Re: Fwd: Polar stereo projection parameter name problem

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On Thu, 18 Oct 2007, Ben Domenico wrote:

> Hi John and Robb,
>
> This is a follow up on an error in a variable name in a file served by th=
e
> NCDC NOMADS TDS.  It turns out the source file is from ncep in grib.
> Perhaps the GRIB iosp for these files is putting the wrong variable name =
in
> for the polar stereographic case.


All,

This is a GRIB table problem and it occurs because the desired table=20
wasn't available, so the code uses the closes table available.

dumping a radar file gives table info:
center =3D 7
sub_center =3D 4
table_version =3D 2

table used was:

center =3D 7
sub_center =3D -1   default sub_center=20
table_version =3D 2

The fix is to get table 7 4 2 and to include in the resources and make a=20
release or if you don't want to change your release, then the table can be=
=20
added and referenced. This is a more time consuming process.

Does anyone have table 7 4 2 in NWS format ?

Once the correct table is added to the code, no modifications need to be=20
done since Grib uses numbers internally so the parameters will be=20
correct.



Thanks,
Robb...



The THREDDS catalog for such datasets is
> at:
>
>
> http://nomads.ncdc.noaa.gov:8085/thredds/catalogServices?catalog=3Dhttp:/=
/nomads.ncdc.noaa.gov:8085/thredds/catalog/radar/StIV/2006/catalog.xml
>
> The NCDC folks are talking about using ncML to correct the problem, but i=
t
> could be that the grib iosp is putting the wrong name in.  I thought this
> was worth checking because, if it is the iosp, it will pop up on any TDS
> that serves grib files in polar stereographic.
>
> -- Ben
>
> ---------- Forwarded message ----------
> From: Steve.Ansari <address@hidden>
> Date: Oct 18, 2007 7:09 AM
> Subject: Re: Polar stereo projection parameter name problem
> To: "Glenn.Rutledge" <address@hidden>
> Cc: Ben Domenico <address@hidden>, John Caron <address@hidden.e=
du>,
> Nomads NCDC <address@hidden>, Brian Nelson <address@hidden>,
> Rich Baldwin <address@hidden>
>
> Hello all,
>
> The STIV (Stage-4 Multisensor Precip from NCEP) are in GRIB files from
> NCEP.
>
> John,
> Is this a parameter that should be different in the GRIB file?  Can we us=
e
> NcML to describe an 'alias' for this parameter?  If so, can you send a
> sample.
>
> Thanks,
> Steve
>
>
>
> Glenn.Rutledge said the following on 10/18/2007 8:24 AM:
>
> Hi Ben,
> This server data is populated and maintained (mostly) by Steve Ansari and
> Brian Nelson.  They are cc;ed to this and I'm certain they'll look into i=
t.
>
>
> It turns out that this data, and some others (GOES),k and projected grids
> have some " incompatibility" issues for their datum description while bei=
ng
> access with the GeoPortal Tooklit by ESRI (aka our ACCESS conversions of
> late)- as reported by Rich Baldwin here and he's also cc:ed just in case
> this might be germane.
>
> Regards, Glenn
>
> Ben Domenico wrote the following on 10/17/2007 3:36 PM:
>
> Hi Glenn,
>
> You may not be the right person for this note, but I'll start with you wi=
th
> the idea you can forward it to the appropriate person.  As the note below
> from John Caron indicates, there is a problem with the name being used to
> specify the latitude coordinate for the polar stereographic coordinate
> system being used to serve STIV radar data on the nomads server.  The
> prescribed CF name is "straight_vertical_longitude_from_pole"  but the
> netCDF file uses "longitude_of_projection_origin."  According to John, th=
is
> is not an uncommon error, but it would be good to fix it.
>
> Thanks.
>
> -- Ben
>
> ---------- Forwarded message ----------
> From: John Caron <address@hidden >
> Date: Oct 17, 2007 1:08 PM
> Subject: Re: attached file
> To: Ben Domenico <address@hidden>
> Cc: Nawajish Noman <address@hidden >, address@hidden.e=
du
>
> Hi Noman:
>
> Unfortunately its common for these files to not follow the conventions
> exactly.
>
> "longitude_of_projection_origin" should be
> "straight_vertical_longitude_from_pole". Its a common error, and we tend =
to
> try to be lenient in these cases, so our software would probably look for
> both names.
>
> Ben, can we notify the writer? Also, can I get a sample of the file for m=
y
> tests?
>
> John
>
> Ben Domenico wrote:
>> Noman,
>>
>> I'm forwarding this message to John Caron who can help you with the
>> details of the projection in that netCDF file.
>>
>> -- Ben
>>
>> On 10/16/07, * Nawajish Noman* <address@hidden
>> <mailto: address@hidden>> wrote:
>>
>>     Hi Ben,
>>
>>     We are working on the problem with Polar stereographic projection. I
>>     am comparing the grid_mapping parameters in the file (see your email
>>     below) and the parameters listed on the CF Convention page at _
>>     http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.0/cf-conventions=
=2Ehtml#appendix-grid-mappings_
>
>>     Example F.5.
>>
>>     *Example F.5. Polar stereographic*
>>
>>     grid_mapping_name =3D polar_stereographic
>>
>>
>>
>>     */Map parameters:/*
>>
>>     straight_vertical_longitude_from_pole
>>
>>     latitude_of_projection_origin - Either +90. or -90.
>>
>>     Either standard_parallel or scale_factor_at_projection_origin
>>
>>     false_easting
>>
>>     false_northing
>>
>>     *Parameters in file are:***
>>
>>     char Polar_Stereographic_projection_Grid;
>>
>>          :grid_mapping_name =3D "polar_stereographic";
>>
>>          :longitude_of_projection_origin =3D - 105.0; // double
>>
>>          :scale_factor_at_projection_origin =3D 0.933; // double
>>
>>     Here are my questions:
>>
>>     Q1: Some of the parameters are missing in file. What do we do about
>>     missing parameters?
>>
>>     Q2: You have " longitude_of_projection_origin " in file but the CF
>>     convention says " latitude_of_projection_origin" - What do with
>>     "longitude_of_projection_origin "?
>>
>>     We look for parameters listed in CF Conventions and map them to our
>>     Spatial reference parameters. If parameters are missing in file we
>>     assume default value. If incorrect parameters are specified - we
>>     ignore them.
>>
>>     I want to make sure we are reading the parameters from your file
>>     correctly. Please comment=85
>>
>>     Thanks,
>>
>>     Noman
>>
>>     -----Original Message-----
>>     From: address@hidden <mailto:address@hidden> [
>>     mailto: address@hidden] On Behalf Of Ben Domenico
>>     Sent: Tuesday, June 05, 2007 1:56 PM
>>     To: Steve Kopp
>>     Cc: Nawajish Noman
>>     Subject: Re: attached file
>>
>>     Steve,
>>
>>     I'll attach jpegs of the dataset as displayed in arcMap and one from
>>
>>     the IDV.  In each case, you can see at the bottom of the screen, the
>>
>>     lat/lon values associated with the cursor position.  I'll also appen=
d
>>
>>     the ncDump output which shows the projection information -- in netCD=
F
>>
>>     terms (i.e., Polar_Stereographic_projection_Grid) anyway.
>>
>>     -- Ben
>>
>>     ncDump output
>>
>>     =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
>>
>>     netcdf C:/Documents and
>>     Settings/ben/Desktop/ST4.2006010100.06hWithLatLon.nc {
>>
>>      dimensions:
>>
>>        time =3D 1;   // (has coord.var)
>>
>>        y =3D 815;   // (has coord.var)
>>
>>        x =3D 1121;   // (has coord.var)
>>
>>      variables:
>>
>>        float Total_precipitation(time=3D1, y=3D815, x=3D1121);
>>
>>          :units =3D "kg/m^2";
>>
>>          :long_name =3D "Total precipitation @ surface";
>>
>>          :missing_value =3D -9999.0f; // float
>>
>>          :grid_mapping =3D "Polar_Stereographic_projection_Grid";
>>
>>          :GRIB_param_name =3D "Total precipitation";
>>
>>          :GRIB_center_id =3D 7; // int
>>
>>          :GRIB_table_id =3D 2; // int
>>
>>          :GRIB_param_number =3D 61; // int
>>
>>          :GRIB_param_id =3D 1, 7, 2, 61; // int
>>
>>          :GRIB_product_definition_type =3D "Accumulation";
>>
>>          :GRIB_level_type =3D 1; // int
>>
>>        int time(time=3D1);
>>
>>          :long_name =3D "forecast time";
>>
>>          :units =3D "hour since 2005-12-31T12:00:00Z";
>>
>>          :GRIB_orgReferenceTime =3D "2005-12-31T12:00:00Z";
>>
>>          :GRIB2_significanceOfRTName =3D "Start of forecast";
>>
>>          :_CoordinateAxisType =3D "Time";
>>
>>        double y(y=3D815);
>>
>>          :units =3D "km";
>>
>>          :long_name =3D "y coordinate of projection";
>>
>>          :standard_name =3D "projection_y_coordinate";
>>
>>          :grid_spacing =3D "4.763 km";
>>
>>          :_CoordinateAxisType =3D "GeoY";
>>
>>        double x(x=3D1121);
>>
>>          :units =3D "km";
>>
>>          :long_name =3D "x coordinate of projection";
>>
>>          :standard_name =3D "projection_x_coordinate";
>>
>>          :grid_spacing =3D "4.763 km";
>>
>>          :_CoordinateAxisType =3D "GeoX";
>>
>>        char Polar_Stereographic_projection_Grid;
>>
>>          :grid_mapping_name =3D "polar_stereographic";
>>
>>          :longitude_of_projection_origin =3D -105.0; // double
>>
>>          :scale_factor_at_projection_origin =3D 0.933 ; // double
>>
>>          :earth_shape =3D "spherical";
>>
>>          :GRIB_param_Dx =3D 4763.0; // double
>>
>>          :GRIB_param_Dy =3D 4763.0; // double
>>
>>          :GRIB_param_GDSkey =3D 1294122487; // int
>>
>>          :GRIB_param_La1 =3D 23.117; // double
>>
>>          :GRIB_param_Lo1 =3D -119.023; // double
>>
>>          :GRIB_param_LoV =3D -105.0; // double
>>
>>          :GRIB_param_Nx =3D 1121; // int
>>
>>          :GRIB_param_Ny =3D 881; // int
>>
>>          :GRIB_param_ProjFlag =3D 0; // int
>>
>>          :GRIB_param_ResCompFlag =3D 8; // int
>>
>>          :GRIB_param_ScanningMode =3D 64; // int
>>
>>          :GRIB_param_grid_name =3D "Polar Stereographic projection Grid"=
;
>>
>>          :GRIB_param_grid_radius_spherical_earth =3D 6367.47; // double
>>
>>          :GRIB_param_grid_shape =3D "spherical";
>>
>>          :GRIB_param_grid_shape_code =3D 0; // int
>>
>>          :GRIB_param_grid_type =3D 5; // int
>>
>>          :_CoordinateTransformType =3D "Projection";
>>
>>          :_CoordinateAxisTypes =3D "GeoX GeoY";
>>
>>        double lat(y=3D815, x=3D1121);
>>
>>          :units =3D "degrees_north";
>>
>>          :long_name =3D "latitude coordinate";
>>
>>          :standard_name =3D "latitude";
>>
>>          :_CoordinateAxisType =3D "Lat";
>>
>>        double lon(y=3D815, x=3D1121);
>>
>>          :units =3D "degrees_east";
>>
>>          :long_name =3D "longitude coordinate";
>>
>>          :standard_name =3D "longitude";
>>
>>          :_CoordinateAxisType =3D "Lon";
>>
>>      :History =3D "GridDatatype extracted from dataset
>>
>>     /eclipse1a/ftp/pub/radar/StIV/2006/01/01/hr/ST4.2006010100.06h";
>>
>>      :Conventions =3D "CF-1.0";
>>
>>      :Originating_center =3D "US National Weather Service (NCEP) subcent=
er
>>     =3D 4";
>>
>>      :Generating_Process_or_Model =3D "River Forecast Center Quantitativ=
e
>>
>>     Precipitation estimate mosaic generated by NCEP";
>>
>>      :Product_Type =3D "Accumulation";
>>
>>      :cdm_data_type =3D "Grid";
>>
>>      :creator_name =3D "US National Weather Service (NCEP) subcenter =3D=
 4";
>>
>>      :file_format =3D "GRIB-1";
>>
>>      :location =3D
>>     "/eclipse1a/ftp/pub/radar/StIV/2006/01/01/hr/ST4.2006010100.06h";
>>
>>      :history =3D "Direct read of GRIB into NetCDF-Java 2.2 API";
>>
>>      :_CoordinateModelRunDate =3D "2005-12-31T12:00:00Z";
>>
>>     =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
>>
>>     On 6/5/07, Steve Kopp < address@hidden <mailto:address@hidden>> wrot=
e:
>>
>>    >
>>
>>    >  Ben, the dataset contains no projection information. Without this,
> we
>>
>>    >  won't know where else to draw anything.
>>
>>    >
>>
>>    >  Could you send us a screen shot of what you are seeing?
>>
>>    >
>>
>>    >  Thanks,
>>
>>    >
>>
>>    >  Steve
>>
>>    >
>>
>>    >
>>
>>    >  -----Original Message-----
>>
>>    >  From: address@hidden <mailto:address@hidden> [
>>     mailto:address@hidden] On Behalf Of
>>
>>    >  Ben Domenico
>>
>>    >  Sent: Tuesday, June 05, 2007 11:32 AM
>>
>>    >  To: Steve Kopp
>>
>>    >  Subject: attached file
>>
>>    >
>>
>>    >  Hi Steve,
>>
>>    >
>>
>>    >  Don't know if this will work, but I'm attaching one of the
> CF-netCDF
>>
>>    >  files I got from that NCDC radar data server.  Let me know whether
>>
>>    >  this comes through OK.
>>
>>    >
>>
>>    >  -- Ben
>>
>>    >
>>
>>    >
>>
>>
>
>
> --=20
> Glenn K. Rutledge
> Services Team Leader
> Remote Sensing and Applications Division
> NOMADS Project Manager
> National Oceanic and Atmospheric Administration
> National Climatic Data Center
> Asheville NC 28801
> Phone: (828) 271-4097
> Fax: (828) 271-4328
>
> NOMADS: http://nomads.ncdc.noaa.gov/
>
>
> --=20
> Steve Ansari
> Physical Scientist
> NOAA's National Climatic Data Center
> Veach-Baley Federal Building
> 151 Patton Avenue
> Asheville, NC 28801
> Ph: 828-271-4611
> Fax: 828-271-4022
>

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=3D=3D=3D=3D
Robb Kambic        =09=09=09   Unidata Program Center
Software Engineer III=09=09=09   Univ. Corp for Atmospheric Research
address@hidden=09=09   WWW: http://www.unidata.ucar.edu/
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