Saturn's Weather‐Driven Aurorae Modulate Oscillations in the Magnetic Field and Radio Emissions

Chowdhury, M. N., Stallard, Tom, Baines, K. H., Provan, G., Melin, H., Hunt, G. J., Moore, L., O’Donoghue, J., Thomas, E. M., Wang, R., Miller, S. and Badman, S. V. (2022) Saturn's Weather‐Driven Aurorae Modulate Oscillations in the Magnetic Field and Radio Emissions. Geophysical Research Letters, 49 (3). e2021GL096492. ISSN 0094-8276

Geophysical Research Letters - 2022 - Chowdhury - Saturn s Weather‐Driven Aurorae Modulate Oscillations in the Magnetic.pdf - Published Version
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The Cassini spacecraft revealed that Saturn's magnetic field displayed oscillations at a period originally thought to match the planetary rotation rate but later found not to. One of many proposed theories predicts that a polar twin-cell neutral weather system drives this variation, producing observable differences in flows within Saturn's ionosphere. Here, using spectral observations of auroral H+3 emission lines taken by the Keck Observatory's Near Infrared Echelle Spectrograph (Keck-NIRSPEC) in 2017, we derive ion line-of-sight velocity maps after grouping spectra into rotational quadrants matching phases of the planetary magnetic field. We measure 0.5 km s−1 wind systems in the ionosphere consistent with predicted neutral twin-vortex flow patterns. These findings demonstrate that neutral winds in Saturn's polar regions cause the rotational period, as determined via the magnetic field, to exhibit differences and time variabilities relative to the planet's true period of rotation in a process never before seen within planetary atmospheres.

Item Type: Article
Additional Information: Funding information: UKRI, Science and Technology Facilities Council (STFC). Grant Numbers: ST/N504117/1, ST/N000749/1, ST/N000749/1, ST/S000364/1, ST/R000816/1, ST/V000748/1 Keck Principal Investigator Data Award European Research Council Consolidator Grant. Grant Number: 723890 National Aeronautics and Space Administration (NASA). Grant Numbers: 80NSSC19K0546, 80NM0018D0004 MEXT, Japan Aerospace Exploration Agency International Top Young Fellowship UKRI, Science and Technology Facilities Council Ernest Rutherford Fellowship. Grant Number: ST/M005534/1 NASA Exoplanet Science Institute Humanities Montana Office of Legacy Management Japan Aerospace Exploration Agency
Uncontrolled Keywords: ground-based astronomy, infrared spectroscopy, H3+, planetary period oscillations, infrared aurorae, Saturn
Subjects: F300 Physics
F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 24 Jan 2023 13:53
Last Modified: 24 Jan 2023 14:00

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