On the relation between plasma escape and the Martian crustal magnetic field

Lundin, R.; Barabash, S.; Yamauchi, M.; Nilsson, Hans; Brain, David

doi:10.1029/2010gl046019

Cited by 55 publications

(69 citation statements)

References 16 publications

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“…Possible sources of asymmetry which could affect our estimate include uneven sampling of the northern and southern hemisphere, and uneven sampling relative to the direction of the solar wind electric field. In Lundin et al (2011) it was shown that the tail fluxes show no hemispheric asymmetry, so this would not affect our results. Nilsson et al (2011) showed that there are flow asymmetries with more escape from the north and dusk as compared to south and dawn.…”

Section: Trans-terminator Flowmentioning

confidence: 78%

“…The influence of magnetic anomalies on ion distributions have also been studied, e.g. Lundin et al (2011) and Nilsson et al (2006aNilsson et al ( , 2011, finding that the magnetic anomalies does affect the ion fluxes in the vicinity of the planet, but does not cause a hemispheric asymmetry of the escape inside the nominal IMB. The escape from the dayside ionosphere and/or pick up ion fluxes are larger from the northern hemisphere, which have less magnetic anomalies.…”

Section: Introductionmentioning

confidence: 99%

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Ion distributions in the vicinity of Mars: Signatures of heating and acceleration processes

et al. 2012

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More than three years of data from the ASPERA-3 instrument on-board Mars Express has been used to compile average distribution functions of ions in and around the Mars induced magnetosphere. We present samples of average distribution functions, as well as average flux patterns based on the average distribution functions, all suitable for detailed comparison with models of the near-Mars space environment. The average heavy ion distributions close to the planet form thermal populations with a temperature of 3 to 10 eV. The distribution functions in the tail consist of two populations, one cold which is an extension of the low altitude population, and one accelerated population of ionospheric origin ions. All significant fluxes of heavy ions in the tail are tailward. The heavy ions in the magnetosheath form a plume with the flow aligned with the bow shock, and a more radial flow direction than the solar wind origin flow. Summarizing the escape processes, ionospheric ions are heated close to the planet, presumably through wave-particle interaction. These heated populations are accelerated in the tailward direction in a restricted region. Another significant escape path is through the magnetosheath. A part of the ionospheric population is likely accelerated in the radial direction, out into the magnetosheath, although pick up of an oxygen exosphere may also be a viable source for this escape. Increased energy input from the solar wind during CIR events appear to mainly increase the number flux of escaping particles, the average energy of the escaping particles is not strongly affected. Heavy ions on the dayside may precipitate and cause sputtering of the atmosphere, though fluxes are likely lower than 0.4 × 10 23 s −1 .

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Section: Trans-terminator Flowmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Ion distributions in the vicinity of Mars: Signatures of heating and acceleration processes

et al. 2012

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“…The mean fluxes of cold and low energy (E i ≤ 50 eV) ionospheric oxygen ions are plotted as a function of the same variables. The observed upward lifting of oxygen ions in the regions with strong crustal magnetization can be responsible for a significant asymmetry of the upper ionosphere (see also Lundin et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Upper ionosphere of Mars is not axially symmetrical

et al. 2012

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The measurements carried out by the ASPERA-3 and MARSIS experiments on board the Mars Express (MEX) spacecraft show that the upper Martian ionosphere (h ≥ 400 km) is strongly azimuthally asymmetrical. There are several factors, e.g., the crustal magnetization on Mars and the orientation of the interplanetary magnetic field (IMF) which can give rise to formation of ionospheric swells and valleys. It is shown that expansion of the ionospheric plasma along the magnetic field lines of crustal origin can produce bulges in the plasma density. The absense of a magnetometer on MEX makes the retrieval of an asymmetry caused by the IMF more difficult. However hybrid simulations give a hint that the ionosphere in the hemisphere (E − ) to which the motional electric field is pointed occurs more inflated than the ionosphere in the opposite (E + ) hemisphere.

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“…On the observational side, there is on one hand no clear evidence that magnetic anomalies actually have a significant influence on the solar wind ion dynamics in the nearMars environment (Diéval et al, submitted, 2011;Stenberg et al, 2011). On the other hand, there is evidence that in the Southern hemisphere, the strong magnetic anomalies reduce the ionospheric ion outflow (Nilsson et al, 2011) and affect the flow pattern of escaping O + ions (Lundin et al, 2011). The possible effect of the magnetic anomalies on proton precipitation will be investigated in a future statistical study using Mars Express observations.…”

Section: Modelmentioning

confidence: 99%

Hybrid simulations of proton precipitation patterns onto the upper atmosphere of Mars

et al. 2012

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We study the dependence of proton precipitation patterns onto the Martian upper atmosphere on altitude, proton energy, proton origin, and in a lesser extent, solar zenith angle, using the HYB-Mars model, a 3D quasineutral hybrid model. We find that the flux of precipitating protons has a strong altitude dependence: on the dayside, the flux of precipitating protons decreases substantially when the altitude over Mars decreases. We also find that the contribution of exospheric protons to the deposition is significant and its spatial distribution is not identical to that of the solar wind protons. In addition, the low energy proton population comes mainly from the newborn planetary protons. The energized pick-up protons and solar wind protons contribute to the higher energy proton population. The study also confirms that the proton precipitation is highly asymmetric with respect to the direction of the convection electric field in the solar wind. The study implies that the Martian induced magnetosphere protects the upper atmosphere effectively against proton precipitation.

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On the relation between plasma escape and the Martian crustal magnetic field

Cited by 55 publications

References 16 publications

Ion distributions in the vicinity of Mars: Signatures of heating and acceleration processes

Ion distributions in the vicinity of Mars: Signatures of heating and acceleration processes

Upper ionosphere of Mars is not axially symmetrical

Hybrid simulations of proton precipitation patterns onto the upper atmosphere of Mars

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