New Metric for Minimum Variance Analysis Validation in the Study of Interplanetary Magnetic Clouds

Oliveira, Rosemeire Aparecida Rosa; Oliveira, Marcos William da Silva; González, Arian Ojeda; Luz, V. De la

doi:10.1007/s11207-020-01610-6

Cited by 8 publications

(9 citation statements)

References 39 publications

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“…In this case, P > 4.5 indicates that the MVA method is consistent (Rosa Oliveira et al, 2020). It also shows the outputs of the automatic processing developed in this research, which are flux-rope type, helicity, and pairs of angles for decision sets.…”

Section: Visualization and Decisionmentioning

confidence: 69%

“…Finally, the MVA Results button presents a table of quantitative and qualitative data resulting from the processing. On this screen: xi (GSE) with i = 1, 2, 3 are the eigenvectors and (λ 1 , λ 2 , λ 3 ) the respective eigenvalues, (φ, θ ) are the MC-axis angles estimated by MVA, χ is the angle of rotation of the magnetic field, and there is the ratio λ 2 /λ 3 based on Lepping and Behannon (1980) and metric P (λ 1 , λ 2 , λ 3 ) based on Rosa Oliveira et al (2020). Both the eigenvectors and the angles of the MC-axis are modified according to the decision recorded on the other screens.…”

Section: Mva Output Mva Validation Resultsmentioning

confidence: 99%

“…MVA is applied to estimate the φ-and θ -angles (Sonnerup and Scheible, 1998;Rosa Oliveira et al, 2020). This method consists of an orthogonal linear transformation applied to the magnetic-field vectors B = (B x , B y , B z ).…”

Section: Methodsmentioning

confidence: 99%

“…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%

“…MVA is a classic eigenvalue and eigenvector problem that projects measured data in situ in a new coordinate system representing the best possible cross section of the cylinder proposed by a force-free model. The eigenvector associated with the intermediate eigenvalue provides the direction to the MC-axis (Klein and Burlaga, 1982;Rosa Oliveira et al, 2020). Interpreting Equation 2, B R ideally corresponds to the minimum-variance direction since B R = 0, while the B T form of J 1 represents a bipolar rotation and the B A form of J 0 is a single unipolar rotation.…”

Section: Introductionmentioning

confidence: 99%

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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: Visualization and Decisionmentioning

confidence: 69%

Section: Mva Output Mva Validation Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Properties of Ion-Inertial Scale Plasmoids Observed by the Juno Spacecraft in the Jovian Magnetotail

Sarkango

Slavin

Jia

et al. 2021

Preprint

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 We identify and analyze 87 ion-inertial scale plasmoids (56 O-lines, 31 flux-ropes) in the Jovian magnetotail using an automated algorithm. North-South field reversals with peak-to-peak durations less than 60 s are more common than those with durations between 60 and 300 s. Ion-inertial scale plasmoids alone cannot account for the >500 kg/s loss-rate deficit unless they are being produced every ~0.1 s or less.

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On the utility of flux rope models for CME magnetic structure below 30R⊙

Lynch

Al-Haddad

et al. 2022

Advances in Space Research

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New Metric for Minimum Variance Analysis Validation in the Study of Interplanetary Magnetic Clouds

Cited by 8 publications

References 39 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

Properties of Ion-Inertial Scale Plasmoids Observed by the Juno Spacecraft in the Jovian Magnetotail

On the utility of flux rope models for CME magnetic structure below 30R⊙

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