Re: [Fwd: RE: [netcdf-java] FW: Adding a new projection to GRIB netcdf decoder] (fwd)

i forgot to mention the uk table ukmet_2_v175, it has the wrong version 
number but it's the latest uk table I have.

Robb...


===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================

---------- Forwarded message ----------
Date: Mon, 10 Nov 2008 19:17:54 -0700
From: John Caron <address@hidden>
To: Robb Kambic <address@hidden>
Subject: Re: [Fwd: RE: [netcdf-java] FW: Adding a new projection to GRIB netcdf
    decoder]

should they agree with NCEP? given thats its a UK file ?

is this the same issue as BUFR of using master ids when they are really local ?

Robb Kambic wrote:
> These are the values from the file, they don't agree with the NCEP
> values for grid 10 parameters Ni,Nj, La1, La2, Di and Dj that are
> included later
> I wonder if the NCEP values are after the rotation is done. But Ni and Nj
>  should agree.
>
> Also, gribtonc decoding got the same values, so maybe the file is
> corrupt or the NCEP values are wrong.
>
>
>
>                         Header : GRIB1
>                     Discipline : 0 Meteorological Products
>                   GRIB Edition : 1
>                    GRIB length : 28014
>             Originating Center : 74 UK Meteorological Office Bracknell
> (RSMC)
>         Originating Sub-Center : 2 Melbourne
>             Product Definition : 0 Forecast/Uninitialized Analysis/Image
> Product
>             Parameter Category : -1 Meteorological Parameters
>                 Parameter Name : 201 VAR201 N1 5m temperature - maximum
> over last 24 hours
>                Parameter Units : K
>                 Reference Time : 2005-03-14T00:00:00Z
>                     Time Units : hour
>           Time Range Indicator : product valid at RT + P1
>                    Time 1 (P1) : 45
>                    Time 2 (P2) : 0
>        Generating Process Type : 1 Unknown
>                     Level Type : 1 surface
>                  Level Value 1 : 0.0
>                  Level Value 2 : 0.0
>                     GDS Exists : true
>                     BMS Exists : false
>          Number of data points : 9216
>                      Grid Name : Rotated latitude/longitude grid
>                      Grid Shape: 0 spherical
>          Spherical earth radius: 6367.47
>                             Nx : 96
>                             Ny : 96
>                            La1 : -0.635
>                            Lo1 : 359.015
>   Resolution & Component flags : 128
>                          Winds : True
>                            La2 : 0.22
>                            Lo2 : 359.87
>                             Dx : 0.0090
>                             Dy : 0.0090
>                  Scanning mode : 64
>      Latitude of southern pole : -19.03
>     Longitude of southern pole : 25.44
>              Angle of Rotation : 2.0
>
> GDS length =122
> GDS  NV = 20
> vertical coordinate values  seem inconsistent****
> vertical coordinate =0 =9.0
> vertical coordinate =1 =2.0
> vertical coordinate =2 =2.0
> vertical coordinate =3 =2.0
> vertical coordinate =4 =2.0
> vertical coordinate =5 =2.0
> vertical coordinate =6 =-134.1875
> vertical coordinate =7 =2.0
> vertical coordinate =8 =2.0
> vertical coordinate =9 =2.0
> vertical coordinate =10 =2.0
> vertical coordinate =11 =36.7575
> vertical coordinate =12 =140.84
> vertical coordinate =13 =2.0
> vertical coordinate =14 =-8.644
> vertical coordinate =15 =0.644
> vertical coordinate =16 =150.43788
> vertical coordinate =17 =0.644
> vertical coordinate =18 =-196608.0
> vertical coordinate =19 =9.0
>
>
> NCEP values from:
> http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html#GRID10
>
> VALUE      GRID DESCRIPTIONS
> 10     Latitude/Longitude Ocean grid
> with (1,1) at (1E,64E) and (180,139) at (1W,74S)
> I increasing Eastward, Equator at J=65
>
>
>
> Ni     180
> Nj     139
> La1     64.000N
> Lo1     1.0E
> Res. & Comp. Flag     1 0 0 0 0 0 0 0
> La2     74.000S
> Lo2     359.000E = 1.000W
> Di     2.000 degrees
> Dj     1.000 degrees
> Scanning Mode     0 0 0(NB: matrix style)
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Thu, 30 Oct 2008, John Caron wrote:
>
> > this file is not reading in, can you look:
> >
> > R:/testdata/grid/transforms/rotlatlon.grb
> >
> >
> > -------- Original Message --------
> > Subject: RE: [netcdf-java] FW: Adding a new projection to GRIB netcdf
> > decoder
> > Date: Thu, 30 Oct 2008 16:55:19 +0100
> > From: Tor Christian Bekkvik <address@hidden>
> > To: caron <address@hidden>
> > CC: Kjell Røang <address@hidden>
> >
> > Hi,
> > Here you have an example GRIB file with rotated LatLon projection..
> > (stored at our ftp for limited time)
> >
> > ftp://ftp.cmr.no/pub/incoming/rotlatlon.grb
> >
> > .. And here is the projection code, in case you would like to compare
> > with yours :
> > (fwd() & inv() are inverse functions)
> >
> >
> >   public RotLatLon(double aLonsp,
> >                    double aLatsp,
> >                    double aRotsp)
> >   {
> >      lonsp = aLonsp;
> >      latsp = aLatsp;
> >      rotsp = aRotsp;
> >      double dlat_rad = (latsp - (-90)) * DEG2RAD; //delta latitude
> >      sinDlat = Math.sin(dlat_rad);
> >      cosDlat = Math.cos(dlat_rad);
> >   }
> >
> >   private double[] transform(double [] lonlat, double rot1, double
> > rot2, double s)
> >   {
> >      double e = DEG2RAD * (lonlat[0] - rot1); //east
> >      double n = DEG2RAD * lonlat[1]; //north
> >      double cn = Math.cos(n);
> >      double x = cn * Math.cos(e);
> >      double y = cn * Math.sin(e);
> >      double z = Math.sin(n);
> >      double x2 = cosDlat * x + s * z;
> >      double z2 = -s * x + cosDlat * z;
> >      double R = Math.sqrt(x2 * x2 + y * y);
> >      double e2 = Math.atan2(y, x2);
> >      double n2 = Math.atan2(z2, R);
> >      double rlon = RAD2DEG * e2 - rot2;
> >      double rlat = RAD2DEG * n2;
> >      return new double[]{rlon, rlat};
> >   }
> >
> >   public double[] fwd(double[] lonlat)
> >   {
> >      return transform(lonlat, lonsp, rotsp, sinDlat);
> >   }
> >
> >   public double[] inv(double[] lonlat)
> >   {
> >      return transform(lonlat, -rotsp, -lonsp, -sinDlat);
> >   }
> >
> >
> > Thanks,
> > Tor C
> >
> >
> >
> > > -----Original Message-----
> > > From: John Caron [mailto:address@hidden]
> > > Sent: 30. oktober 2008 16:30
> > > To: Tor Christian Bekkvik
> > > Cc: netcdf-java
> > > Subject: Re: [netcdf-java] FW: Adding a new projection to
> > > GRIB netcdf decoder
> > >
> > > Hi Tor:
> > >
> > > 1. We do have ucar.unidata.geoloc.projection.RotatedPole in
> > > 4.0. Is that the same projection?
> >
> > Possibly, but I dont have the source..
> >
> > > 2. If so, we can add to the GRIB IOSP. All we need is an
> > > example GRIB file that uses this, so we can test.
> >
> > See ftp link above...
> >
> > > thanks,
> > > John
> > >
> > > Tor Christian Bekkvik wrote:
> > > > -----Original Message-----
> > > > From: Tor Christian Bekkvik
> > > > Sent: 27. oktober 2008 14:48
> > > > To: 'address@hidden'
> > > > Cc: Kjell Røang
> > > > Subject: Adding a new projection to GRIB netcdf decoder
> > > >
> > > > Hi,
> > > > We would like to add support for Rotated LatLon projection when
> > > > reading GRIB files. (using netcdf decoders)
> > > >
> > > >
> > > > To open the gribfile, we have used class  NetcdfDataset:
> > > > NetcdfDataset.openDataset(gribFile,...)
> > > > But this fails for with rotated latlong projection, as it
> > > is not supported:
> > > >   ucar.grib.NoValidGribException: GDS: Unknown Grid Type :
> > > 10) is not supported.
> > > >     at
> > > ucar.grib.grib1.Grib1GridDefinitionSection.<init>(Grib1GridDef
> > > initionSection.java:401)
> > > >     at ucar.grib.grib1.Grib1Input.scan(Grib1Input.java:155)
> > > >     at
> > > ucar.grib.grib1.Grib1Indexer.writeFileIndex(Grib1Indexer.java:90)
> > > >     at
> > > ucar.nc2.iosp.grib.GribServiceProvider.writeIndex(GribServiceP
> > > rovider.java:163)
> > > >     at
> > > ucar.nc2.iosp.grib.GribServiceProvider.getIndex(GribServicePro
> > > vider.java:139)
> > > >     at
> > > ucar.nc2.iosp.grib.GribServiceProvider.open(GribServiceProvide
> > > r.java:75)
> > > >     at ucar.nc2.NetcdfFile.<init>(NetcdfFile.java:1092)
> > > >     at ucar.nc2.NetcdfFile.open(NetcdfFile.java:485)
> > > >     at ucar.nc2.NetcdfFile.open(NetcdfFile.java:278)
> > > >     at
> > > ucar.nc2.dataset.NetcdfDataset.openFile(NetcdfDataset.java:341)
> > > >     at
> > > ucar.nc2.dataset.NetcdfDataset.openDataset(NetcdfDataset.java:175)
> > > >     at
> > > ucar.nc2.dataset.NetcdfDataset.openDataset(NetcdfDataset.java:161)
> > > > To add this new projection, it seems that at least the
> > > following code needs update:
> > > > 1) ProjectionImpl  (I can implement RotLatLonProjection extends
> > > > ProjectionImpl)
> > > > 2) Grib1GridDefinitionSection  (to fix
> > > NoValidGribException, listed above)
> > > > 3) GribHorizCoordSys.makeProjection   (read necessary
> > > parameters from Grib GDS section and return RotLatLonProjection):
> > > >   private void makeProjection(NetcdfFile ncfile) {
> > > >     switch (lookup.getProjectionType(gdsIndex)) {
> > > >       case TableLookup.PolarStereographic:
> > > >         makePS();
> > > >         break;
> > > >       case TableLookup.LambertConformal:
> > > >         makeLC();
> > > >         break;
> > > >       case TableLookup.Mercator:
> > > >         makeMercator();
> > > >         break;
> > > >       case TableLookup.Orthographic:
> > > >         makeSpaceViewOrOthographic();
> > > >         break;
> > > >       default:
> > > >         throw new UnsupportedOperationException("unknown
> > > projection = " + gdsIndex.grid_type);
> > > >     }
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Currently, I don't have sufficient GRIB/NetCDF knowledge
> > > (or source code) to do this.
> > > > But I have already added Rotated LatLon projection for the
> > > JGRIB project (http://jgrib.sourceforge.net/), and we would
> > > like to do the same with NetCDF/GRIB.
> > > > - Any comments how to best do this ?
> > > >
> > > >
> > > >
> > > > Thanks,
> > > > Tor Chr Bekkvik
> > > >
> > > >
> > > > _______________________________________________
> > > > netcdf-java mailing list
> > > > address@hidden
> > > > For list information or to unsubscribe, visit:
> > > > http://www.unidata.ucar.edu/mailing_lists/
>
> ===============================================================================
>
> Robb Kambic                       Unidata Program Center
> Software Engineer III               Univ. Corp for Atmospheric Research
> address@hidden           WWW: http://www.unidata.ucar.edu/
> ===============================================================================