[gradsusr] Issues displaying Himawari-8 NetCDF file in Grads 2.1

[Jennifer Adams]

Hi, Mike — 
This file is tempting, but even if you could build a PDEF file, interpolating this super high-res data on the fly for every display would be intolerably slow. Better to (1) interpolate outside of GrADS and create a compressed netcdf file on a rectilinear grid, or (2) use another tool to look at this data.
—Jennifer

On Jul 24, 2015, at 2:00 AM, Mike Manning <michael at bsch.com.au> wrote:

> Hi all,
>  
> I’m trying to display a Himawari-8 NetCDF file in Grads – here are the attributes of the nc file:
>  
> dimensions:
>         time = UNLIMITED ; // (1 currently)
>         y = 22000 ;
>         x = 22000 ;
>  
> variables:
>         double time(time) ;
>                 time:coordinates = "time" ;
>                 time:long_name = "time" ;
>                 time:standard_name = "time" ;
>                 time:units = "seconds since 1970-01-01 00:00:00" ;
>                 time:calendar = "standard" ;
>                 time:axis = "T" ;
>                 time:unlimited = "True" ;
>         double y(y) ;
>                 y:coordinates = "y" ;
>                 y:long_name = "projection_y_coordinate" ;
>                 y:standard_name = "projection_y_coordinate" ;
>                 y:units = "m" ;
>                 y:axis = "Y" ;
>         double x(x) ;
>                 x:coordinates = "x" ;
>                 x:long_name = "projection_x_coordinate" ;
>                 x:standard_name = "projection_x_coordinate" ;
>                 x:units = "m" ;
>                 x:axis = "X" ;
>         float geostationary ;
>                 geostationary:proj4 = "+proj=geos +lon_0=140.7 +h=35785863 +x_0=0 +y_0=0 +a=6378137 +b=6356752.3 +units=m +no_defs " ;
>                 geostationary:proj_name = "GEOS141" ;
>                 geostationary:grid_mapping_name = "geostationary" ;
>                 geostationary:longitude_of_projection_origin = 140.7 ;
>                 geostationary:perspective_point_height = 35785863. ;
>                 geostationary:satellite_height = 35785863. ;
>                 geostationary:semi_major_axis = 6378137. ;
>                 geostationary:semi_minor_axis = 6356752.3 ;
>                 geostationary:sweep_angle_axis = "y" ;
>                 geostationary:GeoTransform = -5500000., 500., 0., 5500000., 0., -500. ;
>                 geostationary:spatial_ref = "PROJCS[\"unnamed\",GEOGCS[\"unnamed ellipse\",DATUM[\"unknown\",SPHEROID[\"unnamed\",6378137,298.2570248822722]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]],PROJECTION[\"Geostationary_Satellite\"],PARAMETER[\"central_meridian\",140.7],PARAMETER[\"satellite_height\",35785863],PARAMETER[\"false_easting\",0],PARAMETER[\"false_northing\",0]]" ;
>         double scan_line_time(y) ;
>                 scan_line_time:units = "seconds since 2015-07-14 03:00:00" ;
>                 scan_line_time:long_name = "estimated scan line time" ;
>                 scan_line_time:calendar = "standard" ;
>                 scan_line_time:coordinates = "y" ;
>         float channel_0003_brf(time, y, x) ;
>                 channel_0003_brf:_FillValue = 1.e+20f ;
>                 channel_0003_brf:least_significant_digit = 2s ;
>                 channel_0003_brf:algorithm_name = "channel_3_brf" ;
>                 channel_0003_brf:central_wavelength = 6.3915e-07 ;
>                 channel_0003_brf:comment = "bidirectional reflectance factor observed by the Advanced Himawari Imager at 0.64 um (Band 3)" ;
>                 channel_0003_brf:long_name = "bidirectional reflectance factor for channel 3 at 0.64 um" ;
>                 channel_0003_brf:units = "1" ;
>                 channel_0003_brf:valid_max = 1.2 ;
>                 channel_0003_brf:valid_min = 0. ;
>                 channel_0003_brf:coordinates = "time y x" ;
>                 channel_0003_brf:grid_mapping = "geostationary" ;
>  
> I made a sample script as follows:
> 'sdfopen testfile.nc'
> 'd channel_0003_br'
> 'printim satimage.png'
> 'quit'
>  
> Ideally I want to be able to set a lat/lon region, but when I specify any lat/lon region I just get a chart with a red output.  When I don’t specify any lat/lon output at all, I get a bizzare chart (I’m guessing because it’s using x and y coordinates instead of lat/lon?) Is there any way to correctly get this to display in grads at all?
>  
> Cheers, Mike
> <sat1.png>_______________________________________________
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--
Jennifer M. Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
111 Research Hall, Mail Stop 2B3
George Mason University
4400 University Drive
Fairfax, VA 22030 





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