Foreshock compressional boundary

Omidi, N.; Sibeck, D. G.; Blanco‐Cano, X.

doi:10.1029/2008ja013950

Cited by 63 publications

(132 citation statements)

References 26 publications

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“…Since the magnetic field is aligned with the solar wind flow, the turbulent foreshock of the quasi-parallel bow shock covers the whole dayside. The effects of radial IMF are displayed most vividly in the 2.5D hybrid simulations by Sibeck et al (2008), Blanco-Cano et al (2009) Omidi et al (2009). There are also observations that show that during radial IMF the bow shock is closer to the Earth than predicted by the models (see Merka et al, 2003, and references therein).…”

Section: Discussionmentioning

confidence: 70%

“…Some of the foreshock waves can steepen into larger structures, such as Large Amplitude Magnetic Structures (SLAMS), that convect back to the bow shock and modify it (Schwartz, 1991;Lucek et al, 2002Lucek et al, , 2008. Satellite observations and simulation studies have led to the picture of quasi-parallel shock being a patchwork of structures that vary in space and time (e.g., Greenstadt et al, 1982;Gosling et al, 1989;Onsager et al, 1990;Schwartz and Burgess, 1991;Omidi et al, 2005Omidi et al, , 2009Blanco-Cano et al, 2006.…”

Section: Introductionmentioning

confidence: 99%

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Supermagnetosonic subsolar magnetosheath jets and their effects: from the solar wind to the ionospheric convection

et al. 2012

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Abstract. It has recently been proposed that ripples inherent to the bow shock during radial interplanetary magnetic field (IMF) may produce local high speed flows in the magnetosheath. These jets can have a dynamic pressure much larger than the dynamic pressure of the solar wind. On 17 March 2007, several jets of this type were observed by the Cluster spacecraft. We study in detail these jets and their effects on the magnetopause, the magnetosphere, and the ionospheric convection. We find that (1) the jets could have a scale size of up to a few R E but less than ∼6 R E transverse to the X GSE axis; (2) the jets caused significant local magnetopause perturbations due to their high dynamic pressure; (3) during the period when the jets were observed, irregular pulsations at the geostationary orbit and localised flow enhancements in the ionosphere were detected. We suggest that these inner magnetospheric phenomena were caused by the magnetosheath jets.

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Section: Discussionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Supermagnetosonic subsolar magnetosheath jets and their effects: from the solar wind to the ionospheric convection

et al. 2012

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“…Note that Figure 1a also shows the existence of a foreshock compressional boundary (FCB) characterized by in phase density and magnetic field enhancements. The properties of the FCB are discussed by Omidi et al [2009] using both global hybrid simulations and Cluster data. The asymmetry observed in the foreshock shape when the IMF is radial is due to reconnection at the magnetopause, where null points form.…”

Section: Simulation Resultsmentioning

confidence: 99%

Foreshock cavitons for different interplanetary magnetic field geometries: Simulations and observations

et al. 2011

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[1] Global hybrid (kinetic ions, fluid electrons) simulations have shown the existence of foreshock cavitons characterized by large depressions in plasma density and magnetic field magnitude, bounded by enhancements in these two parameters. Foreshock cavitons share some characteristics with reported foreshock cavities, but in contrast to the cavities that often appear as isolated structures, cavitons are always found surrounded by a sea of ultra low frequency (ULF) waves. They always occur in regions deep in the foreshock, downstream from the ion and ULF wave boundaries. We perform global hybrid simulations to show that cavitons can form for a variety of interplanetary magnetic field (IMF) geometries and different solar wind Mach numbers. We use Cluster data to show that cavitons are a common foreshock feature, and that they can form for different IMF orientations, consistent with our simulation results. We find that cavitons show density and field decrements as large as 60% of the ambient values. They are immersed in regions where waves show transverse and compressive components and the presence of diffuse ion distributions. We use linear kinetic theory to estimate wave growth for the two types of waves responsible for caviton formation, i.e., the weakly compressive waves and oblique propagating linearly polarized waves. Some of the cavitons observed by Cluster show trains of high-frequency waves inside them and this is consistent with the predictions of local higher-resolution hybrid simulations.Citation: Blanco-Cano, X., P. Kajdič, N. Omidi, and C. T. Russell (2011), Foreshock cavitons for different interplanetary magnetic field geometries: Simulations and observations,

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“…However, with Mendis 1988) one exception, the limited dimensions and ephemeral nature of most of these features and their magnetospheric responses probably preclude soft X-ray imaging. The exception is the foreshock compressional boundary, a region of enhanced density piled up on the edges of the quasi-parallel foreshock (Omidi et al 2009. Numerical simulations indicate that these structures can be quasi-steady-state features for a wide variety of IMF orientations.…”

Section: Earth's Foreshockmentioning

confidence: 97%

“…Some (e.g. hot flow anomalies) lie centered on tangential discontinuities, others (e.g., foreshock cavities) are bounded by tangential discontinuities (Sibeck et al 2001), some (e.g., compressional boundaries) bound the foreshock (Omidi et al 2009), and yet others (e.g., spontaneous hot flow anomalies) lie within the foreshock but are not associated with discontinuities ). Corresponding (Hietala et al 2012).…”

Section: Transients At Earth's Magnetopause and In The Cuspsmentioning

confidence: 99%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

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Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in con- text by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the KelvinHelmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time-and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ measurements rarely suffice to determine the global extent of these density structures or their global variation as a function of solar wind conditions, except in the form of empirical studies based on observations from many different times and solar wind conditions. Remote sensing observations provide global information about auroral ovals (FUV and hard X-ray), the terrestrial plasmasphere (EUV), and the terrestrial ring current (ENA). ENA instruments with low energy thresholds (∼ 1 keV) have recently been used to obtain important information concerning the magnetosheaths of Venus, Mars, and the Earth. Recent technological developments make these magnetosheaths valuable potential targets for high-cadence wide-field-of-view soft X-ray imagers.Section 2 describes proposed dayside interaction mechanisms, including reconnection, the Kelvin-Helmholtz instability, and other processes in greater detail with an emphasis on the plasma density structures that they generate. It focuses upon the questions that remain as yet unanswered, such as the significanc...

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Foreshock compressional boundary

Cited by 63 publications

References 26 publications

Supermagnetosonic subsolar magnetosheath jets and their effects: from the solar wind to the ionospheric convection

Supermagnetosonic subsolar magnetosheath jets and their effects: from the solar wind to the ionospheric convection

Foreshock cavitons for different interplanetary magnetic field geometries: Simulations and observations

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

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