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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Asymmetric Ionospheric Jets in Jupiter's Aurora
AU - Wang, Ruoyan
AU - Stallard, Tom S.
AU - Melin, Henrik
AU - Baines, Kevin H.
AU - Achilleos, Nicholas
AU - Rymer, Abigail M.
AU - Ray, Licia C.
AU - Nichols, Jonathan D.
AU - Moore, Luke
AU - O’Donoghue, James
AU - Chowdhury, Mohammad N.
AU - Thomas, Emma M.
AU - Knowles, Katie L.
AU - Tiranti, Paola I.
AU - Miller, Steve
PY - 2023/12/31
Y1 - 2023/12/31
N2 - Simultaneous infrared observations of H 3 + ${\mathrm{H}}_{3}^{+}$ and H2 emissions from Jupiter's northern aurora using the Near Infrared Spectrograph at Keck Observatory were used to measure the ionospheric and thermospheric wind velocities. H 3 + ${\mathrm{H}}_{3}^{+}$ ions supercorotate near the dawn auroral oval and subcorotate across the dusk sector and in the dawn polar region relative to the planetary rotation rate, broadly in agreement with past observations and models. An anticyclonic vortex is discovered in H2 flows, closely matching the mean magnetospheric subcorotation when the observed magnetospheric flows are averaged azimuthally. In comparing ion and neutral winds, we measure the line‐of‐sight effective ion drift in the neutral reference frame for the first time, revealing two blue‐shifted sunward flows of ∼2 km/s. Observed H 3 + ${\mathrm{H}}_{3}^{+}$ and H2 emissions overlap with predictions of the Pedersen conductivity layer, suggesting two different regions of the ionosphere: (a) a deep layer, where neutral forces dominate the thermosphere and symmetric breakdown‐in‐corotation currents can close, and (b) a higher layer, where the observed effective ion drift allows dawn‐to‐dusk Pedersen currents within the upper atmosphere, in turn closing asymmetric currents within the magnetosphere. This ionospheric structure aligns well with recent Juno observations of Jupiter's aurora. The detected thermospheric vortex implies the driving of neutral flows by the momentum from the magnetosphere within the thermosphere and deeper in the atmosphere to potentially 20 mbar. Jovian neutral thermosphere might bridge the gap between current observations and modelings and perhaps be significant to the dynamics of aurora on Earth and other outer planets.
AB - Simultaneous infrared observations of H 3 + ${\mathrm{H}}_{3}^{+}$ and H2 emissions from Jupiter's northern aurora using the Near Infrared Spectrograph at Keck Observatory were used to measure the ionospheric and thermospheric wind velocities. H 3 + ${\mathrm{H}}_{3}^{+}$ ions supercorotate near the dawn auroral oval and subcorotate across the dusk sector and in the dawn polar region relative to the planetary rotation rate, broadly in agreement with past observations and models. An anticyclonic vortex is discovered in H2 flows, closely matching the mean magnetospheric subcorotation when the observed magnetospheric flows are averaged azimuthally. In comparing ion and neutral winds, we measure the line‐of‐sight effective ion drift in the neutral reference frame for the first time, revealing two blue‐shifted sunward flows of ∼2 km/s. Observed H 3 + ${\mathrm{H}}_{3}^{+}$ and H2 emissions overlap with predictions of the Pedersen conductivity layer, suggesting two different regions of the ionosphere: (a) a deep layer, where neutral forces dominate the thermosphere and symmetric breakdown‐in‐corotation currents can close, and (b) a higher layer, where the observed effective ion drift allows dawn‐to‐dusk Pedersen currents within the upper atmosphere, in turn closing asymmetric currents within the magnetosphere. This ionospheric structure aligns well with recent Juno observations of Jupiter's aurora. The detected thermospheric vortex implies the driving of neutral flows by the momentum from the magnetosphere within the thermosphere and deeper in the atmosphere to potentially 20 mbar. Jovian neutral thermosphere might bridge the gap between current observations and modelings and perhaps be significant to the dynamics of aurora on Earth and other outer planets.
KW - infrared
KW - ionosphere
KW - magnetosphere
KW - Jupiter
KW - aurora
KW - ion and neutral wind
U2 - 10.1029/2023ja031861
DO - 10.1029/2023ja031861
M3 - Journal article
VL - 128
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
SN - 2169-9402
IS - 12
M1 - e2023JA031861
ER -