“…In contrast to the magnetic fields of Earth, Mercury, Jupiter and Saturn, which are dominated by a dipole nearly co-aligned with the rotation axis, those of Uranus and Neptune are characterised by a large offset and tilt between the dipole and spin axes with strong quadrupole and octupole contributions to the internal magnetic field. The magnetic field data from Voyager 2 are sufficient to crudely constrain the internal field of Uranus, but more complex and (currently) poorly constrained models are required to fit the data (Holme and Bloxham, 1996). At the planetary surface the magnetic dipole, quadruople and octupole components of the total internal field are of comparable strength, but at the top of the dynamo region ( $0.75R U ) the latter two dominate.…”