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RE: attached file
- Subject: RE: attached file
- Date: Thu, 18 Oct 2007 10:53:50 -0700
John,
Thanks for the clarifications.
Noman
-----Original Message-----
From: John Caron [mailto:address@hidden]
Sent: Wednesday, October 17, 2007 12:08 PM
To: Ben Domenico
Cc: Nawajish Noman; address@hidden
Subject: 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.htm
l#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
>
> >
>
> >
>
>