import iris


cube = iris.load_cube("cube_to_intersect_smol.nc")

def extract_region(cube, start_longitude, end_longitude, start_latitude,
                   end_latitude):
    print("Cube before intersection", cube)
    print("Ancil variables", cube.ancillary_variables())
    print("Cell measures", cube.cell_measures())
    region_subset = cube.intersection(
        longitude=(start_longitude, end_longitude),
        latitude=(start_latitude, end_latitude),
        ignore_bounds=True,
    )
    print("Cube after intersection", region_subset)


# intersection cube loses cell measures and ancillary variables
extract_region(cube,
               start_longitude=-90,
               end_longitude=40,
               start_latitude=20,
               end_latitude=80
    )

# intersection cube doesn't lose cell measures and ancillary variables
extract_region(cube,
               start_longitude=160,
               end_longitude=280,
               start_latitude=-5,
               end_latitude=5
    )