A large‐scale flow vortex in the Venus plasma tail and its fluid dynamic interpretation

Lundin, R.; Barabash, S.; Futaana, Yoshifumi; Holmström, M.; Pérez‐de‐Tejada, H.; Sauvaud, J. A.

doi:10.1002/grl.50309

Cited by 24 publications

(22 citation statements)

References 16 publications

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“…In the ionosphere, the plasma velocity is actually dominated by the components along the Y VSO axis (with a contribution of ≈46%) followed by Z VSO (≈39%) and X VSO (≈15%) axes. These results are consistent with Lundin et al(, , ) in which the authors attributed the persistent + Y VSO directed ion flow over the northern polar region to the solar wind aberration.…”

Section: Discussionsupporting

confidence: 93%

A Statistical Study of Ionospheric Boundary Wave Formation at Venus

et al. 2018

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Previous missions to Venus have revealed that encounters with plasma irregularities of atmospheric origin outside the atmosphere are not uncommon. A number of mechanisms have been proposed to discuss their origins as well as their roles in the atmospheric evolution of Venus. One such mechanism involves an ionopause with a wavelike appearance. By utilizing the magnetic field and plasma data from Venus Express, we present the first observational statistical analysis of the ionospheric boundary wave phenomena at Venus using data from 2006 to 2014. Results from the minimum variance analysis of all the photoelectron dropout events in the ionosphere reveal that the ionopause of Venus does not always appear to be smooth but often exhibits a wavelike appearance. In the northern polar region of Venus, the normal directions of the rippled ionospheric boundary crossings lie mainly in the terminator plane with the largest component predominantly along the dawn‐dusk (YVSO) direction. The average estimated wavelength of the boundary wave is 212 ± 12 km, and the average estimated velocity difference across the ionopause is 104 ± 6 km/s. The results suggest that the rippled boundary is a result of Kelvin‐Helmholtz instability. Analysis reveals a correlation between the normal directions and the locations of the boundary wave with respect to Venus. This indicates that the draping of magnetic field lines may play a role in enhancing the plasma flow along the dawn‐dusk direction, which could subsequently set up a velocity shear that favors the excitation of ionospheric boundary wave by the Kelvin‐Helmholtz instability along the dawn‐dusk direction.

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Section: Discussionsupporting

confidence: 93%

A Statistical Study of Ionospheric Boundary Wave Formation at Venus

et al. 2018

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“…Solar wind protons and heavy ionospheric ions display the same vortex pattern, suggesting that energy and momentum are directly transferred from the solar wind plasma to the planetary ions. The origin of the vortex has been proposed to be the orbital motion of Venus, which causes a significant aberration of the solar wind flow around Venus (Lundin et al 2013).…”

Section: Plasma In the Magnetotailmentioning

confidence: 99%

Solar Wind Interaction and Impact on the Venus Atmosphere

et al. 2017

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Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years.Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models, describing the plasma interaction on scales ranging from ion gyro radius to the entire induced magnetosphere. In this review article, we review what has been found from space physics measurements around Venus (from the solar wind down to the ionopause), with a particular emphasis on updated results since the Venus Express mission. We conclude the article by a short discussion on the remaining open scientific questions and the future of this field.

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“…The latter leads to an asymmetry in the location of the Venus ionopause [ Phillips et al ., ], and a curled flow of SWH + and energized O + moving dawnward and tailward through the polar region thermosphere [ Lundin et al ., ]. The height distribution of the SWH + and ionospheric O + momentum fluxes indicates an efficient transfer of SWH + energy and momentum to O + [ Pérez‐de‐Tejada , ] at altitudes up to 1200 km [ Lundin et al ., ]. The ion flux decrease below 1000 km marks a gradual transition of ions to Energetic Neutral Atoms (ENAs) via Charge Exchange (CE).…”

Section: Introductionmentioning

confidence: 99%

“…The average ion flow over the low-altitude polar region displays a steady flow directed tailward and laterally (+Y), the plasma tail forming a large-scale vortex [Lundin et al, 2013]. On the nightside near the planet, the flow is more tangential, moving westward in the direction of the atmospheric super-rotation.…”

Section: Introductionmentioning

confidence: 99%