def METHOD_NAME():
    """Unmasked CO2 cube."""
    coord_spec = get_coord_spec()
    co2_data = da.array([[[[200.0, 100.0],
                           [80.0, 9.0]],
                          [[150.0, 80.0],
                           [70.0, 5.0]],
                          [[100.0, 50.0],
                           [30.0, 1.0]]]])
    co2_cube = iris.cube.Cube(
        co2_data,
        var_name='co2',
        standard_name='mole_fraction_of_carbon_dioxide_in_air',
        units='1e-8',
        dim_coords_and_dims=coord_spec,
    )
    ps_cube = get_ps_cube()
    return iris.cube.CubeList([co2_cube, ps_cube])