LAUSR

Energy transport inside the giant magnetosphere at Jupiter is poorly understood. Since the Pioneer era, mysterious quasiperiodic (QP) pulsations have been reported. Early publications successfully modeled case studies of ∼60-min (rest-frame) pulsations as standing Alfvén waves. Since then, the range of periods has increased to ∼10–60 min, spanning multiple data sets. More work is required to assess whether a common QP modulation mechanism is capable of explaining the full range of wave periods. Here we have modeled standing Alfvén waves to compute the natural periods of the Jovian magnetosphere, for varying plasma sheet thicknesses, field line lengths, and Alfvén speeds. We show that variability in the plasma sheet produces eigenperiods that are consistent with all the reported observations. At least the first half-dozen harmonics (excluding the fundamental) may contribute but are indistinguishable in our analysis. We suggest that all QP pulsations reported at Jupiter may be explained by standing Alfvén waves. Plain Language Summary A magnetized planet produces a global magnetic field that deflects the solar wind, surrounding the planet in a magnetic cavity called a magnetosphere. Jupiter is surrounded by the largest magnetosphere in the solar system. Many aspects of how energy is transported and deposited around Jupiter’s magnetosphere remain mysterious. One such mystery is semiperiodic pulsations that have been observed by spacecraft orbiting Jupiter. These pulsations have been observed in measurements of the magnetic field, the density of the magnetospheric plasma, and emissions from the auroral regions at the planet’s poles. In this study we investigate whether at least some of these pulsations could be the result of the magnetosphere resonating, similar to a ringing bell. The magnetic field can be treated as being composed of lines of magnetic force, and, when perturbed, these lines of force behave like vibrating strings. Using a simple model, we have calculated the frequencies at which these magnetic strings resonate. We found that the resonant frequencies are consistent with all the reported pulsations. This shows that a large body of pulsations can be explained by a single phenomenon, one that constitutes a mechanism for storing, transporting, and dissipating energy around the entire magnetospheric environment.