Characterization of the Complex Ejecta Measured In Situ on 19 – 22 March 2001 by Six Different Methods

González, Arian Ojeda; Klausner, Virginia; Mendes, Odim; Domingues, Margarete Oliveira; Prestes, A.

doi:10.1007/s11207-017-1182-4

Cited by 9 publications

(7 citation statements)

References 70 publications

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“…For an event to be classified as a MC, it must simultaneously have: smooth rotation of the magneticfield vector, increased magnetic-field magnitude, decreased proton temperature, and low plasma-β (β < 1.0) (e.g. Burlaga et al, 1981;Burlaga, 1991;Lepping, Burlaga, and Jones, 1990;Schwenn, Marsch, and Jackson, 1993;Ojeda-González et al, 2017;Rosa Oliveira et al, 2020). These events can cause geomagnetic storms and sub-storms (Gonzalez and Tsurutani, 1987;Burlaga, 1991;Dal Lago et al, 2001;Echer, Alves, and Gonzalez, 2005).…”

Section: Introductionmentioning

confidence: 99%

Resolving the Ambiguity of a Magnetic Cloud’s Orientation Caused by Minimum Variance Analysis Comparing it with a Force-Free Model

Oliveira

González

et al. 2021

Sol Phys

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This study aims to incorporate an algebraic and computational method for calculating the angles of the magnetic clouds' (MC) axis from the minimum variance analysis (MVA) and correcting them compared to a simulated model from the linear, force-free approximation. Consequently, it determines the type of flux-rope consistently and automatically. In general, MCs measured in situ at 1 Astronomical Unit (AU) may be approximated to have a cylindrical geometry, and the internal magnetic-field topology is traditionally described by a force-free equilibrium flux-rope model. Based on the B z -rotation, the flux-rope configuration can be classified in eight groups. This classification is obtained from the angle of rotation of the magnetic-field vector and inclination of the flux-rope axis (φ, θ ) in relation to the plane of the Ecliptic. The MVA is applied to interplanetary magnetic-field (IMF) observations to obtain the direction of the cylinder axis. However, MVA estimates may have an ambiguity of 180 • in this direction. This is directly affected by the eigenvector signal since eigenvalues in MVA are always positive. To apply the methodology, a sample of 50 MC events measured by the Advance Composition Explorer (ACE) spacecraft was investigated in the period from 1998 to 2003. 83.72% of the analysed events achieved a satisfactory match between the maximum-and minimum-variance planes (from MVA) with the model (force-free) and (φ, θ ) angles consistent with the MC geometry. Moreover, automatic classification of the MC or flux-rope tube type related to the MC-axis was consistent for 100% of the events studied. This processing is organized in a computational tool described in this publication. We discuss the results and implications of our analysis of six magnetic cloud events in 2018 during the solar minimum.

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Section: Introductionmentioning

confidence: 99%

Resolving the Ambiguity of a Magnetic Cloud’s Orientation Caused by Minimum Variance Analysis Comparing it with a Force-Free Model

Oliveira

González

et al. 2021

Sol Phys

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“…Tendo em vista este cenário, a reconexão magnética que ocorre na magnetosfera terrestre é um importante fenômeno na ocorrência de sub-tempestades e tempestades geomagnéticas [17,18], que por sua vez pode interferir em nossa tecnologia de satélites e redes elétricas [19]. Neste cenário, a equação apresentada neste artigo se torna importante para estudar a reconexão magnética e fazer reconstruções em modelos semiempíricos na magnetosfera e no vento solar [20][21][22][23][24][25][26].…”

Section: Introductionunclassified

Uma Revisão da Teoria Cinética em Física de Plasma para se Obter uma Forma Simplificada da Equação de Grad-Shafranov

Cristaldo-Oliveira

Ojeda-González

Santos

et al. 2020

Rev. Bras. Ensino Fís.

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Esse trabalho tem por objetivo apresentar uma formulação teórica na área de física de plasma para obter uma forma simplificada da equação de Grad-Shafranov, em outras palavras, obter a lei de Ampère-Maxwell em função do potencial vetor magnético e da densidade de corrente. Buscamos entender melhor alguns fenômenos que ocorrem no plasma interplanetário. Outro objetivo é apresentar essa pesquisa de forma didática com a maior clareza e concisão possíveis. Para tanto, um desenvolvimento matemático se da como introdução ao trabalho, mostrando as equações que queremos deduzir, a cada seção vamos construindo uma base teórica em física de plasma, usando conceitos da termodinâmica e as leis universais da física, além de matemática, culminando na equação simplificada de Grad-Shafranov. Por fim, apresentamos uma das soluções mais conhecidas para equação de Grad-Shafranov, além de referências para quem quiser se aprofundar na pesquisa.

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“…In this way, it is possible to sim-ulate the plasma behavior in regions neighboring the satellite where no measurements were taken. This method is known as Grad-Shafranov reconstruction (GSR), and in the literature several successful studies can be found, for example Hu et al (2004); Lui et al (2008); Ojeda-González et al (2017a).…”

Section: Introductionmentioning

confidence: 99%

Grad-Shafranov equation: MHD simulation of the new solution obtained from the Fadeev and Naval models

González¹,

Santos²,

González-Avilés³

et al. 2020

Preprint

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The new analytical solution has magnetic field lines with neutral points and singular points.• This solution enter as initial condition in an MHD simulation by excluding the singular points.• The MHD simulation shows the fast evolution of magnetic islands into current sheets.• This is the first report shows the magnetic field polarity inversion related to analytical solution of the GS equation.• The importance of the direction and amplitude of the magnetic field near the singular points is explained.

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Characterization of the Complex Ejecta Measured In Situ on 19 – 22 March 2001 by Six Different Methods

Cited by 9 publications

References 70 publications

Resolving the Ambiguity of a Magnetic Cloud’s Orientation Caused by Minimum Variance Analysis Comparing it with a Force-Free Model

Resolving the Ambiguity of a Magnetic Cloud’s Orientation Caused by Minimum Variance Analysis Comparing it with a Force-Free Model

Uma Revisão da Teoria Cinética em Física de Plasma para se Obter uma Forma Simplificada da Equação de Grad-Shafranov

Grad-Shafranov equation: MHD simulation of the new solution obtained from the Fadeev and Naval models

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