[netcdf-java] Rotated-pole data

• To: <netcdf-java@xxxxxxxxxxxxxxxx>
• Subject: [netcdf-java] Rotated-pole data
• From: "Jon Blower" <j.d.blower@xxxxxxxxxxxxx>
• Date: Thu, 20 May 2010 17:39:07 +0100

Hi,

I have some data in rotated-pole coordinates and I'm struggling to get
NetCDF-Java (latest 4.1 version) to recognise the coordinate system.  I
think I'm following CF except that I'm not providing values for the true
lon and lat values at each grid point.  I was assuming that if I
provided the grid mapping details that NetCDF-Java might recognise them
and be able to transform to and from true lat-lon without them (i.e.
this information is redundant).

However, when I load up the file in ToolUI (4.1) the projection (as
revealed under the tabs FeatureTypes->Grids) remains LatLon.

The CDL is at the end of the email.  What am I doing wrong?  Or is it in
fact compulsory to provide the true lon and lats at each grid point?

Thanks,
Jon

netcdf
file:C:/Godiva2_data/Rotated-pole/Stefano/04203_qwq111.oper00.pp_001.MOP
Su.ncml {
 dimensions:
   Longitude = 360;
   Latitude = 288;
   Surface = 1;
   Time = UNLIMITED;   // (4 currently)
 variables:
   float Longitude(Longitude=360);
     :units = "degrees";
     :long_name = "longitude in rotated-pole grid";
     :standard_name = "grid_longitude";
   float Latitude(Latitude=288);
     :units = "degrees";
     :long_name = "latitude in rotated-pole grid";
     :standard_name = "grid_latitude";
   float Surface(Surface=1);
     :units = "surface";
     :positive = "down";
   float Time(Time=4);
     :units = "days since 2007-07-26 11:00:00";
     :long_name = "time";
   float Dynamic_rainfall_rate(Time=4, Surface=1, Latitude=288,
Longitude=360);
     :units = "kg m-2 s-1";
     :long_name = "LARGE SCALE RAINFALL RATE KG M-2 S-1";
     :title = "LARGE SCALE RAINFALL RATE KG M-2 S-1";
     :source = "UM output";
     :missing_value = -32768.0f; // float
     :_FillValue = -32768.0f; // float
     :grid_mapping = "rotated_pole";
   char rotated_pole;
     :grid_mapping_name = "rotated_latitude_longitude";
     :grid_north_pole_latitude = "37.5";
     :grid_north_pole_longitude = "177.5";

 :History = "Created_by_convert_pp_2_netcdf_at_NCEO";
}

--
Dr Jon Blower
Technical Director, Reading e-Science Centre
Environmental Systems Science Centre
University of Reading
Harry Pitt Building, 3 Earley Gate
Reading RG6 6AL. UK
Tel: +44 (0)118 378 5213
Fax: +44 (0)118 378 6413
j.d.blower@xxxxxxxxxxxxx
http://www.nerc-essc.ac.uk/People/Staff/Blower_J.htm