[gradsusr] Reading timesteps in Arpège grib2 file
AMS EmsiWx Bytča
emsiwx at pocasie-bytca.sk
Thu Dec 17 09:31:15 EST 2015
Dear Wesley and All,
I have been communicated ARPEGE grib2 issue with Meteo France for a
month or so,
They claimed the file was ok.
I have copy-pasted your part of the email and have sent them again.
Will see what they say now.
Marian
Dňa 17. 12. 2015 o 14:14 Wesley Ebisuzaki - NOAA Federal napísal(a):
> 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...
>>
>> g2ctl.pl <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:
>>
>> g2ctl.pl <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
>>
>>
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>>
>>
>
>
>
>
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