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Schrijver, Carolus J.; DeRosa, Marc L.

doi:10.1023/a:1022908504100

Cited by 627 publications

(429 citation statements)

References 47 publications

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“…Flux transport computations performed in recent times often start from observed magnetograms, e.g., full disk (Schrijver and De Rosa 2003) or synoptic (Durrant and McCloughan 2004) LOS magnetograms from SOHO/MDI. As a welcome side product, fluxes are obtained also for regions where no LOS measurements can be performed or where they are not reliable (i.e., at the far side and around the poles of the Sun, respectively).…”

Section: Flux Transport Modelsmentioning

confidence: 99%

The magnetic field in the solar atmosphere

Wiegelmann

Thalmann

Solanki

2014

Astron Astrophys Rev

171

123

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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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Section: Flux Transport Modelsmentioning

confidence: 99%

The magnetic field in the solar atmosphere

Wiegelmann

Thalmann

Solanki

2014

Astron Astrophys Rev

171

123

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“…A more specific model was constructed for the period around 12 December 2007, when the AR was at or near central meridian. Here the surface magnetic-field measurements are sampled from an evolving flux model (Schrijver and Title, 2001) using the method for inserting the field data into the PFSS model described by Schrijver and De Rosa (2003). The large-scale topological features of this model, e.g.…”

Section: The Global Magnetic Field Configuration For Ar 10978mentioning

confidence: 99%

“…In the second step, by using the PFSS software and the Michelson Doppler Imager (MDI: Scherrer et al, 1995) data (Schrijver and De Rosa, 2003), we can continue mapping the solar wind and magnetic field down to the photosphere following PFSS coronal-field lines. There are a number of model-dependent factors that are known to affect the distribution of open vs. closed magnetic flux in photospheric-field extrapolations (e.g.…”

Section: Ace In-situ Observations and Their Possible Relation To Ar Omentioning

confidence: 99%

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

Culhane¹,

Brooks

Driel-Gesztelyi

et al. 2014

Sol Phys

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Seeking to establish whether active-region upflow material contributes to the slow solar wind, we examine in detail the plasma upflows from Active Region (AR) 10978, which crossed the Sun's disc in the interval 8 to 16 December 2007 during Carrington rotation (CR) 2064. In previous work, using data from the Hinode/EUV Imaging Spectrometer, upflow velocity evolution was extensively studied as the region crossed the disc, while a linear forcefree-field magnetic extrapolation was used to confirm aspects of the velocity evolution and to establish the presence of quasi-separatrix layers at the upflow source areas. The plasma properties, temperature, density, and first ionisation potential bias [FIP-bias] were measured with the spectrometer during the disc passage of the active region. Global potential-field source-surface (PFSS) models showed that AR 10978 was completely covered by the closed field of a helmet streamer that is part of the streamer belt. Therefore it is not clear how any of the upflowing AR-associated plasma could reach the source surface at 2.5 R and contribute to the slow solar wind. However, a detailed examination of solar-wind in-situ data obtained by the Advanced Composition Explorer (ACE) spacecraft at the L 1 point shows that increases in O 7+ /O 6+ , C 6+ /C 5+ , and Fe/O -a FIP-bias proxy -are present before the heliospheric current-sheet crossing. These increases, along with an accompanying reduction in proton velocity and an increase in density are characteristic of both AR and slow-solarwind plasma. Finally, we describe a two-step reconnection process by which some of the upflowing plasma from the AR might reach the heliosphere.

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“…Well-connected field lines are a subset of open field lines that intersect the source surface at the ecliptic. We adopt the PFSS model, as implemented into SolarSoft by Schrijver and DeRosa (2003), which is based on the photospheric magnetic maps that are constructed from (1) MDI data for the area within 60 • from disk center and (2) the flux-dispersal model (Schri- . "I" and "N" stand for "inside an ICME" and "no ICME", respectively.…”

Section: Magnetic Field Connectionmentioning

confidence: 99%

What Are Special About Ground-Level Events?

et al. 2012

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Ground level events (GLEs) occupy the high-energy end of gradual solar energetic particle (SEP) events. They are associated with coronal mass ejections (CMEs) and solar flares, but we still do not clearly understand the special conditions that produce these rare events. During Solar Cycle 23, a total of 16 GLEs were registered, using ground-based neutron monitor data. We first ask if these GLEs are clearly distinguishable from other SEP events observed from space. Setting aside possible difficulties in identifying all GLEs consistently, we then try to find observables which may unmistakably isolate these GLEs by studying the basic properties of the associated eruptions and the active regions (ARs) that produced them. It is found that neither the magnitudes of the CMEs and flares nor the complexities of the ARs give sufficient conditions for GLEs. It is possible to find CMEs, flares or ARs that are not associated with GLEs but that have more extreme properties than those associated with GLEs. We also try to evaluate the importance of magnetic field connection of the AR with Earth on the detection of GLEs and their onset times. Using the potential field source surface (PFSS) model, a half of the GLEs are found to be well-connected. However, the GLE onset time with respect to the onset of the associated flare and CME does not strongly depend on how well-connected the AR is. The GLE onset behavior may be largely determined by when and where the CME-driven shock develops. We could not relate the shocks responsible for the onsets of past GLEs with features in solar images, but the combined data from the Solar TErrestrial RElations Observatory (STEREO) and the Solar Dynamics Observatory (SDO) have the potential to change this for GLEs that may occur in the rising phase of Solar Cycle 24.

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Untitled

Cited by 627 publications

References 47 publications

The magnetic field in the solar atmosphere

The magnetic field in the solar atmosphere

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

What Are Special About Ground-Level Events?

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