Application of solar quiet day (Sq) current in determining mantle electrical-depth conductivity structure – A review

Okeke, F. N.; Obiora, Daniel N.

doi:10.1016/j.jafrearsci.2015.11.015

Cited by 4 publications

(2 citation statements)

References 31 publications

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“…Geomagnetic disturbances associated with storms and substorms are typically several hundreds of nano teslas on the surface, which can easily mask underlying Sq signals. Despite the small amplitude, studies on Sq have been important for understanding the ionospheric electrodynamics (Richmond 1979(Richmond , 1995b and its coupling to the magnetosphere and lower atmosphere (Wagner et al 1980;Richmond 1995b); for determining a base level for geomagnetic indices (Mayaud 1980;Love and Gannon 2009;Gjerloev 2012); for monitoring solar radiation activity (Svalgaard and Cliver 2007;Svalgaard 2016); and for estimating electrical conductivity within the Earth (Campbell and Schiffmacher 1988a;Campbell et al 1998;Okeke and Obiora 2016).…”

Section: Observational Overviewmentioning

confidence: 99%

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

2016

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A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μA/m 2 flowing on the sunlit side of the Eregion ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the nonspecialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

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Section: Observational Overviewmentioning

confidence: 99%

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

2016

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“…When solar activity is strong, the resulting geomagnetic disturbances are typically of several hundreds of nTs in magnitude at the ground surface, which can easily hide the normal DGVs. However, DGVs have small amplitude, studies of these variations are very significant for understanding the ionospheric electrodynamics [Richmond, 1979], and for estimating underground electrical conductivity [Campbell et al, 1998, Okeke andObiora, 2016]. The DGVs include signals not only related to ionospheric currents but also to underground currents induced in the Earth's interior [Yamazaki and Maute, 2017].…”

Section: Introductionmentioning

confidence: 99%

Daily geomagnetic variations under variable IMF/solar conditions and their connection with underground conductivity changes in Japan

Takla,

Yoshikawa,

Uozumi

et al. 2024

Annals of Geophysics

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Fluctuations in Solar Wind (SW) and Interplanetary Magnetic Field (IMF) significantly affect the Geomagnetic Field (GF) measurements particularly during extreme space weather events. The current study investigates the variations of horizontal (H), vertical (Z) geomagnetic components under quiet and disturbed IMF and solar conditions as well as the effect of underground conductivity on the stationary geomagnetic measurements in Japan. Results of data analysis show that the response of the GF to IMF and solar parameters fluctuations is variable. The H- and Z-components were in good harmony with high visual correlation along a latitudinal profile across Japan during quiet times. On the other hand, during the disturbed times related to a Coronal Mass Ejection (CME) launched on 13 May 2005, the GF components varied with the disturbance of IMF and solar parameters. The H-components showed highly correlated variations with a significant reduction along the examined profile due to intensified ionospheric currents, while the Z-components recorded in the northern part of Japan showed abnormal daily variations pattern (positive daily variations) with an enhanced amplitude which is opposite to the normal behavior of daily variations recorded in the central and southern parts of Japan (negative daily variations). The observed enhanced and abnormal daily variation of Z-components in north Japan, which we consider a remarkable observation here, is possibly linked with underground conductivity anomaly in this region.

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Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Yamazaki¹,

Maute²

2017

Earth's Magnetic Field

153

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A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several µA/m 2 flowing on the sunlit side of the Eregion ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the nonspecialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

show abstract

Application of solar quiet day (Sq) current in determining mantle electrical-depth conductivity structure – A review

Cited by 4 publications

References 31 publications

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Daily geomagnetic variations under variable IMF/solar conditions and their connection with underground conductivity changes in Japan

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

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