[gradsusr] Issues displaying Himawari-8 NetCDF file in Grads 2.1
James T. Potemra
jimp at hawaii.edu
Sun Jul 26 02:41:30 EDT 2015
HI Mike,
I believe the x,y are UTM (Universal Transverse Mercator). You are
seeing the complete "full disk" image, but you
won't be able to specify lat/lon directly. I think you'll have to
either use an external tool (e.g., GDAL) to convert
the file first, or try convert your lat/lon ranges to UTM then specify
them. For example,
set x = 10000 12000
set y = 9000 11000
gives a plot just south of the equator. Note this is a really high-res
image, so it will take a long time to render
the entire thing (22000 by 22000) if it does it at all (you might get an
"Out of buffer space").
Jim
On 7/25/15 6:18 PM, Mike Manning wrote:
> Hi Jim,
>
> It's the sample Himawari-8 data on the BOM site:
> ftp://ftp.bom.gov.au/anon/sample/catalogue/Satellite/IDE00220.201507140300.nc
>
>
> Cheers, Mike
>
> On 25/07/2015 2:56 PM, James T. Potemra wrote:
>> 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
>>>
>>>
>>>
>>> _______________________________________________
>>> gradsusr mailing list
>>> gradsusr at gradsusr.org
>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>
>>
>>
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