Climatology of zonal wind and large-scale FAC with respect to the density anomaly in the cusp region: seasonal, solar cycle, and IMF &amp;lt;i&amp;gt;B&amp;lt;/i&amp;gt;&amp;lt;sub&amp;gt;&amp;lt;i&amp;gt;y&amp;lt;/i&amp;gt;&amp;lt;/sub&amp;gt; dependence

Kervalishvili, Guram; Lühr, Hermann

doi:10.5194/angeo-32-249-2014

Cited by 15 publications

(17 citation statements)

References 50 publications

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“…Just at the R1/R2 FAC interface, we observe an eastward Hall current that is accompanied by a westward zonal wind peak. For higher latitudes where eastward plasma drifts are expected, the zonal wind velocity approaches zero, as has been earlier noted by Kervalishvili and Lühr (). An inspection of the full wind vectors in Figure reveals that for this IMF B y orientation, the wind turns from westward to due nightward in the polar cap region.…”

Section: Discussionsupporting

confidence: 77%

The Relationship of High‐Latitude Thermospheric Wind With Ionospheric Horizontal Current, as Observed by CHAMP Satellite

et al. 2017

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The relationship between high‐latitude ionospheric currents (Hall current and field‐aligned current) and thermospheric wind is investigated. The 2‐D patterns of horizontal wind and equivalent current in the Northern Hemisphere derived from the CHAMP satellite are considered for the first time simultaneously. The equivalent currents show strong dependences on both interplanetary magnetic field (IMF) By and Bz components. However, IMF By orientation is more important in controlling the wind velocity patterns. The duskside wind vortex as well as the antisunward wind in the morning polar cap is more evident for positive By. To better understand their spatial relation in different sectors, a systematic superposed epoch analysis is applied. Our results show that in the dusk sector, the vectors of the zonal wind and equivalent current are anticorrelated, and both of them form a vortical flow pattern for different activity levels. The currents and zonal wind are intensified with the increase of merging electric field. However, on the dawnside, where the relation is less clear, antisunward zonal winds dominate. Plasma drift seems to play a less important role for the wind than neutral forces in this sector. In the noon sector, the best anticorrelation between equivalent current and wind is observed for a positive IMF By component and it is less obvious for negative By. A clear seasonal effect with current intensities increasing from winter to summer is observed in the noon sector. Different from the currents, the zonal wind intensity shows little dependence on seasons. Our results indicate that the plasma drift and the neutral forces are of comparable influence on the zonal wind at CHAMP altitude in the noon sector.

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Section: Discussionsupporting

confidence: 77%

The Relationship of High‐Latitude Thermospheric Wind With Ionospheric Horizontal Current, as Observed by CHAMP Satellite

et al. 2017

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“…This offset could be due to the highly inclined magnetic field lines introducing an equatorward shift at E region height (Lühr & Marker, ). Adding to the studies of Lühr et al (), Kervalishvili and Lühr (, ), and Carlson et al (), Figure c provides the first demonstration with multi‐instrument CHAMP observations that SS‐FACs became enhanced close to the nearby FC underlying the density spike.…”

Section: Results and Interpretations Of The 25 September 2000 And 2 Msupporting

confidence: 57%

High‐Latitude Neutral Density Structures Investigated by Utilizing Multi‐Instrument Satellite Data and NRLMSISE‐00 Simulations

Horvath

Lovell

2018

JGR Space Physics

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This study investigates various types of neutral density features developed in the cusp region during magnetically active and quiet times. Multi‐instrument Challenging Minisatellite Payload data provide neutral density, electron temperature, neutral wind speed, and small‐scale field‐aligned current (SS‐FAC) values. Gravity Recovery and Climate Experiment neutral density data are also employed. During active times, cusp densities or density spikes appeared with their underlying flow channels (FCs) and enhanced SS‐FACs implying upwelling, fueled by Joule heating, within/above FCs. Both the moderate nightside cusp enhancements under disturbed conditions and the minor dayside cusp enhancements under quiet conditions developed without any underlying FC and enhanced SS‐FACs implying the role of particle precipitation in their development. Observations demonstrate the relations of FCs, density spikes, and upwelling‐related divergent flows and their connections to the underlying (1) dayside magnetopause reconnection depositing magnetospheric energy into the high‐latitude region and (2) Joule heating‐driven disturbance dynamo effects. Results provide observational evidence that the moderate nightside cusp enhancements and the minor dayside cusp enhancements detected developed due to direct heating by weak particle precipitation. Chemical compositions related to the dayside density spike and low cusp densities are modeled by Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended 2000. Modeled composition outputs for the dayside density spike's plasma environment depict some characteristic upwelling signatures. Oppositely, in the case of low dayside cusp densities, composition outputs show opposite characteristics due to the absence of upwelling.

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“…Due to the propagation time from the bow shock to the ionosphere we have considered a delay of 20 min and smoothed the E m values over 15 min. This kind of conditioning has been found to be suitable for ionospheric studies like Kervalishvili and Lühr [, and references therein].…”

Section: Data Set and Processing Approachmentioning

confidence: 99%

Net ionospheric currents closing field‐aligned currents in the auroral region: CHAMP results

Zhou

Lühr

2017

JGR Space Physics

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By utilizing the high‐resolution and precise vector magnetic field measurements from CHAMP during 2001–2005, the characteristics of the net auroral currents calculated by Ampère's integral law are comprehensively investigated. It is found that the net currents deduced from noon‐midnight (dawn‐dusk) orbits are directed duskward (antisunward). The intensities of the net currents increase linearly when the merging electric field (Em) is growing, exhibiting maximum values of about 2 (1) MA for the net duskward (antisunward) currents when Em exceeds 4 mV/m. For the first time the seasonal variations of the different net currents are shown. The net currents deduced from full orbits show only little seasonal dependence due to a compensation of the effects between the hemispheres. Conversely, the net currents deduced separately for the two hemispheres exhibit prominent seasonal dependences. For the net duskward currents the amplitudes and slopes of Em dependence are both larger by a factor of about 2 in summer than in winter. The related cross‐polar cap Pedersen currents are higher in the sunlit hemisphere due to enhanced conductivity. The summer‐time duskward currents are larger in the Northern Hemisphere than in the Southern Hemisphere by a factor of 1.5. Conversely, the net antisunward currents show an opposite seasonal dependence. The ratio of summer to winter intensity amounts to about 0.7. In this case the currents are stronger in the Southern Hemisphere.

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Climatology of zonal wind and large-scale FAC with respect to the density anomaly in the cusp region: seasonal, solar cycle, and IMF <i>B</i><sub><i>y</i></sub> dependence

Cited by 15 publications

References 50 publications

The Relationship of High‐Latitude Thermospheric Wind With Ionospheric Horizontal Current, as Observed by CHAMP Satellite

The Relationship of High‐Latitude Thermospheric Wind With Ionospheric Horizontal Current, as Observed by CHAMP Satellite

High‐Latitude Neutral Density Structures Investigated by Utilizing Multi‐Instrument Satellite Data and NRLMSISE‐00 Simulations

Net ionospheric currents closing field‐aligned currents in the auroral region: CHAMP results

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