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- Title
Simultaneous UV Images and High‐Latitude Particle and Field Measurements During an Auroral Dawn Storm at Jupiter.
- Authors
Ebert, R. W.; Greathouse, T. K.; Clark, G.; Hue, V.; Allegrini, F.; Bagenal, F.; Bolton, S. J.; Bonfond, B.; Connerney, J. E. P.; Gladstone, G. R.; Imai, M.; Kotsiaros, S.; Kurth, W. S.; Levin, S.; Louarn, P.; Mauk, B. H.; McComas, D. J.; Paranicas, C.; Sulaiman, A. H.; Szalay, J. R.
- Abstract
We present multi‐instrument Juno observations on day‐of‐year 86, 2017 that link particles and fields in Jupiter's polar magnetosphere to transient UV emissions in Jupiter's northern auroral region known as dawn storms. Juno ranged from 42°N to 51°N in magnetic latitude and 5.8–7.8 Jovian radii (1 RJ = 71,492 km) during this period. These dawn storm emissions consisted of two separate, elongated structures which extended into the nightside, rotated with the planet, had enhanced brightness (up to at least 1.4 megaRayleigh) and high color ratios. The color ratio is a proxy for the atmospheric penetration depth and therefore the energy of the electrons that produce the UV emissions. Juno observed electrons and ions on magnetic field lines mapping to these emissions. The electrons were primarily field‐aligned, bidirectional, and, at times, exhibited sudden intensity decreases below ∼10 keV coincident with intensity enhancements up to energies of ∼1,000 keV, consistent with the high color ratio observations. The more energetic electron distributions had characteristic energies of ∼160–280 keV and downward energy fluxes (∼70–135 mW m−2) that were a significant fraction needed to produce the UV emissions for this event. Magnetic field perturbations up to ∼0.7% of the local magnetic field showing evidence of upward and downward field‐aligned currents, whistler mode waves, and broadband kilometric radio emissions were also observed along Juno's trajectory during this time frame. These high‐latitude observations show similarities to those in the equatorial magnetosphere associated with dynamics processes such as interchange events, plasma injections, and/or tail reconnection. Key Points: Juno concurrently observed UV emissions from a Jupiter dawn storm and high‐latitude plasma mapping to them at radial distances of ∼6–8 RJElectron distributions with energies from ∼10 to 1,000 keV carried a significant fraction of the energy flux needed to produce the UV emissionsEnergetic ions, magnetic perturbations, whistler mode waves, and bKOM radio emissions were observed on field lines mapping to the dawn storm
- Subjects
AURORAS; MAGNETOSPHERE of Jupiter; MAGNETIC storms; FLUX (Energy); WHISTLERS (Radio meteorology); SOLAR radio emission
- Publication
Journal of Geophysical Research. Space Physics, 2021, Vol 126, Issue 12, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2021JA029679