Magnetosheath fluctuations at Venus for two extreme orientations of the interplanetary magnetic field

Du, J.; Zhang, T. L.; Wang, Chao; Volwerk, M.; Delva, M.; Baumjohann, W.

doi:10.1029/2009gl037725

Cited by 14 publications

(20 citation statements)

References 28 publications

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“…Espley et al (2004) interpret their observed fluctuations as mirror mode waves, but they also admit that this interpretation is in conflict with the observation of a moderate elliptical polarisation of the waves, as theoretical studies suggest that mirror modes are linearly polarised. But they argue that elliptically polarised mirror mode waves have also been observed in Earth's magnetosheath.…”

Section: Wave Properties At Venus and Marsmentioning

confidence: 98%

“…We note that according to Song and Russell (1999) high ratios are favoured, because the propagation direction is better determined for higher ratios of the eigenvalues. Therefore, we use a more stringent condition than Espley et al (2004) and consider only cases with the intermediate to minimum eigenvalue ratio greater than 5. This is a compromise, because otherwise we lose a significant portion of the data set in the analysis.…”

Section: Wave Vector Directionmentioning

confidence: 99%

“…A differentiation between the quasi-parallel and quasi-perpendicular bow shock regions based on Venus Express measurements of the IMF direction is beyond the scope of this paper and will be subject of future work. A first case study has recently been presented by Du et al (2009).…”

Section: Wave Properties At Venus and Marsmentioning

confidence: 99%

“…Acuña et al, 1998). A statistical study of low-frequency magnetic field oscillations in the Martian plasma environment is presented by Espley et al (2004).…”

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confidence: 99%

“…We adopt the definition given by Espley et al (2004) who refer frequencies near or below the proton gyrofrequency as the low-frequency range and frequencies below the lowest local ion gyrofrequency as the ultra-low-frequency range. As Espley et al (2004) provide a statistical study of lowfrequency magnetic field oscillations at Mars, including the magnetosheath, the magnetic pileup region, and the tail, our study provides also the basis for a comparative wave study between Venus and Mars.…”

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confidence: 99%

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Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

et al. 2010

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Abstract. We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comparative study of low-frequency waves at Venus and Mars. The spatial distributions of the wave properties, in particular in the dayside and nightside magnetosheath as well as in the tail and mantle region, are similar to observations at Mars. As both planets do not have a global magnetic field, the interaction process of the solar wind with both planets is similar and leads to similar instabilities and wave structures. We focus on the spatial distribution of the wave intensity of the fluctuating magnetic field and detect an enhancement of the intensity in the dayside magnetosheath and a strong decrease towards the terminator. For a detailed investigation of the intensity distribution we adopt an analytical streamline model to describe the plasma flow around Venus. This allows displaying the evolution of the intensity along different streamlines. It is assumed that the waves are generated in the vicinity of the bow shock and are convected downstream with the turbulent magnetosheath flow. However, neither the different Mach numbers upstream and downstream of the bow shock, nor the variation of the cross sectional area and the flow velocity along the streamlines play probably an important role in order to explain the observed concentration of Correspondence to: L. Guicking (l.guicking@tu-bs.de) wave intensity in the dayside magnetosheath and the decay towards the nightside magnetosheath. But, the concept of freely evolving or decaying turbulence is in good qualitative agreement with the observations, as we observe a power law decay of the intensity along the streamlines. The observations support the assumption of wave convection through the magnetosheath, but reveal at the same time that wave sources may not only exist at the bow shock, but also in the magnetosheath.

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Section: Wave Properties At Venus and Marsmentioning

confidence: 98%

Section: Wave Vector Directionmentioning

confidence: 99%

Section: Wave Properties At Venus and Marsmentioning

confidence: 99%

“…Acuña et al, 1998). A statistical study of low-frequency magnetic field oscillations in the Martian plasma environment is presented by Espley et al (2004).…”

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confidence: 99%

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confidence: 99%

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Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

et al. 2010

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Transmission of large‐amplitude ULF waves through a quasi‐parallel shock at Venus

Lun

et al. 2014

JGR Space Physics

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There exist large-amplitude ultralow frequency (ULF) waves in the upstream region of a quasi-parallel shock, which are excited due to the reflected ions by the shock. These waves are then brought back to the shock by the solar wind, and at last they coalesce and merge with the shock. In this paper, with the magnetic field measurements from Venus Express, for the first time we observe the transmission of large-amplitude ULF waves from the upstream region to the downstream under quasi-parallel shock conditions. These waves exist in both the upstream and downstream regions of the Venusian bow shock, which have the similar characteristics: their peak frequencies are 0.04-0.05 Hz in the spacecraft frame, their propagation angles do not change greatly, they have left-hand polarization with respect to the mean magnetic field in the spacecraft frame, and they also have a large compressibility. We conclude that they are magnetosonic waves. The generation mechanism of such waves at the Venusian bow shock is also discussed in the paper.

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Statistical study of low‐frequency magnetic field fluctuations near Venus during the solar cycle

2017

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We statistically investigate the solar cycle dependence of the magnetic field fluctuations in the frequency range 30–300 MHz based on Venus Express data. We present the spatial distributions of fluctuation properties during three typical periods of the solar cycle, and a comparative study is also performed. With the increase of solar activity, the magnetic field is still quiet in the magnetotail region and the wave intensity becomes weaker in the magnetosheath. The transverse component of fluctuations becomes stronger in the magnetosheath region and weaker in the tail region. The proportion of circularly polarized components to incoherent noise of the fluctuations decreases in the magnetosheath region. The proportion of dominant parallel propagation fluctuations tends to be larger in the nightside magnetosheath, and more perpendicular propagation component is shown in the tail region.

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Magnetosheath fluctuations at Venus for two extreme orientations of the interplanetary magnetic field

Cited by 14 publications

References 28 publications

Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

Transmission of large‐amplitude ULF waves through a quasi‐parallel shock at Venus

Statistical study of low‐frequency magnetic field fluctuations near Venus during the solar cycle

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