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Auroral Field-Aligned Current Signatures in Jupiter's Magnetosphere: Juno Magnetic Field Observations and Physical Modeling

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posted on 2023-07-03, 10:51 authored by A Kamran, EJ Bunce, SWH Cowley, MK James, JD Nichols, G Provan, H Cao, V Hue, TK Greathouse, GR Gladstone
We analyze magnetic data obtained during northern high-altitude traversals of Jovian middle magnetosphere (MM) field lines during the first 10 inbound data-taking passes of the Juno spacecraft for azimuthal field perturbations associated with magnetosphere-ionosphere coupling currents. Full traversals across the MM region occur on all 10 passes at radial distances ∼7 to 16 RJ (T1 traversals), followed in four cases by reversed traversals (T2) at ∼4 to 7 RJ. Signatures of upward field-aligned currents were observed in all cases, closely collocated with the statistical main auroral oval when mapped along field lines to the ionosphere. Two T1 sheets carry currents ∼10 MA per radian of azimuth in ionospheric colatitudinal layers ∼1.2°, closely comparable with the ∼8.5 MA rad−1 theoretical model value of Cowley et al. (2008, https://doi.org/10.5194/angeo-26-4051-2008). The other T1 sheets typically carry half this current ∼5.1 MA rad−1 in layers half the width ∼0.56°, thus with comparable current densities ∼425 nA m−2. The T2 currents are smaller ∼3.4 MA rad−1 with current densities ∼120 nA m−2, a difference that may relate to locations on opposite sides of the main oval as reflected in near-contemporaneous ultraviolet observations, though ionospheric field strengths are not greatly different. Comparison with northern near-periapsis currents observed inside ∼2 RJ on the same passes by Kotsiaros et al. (2019, https://doi.org/10.1038/s41550-019-0819-7) yields a cross-correlation coefficient ∼0.7 with our T1 currents, though Kotsiaros et al.’s mean current value of ∼3.8 MA rad−1 is somewhat less than our overall mean T1 value ∼6.2 MA rad−1. The differences may have spatial, temporal, or methodological origins.

Funding

STFC Studentship

A Consolidated Grant Proposal for Solar System Research at the University of Leicester (2016-2019)

Science and Technology Facilities Council

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Royal Society Wolfson Research Merit Award

History

Author affiliation

School of Physics & Astronomy, University of Leicester

Version

  • VoR (Version of Record)

Published in

Journal of Geophysical Research: Space Physics

Volume

127

Issue

12

Publisher

Wiley / American Geophysical Union (AGU)

issn

2169-9380

eissn

2169-9402

Copyright date

2022

Available date

2023-07-03

Language

en

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