Quiet variability of equatorial <b>E</b> × <b>B</b> drifts during a sudden stratospheric warming event

Chau, Jorge L.; Fejer, Bela G.; Гончаренко, Л. П.

doi:10.1029/2008gl036785

Cited by 245 publications

(352 citation statements)

References 15 publications

Supporting

Mentioning

318

Contrasting

Unclassified

Order By: Relevance

“…During stratospheric sudden warming events, dynamo-region electric fields are disturbed due to enhanced solar and lunar tidal forcing. The modulation of the equatorial plasma fountain has been observed in measurements of the F-region equatorial E × B drift (e.g., Chau et al 2009;Fejer et al 2011). Also, the impact on the equatorial anomaly has been revealed by ground-based and satellite measurements of the F-region plasma density (e.g., Goncharenko et al 2010aGoncharenko et al , 2010bYue et al 2010;Pancheva and Mukhtarov 2011;Lin et al 2012).…”

Section: Stratospheric Sudden Warming Effectmentioning

confidence: 96%

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

2016

View full text Add to dashboard Cite

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

Section: Stratospheric Sudden Warming Effectmentioning

confidence: 96%

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

2016

View full text Add to dashboard Cite

show abstract

“…As the year 2008 corresponds to low solar activity, the authors attributed the increase of ion temperature to be associated with the SSW event and from the temporal and altitudinal variations in the temperature anomaly, they inferred that it might be related to semi-diurnal tide modulation. Recently, Chau et al (2009) observed an anomalous temporal variation of the vertical E×B drifts during the minor SSW event, showing a semidiurnal variation with very large amplitudes lasting for several days. The semi-diurnal variation can also be produced due to interaction of a quasi-stationary wave and migrating tides.…”

Section: Discussionmentioning

confidence: 99%

Variabilities of mesospheric tides and equatorial electrojet strength during major stratospheric warming events

Sridharan

Sathishkumar²,

Gurubaran³

2009

Ann. Geophys.

101

View full text Add to dashboard Cite

Abstract. The present study demonstrates the relationship between the high latitude northern hemispheric major sudden stratospheric warming (SSW) events and the reversal in the afternoon equatorial electrojet (EEJ), often called the counter-electrojet (CEJ), during the winter months of 1998-1999, 2001-2002, 2003-2004 and 2005-2006. As the EEJ current system is driven by tidal winds, an investigation of tidal variabilities in the MF radar observed zonal winds during the winters of 1998-1999 and 2005-2006 at 88 km over Tirunelveli, a site close to the magnetic equator, shows that there is an enhancement of semi-diurnal tidal amplitude during the days of a major SSW event and a suppression of the same immediately after the event. The significance of the present results lies in demonstrating the latitudinal coupling between the high latitude SSW phenomenon and the equatorial ionospheric current system with clear evidence for major SSW events influencing the day-to-day variability of the CEJ.

show abstract

“…Only recently it was found that sudden polar stratospheric warming (SSW) events have an influence on the lunitidal signatures in the ionosphere at equatorial latitudes (e.g. Chau et al, 2009). Based on data from Jicamarca (radar and magnetometer) Fejer et al (2010) reported that the lunar modulation of the vertical plasma drift and EEJ intensity increased significantly for a few weeks after the onset of an SSW.…”

Section: Comparison With Other Tidesmentioning

confidence: 99%

Global characteristics of the lunar tidal modulation of the equatorial electrojet derived from CHAMP observations

2012

View full text Add to dashboard Cite

Abstract. It has been known since many decades that lunar tide has an influence on the strength of the equatorial electrojet (EEJ). There has, however, never been a comprehensive study of the tidal effect on a global scale. Based on the continuous magnetic field measurements by the CHAMP satellite over 10 years it is possible to investigate the various aspects of lunar effects on the EEJ. The EEJ intensity is enhanced around times when the moon is overhead or at the antipode. This effect is particularly strong around noon, shortly after new and full moon. The lunar tide manifests itself as a semi-diurnal wave that precesses through all local times within one lunar month. The largest tidal amplitudes are observed around December solstice and smallest around June solstice. The tidal wave crest lags behind the moon phase. During December this amounts to about 4 days while it is around 2 days during other times of the year. We have not found significant longitudinal variations of the lunar influence on the EEJ. When comparing the average EEJ amplitude at high solar activity with that during periods of solar minimum conditions a solar cycle dependence can be found, but the ratio between tidal amplitude and EEJ intensity stays the same. Actually, tidal signatures standout clearer during times of low solar activity. We suggest that the tidal variations are caused by a current system added to the EEJ rather than by modulating the EEJ. Gravitational forcing of the lower atmosphere by the moon and the sun is assumed to be the driver of an upward propagating tidal wave. The larger tidal amplitudes around December solstice can be related to stratospheric warming events which seem to improve the conditions for upward propagation.The results described here have to large extent been presented as a Julius-Bartels Medal Lecture during the General Assembly 2011 of the European Geosciences Union.

show abstract

Quiet variability of equatorial E × B drifts during a sudden stratospheric warming event

Cited by 245 publications

References 15 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

Variabilities of mesospheric tides and equatorial electrojet strength during major stratospheric warming events

Global characteristics of the lunar tidal modulation of the equatorial electrojet derived from CHAMP observations

Contact Info

Product

Resources

About