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5.1. Simple Container¶

This is an example of the degenerate case, where a group in netCDF4 is equivalent to a simple semantic container, which is equivalent to a NetCDF3 simple container.

All four of these examples are semantically identical and software should be able to transform data files between the encoding options at will.

5.1.1. Semantic Container NetCDF3 Classic¶

netcdf foo {    // example netCDF specification in CDL

dimensions:
     instrument___lat = 10 ;
     instrument___lon = 5 ;
     model___lat = 17 ;
     model___lon = 9 ;
     time = 5 ;
variables:
  float time(time) ;
    time:units = "seconds";
           
  int instrument ;
    instrument:measurement_platform = "aircraft" ;
    instrument:container_type = 'simple' ;
    instrument:container_members = "instrument___lat instrument___lon instrument___time" ;
  
  float instrument___lon(instrument___lon);
    instrument___lon:units = "degrees_east";
    
  float instrument___lat(instrument___lat) ;
    instrument___lat:units = "degrees_north";
    
  float instrument___rh(time,instrument___lat,instrument___lon);
    instrument___rh:long_name = "relative humidity of air"
    instrument___rh:_FillValue = -1;


  int model ;
    model:measurement_platform = "global circulation model" ;
    model:container_type = 'simple' ;
    model:container_members = "model___lat model___lon model___time" ;
       
  float model___lat(model___lat) ;
    model___lat:units = "degrees_north";
  
  float model___lon(model___lon) ;
    model___lon:units = "degrees_east";
  
  float model___rh(time,model_lat,model_lon);
    model___rh:_FillValue = -1;
    model___rh:long_name = "relative humidity of air"
  

}

5.1.2. NetCDF4 Group¶

netcdf foo {    // example netCDF specification in CDL

dimensions:
time = 5 ;

variables:
  float time(time);
    time:units = "seconds";

group instrument {

dimensions:
  lat = 10, lon = 5 ;

variables:
  float lat(lat) ;
    lat:units = "degrees_north";
  
  float lon(lon) ;
    lon:units = "degrees_east";
  
  float rh(time,lat,lon);
    rh:_FillValue = -1;
    rh:long_name = "relative humidity of air"

  :measurement_platform = "aircraft"
}
group model {

dimensions:
  lat = 17, lon = 9 ;

variables:
  float lat(lat) ;
    lat:units = "degrees_north";
  
  float lon(lon) ;
    lon:units = "degrees_east";
  
  float rh(time,lat,lon);
    rh:_FillValue = -1;
    rh:long_name = "relative humidity of air"
  
  :measurement_platform = "global circulation model"
}

}

5.1.3. Degenerate netCDF4 Semantic Group¶

netcdf foo {    // example netCDF specification in CDL

dimensions:
time = 5 ;

variables:
  float     time(time);
    time:units = "seconds";

group instrument {

dimensions:
  lat = 10, lon = 5 ;

variables:
  float lat(lat) ;
    lat:units = "degrees_north";
  
  float lon(lon) ;
    lon:units = "degrees_east";
  
  float rh(time,lat,lon) ;
    rh:_FillValue = -1;
    rh:long_name = "relative humidity of air"

  :measurement_platform = "aircraft"
  :container_type = 'simple'
}
group model {

dimensions:
  lat = 17, lon = 9 ;

variables:
  float lat(lat) ;
    lat:units = "degrees_north";
  
  float lon(lon) ;
    lon:units = "degrees_east";
  
  float rh(time,lat,lon);
    rh:_FillValue = -1;
    rh:long_name = "relative humidity of air"
  
  :measurement_platform = "global circulation model"
  :container_type = 'simple'
}

}

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