Geoeffectiveness of solar flares in magnetic crochet (sfe) production: I—Dependence on their spectral nature and position on the solar disk

Curto, J. J.; Gaya–Piqué, Luis R.

doi:10.1016/j.jastp.2008.06.018

Cited by 13 publications

(10 citation statements)

References 24 publications

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“…These results agree with direct measurements of the magnetic field of sunspots, which give a higher magnetic flux for the leading sunspots than for the following ones (Vitinsky, Kopecky, and Kuklin, 1986;Choudhary, Venkatakrishnan, and Gosain, 2002;Fan, 2009). It has been shown that the balance of magnetic fluxes is not observed for all classes of sunspot groups (Vitinsky, Kopecky, and Kuklin, 1986).…”

Section: Positive and Negative Magnetic Fields And Their Imbalance Fosupporting

confidence: 88%

“…The heliographic distribution of significant Hα and X-ray flares has been studied during the period 1975− 1989(Curto and Gaya-Pique, 2009), who found that the northern hemisphere dominates in the ascending part of each solar cycle and the southern hemisphere dominates in the descending part. Li and Gu (2000) collected 20 different solar-activity phenomena to investigate solar activity in Solar Cycle 21, and found that solar activity has a northern bias at first, and as the cycle progresses, southern predominance takes over.…”

Section: Introductionmentioning

confidence: 99%

“…The observed prevalence of the negative mean magnetic field of the Sun as a star in 1968 − 1969 and 1989 − 1990 could not be compensated by the northern field of the polar regions. Choudhary, Venkatakrishnan, and Gosain (2002) studied the magnetic-flux imbalance of active regions using the longitudinal magnetograms obtained from the National Solar Observatory at Kitt Peak. The median value of the flux imbalance in 137 active regions was found to be about 9.5 %.…”

Section: Introductionmentioning

confidence: 99%

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Photospheric Magnetic Field: Relationship Between North–South Asymmetry and Flux Imbalance

Vernova¹,

Tyasto²,

Baranov³

2014

Coronal Magnetometry

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Photospheric magnetic fields were studied using the Kitt Peak synoptic maps for 1976 − 2003. Only strong magnetic fields (B > 100 G) of the equatorial region were taken into account. The north-south asymmetry of the magnetic fluxes was considered as well as the imbalance between positive and negative fluxes. The north-south asymmetry displays a regular alternation of the dominant hemisphere during the solar cycle: the northern hemisphere dominated in the ascending phase, the southern one in the descending phase during Solar Cycles 21 − 23. The sign of the imbalance did not change during the 11 years from one polar-field reversal to the next and always coincided with the sign of the Sun's polar magnetic field in the northern hemisphere. The dominant sign of leading sunspots in one of the hemispheres determines the sign of the magneticflux imbalance. The sign of the north-south asymmetry of the magnetic fluxes and the sign of the imbalance of the positive and the negative fluxes are related to the quarter of the 22-year magnetic cycle where the magnetic configuration of the Sun remains constant (from the minimum where the sunspot sign changes according to Hale's law to the magnetic-field reversal and from the reversal to the minimum). The sign of the north-south asymmetry for the time interval considered was determined by the phase of the 11-year cycle (before or after the reversal); the sign of the imbalance of the positive and the negative fluxes depends on both the phase of the 11-year cycle and on the parity of the solar cycle. The results obtained demonstrate the connection of the magnetic fields in active regions with the Sun's polar magnetic field in the northern hemisphere.

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Section: Positive and Negative Magnetic Fields And Their Imbalance Fosupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Photospheric Magnetic Field: Relationship Between North–South Asymmetry and Flux Imbalance

Vernova¹,

Tyasto²,

Baranov³

2014

Coronal Magnetometry

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“…Emissions containing a different range of frequencies produce diverse geomagnetic effects. Curto and Gaya‐Piqué [2008] showed that the probability of generating a SFE increases when the flare spectrum presents a significant X‐ray and H‐ α wavelength content, probably due to the fact that the ionizing effect of X‐ray radiation on the lower ionosphere region is greater and therefore more efficient in SFE production.…”

Section: Introductionmentioning

confidence: 99%

Equivalent ionospheric currents for the 5 December 2006 solar flare effect determined from spherical cap harmonic analysis

et al. 2008

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[1] In this paper we analyze the prompt solar flare effect (SFE) associated to a strong X-ray flare that occurred on 5 December 2006 by using spherical cap harmonic analysis applied to the variations recorded in the European magnetic observatories network. The regional model allows the simultaneous modeling in space and time of the ionospheric equivalent current system responsible for the SFE, as well as for the regular diurnal variation S R on that day. It is found that the SFE equivalent current system does not form as an enhancement of the S R system. Its focus is distinct from that of the S R , and it is located between 3 and 10°higher in latitude and circa 40 min later in local time.

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“…As a comment on some presented examples, it concludes: "But the following examples, taken also from cases confirmed by direct observation of the solar flare, have an aspect rather confusing". No one looking at only one single magnetogram can conclude whether a movement is or is not, in fact, an Sfe because this is only a partial view of the whole process (Curto & Gaya-Piqué, 2009a, 2009b. Sfe can appear only in the X-magnetic component, only in the Y-magnetic component, in both components, or in neither of them.…”

Section: Difficulties In Sfe Detectionmentioning

confidence: 99%

Geomagnetic solar flare effects: a review

Curto

2020

J. Space Weather Space Clim.

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Solar flare effects (Sfe) are rapid variations in the Earth’s magnetic field and are related to the enhancement of the amount of radiation produced during Solar flare events. They mainly appear in the Earth’s sunlit hemisphere at the same time as the flare observation and have a crochet-like shape. Much progress has been made since Carrington’s first observations in 1859 which are considered to represent the first direct evidence of the connection between the Sun and the Earth’s environment but there is still much to discover. In this paper, we review state-of-the-art developments and the advances made in the knowledge concerning Sfe phenomena while also looking at the challenges that lie ahead. First, we offer a historical approach with a comprehensive description that allows for a better understanding of the main characteristics of Sfe. This frames specific topics like the puzzling reversed-Sfe or the nighttime Sfe. The role played by the Service of Rapid Magnetic variations (SRMV) is also assessed, followed by a discussion of the main current limiting factors in the process of detection and proposed ways to overcome challenges such as by creating an automatic detection method. The paper clarifies some aspects related to the geo-effectiveness of the solar flares producing magnetic disturbances. The importance of the global modelling studies covering critical aspects needed to understand this Sun–Earth system is assessed. Also, we provide an overview of the temporal evolution of the electric currents producing Sfe. The importance of key subjects such as the dynamic aspects of Sfe is developed in another section. Finally, estimations of the size of large flares using ionospheric and magnetic data are reviewed as well as the prospects of these large flare events putting technological systems in danger.

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Geoeffectiveness of solar flares in magnetic crochet (sfe) production: I—Dependence on their spectral nature and position on the solar disk

Cited by 13 publications

References 24 publications

Photospheric Magnetic Field: Relationship Between North–South Asymmetry and Flux Imbalance

Photospheric Magnetic Field: Relationship Between North–South Asymmetry and Flux Imbalance

Equivalent ionospheric currents for the 5 December 2006 solar flare effect determined from spherical cap harmonic analysis

Geomagnetic solar flare effects: a review

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