air_potential_temperature / (K)     (time: 6; model_level_number: 70; grid_latitude: 100; grid_longitude: 100)
    Dimension coordinates:
        time                             x                      -                  -                    -
        model_level_number               -                      x                  -                    -
        grid_latitude                    -                      -                  x                    -
        grid_longitude                   -                      -                  -                    x
    Auxiliary coordinates:
        level_height                     -                      x                  -                    -
        sigma                            -                      x                  -                    -
    Derived coordinates:
        altitude                         -                      x                  -                    -
    Scalar coordinates:
        forecast_period             0.0 hours
    Attributes:
        source                      'Iris test case'