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[GEMPAK #TVE-191694]: problems with decoding grb to grd

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Subject: [GEMPAK #TVE-191694]: problems with decoding grb to grd
Date: Thu, 27 Jul 2006 11:03:14 -0600
> Dear Mr. Chiswell,
> 
> Thank you very much for your help!
> I have changed now the gridtype from spectral to gaussian.
> I still have the same problem with NAGRIB.

Kathrin,

GEMPAK does not support Gaussian grids (eg, distance between grid rows not 
constant).
The documentation  I referenced stated that a 2.5 degree grid was available, 
which you should be
able to decode (eg WMO grid #002).

Steve Chiswell
Unidata User Support


> 
> Kathrin
> 
> GEMPAK-NAGRIB>d
> GBFILE    GRIB data file name               ERA40test.grib
> INDXFL    GRIB index file name
> GDOUTF    Output grid file                  era40testg.grd
> PROJ      Map projection/angles/margins|dr  ced/0;0;0
> GRDAREA   Area covered by grid              -90;-180;90;180
> KXKY      Number of grid points in x;y      480;240
> MAXGRD    Maximum number of grids           3000
> CPYFIL    Grid file whose navigation is to
> GAREA     Graphics area                     -90;-180;90;180
> OUTPUT    Output device/filename            t
> GBTBLS    Input GRIB decoding tables
> GBDIAG    GRIB diagnostic elements          all
> PDSEXT    Y or N, add PDS extension if fou  NO
> OVERWR    Overwr flag                       yes
> GEMPAK-NAGRIB>r
> IDS bytes 0 -  4 (GRIB msg id)    = GRIB
> IDS bytes 5 -  7 (ids.msg_length) = 230484
> IDS byte       8 (ids.edition)    = 1
> PDS bytes  1- 3 (pds.length)      = 28
> PDS byte      4 (pds.version)     = 128
> PDS byte      5 (pds.center)      = 98
> PDS byte      6 (pds.process)     = 199
> PDS byte      7 (pds.grid_id)     = 255
> PDS byte      8 (pds.flag)        = 128
> PDS byte      9 (pds.parameter)   = 130
> PDS byte     10 (pds.vcoord)      = 100
> PDS bytes    11 (pds.level_1)     = 0
> PDS bytes    12 (pds.level_2)     = 1
> PDS bytes 11-12 (pds.level)       = 1
> PDS byte     13 (pds.year)        = 2
> PDS byte     14 (pds.month)       = 6
> PDS byte     15 (pds.day)         = 1
> PDS byte     16 (pds.hour)        = 0
> PDS byte     17 (pds.minute)      = 0
> PDS byte     18 (pds.time_unit)   = 2
> PDS byte     19 (pds.time_p1)     = 0
> PDS byte     20 (pds.time_p2)     = 0
> PDS byte     21 (pds.time_range)  = 3
> PDS bytes 22-23 (pds.avg_num)     = 120
> PDS byte     24 (pds.avg_miss)    = 0
> PDS byte     25 (pds.century)     = 21
> PDS byte     26 (pds.izero)       = 0
> PDS bytes 27-28 (pds.dec_scale)   = 0
> PDS EXT FLAG (1-app,0-nc,-1-rep)  = 0
> PDS EXT STRING                    =
> Changing center table to cntrgrib1.tbl
> Changing vertical coord table to vcrdgrib1.tbl
> Changing WMO parameter table to wmogrib128.tbl
> Changing center parameter table to ecmwfgrib128.tbl
> GDS bytes  1 -  3 (gds.length)    = 32
> GDS byte        4 (gds.NV)        = 0
> GDS byte        5 (gds.PV)        = 255
> GDS byte        6 (gds.grid_proj) = 4
> GDS bytes  7 -  8 (Nx)            = 480
> GDS bytes  9 - 10 (Ny)            = 240
> GDS bytes 11 - 13 (La1)           = 89427
> GDS bytes 14 - 16 (Lo1)           = 0
> GDS byte       17 (flag)          = 128
> GDS bytes 18 - 20 (La2)           = -89427
> GDS bytes 21 - 23 (Lo2)           = 359250
> GDS bytes 24 - 25 (skipped)
> GDS bytes 26 - 27 (skipped)
> GDS byte       28 (mode)          = 0
> GDS bytes 29 - 32 (skipped)
> GDS bytes 33 - 35 (skipped)
> GDS bytes 36 - 38 (skipped)
> GDS byte       39 (skipped)
> GDS bytes 40 - 42 (skipped)
> GDS bytes 43 - 45 (skipped)
> GDS bytes 46 - 48 (skipped)
> GDS byte       49 (skipped)
> GDS bytes 50 - 52 (skipped)
> Creating the GEMPAK grid file...
> GEMPAK grid file is ready...
> IDS bytes 0 -  4 (GRIB msg id)    = GRIB
> IDS bytes 5 -  7 (ids.msg_length) = 230484
> IDS byte       8 (ids.edition)    = 1
> PDS bytes  1- 3 (pds.length)      = 28
> PDS byte      4 (pds.version)     = 128
> PDS byte      5 (pds.center)      = 98
> PDS byte      6 (pds.process)     = 199
> PDS byte      7 (pds.grid_id)     = 255
> PDS byte      8 (pds.flag)        = 128
> PDS byte      9 (pds.parameter)   = 130
> PDS byte     10 (pds.vcoord)      = 100
> PDS bytes    11 (pds.level_1)     = 0
> PDS bytes    12 (pds.level_2)     = 1
> PDS bytes 11-12 (pds.level)       = 1
> PDS byte     13 (pds.year)        = 2
> PDS byte     14 (pds.month)       = 7
> PDS byte     15 (pds.day)         = 1
> PDS byte     16 (pds.hour)        = 0
> PDS byte     17 (pds.minute)      = 0
> PDS byte     18 (pds.time_unit)   = 2
> PDS byte     19 (pds.time_p1)     = 0
> PDS byte     20 (pds.time_p2)     = 0
> PDS byte     21 (pds.time_range)  = 3
> PDS bytes 22-23 (pds.avg_num)     = 120
> PDS byte     24 (pds.avg_miss)    = 0
> PDS byte     25 (pds.century)     = 21
> PDS byte     26 (pds.izero)       = 0
> PDS bytes 27-28 (pds.dec_scale)   = 0
> PDS EXT FLAG (1-app,0-nc,-1-rep)  = 0
> PDS EXT STRING                    =
> GDS bytes  1 -  3 (gds.length)    = 32
> GDS byte        4 (gds.NV)        = 0
> GDS byte        5 (gds.PV)        = 255
> GDS byte        6 (gds.grid_proj) = 4
> GDS bytes  7 -  8 (Nx)            = 480
> GDS bytes  9 - 10 (Ny)            = 240
> GDS bytes 11 - 13 (La1)           = 89427
> GDS bytes 14 - 16 (Lo1)           = 0
> GDS byte       17 (flag)          = 128
> GDS bytes 18 - 20 (La2)           = -89427
> GDS bytes 21 - 23 (Lo2)           = 359250
> GDS bytes 24 - 25 (skipped)
> GDS bytes 26 - 27 (skipped)
> GDS byte       28 (mode)          = 0
> GDS bytes 29 - 32 (skipped)
> GDS bytes 33 - 35 (skipped)
> GDS bytes 36 - 38 (skipped)
> GDS byte       39 (skipped)
> GDS bytes 40 - 42 (skipped)
> GDS bytes 43 - 45 (skipped)
> GDS bytes 46 - 48 (skipped)
> GDS byte       49 (skipped)
> GDS bytes 50 - 52 (skipped)
> IDS bytes 0 -  4 (GRIB msg id)    = GRIB
> IDS bytes 5 -  7 (ids.msg_length) = 230484
> IDS byte       8 (ids.edition)    = 1
> PDS bytes  1- 3 (pds.length)      = 28
> PDS byte      4 (pds.version)     = 128
> PDS byte      5 (pds.center)      = 98
> PDS byte      6 (pds.process)     = 199
> PDS byte      7 (pds.grid_id)     = 255
> PDS byte      8 (pds.flag)        = 128
> PDS byte      9 (pds.parameter)   = 130
> PDS byte     10 (pds.vcoord)      = 100
> PDS bytes    11 (pds.level_1)     = 0
> PDS bytes    12 (pds.level_2)     = 1
> PDS bytes 11-12 (pds.level)       = 1
> PDS byte     13 (pds.year)        = 2
> PDS byte     14 (pds.month)       = 8
> PDS byte     15 (pds.day)         = 1
> PDS byte     16 (pds.hour)        = 0
> PDS byte     17 (pds.minute)      = 0
> PDS byte     18 (pds.time_unit)   = 2
> PDS byte     19 (pds.time_p1)     = 0
> PDS byte     20 (pds.time_p2)     = 0
> PDS byte     21 (pds.time_range)  = 3
> PDS bytes 22-23 (pds.avg_num)     = 120
> PDS byte     24 (pds.avg_miss)    = 0
> PDS byte     25 (pds.century)     = 21
> PDS byte     26 (pds.izero)       = 0
> PDS bytes 27-28 (pds.dec_scale)   = 0
> PDS EXT FLAG (1-app,0-nc,-1-rep)  = 0
> PDS EXT STRING                    =
> GDS bytes  1 -  3 (gds.length)    = 32
> GDS byte        4 (gds.NV)        = 0
> GDS byte        5 (gds.PV)        = 255
> GDS byte        6 (gds.grid_proj) = 4
> GDS bytes  7 -  8 (Nx)            = 480
> GDS bytes  9 - 10 (Ny)            = 240
> GDS bytes 11 - 13 (La1)           = 89427
> GDS bytes 14 - 16 (Lo1)           = 0
> GDS byte       17 (flag)          = 128
> GDS bytes 18 - 20 (La2)           = -89427
> GDS bytes 21 - 23 (Lo2)           = 359250
> GDS bytes 24 - 25 (skipped)
> GDS bytes 26 - 27 (skipped)
> GDS byte       28 (mode)          = 0
> GDS bytes 29 - 32 (skipped)
> GDS bytes 33 - 35 (skipped)
> GDS bytes 36 - 38 (skipped)
> GDS byte       39 (skipped)
> GDS bytes 40 - 42 (skipped)
> GDS bytes 43 - 45 (skipped)
> GDS bytes 46 - 48 (skipped)
> GDS byte       49 (skipped)
> GDS bytes 50 - 52 (skipped)
> 
> 
> 3 GRIB messages were read or scanned from the GRIB file:
> ERA40test.grib
> 
> 0 grids were written to the GEMPAK file:
> era40testg.grd
> 
> 
> GRID FILE: era40testg.grd
> 
> GRID NAVIGATION:
> PROJECTION:          CED
> ANGLES:                 0.0     0.0     0.0
> GRID SIZE:          480 240
> LL CORNER:             -90.00   -180.00
> UR CORNER:              90.00    180.00
> 
> GRID ANALYSIS BLOCK:
> ANALYSIS TYPE:        BARNES
> DELTAN:               4.000
> DELTAX:           -9999.000
> DELTAY:           -9999.000
> GRID AREA:           -90.00 -180.00   90.00  180.00
> EXTEND AREA:         -90.00 -180.00   90.00  180.00
> DATA AREA:           -90.00 -180.00   90.00  180.00
> 
> Number of grids in file:     0
> 
> Maximum number of grids in file:   3000
> 
> @First time in file:  @@&#65533;@(
> Last  time in file: [&#65533;p&#65533;
> @&#65533;@+
> 
> Parameters requested: GBFILE,INDXFL,GDOUTF,PROJ,GRDAREA,KXKY,MAXGRD,CPYFIL,
> GAREA,OUTPUT,GBTBLS,GBDIAG,PDSEXT,OVERWR.
> 
> 
> 
> 
> Am Mittwoch, 26. Juli 2006 18:12 schrieb Unidata GEMPAK Support:
> > Kathrin,
> >
> > Your NAGRIB output shows
> >
> > >GDS byte        6 (gds.grid_proj) = 50
> >
> > That means that your data is spherical harmonic coefficients, which is
> > not a data type that GEMPAK can handle. I looked up the ERA40 information:
> > http://dss.ucar.edu/datasets/common/ecmwf/ERA40/docs/horizontal-coordinate/
> >index.html#sec1 This mentions that there are 2.5 degree grid data available
> > for some parameters. If you have access to that, you should be able to
> > decode it into GEMPAK format.
> >
> > Steve Chiswell
> > Unidata User Support
> >
> > > Dear GEMPAK support team,
> > >
> > > I'm trying to decode ERA40 data from grb to grd by using NAGRIB. The
> > > problem is that NAGRIB cannot read the date and time format of my ERA40
> > > dataset. GDLIST returns the error [DG -22] when reading the NAGRIB
> > > decoded ERA40 file. I downloaded the ERA40 dataset from WDCC  (world data
> > > center for climate) in Germany. They provide ERA40 datasets in grib
> > > format. I have also tried to decode an ERA40 data file which has been
> > > directly provided by ECMWF with the same effect. To see the difference in
> > > time format I have tried to compare the ERA40 dataset with the
> > > eta_00hr.grib file, which is an example file provided by unidata and
> > > which can be decoded without any problems. Unfortunately, the programs
> > > I'm using to read grib files (cdo) cannot open eta_00hr.grib. Could you
> > > please help me finding the difference between the ERA40 time format in
> > > grib and the time format from eta_00hr.grib.
> > > I have attached the nagrib.fil file which also includes all NAGRIB output
> > > displayed onto my screen.
> > >
> > > Yours sincerely,
> > > Kathrin Riemann
> > > Master student from University of Hamburg, Germany
> >
> > Ticket Details
> > ===================
> > Ticket ID: TVE-191694
> > Department: Support GEMPAK
> > Priority: Normal
> > Status: Closed
> 
> 


Ticket Details
===================
Ticket ID: TVE-191694
Department: Support GEMPAK
Priority: Normal
Status: Closed
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