Power spectra of magnetic‐field fluctuations near Jupiter have been analyzed since the early days of space exploration with Voyager and Ulysses flyby of Jupiter. Power spectra of velocity and density fluctuations, however, have not been as well studied, due to the lack of high‐resolution measurements required to resolve a significant fraction of the inertial range. Here, we investigate fluid‐scale turbulence in Jupiter's magnetosheath using measurements from the Jovian Auroral Distributions Experiment (JADE) instrument onboard Juno spacecraft. Both ion density and velocity spectra exhibit nearly Kolmogorov scaling ∼f−5/3. This indicates weakly compressible fluctuations and the presence of a scale‐invariant cascade through the inertial range. Although this is a specific case study and not necessarily representative of the overall behavior, our result shows that Alfvénic Kolmogorov‐type turbulence exists in at least some locations in Jupiter's magnetosheath.
Plain Language Summary
The classical theory of turbulence, given by Kolmogorov in 1941, predicts that the size scales of various turbulent structures follow a specific pattern, with more power held in larger turbulent structures. The region where the Sun's outflowing plasma—the solar wind—is diverted around Jupiter's magnetic environment, is called the magnetosheath. Using NASA's Juno mission data, we show for the first time that the ion fluctuations in Jupiter's magnetosheath region follow the expected pattern of power in different spatial scales. This result indicates that fully developed turbulence, consistent with classical (Kolmogorov) turbulence theory, is present in Jupiter's magnetosheath. We also characterize the size of the large‐scale turbulent structures in the system. These results provide insights into the nature of plasma turbulence in other similar astrophysical systems.
Jovian Auroral Distributions Experiment measurements, collected in Jupiter's dawnside magnetosheath, show turbulent fluctuations
Both ion density and velocity spectra show Kolmogorov k−5/3 scaling in the inertial range, indicating fully developed turbulence
The characteristic “system size” of the turbulence, estimated by the correlation length, is obtained to be Lc ∼ 5 × 105 km (≈7 RJ)