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Models of Saturn's equatorial ionosphere based on in situ data from Cassini's grand finale

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Title: Models of Saturn's equatorial ionosphere based on in situ data from Cassini's grand finale
Authors: Moore, L
Cravens, TE
Mueller-Wodarg, I
Perry, ME
Waite, JH
Perryman, R
Nagy, A
Mitchell, D
Persoon, A
Wahlund, J-E
Morooka, MW
Item Type: Journal Article
Abstract: We present new models of Saturn's equatorial ionosphere based on the first in situ measurements of its upper atmosphere. The neutral spectrum measured by Cassini's Ion and Neutral Mass Spectrometer, which includes substantial methane, ammonia, and organics in addition to the anticipated molecular hydrogen, helium, and water, serves as input for unexpectedly complex ionospheric chemistry. Heavy molecular ions are found to dominate Saturn's equatorial low‐altitude ionosphere, with a mean ion mass of 11 Da. Key molecular ions include H3O+ and HCO+; other abundant heavy ions depend upon the makeup of the mass 28 neutral species, which cannot be uniquely determined. Ion and Neutral Mass Spectrometer neutral species lead to generally good agreement between modeled and observed plasma densities, though poor reproduction of measured H+ and H3+ variability and an overabundance of modeled H3+ potentially hint at missing physical processes in the model, including a loss process that affects H3+ but not H+.
Issue Date: 27-Sep-2018
Date of Acceptance: 3-Jul-2018
URI: http://hdl.handle.net/10044/1/77469
DOI: 10.1029/2018GL078162
ISSN: 0094-8276
Publisher: American Geophysical Union
Start Page: 9398
End Page: 9407
Journal / Book Title: Geophysical Research Letters
Volume: 45
Issue: 18
Copyright Statement: ©2018. American Geophysical Union. All Rights Reserved.
Keywords: Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
Saturn
Cassini
ionosphere
ATMOSPHERE
THERMOSPHERE
CHEMISTRY
INFLUX
SYSTEM
WATER
ION
Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
Saturn
Cassini
ionosphere
ATMOSPHERE
THERMOSPHERE
CHEMISTRY
INFLUX
SYSTEM
WATER
ION
Meteorology & Atmospheric Sciences
Publication Status: Published
Online Publication Date: 2018-09-25
Appears in Collections:Space and Atmospheric Physics
Physics