MAPL Grids File Spec

This describes the NetCDF file format that is emitted and understood by the common IO layer used by History/ExtData and any utility that uses the same IO layer. The file metadata consists of two parts, one is grid specific, i.e. a file on say a Lat-Lon grid will have a different metadata than say a Tripolar grid. Some metadata would be consistent however, that being the time and any sort of non-horizontal levels.

Lat-Lon

dimensions:
        lon = 180 ;
        lat = 91 ;
        time = UNLIMITED ; // (1 currently)
variables:
        double lon(lon) ;
                lon:long_name = "longitude" ;
                lon:units = "degrees_east" ;
        double lat(lat) ;
                lat:long_name = "latitude" ;
                lat:units = "degrees_north" ;
        int time(time) ;
                time:long_name = "time" ;
                time:units = "minutes since 2000-04-15 00:00:00" ;
                time:time_increment = 60000 ;
                time:begin_date = 20000415 ;
        float example_variable(time, lat, lon) ;
                PS:long_name = "surface_pressure" ;
                PS:units = "Pa" ;
                PS:_FillValue = 1.e+15f ;
                PS:missing_value = 1.e+15f ;
                PS:fmissing_value = 1.e+15f ;
                PS:scale_factor = 1.f ;
                PS:add_offset = 0.f ;
                PS:standard_name = "surface_pressure" ;
                PS:vmin = -1.e+15f ;
                PS:vmax = 1.e+15f ;
                PS:valid_range = -1.e+15f, 1.e+15f ;

The latitude and longitude arrays are double precision MONOTONICALLY increasing coordinates that either spend the entire globe or can be a regional (non-global lat-long grid).

Cubed-Sphere

Tripolar

Generic XY grid

Level Metadata (common across all grid formats)

Time Metadata (common across all grid formats)