[gradsusr] Issues displaying Himawari-8 NetCDF file in Grads 2.1
James T. Potemra
jimp at hawaii.edu
Sat Jul 25 00:56:47 EDT 2015
Hi Mike,
From where are you getting these files? The x,y coordinates are in
meters and not degrees. Without specifying the
lat/lon it looks like you are getting the full disk image. The netcdf
files at JMA appear to be in lat/lon
http://www.data.jma.go.jp/mscweb/en/himawari89/space_segment/sample_netcdf.html,
but as yet they only
seem to have the Japan-centric images.
Jim
On 7/23/15 8:00 PM, Mike Manning 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
>
>
>
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