Locally Generated ULF Waves in the Martian Magnetosphere: MAVEN Observations

Y. Harada; S. Ruhunusiri; J. S. Halekas; J. Espley; G. A. DiBraccio; J. P. Mcfadden; D. L. Mitchell; C. Mazelle; G. Collinson; D. A. Brain; T. Hara; M. Nosé; S. Oimatsu; K. Yamamoto; B. M. Jakosky

doi:10.1029/2019JA027312

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Locally Generated ULF Waves in the Martian Magnetosphere: MAVEN Observations

Journal article

Peer reviewed

Locally Generated ULF Waves in the Martian Magnetosphere: MAVEN Observations

Y. Harada, S. Ruhunusiri, J. S. Halekas, J. Espley, G. A. DiBraccio, J. P. Mcfadden, D. L. Mitchell, C. Mazelle, G. Collinson, D. A. Brain, …

Journal of geophysical research. Space physics, Vol.124(11), pp.8707-8726

11/2019

DOI: 10.1029/2019JA027312

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Abstract

We investigate Martian ultralow frequency (ULF) electromagnetic waves generated by local plasma instabilities below the Martian bow shock. Recent Mars Atmosphere and Volatile EvolutioN (MAVEN) observations have shown that ULF waves generated upstream of the Martian bow shock can propagate down to the upper ionosphere, possibly facilitating heavy ion escape from Mars by heating the ionospheric plasma. In contrast to the upstream waves oscillating near the upstream proton cyclotron frequency, we identify narrow band ULF magnetic field fluctuations with frequencies near the local proton cyclotron frequency (fcp(local)) from MAVEN data. In addition to expected proton cyclotron waves locally generated in the magnetosheath, we newly identify compressional narrow band emissions near fcp(local) (and its harmonics for some cases) in the dayside upper ionosphere and in the nightside magnetotail. The dayside waves are preferentially observed for high solar extreme ultraviolet (EUV) conditions and are often associated with ring/shell‐like, hot protons of magnetosheath origin in the presence of cold, dense ionospheric protons. The nightside waves exhibit distinct preference for high‐solar‐EUV, strong‐solar‐wind conditions, under which both warm and cold protons are enhanced. The observed properties of these compressional waves are generally consistent with a proton Bernstein mode instability driven by a positive perpendicular slope in proton velocity distribution functions. The excited waves can cause perpendicular heating of thermal protons, thereby transferring energy from precipitating hot protons to cold ionospheric protons. Key Points MAVEN observes narrow band ULF waves near the local proton cyclotron frequency below the Martian bow shock Compressional narrow band emissions are newly identified in the dayside upper ionosphere and in the nightside magnetotail The wave‐particle interaction facilitates energy transfer from hot protons of magnetosheath origin to cold ionospheric protons

magnetosphere

Mars

MAVEN

ULF waves

Details

Title: Subtitle: Locally Generated ULF Waves in the Martian Magnetosphere: MAVEN Observations
Creators: Y. Harada - Kyoto University
S. Ruhunusiri - University of Iowa
J. S. Halekas - University of Iowa
J. Espley - Goddard Space Flight Center
G. A. DiBraccio - Goddard Space Flight Center
J. P. Mcfadden - University of California, Berkeley
D. L. Mitchell - University of California
C. Mazelle - Université Fédérale de Toulouse Midi-Pyrénées
G. Collinson - Goddard Space Flight Center
D. A. Brain - University of Colorado Boulder
T. Hara - University of California, Berkeley
M. Nosé - Nagoya University
S. Oimatsu - Kyoto University
K. Yamamoto - Kyoto University
B. M. Jakosky - Laboratory for Atmospheric and Space Physics
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.124(11), pp.8707-8726
DOI: 10.1029/2019JA027312
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 20
Grant note: MEXT | Japan Society for the Promotion of Science (JSPS) (JP19K14784; 19J14368; 19J14222)
Language: English
Date published: 11/2019
Academic Unit: Physics and Astronomy
Record Identifier: 9984428800402771

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