Re: attached file

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 my
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.html#appendix-grid-mappings_
>     Example F.5.
>
>     *Example F.5. Polar stereographic*
>
>     grid_mapping_name = 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 = "polar_stereographic";
>
>          :longitude_of_projection_origin = -105.0; // double
>
>          :scale_factor_at_projection_origin = 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
>
>     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 append
>
>     the ncDump output which shows the projection information -- in netCDF
>
>     terms (i.e., Polar_Stereographic_projection_Grid) anyway.
>
>     -- Ben
>
>     ncDump output
>
>     ===================================================
>
>     netcdf C:/Documents and
>     Settings/ben/Desktop/ST4.2006010100.06hWithLatLon.nc {
>
>      dimensions:
>
>        time = 1;   // (has coord.var)
>
>        y = 815;   // (has coord.var)
>
>        x = 1121;   // (has coord.var)
>
>      variables:
>
>        float Total_precipitation(time=1, y=815, x=1121);
>
>          :units = "kg/m^2";
>
>          :long_name = "Total precipitation @ surface";
>
>          :missing_value = -9999.0f; // float
>
>          :grid_mapping = "Polar_Stereographic_projection_Grid";
>
>          :GRIB_param_name = "Total precipitation";
>
>          :GRIB_center_id = 7; // int
>
>          :GRIB_table_id = 2; // int
>
>          :GRIB_param_number = 61; // int
>
>          :GRIB_param_id = 1, 7, 2, 61; // int
>
>          :GRIB_product_definition_type = "Accumulation";
>
>          :GRIB_level_type = 1; // int
>
>        int time(time=1);
>
>          :long_name = "forecast time";
>
>          :units = "hour since 2005-12-31T12:00:00Z";
>
>          :GRIB_orgReferenceTime = "2005-12-31T12:00:00Z";
>
>          :GRIB2_significanceOfRTName = "Start of forecast";
>
>          :_CoordinateAxisType = "Time";
>
>        double y(y=815);
>
>          :units = "km";
>
>          :long_name = "y coordinate of projection";
>
>          :standard_name = "projection_y_coordinate";
>
>          :grid_spacing = "4.763 km";
>
>          :_CoordinateAxisType = "GeoY";
>
>        double x(x=1121);
>
>          :units = "km";
>
>          :long_name = "x coordinate of projection";
>
>          :standard_name = "projection_x_coordinate";
>
>          :grid_spacing = "4.763 km";
>
>          :_CoordinateAxisType = "GeoX";
>
>        char Polar_Stereographic_projection_Grid;
>
>          :grid_mapping_name = "polar_stereographic";
>
>          :longitude_of_projection_origin = -105.0; // double
>
>          :scale_factor_at_projection_origin = 0.933; // double
>
>          :earth_shape = "spherical";
>
>          :GRIB_param_Dx = 4763.0; // double
>
>          :GRIB_param_Dy = 4763.0; // double
>
>          :GRIB_param_GDSkey = 1294122487; // int
>
>          :GRIB_param_La1 = 23.117; // double
>
>          :GRIB_param_Lo1 = -119.023; // double
>
>          :GRIB_param_LoV = -105.0; // double
>
>          :GRIB_param_Nx = 1121; // int
>
>          :GRIB_param_Ny = 881; // int
>
>          :GRIB_param_ProjFlag = 0; // int
>
>          :GRIB_param_ResCompFlag = 8; // int
>
>          :GRIB_param_ScanningMode = 64; // int
>
>          :GRIB_param_grid_name = "Polar Stereographic projection Grid";
>
>          :GRIB_param_grid_radius_spherical_earth = 6367.47; // double
>
>          :GRIB_param_grid_shape = "spherical";
>
>          :GRIB_param_grid_shape_code = 0; // int
>
>          :GRIB_param_grid_type = 5; // int
>
>          :_CoordinateTransformType = "Projection";
>
>          :_CoordinateAxisTypes = "GeoX GeoY";
>
>        double lat(y=815, x=1121);
>
>          :units = "degrees_north";
>
>          :long_name = "latitude coordinate";
>
>          :standard_name = "latitude";
>
>          :_CoordinateAxisType = "Lat";
>
>        double lon(y=815, x=1121);
>
>          :units = "degrees_east";
>
>          :long_name = "longitude coordinate";
>
>          :standard_name = "longitude";
>
>          :_CoordinateAxisType = "Lon";
>
>      :History = "GridDatatype extracted from dataset
>
>     /eclipse1a/ftp/pub/radar/StIV/2006/01/01/hr/ST4.2006010100.06h";
>
>      :Conventions = "CF-1.0";
>
>      :Originating_center = "US National Weather Service (NCEP) subcenter
>     = 4";
>
>      :Generating_Process_or_Model = "River Forecast Center Quantitative
>
>     Precipitation estimate mosaic generated by NCEP";
>
>      :Product_Type = "Accumulation";
>
>      :cdm_data_type = "Grid";
>
>      :creator_name = "US National Weather Service (NCEP) subcenter = 4";
>
>      :file_format = "GRIB-1";
>
>      :location =
>     "/eclipse1a/ftp/pub/radar/StIV/2006/01/01/hr/ST4.2006010100.06h";
>
>      :history = "Direct read of GRIB into NetCDF-Java 2.2 API";
>
>      :_CoordinateModelRunDate = "2005-12-31T12:00:00Z";
>
>     =====================================================
>
>     On 6/5/07, Steve Kopp <address@hidden <mailto:address@hidden>> wrote:
>
>     >
>
>     >  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
>
>     >
>
>     >