Forecasting a CME by Spectroscopic Precursor?

Baker, D.; Driel-Gesztelyi, L. van; Green, L. M.

doi:10.1007/s11207-011-9893-4

Cited by 20 publications

(20 citation statements)

References 63 publications

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“…The amount of flux canceled is very similar to that found in Yardley et al (2017) despite the difference in methods used to calculate the magnetic flux. This is also consistent with previous studies such as Green et al (2011), Baker et al (2012), and Yardley et al (2016. The AR also rotates clockwise during this period.…”

Section: Summary and Discussionsupporting

confidence: 93%

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Yardley

Mackay

Green

2018

ApJ

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The coronal magnetic field evolution of AR 11437 is simulated by applying the magnetofrictional relaxation technique of Mackay et al. A sequence of photospheric line-of-sight magnetograms produced by the Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) is used to drive the simulation and continuously evolve the coronal magnetic field of the active region through a series of nonlinear force-free equilibria. The simulation is started during the first stages of the active region emergence so that its full evolution from emergence to decay can be simulated. A comparison of the simulation results with SDO/Atmospheric Imaging Assembly (AIA) observations show that many aspects of the active region's observed coronal evolution are reproduced. In particular, it shows the presence of a flux rope, which forms at the same location as sheared coronal loops in the observations. The observations show that eruptions occurred on 2012 March 17 at 05:09 UT and 10:45 UT and on 2012 March 20 at 14:31 UT. The simulation reproduces the first and third eruption, with the simulated flux rope erupting roughly 1 and 10 hr before the observed ejections, respectively. A parameter study is conducted where the boundary and initial conditions are varied along with the physical effects of Ohmic diffusion, hyperdiffusion, and an additional injection of helicity. When comparing the simulations, the evolution of the magnetic field, free magnetic energy, relative helicity and flux rope eruption timings do not change significantly. This indicates that the key element in reproducing the coronal evolution of AR 11437 is the use of line-of-sight magnetograms to drive the evolution of the coronal magnetic field.

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Section: Summary and Discussionsupporting

confidence: 93%

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Yardley

Mackay

Green

2018

ApJ

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“…Flux cancellation within the AR can be as large is 10%/day of the total AR flux (Sterling et al, 2010;Baker et al, 2012;Green et al, 2011). The size of the ratio of in-AR cancellation to dispersing flux may be inversely related to the AR size (flux content) being the largest in ephemeral ARs.…”

Section: Main Laws and Intrinsic Characteristics Of Large-scale Magnementioning

confidence: 99%

“…Baker et al (2012) and Sterling et al (2010) studied different regions that both showed that 20% of the flux was lost over just two days and Green et al (2011) tracked an active region from emergence to decay and found that 34% of the active region flux was cancelled along the active region's internal polarity inversion within 3.5 days of the flux emergence ending.…”

Section: Flux Cancellation and Removal Of Flux From The Photospherementioning

confidence: 99%

Evolution of Active Regions

Driel-Gesztelyi

Green

2015

Living Rev. Sol. Phys.

252

131

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The evolution of active regions (AR) from their emergence through their long decay process is of fundamental importance in solar physics. Since large-scale flux is generated by the deepseated dynamo, the observed characteristics of flux emergence and that of the subsequent decay provide vital clues as well as boundary conditions for dynamo models. Throughout their evolution, ARs are centres of magnetic activity, with the level and type of activity phenomena being dependent on the evolutionary stage of the AR. As new flux emerges into a pre-existing magnetic environment, its evolution leads to re-configuration of small-and large-scale magnetic connectivities. The decay process of ARs spreads the once-concentrated magnetic flux over an ever-increasing area. Though most of the flux disappears through small-scale cancellation processes, it is the remnant of large-scale AR fields that is able to reverse the polarity of the poles and build up new polar fields. In this Living Review the emphasis is put on what we have learned from observations, which is put in the context of modelling and simulation efforts when interpreting them. For another, modelling-focused Living Review on the sub-surface evolution and emergence of magnetic flux see Fan (2009). In this first version we focus on the evolution of dominantly bipolar ARs. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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“…The zoomed map shows an inverse S-channel of low-FIP bias along the main PIL which hosts a filament within the AR where a sigmoid/flux rope is forming and will erupt soon thereafter (Baker et al 2012). The two principal sites of flux cancellation along the PIL, indicated by the red circles in Figure 2, are located in low-FIP bias areas.…”

Section: Resultsmentioning

confidence: 99%

“…The Hinode/EIS Fe xii 195.119Å intensity map (left panel) and S x 264.223Å -Si x 258.375Å (middle and right panels) abundance map are shown in Figure 1. See Baker et al (2012) for a complete account of the AR-CH complex observations and Baker et al (2013) for a description of the method used to construct the abundance map derived from Hinode/EIS spectra.…”

Section: Observationsmentioning

confidence: 99%

FIP bias in a sigmoidal active region

et al. 2013

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Abstract. We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) -coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359 × 485 . Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ∼1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

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Forecasting a CME by Spectroscopic Precursor?

Cited by 20 publications

References 63 publications

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Evolution of Active Regions

FIP bias in a sigmoidal active region

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