The equatorial electrojet during geomagnetic storms and substorms

Yamazaki, Yosuke; Kosch, M. J.

doi:10.1002/2014ja020773

Cited by 80 publications

(65 citation statements)

References 48 publications

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“…Third plot is the cross correlation of IMF-Bz with SYM-H, Utot, Ua, Ur, and Uj quantifying the response of the solar wind invasion in the magnetosphere. This observation is similar to the summary of substorm analysis of Yamazaki and Kosch (2015) where AE was showing abrupt response at least of every 3-4 hr. The correlation curve near the value zero shows the weaker correlation whereas the curve near the region of +1 or −1 represents higher correlation (Katz, 1988).…”

Section: Resultssupporting

confidence: 86%

Variation of Solar Wind Parameters Along With the Understanding of Energy Dynamics Within the Magnetospheric System During Geomagnetic Disturbances

Poudel

Simkhada

Adhikari

et al. 2019

Earth and Space Science

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Interplanetary solar wind parameters (velocity of solar wind particle [Vp], proton density [Nsw], and component of solar magnetic field [IMF‐Bz]) and geomagnetic indices (symmetric horizontal component of geomagnetic field [SYM‐H], auroral electrojet [AE]) divulge great deal of information about geomagnetic disturbances. To better understand the influence of solar wind invasion into the energy dynamics of magnetosphere system, we have chosen five geomagnetic disturbance events of completely different nature as the quietest days, intense storm, High Intensity Long Duration Continuous Auroral Activity, Substorm, and Supersubstorm. The statistical analysis of these five events clearly supports the case that most of the time IMF‐Bz plays major role to create magnetic reconnection leading to the geomagnetic disturbances. Our study shows that Joule heating covers the largest fraction of energy dissipation, averaging 53.6% of total deposited energy for all events. Even though, in case of Supersubstorm, the major contribution due to the ring current (47%) surpasses Joule heating (43%). The cross‐correlation analysis applied for the IMF‐Bz with SYM‐H, solar wind energy and magnetospheric sinks explain and quantify the relation between them. The positive correlation of IMF‐Bz with SYM‐H value in each event delineates that southward orientation of IMF‐Bz is responsible for the depression of SYM‐H. However, an interesting result that IMF‐Bz correlated negatively with SYM‐H value for the quiet event suggests the southward orientation of IMF‐Bz does not necessarily have to be the cause of disturbance always. In few occasion, Solar Quiet (Sq) and Lunar (L) current is found to be taking over the role of IMF‐Bz to create disturbance.

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Section: Resultssupporting

confidence: 86%

Variation of Solar Wind Parameters Along With the Understanding of Energy Dynamics Within the Magnetospheric System During Geomagnetic Disturbances

Poudel

Simkhada

Adhikari

et al. 2019

Earth and Space Science

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“…The observed ∆H decrease almost 10 hrs after the commencement of main phase makes disturbance dynamo effect a possible contributor to the westward electric field during 1100-1300 UT (0600-0800 LT). Numerical and observational investigations have indicated that the disturbance dynamo electric field can last hours to a day after the ceasing of high latitude activity/maximum geomagnetic activity [Huang et al, 2005;Yamazaki and Kosch, 2015]. The downward vertical drift observed in magnetometer data There should be a source of eastward electric field leading to enhanced vertical drifts which could later drive the observed TIDs.…”

Section: Resultsmentioning

confidence: 98%

Simultaneous storm time equatorward and poleward large‐scale TIDs on a global scale

Habarulema

Katamzi

Yizengaw

et al. 2016

Geophysical Research Letters

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We report on the first simultaneous observations of poleward and equatorward traveling ionospheric disturbances (TIDs) during the same geomagnetic storm period on a global scale. While poleward propagating TIDs originate from the geomagnetic equator region, equatorward propagating TIDs are launched from the auroral regions. On a global scale, we use total electron content observations from the Global Navigation Satellite Systems to show that these TIDs existed over South American, African, and Asian sectors. The American and African sectors exhibited predominantly strong poleward TIDs, while the Asian sector recorded mostly equatorward TIDs which crossed the geomagnetic equator to either hemisphere on 9 March 2012. However, both poleward and equatorward TIDs are simultaneously present in all three sectors. Using a combination of ground‐based magnetometer observations and available low‐latitude radar (JULIA) data, we have established and confirmed that poleward TIDs of geomagnetic equator origin are due to ionospheric electrodynamics, specifically changes in E × B vertical drift after the storm onset.

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“…Yamazaki and Kosch [] reported that the EEJ shows a different after storm response between the Indian and Peruvian sectors. They found a depression of the EEJ at Trivandrum (77°E) during afternoon hours but a little effect or even enhancement of the EEJ at Huancayo (285°E) within that local time sector.…”

Section: Discussionmentioning

confidence: 99%

The response of equatorial electrojet, vertical plasma drift, and thermospheric zonal wind to enhanced solar wind input

2016

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In this study we used observations from the CHAMP and ROCSAT‐1 satellites to investigate the solar wind effects on the equatorial electrojet (EEJ), vertical plasma drift, and thermospheric zonal wind. We show that an abrupt increase in solar wind input has a significant effect on the low‐latitude ionosphere‐thermosphere system, which can last for more than 24 h. The disturbance EEJ and zonal wind are mainly westward for all local times and show most prominent responses during 07–12 and 00–06 magnetic local time (MLT), respectively. The equatorial disturbance electric field is mainly eastward at night (most prominent for 00–05 MLT) and westward at daytime with small amplitudes. In this study we show for the first time that the penetration electric field is little dependent on longitude at both the day and night sides, while the disturbance zonal wind is quite different at different longitude sectors, implying a significant longitudinal dependence of the ionospheric disturbance dynamo. Our result also indicates that the F region equatorial zonal electric field reacts faster than E region dynamo, to the enhanced solar wind input.

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The equatorial electrojet during geomagnetic storms and substorms

Cited by 80 publications

References 48 publications

Variation of Solar Wind Parameters Along With the Understanding of Energy Dynamics Within the Magnetospheric System During Geomagnetic Disturbances

Variation of Solar Wind Parameters Along With the Understanding of Energy Dynamics Within the Magnetospheric System During Geomagnetic Disturbances

Simultaneous storm time equatorward and poleward large‐scale TIDs on a global scale

The response of equatorial electrojet, vertical plasma drift, and thermospheric zonal wind to enhanced solar wind input

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