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2.2 The sfc_pres_temp Example

This example has been constructed for the meteorological mind.

Suppose you have some data you want to write to a netCDF file. For example, you have one time step of surface temperature and surface pressure, on a 6 x 12 latitude longitude grid.

To store this in netCDF, create a file, add two dimensions (latitude and longitude) and two variables (pressure and temperature).

In this example we add some netCDF attributes, as is typical in scientific applications, to further describe the data. In this case we add a units attribute to every netCDF variable.

In this example we also add additional netCDF variables to describe the coordinate system. These “coordinate variables” allow us to specify the latitudes and longitudes that describe the data grid.

The CDL version of the data file, generated by ncdump, is shown below.

For more information on ncdump and ncgen see NetCDF Utilities (The NetCDF Users Guide).

     netcdf sfc_pres_temp {
     dimensions:
     	latitude = 6 ;
     	longitude = 12 ;
     variables:
     	float latitude(latitude) ;
     		latitude:units = "degrees_north" ;
     	float longitude(longitude) ;
     		longitude:units = "degrees_east" ;
     	float pressure(latitude, longitude) ;
     		pressure:units = "hPa" ;
     	float temperature(latitude, longitude) ;
     		temperature:units = "celsius" ;
     data:
     
      latitude = 25, 30, 35, 40, 45, 50 ;
     
      longitude = -125, -120, -115, -110, -105, -100, -95, -90, -85, -80, -75, -70 ;
     
      pressure =
       900, 906, 912, 918, 924, 930, 936, 942, 948, 954, 960, 966,
       901, 907, 913, 919, 925, 931, 937, 943, 949, 955, 961, 967,
       902, 908, 914, 920, 926, 932, 938, 944, 950, 956, 962, 968,
       903, 909, 915, 921, 927, 933, 939, 945, 951, 957, 963, 969,
       904, 910, 916, 922, 928, 934, 940, 946, 952, 958, 964, 970,
       905, 911, 917, 923, 929, 935, 941, 947, 953, 959, 965, 971 ;
     
      temperature =
       9, 10.5, 12, 13.5, 15, 16.5, 18, 19.5, 21, 22.5, 24, 25.5,
       9.25, 10.75, 12.25, 13.75, 15.25, 16.75, 18.25, 19.75, 21.25, 22.75, 24.25,
         25.75,
       9.5, 11, 12.5, 14, 15.5, 17, 18.5, 20, 21.5, 23, 24.5, 26,
       9.75, 11.25, 12.75, 14.25, 15.75, 17.25, 18.75, 20.25, 21.75, 23.25, 24.75,
         26.25,
       10, 11.5, 13, 14.5, 16, 17.5, 19, 20.5, 22, 23.5, 25, 26.5,
       10.25, 11.75, 13.25, 14.75, 16.25, 17.75, 19.25, 20.75, 22.25, 23.75,
         25.25, 26.75 ;
     }
 
 
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