The Effect of Solar Wind Variations on the Escape of Oxygen Ions From Mars Through Different Channels: MAVEN Observations

Dubinin, E.; Fräenz, M.; Pätzold, M.; McFadden, J. P.; Halekas, J. S.; DiBraccio, G. A.; Connerney, J. E. P.; Eparvier, F.; Brain, David; Jakosky, B. M.; Вайсберг, О. Л.; Zelenyǐ, L. M.

doi:10.1002/2017ja024741

Cited by 55 publications

(89 citation statements)

References 57 publications

(103 reference statements)

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“…Observations of this tail twist have also been recently reported in an investigation of solar wind variation effects on oxygen ion escape at Mars (Dubinin et al, 2017). We have performed data-model comparisons using MAVEN MAG/SWIA data along with the BATS-R-US MHD model coupled with the MTGCM and the Arkani-Hamed (2002) spherical harmonic crustal field model.…”

Section: Discussionmentioning

confidence: 82%

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

DiBraccio

Luhmann

Curry

et al. 2018

Geophysical Research Letters

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Measurements provided by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are analyzed to investigate the Martian magnetotail configuration as a function of interplanetary magnetic field (IMF) BY. We find that the magnetotail lobes exhibit a ~45° twist, either clockwise or counterclockwise from the ecliptic plane, up to a few Mars radii downstream. Moreover, the associated cross‐tail current sheet is rotated away from the expected location for a Venus‐like induced magnetotail based on nominal IMF draping. Data‐model comparisons using magnetohydrodynamic simulations are in good agreement with the observed tail twist. Model field line tracings indicate that a majority of the twisted tail lobes are composed of open field lines, surrounded by draped IMF. We infer that dayside magnetic reconnection between the crustal fields and draped IMF creates these open fields and may be responsible for the twisted tail configuration, similar to what is observed at Earth.

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Section: Discussionmentioning

confidence: 82%

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

DiBraccio

Luhmann

Curry

et al. 2018

Geophysical Research Letters

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110

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“…The solar wind dynamic pressure, typically calculated in space physics with P = m p n | v | 2 where m p is the proton mass and n is the number density, shown above along with the speed | v |, is important because of its use as an indicator of the solar energy input into the Martian system, especially as it influences loss rates (e.g., Dubinin et al, ). It ranges from roughly 0.01 nPa to 21 nPa due to its dependence on the widely varying density.…”

Section: Resultsmentioning

confidence: 99%

Autocorrelation Study of Solar Wind Plasma and IMF Properties as Measured by the MAVEN Spacecraft

et al. 2018

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It has long been a goal of the heliophysics community to understand solar wind variability at heliocentric distances other than 1 AU, especially at ∼1.5 AU due to not only the steepening of solar wind stream interactions outside 1 AU but also the number of missions available there to measure it. In this study, we use 35 months of solar wind and interplanetary magnetic field (IMF) data taken at Mars by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to conduct an autocorrelation analysis of the solar wind speed, density, and dynamic pressure, which is derived from the speed and density, as well as the IMF strength and orientation. We found that the solar wind speed is coherent, that is, has an autocorrelation coefficient above 1/e, over roughly 56 hr, while the density and pressure are coherent over smaller intervals of roughly 25 and 20 hr, respectively, and that the IMF strength is coherent over time intervals of approximately 20 hr, while the cone and clock angles are considerably less steady but still somewhat coherent up to time lags of roughly 16 hr. We also found that when the speed, density, pressure, or IMF strength is higher than average, the solar wind or IMF becomes uncorrelated more quickly, while when they are below average, it tends to be steadier. This analysis allows us to make estimates of the values of solar wind plasma and IMF parameters when they are not directly measured and provide an approximation of the error associated with that estimate.

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“…Large variations in the size of the ionospheric obstacle can even lead to the noticeable motions of the bow shock (Hall et al, ). The ionosphere expansion with an increase of the EUV flux is also accompanied by enhanced transterminator fluxes of ionospheric ions and their losses (Fraenz et al, ; Dubinin, Fraenz, Pätzold, Andrews, et al, ; Dubinin, Fraenz, Pätzold, McFadden, Halekas, et al, ). Similar variability with solar EUV flux was observed on Venus (Bauer & Taylor, ).…”

Section: Discussionmentioning

confidence: 99%

Expansion and Shrinking of the Martian Topside Ionosphere

et al. 2019

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The observations made by the Mars Atmosphere and Volatile EvolutioN spacecraft in the topside (≥200 km) ionosphere of Mars show that this region is very responsive to the variations of the external (solar extreme ultraviolet flux, solar wind, and interplanetary magnetic field [IMF]) and internal (the crustal magnetic field) drivers. With the growth of the solar irradiance the ionosphere broadens while with increase of the solar wind dynamic pressure it shrinks. As a result, the upper ionospheric boundary at solar zenith angles of 60-70 • can move from ∼400 to ∼1,200 km. Similar trends are observed at the nightside ionosphere. At P dyn ≥ 1-2 nPa the nightside ionosphere becomes very fragmented and depleted. On the other hand, the ion density in the nightside ionosphere significantly (up to a factor of 10) increases with the rise of the solar extreme ultraviolet flux. Large-amplitude motions of the topside ionosphere also occur with variations of the value of the cross-flow component of the IMF. The upper dayside ionosphere at altitudes of more than 300-400 km is sensitive also to the direction of the cross-flow component of the IMF or, correspondingly, to the direction of the motional electric field in the solar wind. The ionosphere becomes very asymmetrical with respect to the V sw × B IMF direction and the asymmetry strongly enhances at the nightside. The topside ionosphere above the areas with strong crustal magnetic field in the dayside southern hemisphere is significantly denser and expands to higher altitudes as compared to the ionosphere above the northern nonmagnetized lowlands. The crustal magnetic field also protects the nightside ionosphere from being filled by plasma transported from the dayside. The draping IMF penetrates deeply into the ionosphere and actively influences its structure. Weak fields and, correspondingly, weak magnetic field forces only slightly affect the ionosphere. With increase of the induced magnetic field strength the transport motions driven by the magnetic field pressure and field tensions seem to be intensified and we observe that the local ion densities at the dayside considerably decrease. A different trend is observed at the nightside. The ion density in the nightside ionosphere above the northern lowlands is higher than in the southern hemisphere indicating that plasma transport from the dayside is the main source of the nightside ionosphere. Nonstop variations in the solar wind, the IMF and the solar irradiance together with planetary rotation of the crustal magnetic field sources lead to a continuous expansion/shrinking and reconfiguration of the topside ionosphere of Mars. 2 ions (see, e.g., Schunk &Nagy, 2009 andFox et al., 2017). A balance between photoionization and recombination (photochemical equilibrium) forms the peak electron density at altitudes between 120 and 150 km, depending on the solar zenith angle (SZA). The electron density in the peak and the SZA dependence are in a reasonable agreement with the Chapman model. The direct photoionization of oxygen atoms ...

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The Effect of Solar Wind Variations on the Escape of Oxygen Ions From Mars Through Different Channels: MAVEN Observations

Cited by 55 publications

References 57 publications

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

Autocorrelation Study of Solar Wind Plasma and IMF Properties as Measured by the MAVEN Spacecraft

Expansion and Shrinking of the Martian Topside Ionosphere

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