Space Weather: Historical and Contemporary Perspectives

Lanzerotti, L. J.

doi:10.1007/s11214-017-0408-y

Cited by 47 publications

(36 citation statements)

References 64 publications

(58 reference statements)

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“…Other released magnetic energy is transferred to CMEs and SEPs associated with flares. Big solar flares and the associated CMEs and SEPs can cause severe disturbances to the space weather condition in the solar-terrestrial space as well as in the whole heliosphere [14,[23][24][25].…”

Section: Author Detailsmentioning

confidence: 99%

Variation of Coronal Magnetic Field and Solar Flare Eruption

He¹

2020

Nanofluid Flow in Porous Media

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Solar flares are prominent eruptive phenomenon happening in the solar atmosphere. Major flares usually come from solar active regions (ARs) where strong and concentrated bipolar magnetic field exists and manifests as dark sunspots in photosphere. The photospheric magnetic field acts as the bottom boundary of corona system and confines the magnetic structure of the corona. For complex ARs, the coronal magnetic field generally contains electric current around the magnetic polarity inversion lines, which corresponds to the nonpotential magnetic field and manifests as twisted field lines. The coronal magnetic field structure evolves as the response to the variations of the photospheric magnetic field. This coronal evolution can be quasi-steady and approximated by the force-free condition. In some situations, the variations of photospheric magnetic field may cause sudden changes of topological structure of coronal magnetic field at certain sites in the corona. The plasmas at these sites lost equilibrium and are ejected from their original positions. This process is accompanied with magnetic reconnection and leads to the release of magnetic energy in the corona. Part of the released magnetic energy is converted to the electromagnetic emission which manifests as sudden brightening across a broad range of electromagnetic wave spectrum, and hence the flare phenomenon is initiated.

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Section: Author Detailsmentioning

confidence: 99%

Variation of Coronal Magnetic Field and Solar Flare Eruption

He¹

2020

Nanofluid Flow in Porous Media

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“…This kind of typical solar flare events are also called two-ribbon flares. Big flares and associated CMEs may cause drastic disturbances to the solar-terrestrial space weather and impact the safety of spacecraft as well as the human life on the Earth (Schwenn 2006;Pulkkinen 2007;Koskinen et al 2017;Lanzerotti 2017). Flare activity was also discovered on the solar-type stars other than the Sun (Schaefer et al 2000;Benz & Güdel 2010;Shibata & Magara 2011;Maehara et al 2012;Notsu et al 2013;Shibayama et al 2013;Balona 2015;Davenport 2016).…”

Section: Introductionmentioning

confidence: 99%

Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158

Wang

Yan

et al. 2020

Advances in Space Research

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The magnetic configuration of flare-bearing active regions (ARs) is one key aspect for understanding the initiation of solar flares. In this paper, we perform a comparative analysis on the chiral characteristics and the magnetic configurations of two X-class two-ribbon flares happening in AR 10930 and AR 11158, whose photospheric magnetic fields were observed by the Hinode and SDO satellites, respectively. The corresponding coronal magnetic fields were calculated based on the nonlinear forcefree field model. It is found that both the flares were initiated in local areas with extremely strong electric current density. The chirality of the magnetic field (indicated by the sign of force-free factor α) along the main polarity inversion line (PIL) is opposite for the two ARs, that is, left-handed (α < 0) for AR 10930 and right-handed (α > 0) for AR 11158. The analysis shows that, for both flare events, prominent magnetic connectivity (indicated by both high α and strong current distributions) was formed above the main PIL before the flare and was totally broken after the flare eruption. Yet the two branches of broken magnetic connectivity, combined with the isolated electric current at the magnetic connectivity breaking site, compose the opposite magnetic configurations for the two ARs owing to their opposite chiral characteristics. That is, Z-shaped configuration for AR 10930 with negative α and left-handed chirality, and inverse Z-shaped configuration for AR 11158 with positive α and right-handed chirality. We speculate that two-ribbon flares can be generally classified to these two magnetic configurations by chirality (α sign) of ARs.

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“…An extreme space weather event, or solar/geomagnetic/ionospheric superstorm, is one of a number of potentially high impact natural hazards on engineering infrastructure such as the electricity grid, satellite technology, and the air passenger safety (Cannon, 2009(Cannon, , 2013Koskinen et al, 2018;Lanzerotti, 2018;Riley et al, 2018). The strength and a substantial impact of the geomagnetic and ionospheric superstorms on geospace have been addressed by different authors with different criteria applied to various solar, interplanetary, geomagnetic, and ionospheric parameters (Balan et al, 2017;Bell et al, 1997;Fok et al, 2011;Gulyaeva & Stanislawska, 2010;Gulyaeva, 2017;Kane, 2005;Lakhina & Tsurutani, 2018;Loewe & Prölss, 1997;Liu et al, 2010;Riley et al, 2018;Shirochkov et al, 2015;Verkhoglyadova et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Ionospheric Weather During Five Extreme Geomagnetic Superstorms Since IGY Deduced With the Instantaneous Global Maps GIM‐foF2

et al. 2018

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An assessment of the ionosphere perturbations can be made through the construction of the global instantaneous maps of the foF2 critical frequency (GIM‐foF2) and the ionospheric weather index maps GIM‐Wf. These maps can offer a potentially useful tool to provide users with a proper selection of the best radio wave propagation conditions over a certain area and also be used to help mitigate the effects of the disturbances on HF (High Frequency) communication and Global Navigation Satellite System positioning. This paper presents results of reconstruction of the ionospheric weather during five of the most intense superstorms observed since International Geophysical Year, IGY (1957, 1958, 1959, 1989, and 2003) with the instantaneous global maps of the F2 layer critical frequency, GIM‐foF2, and the ionospheric weather index maps, GIM‐Wf. The intensity of the ionospheric superstorm is characterized by the planetary Wfp index derived from GIM‐Wf maps. Superposed epoch analysis of the extreme superstorms is made during 24 hr before the Wfp peak (time zero t0 = 0 hr) and 48 hr afterwards. Model relationship is established between mean Wfp profile and geomagnetic superstorm profiles demonstrating saturation of the ionospheric storm activity toward the peak of geomagnetic storm. Time lag of Wfpmax is found equal to 9 hr after AEmax, 6 hr after apmax and aamax, and 2 hr after Dstmin, which allows model forecast of ionospheric superstorm when geomagnetic superstorm is captured with one or more of geomagnetic indices.

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Space Weather: Historical and Contemporary Perspectives

Cited by 47 publications

References 64 publications

Variation of Coronal Magnetic Field and Solar Flare Eruption

Variation of Coronal Magnetic Field and Solar Flare Eruption

Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158

Ionospheric Weather During Five Extreme Geomagnetic Superstorms Since IGY Deduced With the Instantaneous Global Maps GIM‐foF2

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