ULF waves in other magnetospheres - observations and possible source mechanisms.

Abstract

This paper presents an overview of the work done so far in the field of the ULF waves in the magnetospheres of Mercury, Jupiter, Saturn and Uranus. In the magnetosphere of Mercury, ULF waves were observed in the vicinity of the magnetopause and in the inner magnetosphere with frequencies in the range of 0.1 - 0.5 Hz. In the magnetosphere of Jupiter, at least three different types of wave sources are observed. Near the dayside and the dawn magnetopause, waves with periods 5 - 20 min and amplitudes between 5 and 10 nT are observed. In the middle and the inner magnetosphere, waves strongly confined to the low magnetic latitudes are observed which have wave periods of 5 - 20 min and have amplitudes of several nT. The third type of waves observed in the Jovian magnetosphere are the multiply-reflected Alfven wave in Io's torus. In Saturn's magnetosphere, ULF waves have been observed to be strongly confined to the plasma sheet and have wave periods in the range of 5 - 60 min. The calculated fundamental has a wave period of 5 - 6 hours in the region where these waves were observed. The ULF waves have extremely small amplitudes (≡0.3 nT) in the magnetosphere of Uranus. These waves were also seen to be confined to the low magnetic latitudes and have periods much shorter than that of the fundamental of a standing Alfvén wave.