Abstract
Jupiter’s giant magnetosphere is a complex system seldom in a
configuration approximating steady state, and a clear picture of its
governing dynamics remains elusive. Crucial to understanding how the
magnetosphere behaves on a large scale are disturbances to the system on
length-scales comparable to the cavity, which are communicated by
magnetohydrodynamic waves in the ultra-low-frequency band (≤ 1 mHz). In
this study we used magnetometer data from multiple spacecraft to perform
the first global heritage survey of these waves in the magnetosphere. To
map the equatorial region, we relied on the large local-time coverage
provided by the Galileo spacecraft. Flyby encounters performed by
Voyager 1 and 2, Pioneer 10 and 11, and Ulysses provided local-time
coverage of the dawn sector. We found several hundred events where
significant wave power was present, with periods spanning
~5-60 min. The majority of events consisted of multiple
superposed discrete periods. Periods at ~15,
~30 and ~40 min dominated the
event-averaged spectrum, consistent with the spectra of quasi-periodic
pulsations often reported in the literature. Most events were clustered
in the outer magnetosphere close to the magnetopause at noon and dusk,
suggesting that an external driving mechanism may dominate. The most
energetic events occurred close to the planet, though more sporadically,
indicating an accumulation of wave energy in the inner magnetosphere or
infrequent impulsive drivers in the region. Our findings suggest that
dynamics of the system at large scales is modulated by this diverse
population of waves, which permeate the magnetosphere through several
cavities and waveguides.