An Introduction to Quiet Daily Geomagnetic Fields

Campbell, Wilbur H.

doi:10.1007/978-3-0348-9280-3_1

Cited by 15 publications

(16 citation statements)

References 89 publications

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“…The quiet daily geomagnetic ÿeld variations are primarily due to the dynamo currents owing in the ionospheric E-layer. Numerous investigators have studied the ionospheric dynamo theory and regular quiet daily variation of the geomagnetic ÿeld (Campbell, 1989;Cole, 1995Cole, , 1997Alex et al, 1998;Du and Stening, 1999a, b).…”

Section: Introductionmentioning

confidence: 97%

Possible effects of the total solar eclipse of August 11, 1999 on the geomagnetic field variations over Elaziǧ-Turkey

Özcan

Aydoǧdu

2004

Journal of Atmospheric and Solar-Terrestrial Physics

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Section: Introductionmentioning

confidence: 97%

Possible effects of the total solar eclipse of August 11, 1999 on the geomagnetic field variations over Elaziǧ-Turkey

Özcan

Aydoǧdu

2004

Journal of Atmospheric and Solar-Terrestrial Physics

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“…The horizontal currents flow mostly in the daytime ionosphere within the altitude range 90–150 km where the ionospheric conductivity is large; this region is often called the dynamo region. During geomagnetically quiet periods, the dynamo region currents produce regular daily variations of the geomagnetic field (of the order of tens of nanoteslas), commonly known as solar quiet ( S q ) variations [e.g., Campbell , ]. For this reason, the dynamo region currents are often referred to as S q currents.…”

Section: Introductionmentioning

confidence: 99%

Day‐to‐day variability of midlatitude ionospheric currents due to magnetospheric and lower atmospheric forcing

2016

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As known from previous studies on the solar quiet (Sq) variation of the geomagnetic field, the strength and pattern of ionospheric dynamo currents change significantly from day to day. The present study investigates the relative importance of two sources that contribute to the day‐to‐day variability of the ionospheric currents at middle and low latitudes. One is high‐latitude electric fields that are caused by magnetospheric convection, and the other is atmospheric waves from the lower atmosphere. Global ionospheric current systems, commonly known as Sq current systems, are simulated using the National Center for Atmospheric Research thermosphere‐ionosphere‐mesosphere‐electrodynamics general circulation model. Simulations are run for 1–30 April 2010 with a constant solar energy input but with various combinations of high‐latitude forcing and lower atmospheric forcing. The model well reproduces geomagnetic perturbations on the ground, when both forcings are taken into account. The contribution of high‐latitude forcing to the total Sq current intensity (Jtotal) is generally smaller than the contribution of wave forcing from below 30 km, except during active periods (Kp≥4), when Jtotal is enhanced due to the leakage of high‐latitude electric fields to lower latitudes. It is found that the penetration electric field drives ionospheric currents at middle and low latitudes not only on the dayside but also on the nightside, which has an appreciable effect on the Dst index. It is also found that quiet time day‐to‐day variability in Jtotal is dominated by symmetric‐mode migrating diurnal and semidiurnal tidal winds at 45–60° latitude at ∼110 km.

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“…It is basically driven by the E region dynamo electric field [ Fejer and Kelley , ] and represents an important aspect of the phenomenology of the equatorial ionosphere‐thermosphere system. Magnetic observations of the ground‐derived EEJ strength have being studied in several longitudinal sectors for many years [ Sugiura and Cain , ; Mayaud , ; Campbell , , and references therein]. Sounding observations of the equatorial ionospheric E region using VHF radars have been reported since the 1960s.…”

Section: Introductionmentioning

confidence: 99%

E region electric field dependence of the solar activity

et al. 2015

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We have being studying the zonal and vertical E region electric field components inferred from the Doppler shifts of type 2 echoes (gradient drift irregularities) detected with the 50 MHz backscatter coherent radar set at São Luis, Brazil (SLZ, 2.3°S, 44.2°W) during the solar cycle 24. In this report we present the dependence of the vertical and zonal components of this electric field with the solar activity, based on the solar flux F10.7. For this study we consider the geomagnetically quiet days only (Kp ≤ 3+). A magnetic field‐aligned‐integrated conductivity model was developed for proving the conductivities, using the IRI‐2007, the MISIS‐2000, and the IGRF‐11 models as input parameters for ionosphere, neutral atmosphere, and Earth magnetic field, respectively. The ion‐neutron collision frequencies of all the species are combined through the momentum transfer collision frequency equation. The mean zonal component of the electric field, which normally ranged from 0.19 to 0.35 mV/m between the 8 and 18 h (LT) in the Brazilian sector, show a small dependency with the solar activity. Whereas the mean vertical component of the electric field, which normally ranges from 4.65 to 10.12 mV/m, highlights the more pronounced dependency of the solar flux.

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An Introduction to Quiet Daily Geomagnetic Fields

Cited by 15 publications

References 89 publications

Possible effects of the total solar eclipse of August 11, 1999 on the geomagnetic field variations over Elaziǧ-Turkey

Possible effects of the total solar eclipse of August 11, 1999 on the geomagnetic field variations over Elaziǧ-Turkey

Day‐to‐day variability of midlatitude ionospheric currents due to magnetospheric and lower atmospheric forcing

E region electric field dependence of the solar activity

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