Structure and Dynamics of the Magnetosheath

Nykyri, K.

doi:10.1002/9781119509592.ch7

Cited by 3 publications

(3 citation statements)

References 122 publications

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“…The supersonic (i.e., the Mach number is about 10) solar wind plasma near 1 AU is significantly slowed down to the subsonic speed by the bow shock at a typical distance about 13 R E away from the Earth at the subsolar point (Merka et al., 2003). The region between the bow shock and magnetosphere is referred to as the magnetosheath region, which in addition to the ionosphere is the source plasma for the magnetosphere (see, e.g., Nykyri, 2020) and references therein). Note that the interplanetary magnetic field (IMF) in the equatorial plane is mostly in Parker spiral orientation (PS hereafter), which on average generates the quasi‐parallel bow shock on the dawnside and quasi‐perpendicular bow shock on the duskside.…”

Section: Introductionmentioning

confidence: 99%

Statistical Study of Solar Wind, Magnetosheath, and Magnetotail Plasma and Field Properties: 12+ Years of THEMIS Observations and MHD Simulations

Nykyri

Dimmock

et al. 2020

JGR Space Physics

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The solar wind plasma is a major plasma source for the Earth's magnetosphere, which has a strong influence on the magnetotail plasma and field properties. The relative importance of different plasma entry mechanisms and pathways is largely determined by the solar wind conditions. Therefore, the spatial and temporal dependence of magnetotail plasma and field properties under different kinds of solar wind conditions is critically important for understanding the Earth's magnetosphere. This study presents a statistical study of fundamental magnetotail plasma properties in a normalized reference frame by utilizing 12+ years of data from NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission. These statistical maps are mostly in agreement with the magnetosheath of MHD runs from the CCMC BATS-R-US model, but some features in the maps can be explained by kinetic particle physics, not present in the MHD. The results are also used to investigate the presence of any magnetotail plasma parameter asymmetries and their possible causes. Plain Language Summary Earth's intrinsic magnetic field, generated by the currents in the Earth's interior, protects our planet from solar radiation and plasma called the solar wind. However, physical processes such as magnetic reconnection occurring at the boundary of this magnetic barrier, the magnetosphere, can break this shield, enabling access of solar wind plasma into the Earth's magnetosphere. Earth's ionosphere provides another source for magnetospheric plasma. This plasma can be further accelerated to huge energies, which provides a threat for astronauts and satellites. The effectiveness of physical mechanisms that control the entry and acceleration of this plasma strongly depends on the local magnetic field geometry and plasma properties, which in turn are affected by the solar wind. However, the solar wind properties are not constant but vary as it can originate from different regions of the sun. While the magnetic field of the Sun, the interplanetary magnetic field (IMF), on average forms an "Archimedean Spiral," flapping of the heliospheric current sheet and fluctuations along field lines will make the IMF "hit" the Earth at different orientations, thus impacting the shock geometry in front of the planet, which in turn affects the downstream plasma and field properties in the turbulent boundary layer called the magnetosheath. In this paper, we have characterized the dependence of the large-scale plasma properties in the Earth's magnetosphere and magnetosheath on the solar wind and IMF conditions by using over 12 years (thus covering over one solar cycle) of data from NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission.

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Section: Introductionmentioning

confidence: 99%

Statistical Study of Solar Wind, Magnetosheath, and Magnetotail Plasma and Field Properties: 12+ Years of THEMIS Observations and MHD Simulations

Nykyri

Dimmock

et al. 2020

JGR Space Physics

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“…This structure would affect the shock geometry on Earth and the properties of the magnetopause impacting the onset conditions and driving various processes at the MSH and magnetopause (Nykyri, 2013;Hietala et al, 2018;Burkholder et al, 2020b;Nykyri, 2020;Nykyri et al, 2021a;Nykyri et al, 2021b).…”

Section: Stream Interaction and Co-rotating Interaction Regionsmentioning

confidence: 99%

Seven Sisters: a mission to study fundamental plasma physical processes in the solar wind and a pathfinder to advance space weather prediction

Nykyri

Burkholder

et al. 2023

Front. Astron. Space Sci.

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This paper summarizes the Seven Sisters solar wind mission concept and the outstanding science questions motivating the mission science objectives. The Seven Sisters mission includes seven individual spacecraft designed to uncover fundamental physical processes in the solar wind and provides up to ≈ 2 days of advanced space weather warnings for 550 Earth days during the mission. The mission will collect critical measurements of the thermal and suprathermal plasma and magnetic fields, utilizing, for the first time, Venus–Sun Lagrange points. The multi-spacecraft configuration makes it possible to distinguish between spatial and temporal changes, define gradients, and quantify cross-scale transport in solar wind structures. Seven Sisters will determine the 3-D structure of the solar wind and its transient phenomena and their evolution in the inner heliosphere. Data from the Seven Sisters mission will allow the identification of physical processes and the quantification of the relative contribution of different mechanisms responsible for suprathermal particle energization in the solar wind.

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“…Figure 1 (right) reveals that highly structured SW along the X GSE -and Y GSE -directions is comparable to the scale-size of the dayside magnetosheath(MSH)-magnetosphere(MSP) system along the Y GSE -direction. This structure would affect the shock geometry at Earth and the properties of the magnetopause, impacting the onset conditions and driving of the various processes at the magnetosheath and magnetopause [50,59,53]. What are the detailed particle acceleration mechanisms at SIRs/CIRs is a major SQ in heliophysics.…”

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confidence: 99%

Critical Solar Wind Measurements Required For the Next Generation Space Weather Prediction Mission: Science Motivation for the Seven Sisters Mission

Nykyri,

Adhikari,

Argall

et al. 2023

Bulletin of the AAS

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The large (0.6-1 AU) and intermediate-scale (1.5-100 Mm) structure, processes and properties of the solar wind (SW), such as heliospheric current sheet (HCS) dynamics, coronal mass ejections (CMEs), stream interaction (or co-rotating interaction) regions (SIRs), and interplanetary (IP) shocks, have a crucial impact on particle energization and propagation, as well as on the evolution of various magnetospheric processes. However, their detailed evolution in the inner heliosphere has not been adequately investigated yet, due to the lack of simultaneous, multi-point, coordinated in-situ observations at appropriate length-scales. As is takes about ≈ 1 h with typical SW speeds to reach Earth from Earth-Sun L1 (EL-1) point, the EL-1 measurements cannot provide sufficient warning time for space weather operations. Furthermore, if this structure is present in the SW [10], single spacecraft (SC) measurements at EL-1 will lead to inaccuracies when forecasting or developing various space weather warnings, e.g., for radiation belt electron flux enhancements etc. Missing this structure would also lead to wrong conclusions when interpreting the onset conditions of the physical processes at the magnetopause [51, 10], and in statistical magnetospheric studies that use lagged observations from a single monitor at EL-1 for characterizing SW properties and interplanetary magnetic field (IMF) orientation at the bow-shock nose. Thus, the goal of this white paper is to discuss the physical processes and structures in the SW which hinder accurate space weather forecasting and therefore motivate new, multi-point and multi-scale, critical measurements to improve our knowledge of the 3-D, large to intermediate-scale structures in the SW, azimuthal variation, radial evolution, as well as their impact on the charged particle acceleration, heating, and transport in the inner heliosphere. This science whitepaper also motivates our Seven Sisters inner heliospheric mission concept (see our companion mission concept white-paper), which is designed to solve these science questions.

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Structure and Dynamics of the Magnetosheath

Cited by 3 publications

References 122 publications

Statistical Study of Solar Wind, Magnetosheath, and Magnetotail Plasma and Field Properties: 12+ Years of THEMIS Observations and MHD Simulations

Statistical Study of Solar Wind, Magnetosheath, and Magnetotail Plasma and Field Properties: 12+ Years of THEMIS Observations and MHD Simulations

Seven Sisters: a mission to study fundamental plasma physical processes in the solar wind and a pathfinder to advance space weather prediction

Critical Solar Wind Measurements Required For the Next Generation Space Weather Prediction Mission: Science Motivation for the Seven Sisters Mission

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