[ncl-talk] Wrong time decoding on grib2

David Brown dbrown at ucar.edu
Fri May 13 16:10:40 MDT 2016


Hi Nicolas,

I apologize this has taken so long, but I have fixed the issue with
the ARPEGE GRIB2 files. This will be in the new version of NCL: 6.4.0.
Let us know if you would like a test version of NCL prior to the
release.
 -dave

On Wed, Aug 5, 2015 at 12:56 AM, Nicolas GASNIER <ngprod41 at gmail.com> wrote:
> Hi Dave,
>
> Thank you very much for that very quick answer.
> I will wait until this is fixed. If I can be of any help just ask me.
>
> Regards
>
> Nicolas Gasnier
>
>
>
> Le 04/08/2015 23:34, David Brown a écrit :
>>
>> Hi Nicolas,
>> I have confirmed this problem. It appears to happen with the
>> statistically processed variables, TPRATE, an accumulated quantity and
>> SNOM, an averaged quantity. I am opening a ticket for this issue. I
>> can tell you that it will almost definitely involved a change to the
>> source code to fix it, but hopefully it will be a small change. We
>> will be able to supply you with a new binary when it gets fixed.
>> Thanks for bringing this issue to our attention.
>>   -dave
>>
>> On Tue, Aug 4, 2015 at 3:50 AM, Nicolas GASNIER <ngprod41 at gmail.com>
>> wrote:
>>>
>>> Hello NCL users,
>>>
>>> I'm facing another GRIB problem with the new Meteo France datasets.
>>>
>>> This is the ARPEGE and AROME model outputs, freely available as GRIB2
>>> files. Datas are stored in different grib sets for surface data and
>>> pressure level/height data, with a set for a group of 12 and 6 hours
>>> forecasts respectively.
>>>
>>> NCL can read correctly the first time set (00H12H for ARPEGE for
>>> example), but it starts to bug for further forecasts. It seems like NCL
>>> doesn't interpret correctly the time variable, and that problem seems to
>>> increase as the forecast time increase.
>>>
>>> For example, for the first surface dataset for ARPEGE (SP1), if you
>>> print ncl_filedump, the dimension of forecast_time0 variable
>>> is 12 for the 00H12H echeances and the dimension of the TPRATE variable
>>> is (time, lat, lon). It has only 4 for the next 13H24H, and for the
>>> latest sets (75H84H or 85H96H) it alternates between 1 and 2. The TPRATE
>>> variable is 2D only (lat, lon). The expected result is 12 forecast hours
>>> for every set, and the TPRATE variable shoud be always (forecast_time,
>>> lat, lon), as one can see with a wgrib2 ouput (see example output at end
>>> of mail).
>>>
>>> I can convert to netcdf, using wgrib2 or grib_to_netcdf utility : the
>>> time dimension becomes correct. But that process crash sometimes - maybe
>>> due to particularities of the dataset. Anyway, it is too disk and CPU
>>> intensive to be reasonable for my application.
>>>
>>> I hope this issue can be worked around. Any clue about that will be much
>>> appreciated, even solutions involving source patching and compiling !
>>>
>>> The files are too big to be included, but one can get the datasets
>>> directly on MF web site for a test (use SP1 dataset for example) :
>>>
>>> For ARPEGE :
>>>
>>> https://donneespubliques.meteofrance.fr/?fond=produit&id_produit=130&id_rubrique=51
>>>
>>> For AROME
>>>
>>> https://donneespubliques.meteofrance.fr/?fond=produit&id_produit=131&id_rubrique=51
>>>
>>> Thanks for any help.
>>>
>>> Regards
>>>
>>> Nicolas Gasnier
>>>
>>> -------------------------------------------------
>>> Result for the 00H12H dataset :
>>>
>>> $ ncl_filedump ARPEGE_0.1_00H12H_SP1.grib2
>>>    Copyright (C) 1995-2015 - All Rights Reserved
>>>    University Corporation for Atmospheric Research
>>>    NCAR Command Language Version 6.3.0
>>>    The use of this software is governed by a License Agreement.
>>>    See http://www.ncl.ucar.edu/ for more details.
>>>
>>> Variable: f
>>> Type: file
>>> filename:    ARPEGE_0.1_00H12H_SP1
>>> path:    ARPEGE_0.1_00H12H_SP1.grib2
>>>      file global attributes:
>>>      dimensions:
>>>         forecast_time0 = 13
>>>         lat_0 = 521
>>>         lon_0 = 741
>>>         forecast_time1 = 12
>>>      variables:
>>>
>>> ...
>>>
>>>         float TPRATE_P8_L1_GLL0_acc ( forecast_time1, lat_0, lon_0 )
>>>            center :    French Weather Service - Toulouse
>>>            production_status :    Operational products
>>>            long_name :    Total precipitation rate
>>>            units :    kg m-2s-1
>>>            _FillValue :    1e+20
>>>            grid_type :    Latitude/longitude
>>>            parameter_discipline_and_category :    Meteorological
>>> products, Moisture
>>>            parameter_template_discipline_category_number :    ( 8, 0, 1,
>>> 52 )
>>>            level_type :    Ground or water surface
>>>            type_of_statistical_processing :    Accumulation
>>>            statistical_process_duration :    initial time to forecast
>>> time
>>>            initial_time :    08/04/2015 (00:00)
>>>
>>>         integer forecast_time1 ( forecast_time1 )
>>>            long_name :    Forecast offset from initial time
>>>            units :    hours
>>> ...
>>>
>>> $ wgrib2 ARPEGE_0.1_00H12H_SP1.grib2
>>> 1:0:d=2015080400:PRES:mean sea level:anl:
>>> ...
>>> 144:36148384:d=2015080400:TPRATE:surface:0-1 hour acc fcst:
>>> 145:36345772:d=2015080400:TPRATE:surface:0-2 hour acc fcst:
>>> 146:36550429:d=2015080400:TPRATE:surface:0-3 hour acc fcst:
>>> 147:36778596:d=2015080400:TPRATE:surface:0-4 hour acc fcst:
>>> 148:36995319:d=2015080400:TPRATE:surface:0-5 hour acc fcst:
>>> 149:37226250:d=2015080400:TPRATE:surface:0-6 hour acc fcst:
>>> 150:37469285:d=2015080400:TPRATE:surface:0-7 hour acc fcst:
>>> 151:37723534:d=2015080400:TPRATE:surface:0-8 hour acc fcst:
>>> 152:37989302:d=2015080400:TPRATE:surface:0-9 hour acc fcst:
>>> 153:38266837:d=2015080400:TPRATE:surface:0-10 hour acc fcst:
>>> 154:38556419:d=2015080400:TPRATE:surface:0-11 hour acc fcst:
>>> 155:38821541:d=2015080400:TPRATE:surface:0-12 hour acc fcst:
>>> ...
>>>
>>>
>>> -------------------------------------------------
>>> Result for the 73H84H dataset :
>>>
>>> $ ncl_filedump ARPEGE_0.1_73H84H_SP1.grib2
>>>    Copyright (C) 1995-2015 - All Rights Reserved
>>>    University Corporation for Atmospheric Research
>>>    NCAR Command Language Version 6.3.0
>>>    The use of this software is governed by a License Agreement.
>>>    See http://www.ncl.ucar.edu/ for more details.
>>>
>>> Variable: f
>>> Type: file
>>> filename:    ARPEGE_0.1_73H84H_SP1
>>> path:    ARPEGE_0.1_73H84H_SP1.grib2
>>>      file global attributes:
>>>      dimensions:
>>>         forecast_time0 = 12
>>>         lat_0 = 521
>>>         lon_0 = 741
>>>      variables:
>>> ...
>>>         float TPRATE_P8_L1_GLL0_acc ( lat_0, lon_0 )
>>>            center :    French Weather Service - Toulouse
>>>            production_status :    Operational products
>>>            long_name :    Total precipitation rate
>>>            units :    kg m-2 s-1
>>>            _FillValue :    1e+20
>>>            grid_type :    Latitude/longitude
>>>            parameter_discipline_and_category :    Meteorological
>>> products, Moisture
>>>            parameter_template_discipline_category_number :    ( 8, 0, 1,
>>> 52 )
>>>            level_type :    Ground or water surface
>>>            type_of_statistical_processing :    Accumulation
>>>            statistical_process_duration :    initial time to forecast
>>> time
>>>            forecast_time :    72
>>>            forecast_time_units :    hours
>>>            initial_time :    08/04/2015 (00:00)
>>> ...
>>>
>>> $ wgrib2 ARPEGE_0.1_73H84H_SP1.grib2
>>> ...
>>> 133:34691684:d=2015080400:TPRATE:surface:0-73 hour acc fcst:
>>> 134:35059823:d=2015080400:TPRATE:surface:0-74 hour acc fcst:
>>> 135:35429187:d=2015080400:TPRATE:surface:0-75 hour acc fcst:
>>> 136:35799682:d=2015080400:TPRATE:surface:0-76 hour acc fcst:
>>> 137:36171501:d=2015080400:TPRATE:surface:0-77 hour acc fcst:
>>> 138:36544719:d=2015080400:TPRATE:surface:0-78 hour acc fcst:
>>> 139:36919171:d=2015080400:TPRATE:surface:0-79 hour acc fcst:
>>> 140:37294798:d=2015080400:TPRATE:surface:0-80 hour acc fcst:
>>> 141:37671824:d=2015080400:TPRATE:surface:0-81 hour acc fcst:
>>> 142:38049918:d=2015080400:TPRATE:surface:0-82 hour acc fcst:
>>> 143:38429238:d=2015080400:TPRATE:surface:0-83 hour acc fcst:
>>> 144:38809833:d=2015080400:TPRATE:surface:0-84 hour acc fcst:
>>> ...
>>>
>>>
>>> -------------------------------------------------
>>> Result for the 85H96H dataset :
>>>
>>> $ ncl_filedump ARPEGE_0.1_85H96H_SP1.grib2
>>>    Copyright (C) 1995-2015 - All Rights Reserved
>>>    University Corporation for Atmospheric Research
>>>    NCAR Command Language Version 6.3.0
>>>    The use of this software is governed by a License Agreement.
>>>    See http://www.ncl.ucar.edu/ for more details.
>>>
>>> Variable: f
>>> Type: file
>>> filename:    ARPEGE_0.1_85H96H_SP1
>>> path:    ARPEGE_0.1_85H96H_SP1.grib2
>>>      file global attributes:
>>>      dimensions:
>>>         forecast_time0 = 12
>>>         lat_0 = 521
>>>         lon_0 = 741
>>>         forecast_time1 = 2
>>>      variables:
>>> ...
>>>         float TPRATE_P8_L1_GLL0_acc ( forecast_time1, lat_0, lon_0 )
>>>            center :    French Weather Service - Toulouse
>>>            production_status :    Operational products
>>>            long_name :    Total precipitation rate
>>>            units :    kg m-2 s-1
>>>            _FillValue :    1e+20
>>>            grid_type :    Latitude/longitude
>>>            parameter_discipline_and_category :    Meteorological
>>> products, Moisture
>>>            parameter_template_discipline_category_number :    ( 8, 0, 1,
>>> 52 )
>>>            level_type :    Ground or water surface
>>>            type_of_statistical_processing :    Accumulation
>>>            statistical_process_duration :    initial time to forecast
>>> time
>>>            initial_time :    08/04/2015 (00:00)
>>>
>>> $ wgrib2 ARPEGE_0.1_85H96H_SP1.grib2
>>> ...
>>> 133:33228276:d=2015080400:TPRATE:surface:0-85 hour acc fcst:
>>> 134:33612201:d=2015080400:TPRATE:surface:0-86 hour acc fcst:
>>> 135:33997998:d=2015080400:TPRATE:surface:0-87 hour acc fcst:
>>> 136:34385885:d=2015080400:TPRATE:surface:0-88 hour acc fcst:
>>> 137:34775283:d=2015080400:TPRATE:surface:0-89 hour acc fcst:
>>> 138:35165904:d=2015080400:TPRATE:surface:0-90 hour acc fcst:
>>> 139:35557513:d=2015080400:TPRATE:surface:0-91 hour acc fcst:
>>> 140:35949966:d=2015080400:TPRATE:surface:0-92 hour acc fcst:
>>> 141:36343265:d=2015080400:TPRATE:surface:0-93 hour acc fcst:
>>> 142:36737384:d=2015080400:TPRATE:surface:0-94 hour acc fcst:
>>> 143:37132325:d=2015080400:TPRATE:surface:0-95 hour acc fcst:
>>> 144:37528229:d=2015080400:TPRATE:surface:0-4 day acc fcst:
>>>
>>>
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