Geomagnetic Sq field at successive Universal Times

Suzuki, Akira

doi:10.1016/0021-9169(78)90177-0

Cited by 23 publications

(22 citation statements)

References 14 publications

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“…It is particularly strong in the European longitude sector of Saint. Santin in the solstitial seasons [Matsushita, 1967;Suzuki, 1978]. Our hypothesis of field-aligned currents over Saint-Santin may be testable from geomagnetic D component records.…”

Section: Confirmation Of the Anomalymentioning

confidence: 93%

Strange currents over Saint‐Santin

Mazaudier¹,

Venkateswaran²

1985

J. Geophys. Res.

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Analysis of 29 days of ionospheric current data obtained by Saint-Santin radar, including both magnetically quiet and disturbed periods, has confirmed the existence of northward currents at all daytime hours. The postulate of field-aligned Van Sabben currents driven by interhemispherical asymmetries seems to be able to account for the anomaly. The desirability of quantitative modeling of the Van Sabben currents on a seasonal or day-to-day basis is highlighted by the Saint-Santin measurements.

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Section: Confirmation Of the Anomalymentioning

confidence: 93%

Strange currents over Saint‐Santin

Mazaudier¹,

Venkateswaran²

1985

J. Geophys. Res.

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“…We describe two methods in this paper, namely, the "instantaneous method" and the "slice method". The instantaneous method determines the Sq field and equivalent current system at a specific moment in time using simultaneous measurements from globally distributed magnetometers (e.g., Malin 1973;Parkinson 1977;Suzuki 1978Suzuki , 1979Takeda and Araki 1984a;Takeda 1999Takeda , 2002aTakeda , 2002b). This method is useful when a large number of magnetic data are available from all over the world.…”

Section: Spherical Harmonic Analysismentioning

confidence: 99%

“…The day-to-day variation in the equivalent Sq current system has been studied by many researchers (Hasegawa 1960;Suzuki 1978Suzuki , 1979Takeda 1984;Takeda and Araki 1984a;Stening 2008;Yamazaki 2011). As is clear from Figs.…”

Section: Irregular Changesmentioning

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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“…The resulting solar cycle variation dominates long‐term (year‐to‐year) variability of the S q currents [e.g., Campbell and Matsushita , ; Takeda , , ]. Previous studies have also recognized significant short‐term (hour‐to‐hour and day‐to‐day) variability in the S q currents [e.g., Hasegawa , ; Suzuki , , ; Briggs , ; Takeda , ]. The day‐to‐day variation of S q is often “random‐like,” and the driving mechanism is not well understood.…”

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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Geomagnetic Sq field at successive Universal Times

Cited by 23 publications

References 14 publications

Strange currents over Saint‐Santin

Strange currents over Saint‐Santin

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

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

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