Journal article
Electron Densities in Jupiter's Upper Ionosphere Inferred From Juno Plasma Wave Observations
Journal of geophysical research. Planets, Vol.130(3), e2024JE008845
03/2025
DOI: 10.1029/2024JE008845
Appears in UI Libraries Support Open Access
Abstract
Juno's highly eccentric polar orbit takes it to perijove distances of 1.06 on each orbit. For the first perijove, this occurred just north of the jovigraphic equator, but has precessed north by about a degree per orbit over the mission. Minimum altitudes vary from 3,200–8,000 km through the mission. The Waves instrument observes a number of plasma wave modes in and near the non‐auroral ionosphere that provide information on the local electron number density, including electron plasma oscillations that occur at the electron plasma frequency and whistler‐mode hiss which has an upper frequency limit of in Jupiter's strongly magnetized inner magnetosphere. The electron plasma frequency provides the electron number density. We present electron densities in the topside ionosphere, similar to Earth's F2 layer, from the 59 perijoves analyzed to date. Peak densities range from 100 to 80,000 at latitudes up to . The density profiles can be highly variable from one perijove to the next. And, there can be deviations from simple smooth variations with altitude within individual ionospheric passes. Spatial variations may be responsible for some of the variability, perhaps related to Jupiter's complex magnetic field. We show the variation in ionospheric density profiles and the distribution of peak densities as a function of latitude and longitude as well as other geometric parameters. In addition to the complex magnetic field, possible factors affecting ionospheric density variations investigated here are ionospheric dynamos analogous to those at Earth and precipitation of energetic particles.
The Juno Waves instrument obtains spectra of plasma waves as the Juno spacecraft orbits Jupiter. Near perijove, Juno flies through the upper portion of Jupiter's ionosphere, where Jupiter's atmosphere is primarily composed of charged electrons and ions (a plasma) instead of neutral atoms and molecules. Using particular spectral features that depend on the number of electrons per unit volume, electron density profiles of Jupiter's ionosphere can be inferred. Through its first 59 orbits, Juno has sampled the ionosphere at latitudes from near‐equatorial to mid‐latitudes and has observed peak electron densities ranging from a few hundred per cubic centimeter to 80,000. Interestingly, these densities vary widely, not just from orbit to orbit, but on short time scales on individual passes through the ionosphere. Here, we investigate these density variations to understand what controls them. While a complete picture is not yet in hand, it seems clear that Jupiter's highly complex magnetic fields, atmospheric winds, and the influence of energetic particles entering the upper atmosphere all play roles in the variations.
In situ electron densities in the non‐auroral ionosphere above about 3,500 km from the first 59 Juno perijoves are reported Densities are highly variable and may reach 80,000 cm −3 but can be as low as a few hundred cm −3 Jupiter's complex magnetic field, ionospheric dynamics, and mid‐latitude precipitation may play a role in the variations
Details
- Title: Subtitle
- Electron Densities in Jupiter's Upper Ionosphere Inferred From Juno Plasma Wave Observations
- Creators
- W. S. Kurth - University of IowaJ. B. Faden - University of IowaJ. H. Waite - Waite Science LLC Pensacola FL USAA. H. Sulaiman - University of MinnesotaS. S. Elliott - University of MinnesotaG. B. Hospodarsky - University of IowaJ. E. P. Connerney - Goddard Space Flight CenterJ. A. Kammer - Southwest Research InstituteT. Greathouse - Southwest Research InstituteP. Valek - Southwest Research InstituteF. Allegrini - The University of Texas at San AntonioF. Bagenal - Laboratory for Atmospheric and Space PhysicsT. Stallard - Northumbria UniversityL. Moore - Boston UniversityD. A. Coffin - Boston UniversityO. Agiwal - Boston UniversityP. Withers - Boston UniversityS. J. Bolton - Southwest Research Institute
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Planets, Vol.130(3), e2024JE008845
- Publisher
- Wiley
- DOI
- 10.1029/2024JE008845
- ISSN
- 2169-9097
- eISSN
- 2169-9100
- Grant note
- Southwest Research InstituteNASA: 699041X NASA's New Frontiers Program for Juno: NNM06AA75C, 80NSSC23K0661 NASA New Frontiers Data Analysis ProgramNASA's Juno Participating Scientist program: 80NSSC23K0020 Roy J. Carver Charitable TrustInternational Space Science Institute (ISSI) in Bern, through ISSI International Team project: 23-592
The research at the University of Iowa is supported by NASA through Contract 699041X with the Southwest Research Institute. JHW was funded under a Southwest Research Institute subcontract (25-1031) to the University of Alabama. FA, JAK, and TG were funded by NASA's New Frontiers Program for Juno via contract NNM06AA75C with the Southwest Research Institute. LM was supported by Grant 80NSSC23K0661 issued through the NASA New Frontiers Data Analysis Program. DAC, OA, and PW acknowledge support from NASA's Juno Participating Scientist program via award 80NSSC23K0020. WSK acknowledges the use of the Space Physics Data Repository at the University of Iowa supported by the Roy J. Carver Charitable Trust. This research was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project 23-592 (Jupiter's Non-Auroral Ionosphere).
- Language
- English
- Date published
- 03/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984800201702771
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