Concerning long-term geomagnetic variations and space climatology

Glaßmeier, Karl‐Heinz; Vogt, Joachim; Stadelmann, A.; Buchert, Stephan

doi:10.5194/angeo-22-3669-2004

Cited by 45 publications

(76 citation statements)

References 27 publications

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“…The question now is to infer how the flux of particles above the South Atlantic and South America will change in response to the evolution of the magnetic field. Glassmeier et al (2004) have shown that less particles can be trapped in a weaker magnetic field. We can also anticipate that interactions between protons trapped in the inner radiation belt and the thermosphere will increase as the SAA grows (Roederer and Zhang (2014)).…”

Section: Discussionmentioning

confidence: 99%

The South Atlantic Anomaly throughout the solar cycle

Domingos

Jault

Pais

et al. 2017

Earth and Planetary Science Letters

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The Sun-Earth's interaction is characterized by a highly dynamic electromagnetic environment, in which the magnetic field produced in the Earth's core plays an important role. One of the striking characteristics of the present geomagnetic field is denoted the South Atlantic Anomaly (SAA) where the total field intensity is unusually low and the flux of charged particles, trapped in the inner Van Allen radiation belts, is maximum. Here, we use, on one hand, a recent geomagnetic field model, CHAOS-6, and on the other hand, data provided by different platforms (satellites orbiting the Earth -POES NOAA for 1998 and CALIPSO for 2006. Evolution of the SAA particle flux can be seen as the result of two main effects, the secular variation of the Earth's core magnetic field and the modulation of the density of the inner radiation belts during the solar cycle, as a function of the L value that characterises the drift shell, where charged particles are trapped. To study the evolution of the particle flux anomaly, we rely on a Principal Component Analysis (PCA) of either POES particle flux or CALIOP dark noise. Analysed data are distributed on a geographical grid at satellite altitude, based on a L-shell reference frame constructed from the moving eccentric dipole. Changes in the main magnetic field are responsible for the observed westward drift. Three PCA modes account for the time evolution related to solar effects. Both the first and second modes have a good correlation with the thermospheric density, which varies in response to the solar cycle. The first mode represents the total intensity variation of the particle flux in the SAA, and the second the movement of the anomaly between different L-shells. The proposed analysis allows us to well recover the westward drift rate, as well as the latitudinal and longitudinal solar cycle oscillations, although the analysed data do not cover a complete (Hale) magnetic solar cycle (around 22 yr). Moreover, the developments made here would enable us to forecast the impact of the South Atlantic Anomaly on space weather. A model of the evolution of the eccentric dipole field (magnitude, offset and tilt) would suffice, together with a model for the solar cycle evolution.

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Section: Discussionmentioning

confidence: 99%

The South Atlantic Anomaly throughout the solar cycle

Domingos

Jault

Pais

et al. 2017

Earth and Planetary Science Letters

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“…For the geostrophic balance, the scaling law for the size of the magnetic field can be obtained in the following way (Glaßmeier and Vogt 2001). In eq.…”

Section: Magnetic Moment Scaling Lawsmentioning

confidence: 99%

Aspects of the magnetosphere–stellar wind interaction of close-in extrasolar planets

Grießmeier¹

2007

Planetary and Space Science

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“…For example, Glassmeier et al [2004] examined the effects of long-term geomagnetic variation on the magnetospheric and ionospheric physics and emphasized the importance of the geomagnetic main field in studying the physics. Clilverd et al [2005] reported that a long-term increase in the solar coronal magnetic field strength causes the long trend of the aa index, and thus, the long trend of the Sq field can be at least partly due to solar activity.…”

Section: Introductionmentioning

confidence: 99%

Contribution of wind, conductivity, and geomagnetic main field to the variation in the geomagnetic Sq field

Takeda

2013

JGR Space Physics

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[1] Long-term variation in the geomagnetic Sq field and the cause of the variation were examined. The amplitude of the geomagnetic Y component (Sq(Y)) in equinox was averaged for each year and adopted as a proxy of the Sq field. Sq(Y) was combined with the ionospheric conductivity estimated by the International Reference Ionosphere model to determine the dynamo electric field and neutral wind velocity by using the geomagnetic main field strength. It was found that the solar activity dependence of the Sq field could be almost completely attributed to the conductivity variation, and neutral winds tend to decrease when the solar activity increases. Although the long-term variation in the dynamo field differed among observatories, these differences were mostly attributed to the locality of the geomagnetic secular variation, whereas the variations in neutral wind amplitude were nearly the same in all regions. On the other hand, no clear long-term variation in neutral wind was detected other than that by solar activity.Citation: Takeda, M. (2013), Contribution of wind, conductivity, and geomagnetic main field to the variation in the geomagnetic Sq field,

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Concerning long-term geomagnetic variations and space climatology

Cited by 45 publications

References 27 publications

The South Atlantic Anomaly throughout the solar cycle

The South Atlantic Anomaly throughout the solar cycle

Aspects of the magnetosphere–stellar wind interaction of close-in extrasolar planets

Contribution of wind, conductivity, and geomagnetic main field to the variation in the geomagnetic Sq field

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