Journal article
Statistical Study of Relations Between the Induced Magnetosphere, Ion Composition, and Pressure Balance Boundaries Around Mars Based On MAVEN Observations
Journal of geophysical research. Space physics, Vol.122(9), pp.9723-9737
09/2017
DOI: 10.1002/2017JA024217
Abstract
Direct interaction between the solar wind (SW) and the Martian upper atmosphere forms a characteristic region, called the induced magnetosphere between the magnetosheath and the ionosphere. Since the SW deceleration due to increasing mass loading by heavy ions plays an important role in the induced magnetosphere formation, the ion composition is also expected to change around the induced magnetosphere boundary (IMB). Here we report on relations of the IMB, the ion composition boundary (ICB), and the pressure balance boundary based on a statistical analysis of about 8 months of simultaneous ion, electron, and magnetic field observations by Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We chose the period when MAVEN observed the SW directly near its apoapsis to investigate their dependence on SW parameters. Results show that IMBs almost coincide with ICBs on the dayside and locations of all three boundaries are affected by the SW dynamic pressure. A remarkable feature is that all boundaries tend to locate at higher altitudes in the southern hemisphere than in the northern hemisphere on the nightside. This clear geographical asymmetry is permanently seen regardless of locations of the strong crustal B fields in the southern hemisphere, while the boundary locations become higher when the crustal B fields locate on the dayside. On the nightside, IMBs usually locate at higher altitude than ICBs. However, ICBs are likely to be located above IMBs in the nightside, southern, and downward ESW hemisphere when the strong crustal B fields locate on the dayside.
Key Points
Locations of boundaries (the IMB, the ICB, and the β∗) at Mars show a north‐south asymmetry mainly on the nightside
IMBs coincide with ICBs on the dayside, and all boundaries depend on the SW dynamic pressure and the southern crustal B fields
IMBs and ICBs tend to be located at high altitudes in the nightside, southern, and downward ESW hemisphere
Details
- Title: Subtitle
- Statistical Study of Relations Between the Induced Magnetosphere, Ion Composition, and Pressure Balance Boundaries Around Mars Based On MAVEN Observations
- Creators
- Kazunari Matsunaga - Nagoya UniversityKanako Seki - The University of TokyoDavid A Brain - University of Colorado BoulderTakuya Hara - University of California, BerkeleyKei Masunaga - Swedish Institute of Space PhysicsJames P Mcfadden - University of California, BerkeleyJasper S Halekas - University of IowaDavid L Mitchell - University of California, BerkeleyChristian Mazelle - Université de ToulouseJ. R Espley - Goddard Space Flight CenterJacob Gruesbeck - University of Maryland, College ParkBruce M Jakosky - University of Colorado Boulder
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.122(9), pp.9723-9737
- DOI
- 10.1002/2017JA024217
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 15
- Grant note
- Grant‐in‐Aid for Scientific Research (16H02229) Japan Society for the Promotion of Science (JSPS) (15H03731) Nagoya University Program for Leading Graduate Schools NASA Mars Exploration Program
- Language
- English
- Date published
- 09/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984200058602771
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