;; convert to degrees
> ;t2m = t2m-273.15
>
> end
>
> I get the following error message:
>
> warning:NclGRIB2: APCP_P8_L1 contains records that NCL cannot currently
> differentiate. One or more records will be ignored.
> warning:NclGRIB2: ACPCP_P8_L1 contains records that NCL cannot currently
> differentiate. One or more records will be ignored.
> fatal:GdsCEGrid: Invalid grid detected
> fatal:NclGRIB2: Couldn't handle dimension information returned by grid
> decoding
> fatal:NclGRIB2: Deleting reference to parameter because of decoding
> error
> fatal:GdsCEGrid: Invalid grid detected
> fatal:NclGRIB2: Couldn't handle dimension information returned by grid
> decoding
> fatal:NclGRIB2: Deleting reference to parameter because of decoding
> error
> ...
> ...
> ...
> fatal:GdsCEGrid: Invalid grid detected
> fatal:NclGRIB2: Couldn't handle dimension information returned by grid
> decoding
> fatal:NclGRIB2: Deleting reference to parameter because of decoding
> error
> fatal:GdsCEGrid: Invalid grid detected
> fatal:NclGRIB2: Couldn't handle dimension information returned by grid
> decoding
> fatal:NclGRIB2: Deleting reference to parameter because of decoding
> error
>
>
> Variable: varnames
> Type: string
> Total Size: 144 bytes
> 18 values
> Number of Dimensions: 1
> Dimensions and sizes: [18]
> Coordinates:
> (0) lv_DBLL14_l1
> (1) lv_DBLL14_l0
> (2) lv_ISBL13
> (3) lv_ISBL12
> (4) lv_SPDL11_l1
> (5) lv_SPDL11_l0
> (6) lv_ISBL10
> (7) lv_ISBL9
> (8) lv_HTGL8
> (9) lv_ISBL7
> (10) lv_SIGL6_l1
> (11) lv_SIGL6_l0
> (12) lv_ISBL5
> (13) lv_HTGL4
> (14) lv_PVL3
> (15) lv_HTGL2
> (16) lv_AMSL1
> (17) lv_ISBL0
> fatal:["Execute.c":6397]:variable (TMP_P0_L102_GLL0) is not in file
> (fin)
> fatal:["Execute.c":8640]:Execute: Error occurred at or near line 14 in
> file temperature_tmp.ncl
>
> Do I understand correctly that ncl has detected an invalid grid? Why?
>
> Thanks.
>
>
>
> Am 08.03.2021 16:44 schrieb Lyndz:
> > Hi,
> >
> > I'm not sure if this is an ncl question. You should have directed your
> > questions to the ncep help page (
> > https://www.ncep.noaa.gov/mail_dataquestions/)
> >
> > *[1] *As far as I know, the .anl files are analyses files and were
> > already
> > assimilated with observations.
> >
> > *[2]* If you want to use the forecast, then use the files with the
> > following format (
> > https://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.20210308/12/
> ):
> >
> > gfs.t12z.pgrb2.0p25.f000
> > <
> https://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.20210308/12/gfs.t12z.pgrb2.0p25.f000
> >
> >
> > gfs.t12z.pgrb2.0p25.f001
> > <
> https://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.20210308/12/gfs.t12z.pgrb2.0p25.f001
> >
> >
> > etc..
> >
> > No need to download the other files!
> >
> > ncl_filedump gfs.t12z.pgrb2.0p25.f000.grb will give you the contents
> > of the file.
> >
> > If you want temperature, then look for the keyword "Temperature". This
> > will give u information about the variables such as below:
> >
> > float TMP_P0_L102_GLL0 ( lv_AMSL1, lat_0, lon_0 )
> >
> > center : US National Weather Service - NCEP (WMC)
> >
> > production_status : Operational products
> >
> > long_name : Temperature
> >
> > units : K
> >
> > _FillValue : 1e+20
> >
> > grid_type : Latitude/longitude
> >
> > parameter_discipline_and_category : Meteorological
> > products, Temperature
> >
> > parameter_template_discipline_category_number : ( 0, 0,
> > 0, 0 )
> >
> > level_type : Specific altitude above mean sea level (m)
> >
> > forecast_time : 72
> >
> > forecast_time_units : hours
> >
> > initial_time : 03/08/2021 (00:00)
> >
> > The variable name is the same for other GFS files, regardless of
> > resolution.
> >
> > *[3]* For documentation, check this:
> >
> https://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs/documentation.php
> >
> > *[4] *The files are archived in rda.ucar.edu. For the 25km GFS, for
> > example, see this link:
> >
> > https://rda.ucar.edu/datasets/ds084.1/#!docs
> >
> >
> >
> > Hope this helps.
> >
> > --Lyndz
> >
> >
> >
> > On Mon, Mar 8, 2021 at 8:05 PM dr.hieronymus--- via ncl-talk <
> > ncl-talk at mailman.ucar.edu> wrote:
> >
> >> Hello,
> >>
> >> I am trying to dig through GFS files in GRIB2 format on NCEP's FTP
> >> server (https://www.nco.ncep.noaa.gov/pmb/products/gfs/).
> >>
> >> Unfortunately, it is not very easy to get a proper overview.
> >> Therefore,
> >> my first question is whether there is documentation somewhere that
> >> describes the different formats/variants in detail.
> >>
> >> What one quickly notice and easy understand is that the GFS files are
> >> available in different resolutions (0.25°, 0.50°, 1.00°) and each GFS
> >> file is described by an index file. The GFS files with 0.25°
> >> resolution
> >> have an hourly granularity and the GFS files with 0.50° and 1.00°
> >> resolution have a three-hourly granularity.
> >>
> >> Then, there are the .anl and .f000 GFS files. I don't understand the
> >> difference between .anl and .f000. Is .f000 not a forecast?
> >> Furthermore,
> >> I noticed that the index files are different regarding .f000 and
> >> .f001-384 (0.25°) and .f000 and .f003-384 (0.50°, 1.00°).
> >>
> >> What also confuses me are the different GFS files, namely pgrb2,
> >> pgrb2b,
> >> pgrb2full and sfluxgrbfFFF. What are the differences exactly?
> >> According
> >> to the corresponding index files, the same physical variables are
> >> available in all different GFS files. Do these variables always have
> >> the
> >> same values in all GFS files? Doesn't it matter which file I use
> >> when
> >> I have decided on a resolution?
> >>
> >> I am actually only interested in the temperature 2 meters above the
> >> ground. Which file should I simply use?
> >>
> >> In addition, I also wanted to know if the initial values for each
> >> model
> >> run (00, 06, 12, 18) are published somewhere.
> >>
> >> Thank you in advance for your help.
> >> _______________________________________________
> >> ncl-talk mailing list
> >> ncl-talk at mailman.ucar.edu
> >> List instructions, subscriber options, unsubscribe:
> >> https://mailman.ucar.edu/mailman/listinfo/ncl-talk
> _______________________________________________
> ncl-talk mailing list
> ncl-talk at mailman.ucar.edu
> List instructions, subscriber options, unsubscribe:
> https://mailman.ucar.edu/mailman/listinfo/ncl-talk
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.ucar.edu/pipermail/ncl-talk/attachments/20210308/9cea1286/attachment.html>
More information about the ncl-talk
mailing list