Automated Detection of Small-scale Magnetic Flux Ropes and Their Association with Shocks

Zheng, Jinlei; Hu, Qiang; Chen, Yu; Roux, J. A. le

doi:10.1088/1742-6596/900/1/012024

Cited by 16 publications

(10 citation statements)

References 26 publications

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“…Through our unique approach, we provided the direct evidence in supporting the view of locally generated coherent structures intrinsic to the dynamic processes in the solar wind as manifested by magnetic reconnection and inverse turbulence cascade. We also performed case studies on the small-scale magnetic flux ropes downstream of interplanetary shocks, and found that the peaks of enhanced ions flux correspond to the merging X-line between two adjacent flux ropes, indicating that the merging flux ropes are able to energize particles within certain energy bands (Zheng et al 2017).…”

Section: Summary and Discussionmentioning

confidence: 99%

Automated Detection of Small-scale Magnetic Flux Ropes in the Solar Wind: First Results from the Wind Spacecraft Measurements

Zheng

Chen

et al. 2018

ApJS

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126

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We have developed a new automated small-scale magnetic flux rope (SSMFR) detection algorithm based on the Grad-Shafranov (GS) reconstruction technique. We have applied this detection algorithm to the Wind spacecraft in-situ measurements during 1996 -2016, covering two solar cycles, and successfully detected a total number of 74,241 small-scale magnetic flux rope events with duration from 9 to 361 minutes. This large number of small-scale magnetic flux ropes has not been discovered by any other previous studies through this unique approach. We perform statistical analysis of the small-scale magnetic flux rope events based on our newly developed database, and summarize the main findings as follows. (1) The occurrence of small-scale flux ropes has strong solar cycle dependency with a rate of a few hundreds per month on average. (2) The small-scale magnetic flux ropes in the ecliptic plane tend to align along the Parker spiral. (3) In low speed (< 400 km/s) solar wind, the flux ropes tend to have lower proton temperature and higher proton number density, while in high speed (≥ 400 km/s) solar wind, they tend to have higher proton temperature and lower proton number density. (4) Both the duration and scale size distributions

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Section: Summary and Discussionmentioning

confidence: 99%

Automated Detection of Small-scale Magnetic Flux Ropes in the Solar Wind: First Results from the Wind Spacecraft Measurements

Zheng

Chen

et al. 2018

ApJS

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126

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“…The GSR method models the magnetic field structure traversed by a spacecraft [43] and is the same technique employed in [39] to reconstruct interplanetary magnetic flux ropes. Another example of the use of the GSR method is the reconstruction of flux ropes from ACE and Wind spacecraft data, which was recently used to study flux ropes merging in the solar wind by Zheng et al [44]. This renders support for the use of IACD not only in numerical simulations, but also in observational data.…”

Section: Discussionmentioning

confidence: 99%

Objective magnetic vortex detection

et al. 2019

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Magnetic coherent vortical structures are ubiquitous in space and astrophysical plasmas and their detection is key to understanding the nature of the intrinsic turbulence in those conducting fluids. A recently developed method to detect magnetic vortices is explored in problems of two-and three-dimensional magnetohydrodynamic simulations. The integrated averaged current deviation, the normed difference of the current density at a point and the mean current density in the domain, integrated along a magnetic field line, is proved to be objective, i.e., invariant under rotations and translations of the observer. The method is shown to detect accurately the boundary of magnetic vortices in two-dimensional simulations, as well as magnetic flux ropes in three dimensions.

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“…sizes of magnetic-field domains (Borovsky, 2008;Zheng et al, 2017), and (3) ~ 10 5 -10 6 km for the scale sizes of plasma structures (Borovsky, 2012b). The spatial scale of variations in the magnetic field orientation (and hence the spatial scale of variations of Bn) are the scale sizes of the magnetic domains, ~ 10 5 -10 6 km.…”

Section: Introductionmentioning

confidence: 99%

A Statistical Analysis of the Fluctuations in the Upstream and Downstream Plasmas of 109 Strong‐Compression Interplanetary Shocks at 1 AU

Borovsky

2020

JGR Space Physics

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The upstream and downstream plasmas of 109 strong-compression forward interplanetary shocks are statistically analyzed using 3-s measurements from the WIND spacecraft. The goal is a comparison of the fluctuation properties of downstream plasmas in comparison with the fluctuation properties of upstream plasmas in the inertial range of frequencies and the magnetic-structure range of spatial scales. The shocks all have density compression rations of ~2 of more. When possible, each shock is categorized according to the type of solar wind plasma it propagates through: 15 shocks are in coronal-hole-origin plasma, 42 shocks are in streamer-belt-origin plasma, 36 shocks are in sector-reversal-region plasmas, and 11 shocks are in ejecta plasma. The statistical study examines magnetic-field and velocity spectral indices, the Alfvénicity, the fluctuation amplitudes, Alfvén ratios, the degree of plasma inhomogeneity, and Taylor microscales, looking in particular at (1) fluctuation values downstream that are related to fluctuation values upstream and (2) systematic differences in fluctuation values associated with the type of plasma. It is argued that inhomogeneity of the downstream plasma can be caused by spatial variations in the shock normal angle Bn caused by field-direction variations in the upstream magnetic structure. The importance of determining the type of plasma that the shock propagates through is established. Key Points: 1. Spectral indices, amplitudes, Alfvénicity, Alfvén ratios, the degree of plasma inhomogeneity, and Taylor microscales are examined. 2. Statistically, the properties of downstream fluctuations are correlated with the properties of upstream fluctuations. 3. Because of variations in the shock normal angle, upstream magnetic structure can lead to downstream plasma structure.

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Automated Detection of Small-scale Magnetic Flux Ropes and Their Association with Shocks

Cited by 16 publications

References 26 publications

Automated Detection of Small-scale Magnetic Flux Ropes in the Solar Wind: First Results from the Wind Spacecraft Measurements

Automated Detection of Small-scale Magnetic Flux Ropes in the Solar Wind: First Results from the Wind Spacecraft Measurements

Objective magnetic vortex detection

A Statistical Analysis of the Fluctuations in the Upstream and Downstream Plasmas of 109 Strong‐Compression Interplanetary Shocks at 1 AU

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