Alfvénic Fluctuations Associated With Jupiter's Auroral Emissions. Issue 13 (4th July 2019)

• Record Type: Journal Article
• Authors: Gershman, Daniel J.; Connerney, John E. P.; Kotsiaros, Stavros; DiBraccio, Gina A.; Martos, Yasmina M.; ‐Viñas, Adolfo F.; Hue, Vincent; Clark, George; Bagenal, Fran; Levin, Steve; Bolton, Scott J.
• Is Part Of: Geophysical research letters. Volume 46:Issue 13(2019)
• Page Start: 7157
• Page End: 7165
• Publication Date: 2019-07-04
• Subjects: Jupiter -- aurora -- magnetosphere -- Alfven -- turbulence -- MHD; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL082951
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The Alfvén wave mode transmits field‐aligned currents and large‐scale turbulence throughout Jupiter's magnetosphere. Magnetometer data from the Juno spacecraft have provided the first observations of Alfvénic fluctuations along the polar magnetic flux tubes connected to Jupiter's main auroral oval and the Jovian satellites. Transverse magnetic field perturbations associated with Io are observed up to ~90° away from main Io footprint, supporting the presence of extended Alfvénic wave activity throughout the Io footprint tail. Additional broadband fluctuations measured equatorward of the statistical auroral oval are composed of incompressible magnetic turbulence that maps to Jupiter's equatorial plasma sheet at radial distances within ~20 R J. These fluctuations exhibit a k || power spectrum consistent with strong magnetohydrodynamic turbulence. This turbulence can generate up to ~100 mW/m 2 of Poynting flux to power the Jovian aurora in regions connected to the inner magnetosphere's central plasma sheet. Plain Language Summary: Here we provide the first direct observations of magnetic turbulence near Jupiter's poles. The locations and power of these turbulent fluctuations provide new constraints for modeling the particle acceleration that leads to the generation of Jupiter's aurora. We find that this turbulence provides sufficient energy to produce the aurora at Jupiter, as well as emission associated with Jupiter's moon Io. Constraints on turbulent auroral heating at Jupiter are relevant for analogous processes at other giant magnetospheres such as Saturn, Uranus, and Neptune. Key Points: Alfvénic turbulence is observed in high‐latitude regions associated with Jupiter's auroral emission Turbulent magnetic field fluctuations at high latitude map to the central plasma sheet in the inner magnetosphere High-latitude fluctuations indicate the presence of significant Alfvénic wave activity at longitudes up to ~90° along the Io footprint tail