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Geophysical Research Letters - 2022 - Chowdhury - Saturn s Weather‐Driven Aurorae Modulate Oscillations in the Magnetic.pdf (507.04 kB)

Saturn’s weather‐driven aurorae modulate oscillations in the magnetic field and radio emissions

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posted on 2023-12-11, 12:04 authored by MN Chowdhury, TS Stallard, KH Baines, G Provan, H Melin, GJ Hunt, L Moore, J O’Donoghue, EM Thomas, R Wang, S Miller, SV Badman

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 https://agupubs.onlinelibrary.wiley.com/cms/asset/62ebcbcd-6654-4eeb-8580-c7c18ce6bcc0/grl63524-math-0001.png 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. 

Funding

STFC Leicester 2015 DTP

Science and Technology Facilities Council

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

Science and Technology Facilities Council

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Space and planetary physics 2019-2022

Science and Technology Facilities Council

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Space and Planetary Research at Lancaster University

Science and Technology Facilities Council

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Giants through Time: Towards a Comprehensive Giant Planet Climatology

European Research Council

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IONOSPHERIC CHEMISTRY AND STRUCTURE OF THE GIANT PLANETS

National Aeronautics and Space Administration

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80NM0018D0004

ASTIlluminating Solar-Planetary Interactions

Science and Technology Facilities Council

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Keck Principal Investigator Award

MEXT, Japan Aerospace Exploration Agency International Top Young Fellowship

NASA Exoplanet Science Institute

Humanities Montana

Office of Legacy Management

Japan Aerospace Exploration Agency

History

Citation

Chowdhury, M. N., Stallard, T. S., Baines, K. H., Provan, G., Melin, H., Hunt, G. J., et al. (2022). Saturn's weather-driven aurorae modulate oscillations in the magnetic field and radio emissions. Geophysical Research Letters, 49, e2021GL096492.

Author affiliation

School of Physics and Astronomy, University of Leicester

Version

  • VoR (Version of Record)

Published in

Geophysical Research Letters

Publisher

American Geophysical Union (AGU)

issn

0094-8276

eissn

1944-8007

Acceptance date

2021-12-20

Copyright date

2021

Available date

2023-12-11

Language

en

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