Journal article
Variability of the Solar Wind Flow Asymmetry in the Martian Magnetosheath Observed by MAVEN
Geophysical research letters, Vol.47(22), e2020GL090793
11/28/2020
DOI: 10.1029/2020GL090793
Abstract
We perform the first statistical analysis of effects that different external conditions have on a solar wind (SW) flow asymmetry observed in the Martian magnetosheath due to mass loading, making use of ∼5 years of Mars Atmosphere and Volatile EvolutioN (MAVEN) observations. We find that the difference between the mean magnetosheath SW velocity component along the SW convective electric field direction in regions in the positive and negative hemispheres displays a strong linear correlation with the ratio between the upstream Interplanetary Magnetic Field (IMF) cross‐flow component (By) and the SW proton density (nsw). The asymmetry is maximized (∼25–35 km s−1) for low nsw (∼1 cm−3) and large IMF By (∼2 nT). These results suggest that the SW flow asymmetry variability is due to a force arising from the differential streaming between SW protons and oxygen ions, with boundary conditions partly defined by the pristine SW properties.
Plain Language Summary
In this work we study a solar wind flow asymmetry observed in the Martian magnetosheath that is an indirect result of the presence of an extended oxygen corona. This asymmetry is due to the lateral deflection of the oxygen ion mass loaded solar wind in the direction opposite to that of the solar wind convective electric field. In turn, this deflection can be understood in terms of total linear momentum conservation, since oxygen ions are initially accelerated along the latter field. By analyzing Mars Atmosphere and Volatile EvolutioN magnetic field and plasma observations, we find that this asymmetry is observed more clearly for relatively low solar wind proton density and large Interplanetary Magnetic Field cross‐flow component values. The results emphasize the influence of pristine solar wind properties in the shocked solar wind deflection around Mars and its interaction with the oxygen corona.
Key Points
The solar wind is deflected asymmetrically around Mars as a result of mass loading by oxygen ions derived from the extended oxygen corona
MAVEN data reveal a linear correlation between the flow asymmetry and the IMF cross‐flow component to the solar wind proton density ratio
The asymmetry can be understood by means of a two‐fluid description, with boundary conditions defined by the pristine solar wind properties
Details
- Title: Subtitle
- Variability of the Solar Wind Flow Asymmetry in the Martian Magnetosheath Observed by MAVEN
- Creators
- N. Romanelli - Goddard Space Flight CenterG. DiBraccio - Goddard Space Flight CenterJ. Halekas - University of IowaE. Dubinin - Max Planck Institute for Solar System ResearchJ. Gruesbeck - Goddard Space Flight CenterJ. Espley - Goddard Space Flight CenterG. Poh - Goddard Space Flight CenterY. Ma - University of California, Los AngelesJ. G. Luhmann - University of California, Berkeley
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.47(22), e2020GL090793
- DOI
- 10.1029/2020GL090793
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 10
- Grant note
- DFG (PA 525/24‐1)
- Language
- English
- Date published
- 11/28/2020
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984429024402771
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