[gradsusr] Reading timesteps in Arpège grib2 file
Brian Gaze
brian.gaze at ntlworld.com
Thu Dec 17 17:17:04 EST 2015
Wesley,
Many thanks for the explanation and solution using alt_g2ctl and alt_gmp.
Brian
> On 17 December 2015 at 13:14 Wesley Ebisuzaki - NOAA Federal
> <wesley.ebisuzaki at noaa.gov> wrote:
>
> Brian,
>
> I am being pedantic because I hope that the ARPEGE and AROME
> people will get word and fix their grib2 files.
>
> In order for GrADS to plot the ARPEGE file, GrADS needs to know the
> time of the fields. For Product Definition Template (PDT) 4.8 which is
> used to describe averages and accumulations, there are 3 different times.
>
> Reference time: start of the forecast
> Section 1, octets 13-19
>
> Start of the forecast time interval:
> reference time + forecast time (Section 3, octets 18-22)
>
> End of the forecast time interval:
> Section 3, octets 35-41
>
> For your ARPEGE file, the only unique time should be the end of the
> forecast
> time interval. However when you examine the ARPEGE file.
>
> ebis at linux-landing:~/Downloads$ wgrib2
> ARPEGE_0.1_SP1_37H48H_201512150000.grib2 -s -start_ft -end_ft -match PRATE
> 133:32079786:d=2015121500:TPRATE:surface:0-37 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 134:32391856:d=2015121500:TPRATE:surface:0-38 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 135:32706662:d=2015121500:TPRATE:surface:0-39 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 136:33024062:d=2015121500:TPRATE:surface:0-40 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 137:33344053:d=2015121500:TPRATE:surface:0-41 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 138:33666613:d=2015121500:TPRATE:surface:0-42 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 139:33991684:d=2015121500:TPRATE:surface:0-43 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 140:34319034:d=2015121500:TPRATE:surface:0-44 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 141:34648323:d=2015121500:TPRATE:surface:0-45 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 142:34979540:d=2015121500:TPRATE:surface:0-46 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 143:35312524:d=2015121500:TPRATE:surface:0-47 hour acc
> fcst::start_ft=2015121500:end_ft=2015121600
> 144:35647622:d=2015121500:TPRATE:surface:0-2 day acc
> fcst::start_ft=2015121500:end_ft=2015121700
>
> You see that the TPRATE (totat precipitation rate) has the end of
> the forecast time interval of 2015121600 which is wrong. This ARPEGE file
> needs to be fixed. A few weeks ago, someone sent me a AROME
> forecast file which had the same problem.
>
> So g2ctl and gribmap will not work until the grib file is fixed.
>
> You can display the fields using
>
> alt_g2ctl -0t ARPEGE_0.1_SP1_37H48H_201512150000.grib2 >a.ctl
> alt_gmp -i a.ctl
>
> This solution gives each field a unique name and doesn't use the
> end of the forecast time.
>
> Maybe someone will inform the ARPEGE and AROME people and they
> will fix their files.
>
> Wesley
>
>
> On Thu, Dec 17, 2015 at 6:13 AM, Brian Gaze < brian.gaze at ntlworld.com
> <mailto:brian.gaze at ntlworld.com> > wrote:
>
> > >
> > Wesley,
> >
> > You can ftp down the grib file here using anonymous:
> >
> > 137.135.248.188
> >
> > ARPEGE_0.1_SP1_37H48H_201512150000.grib2
> >
> > PS: It's about 40 meg and I tested the ftp download successfully
> > from a command line rather than gui client
> >
> > Cheers
> >
> > Brian
> >
> >
> > > > > On 16 December 2015 at 15:03 Wesley Ebisuzaki - NOAA
> > > > > Federal < wesley.ebisuzaki at noaa.gov
> > > > > <mailto:wesley.ebisuzaki at noaa.gov> > wrote:
> > >
> > > Brian,
> > >
> > > It would be much easier if you made your grib file available
> > > by FTP. If the file is huge or is a proprietary forecast, you
> > > can
> > > zero out the data by
> > >
> > > wgrib2 file.grib -rpn 0 -grib_out file00.grb
> > >
> > > Wesley
> > >
> > >
> > >
> > > On Tue, Dec 15, 2015 at 4:32 PM, Brian Gaze <
> > > brian.gaze at ntlworld.com <mailto:brian.gaze at ntlworld.com> > wrote:
> > >
> > > > > > >
> > > > Hi,
> > > >
> > > > I'm working with Arpège grib2 files. These should I
> > > > think each contain up to 13 hourly forecast timesteps. If I
> > > > run...<http://g2ctl.pl>
> > > >
> > > > -verf -b file.grib2 > file.ctl
> > > > gribmap -i file.ctl
> > > >
> > > > ...I'm able to open the .ctl file in GrADS but it only
> > > > has 2 timesteps. T1 seems to be the time the model was initialized and
> > > > T2 the time of the first forecast step.
> > > >
> > > >
> > > > If I try:<http://g2ctl.pl>
> > > >
> > > > -b -ts1hr file.grib2 > file.ctl
> > > > gribmap -i file.ctl
> > > >
> > > > It opens ok in GrADS and the correct number of timesteps
> > > > are present but they begin from the model initialization hour rather
> > > > than incrementing from the time of the first forecast step. For example:
> > > >
> > > > Model initialization: 0z 15/12
> > > > Forecast time range contained in the file is +37 hours
> > > > to +48 hours after initialization
> > > >
> > > > t2 = 1z 15/12
> > > > t3 = 2z 15/12
> > > > .. etc
> > > >
> > > > As a consequence, when I try to plot a variable the grid
> > > > is undefined.
> > > >
> > > >
> > > > What should I think be present is:
> > > > t2 = 13z 16/12
> > > > t3 = 14z 16/12
> > > > ..etc
> > > >
> > > > Any suggestions / ideas on what I'm doing wrong?
> > > >
> > > > Thanks
> > > >
> > > > BWG
> > > >
> > > >
> > > > _______________________________________________
> > > > gradsusr mailing list
> > > > gradsusr at gradsusr.org <mailto:gradsusr at gradsusr.org>
> > > > http://gradsusr.org/mailman/listinfo/gradsusr
> > > >
> > > >
> > > > > > >
> > >
> > > > >
> >
> > >
>
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