Saturn's Weather‐Driven Aurorae Modulate Oscillations in the Magnetic Field and Radio Emissions
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- School of Physics and Astronomy University of Leicester Leicester UK
- Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA, Space Science and Engineering Center University of Wisconsin‐Madison Madison WI USA
- Blackett Laboratory Imperial College London London UK
- Center for Space Physics Boston University Boston MA USA
- Institute for Space and Astronautical Science JAXA Kanagawa Japan
- Department of Physics and Astronomy University College London London UK
- Department of Physics Lancaster University Lancaster UK
Abstract 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 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.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1843888
- Journal Information:
- Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 3 Vol. 49; ISSN 0094-8276
- Publisher:
- American Geophysical Union (AGU)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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