Preprocessing Magnetic Fields With Chromospheric Longitudinal Fields

Yamamoto, T.; Kusano, K.

doi:10.1088/0004-637x/752/2/126

Cited by 20 publications

(15 citation statements)

References 18 publications

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“…We simulate such broadening using Gauss smoothing of the data with σ =2 arcsec as suggested in ref. 63 . We also smooth the data in time with Gaussian window of σ =4 × 12 min to remove short-term temporal oscillations and spikes due to bad pixels ( Supplementary Fig.…”

Section: Methodsmentioning

confidence: 99%

Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption

et al. 2016

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Solar eruptions are well-recognized as major drivers of space weather but what causes them remains an open question. Here we show how an eruption is initiated in a non-potential magnetic flux-emerging region using magnetohydrodynamic modelling driven directly by solar magnetograms. Our model simulates the coronal magnetic field following a long-duration quasi-static evolution to its fast eruption. The field morphology resembles a set of extreme ultraviolet images for the whole process. Study of the magnetic field suggests that in this event, the key transition from the pre-eruptive to eruptive state is due to the establishment of a positive feedback between the upward expansion of internal stressed magnetic arcades of new emergence and an external magnetic reconnection which triggers the eruption. Such a nearly realistic simulation of a solar eruption from origin to onset can provide important insight into its cause, and also has the potential for improving space weather modelling.

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Section: Methodsmentioning

confidence: 99%

Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption

et al. 2016

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“…We first smoothed the magnetograms with Gaussian window of σ = 2 arcsec. To remove the temporal oscillations, we also smoothed the data in time with Gaussian window of σ = 4 × 12 min (Yamamoto & Kusano 2012;Jiang et al 2016). Then, following the approach proposed by Wu et al (2006), we reduced the strength of the magnetic field by dividing the smoothed magnetograms by 40 to get the final magnetic field maps that are input into the numerical model.…”

Section: Boundary Conditionsmentioning

confidence: 99%

New data-driven method of simulating coronal mass ejections

Liu

Chen

Zhao

2019

A&A

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Context. Coronal mass ejections (CMEs) are large eruptions of plasma and magnetic field from the Sun’s corona. Understanding the evolution of the CME is important to evaluate its impact on space weather. Using numerical simulation, we are able to reproduce the occurrence and evolution process of the CME. Aims. The aim of this paper is to provide a new data-driven method to mimic the coronal mass ejections. By using this method, we can investigate the phsical mechanisms of the flux rope formation and the cause of the CME eruption near the real background. Methods. Starting from a potential magnetic field extrapolation, we have solved a full set of magnetohydrodynamic (MHD) equations by using the conservation element and solution element (CESE) numerical method. The bottom boundary is driven by the vector magnetograms obtained from SDO/HMI and vector velocity maps derived from DAVE4VM method. Results. We present a three-dimensional numerical MHD data-driven model for the simulation of the CME that occurred on 2015 June 22 in the active region NOAA 12371. The numerical results show two elbow-shaped loops formed above the polarity inversion line (PIL), which is similar to the tether-cutting picture previously proposed. The temporal evolutions of magnetic flux show that the sunspots underwent cancellation and flux emergence. The signature of velocity field derived from the tracked magnetograms indicates the persistent shear and converging motions along the PIL. The simulation shows that two elbow-shaped loops were reconnected and formed an inverse S-shaped sigmoid, suggesting the occurrence of the tether-cutting reconnection, which was supported by observations of the Atmospheric Imaging Assembly (AIA) telescope. Analysis of the decline rate of the magnetic field indicates that the flux rope reached a region where the torus instability was triggered. Conclusions. We conclude that the eruption of this CME was caused by multiple factors, such as photosphere motions, reconnection, and torus instability. Moreover, our simulation successfully reproduced the three-component structures of typical CMEs.

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“…Moreover, based on their findings, they explicitly support schemes which propose the inclusion of the spatial information delivered by chromospheric fibril observations to increase the success of force-free coronal magnetic field models. Such proposed schemes use the fibril information to increase the match between the modeled and observed horizontal field at chromospheric heights (where the magnetic field vector is not routinely measured; see Wiegelmann et al 2005aWiegelmann et al , 2008Yamamoto and Kusano 2012).…”

Section: Indirect Tracing Of Chromospheric Fieldsmentioning

confidence: 99%

The magnetic field in the solar atmosphere

Wiegelmann

Thalmann

Solanki

2014

Astron Astrophys Rev

182

125

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This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In addition, the field also plays a crucial role in heating the solar chromosphere and corona as well as in accelerating the solar wind. Our main emphasis is the magnetic field in the upper solar atmosphere so that photospheric and chromospheric magnetic structures are mainly discussed where relevant for higher solar layers. Also, the discussion of the solar atmosphere and activity is limited to those topics of direct relevance to the magnetic field. After giving a brief overview about the solar magnetic field in general and its global structure, we discuss in more detail the magnetic field in active regions, the quiet Sun and coronal holes.

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Preprocessing Magnetic Fields With Chromospheric Longitudinal Fields

Cited by 20 publications

References 18 publications

Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption

Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption

New data-driven method of simulating coronal mass ejections

The magnetic field in the solar atmosphere

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