On the role of neutral flow in field-aligned currents

Mannucci, A. J.; Verkhoglyadova, O. P.; Meng, Xing; McGranaghan, Ryan

doi:10.5194/angeo-36-53-2018

Cited by 6 publications

(8 citation statements)

References 28 publications

(40 reference statements)

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“…The conventional ionospheric electrodynamics greatly simplifies the physical equations and brings conveniences in studying slow time variations and numerical simulations (Vasyliūnas, 2012). Vasyliūnas's theory is clearly valid in the case of the solar wind and magnetosphere, and it is more rigorous in describing the real physical processes, and it is suitable for wider scope and could be used to deal with the short time scales variations and more detailed physical phenomena (Lotko, 2004; Mannucci, 2018; Song et al, 2009; Tu & Song, 2016, 2019; Tu et al, 2014), though the complex equations could bring large computational burden in numerical simulations. Nevertheless, Vasyliūnas's and the traditional viewpoints give the same quantitative relationship between the electric field and plasma flow, when quasi‐steady equilibrium is satisfied.…”

Section: Discussionmentioning

confidence: 99%

“…During geomagnetic storms, a large coupling energy from the magnetosphere and solar wind into Earth's ionosphere and thermosphere is significantly enhanced as increased joule heating and particle precipitation, causing global ionospheric disturbances known as ionospheric storms. The main drivers for the ionospheric storm at low and middle latitudes include (1) the disturbed vertical drifts at low and middle latitudes caused by the solar wind‐magnetosphere‐ionosphere (SW‐M‐I) coupling through closed geomagnetic filed lines (Fejer, 1997; Huang et al, 2005; Kikuchi, 2014; Kikuchi et al, 1978; Lei, Wang, et al, 2008; Lotko, 2004; Mannucci, 2018; Song et al, 2005, 2009; Tu & Song, 2016, 2019; Tu et al, 2008, 2014; Wei et al, 2015) and (2) the long‐lasting equatorward‐propagating disturbed thermospheric circulation, including composition changes, plasma drifts changes owing to ionospheric disturbance dynamo, disturbed winds, and traveling ionospheric disturbances (Blanc & Richmond, 1980; Burns et al, 1989; Prölss, 1995, 2008). The ionospheric electron density and total electron content (TEC) display large increase or decrease, called positive or negative storm, due to different and mixed drivers depending on the storm periods, universal time of the geomagnetic storm onset, longitudes, and the ionospheric background (Danilov & Lăstovička, 2001; Mendillo, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Persistence of the Long‐Duration Daytime TEC Enhancements at Different Longitudinal Sectors During the August 2018 Geomagnetic Storm

Huang

Zhong

et al. 2020

JGR Space Physics

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In this study, the ionospheric responses in the Asian-Australian, American, and African sectors during the August 2018 geomagnetic storm were investigated based on the Beidou geostationary orbit (GEO) satellite and Massachusetts Institute of Technology (MIT) Madrigal total electron contents (TECs), combined with measurements from ionosondes, magnetometers, and Global Ultraviolet Imager (GUVI). The middle-and low-latitude TECs were dominated by positive responses over the three longitudinal sectors during the storm on 26-29 August. It is unique that daytime TECs at the Asian-Australian, American, and African sectors displayed large enhancements larger than 10 TEC units (TECu) on 27-29 August, during the recovery phase, when the ionosphere is usually dominated by plasma depletions due to the ionospheric disturbance dynamo and/or disturbed thermospheric compositions. The combination and competition of the disturbed vertical plasma drifts through the solar wind-magnetosphere-ionosphere (SW-M-I) coupling and disturbed neutral compositions contribute significantly to the daytime TEC responses at different longitudinal sectors on 26 August during the main and early recovery phases. The eastward equatorial electrojet and O/N 2 during the recovery phase on 27-29 August are larger than the quiet reference, which suggest that the enhanced upward vertical plasma drifts combining with higher O/N 2 make an important contribution on the daytime positive ionospheric storm during the recovery phase. The enhanced vertical plasma drifts could not be driven by the SW-M-I coupling or ionospheric disturbance dynamo associated with the geomagnetic storm. Further studies should be untaken to explore the dominant sources for the enhanced upward vertical drifts during the recovery phase.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Persistence of the Long‐Duration Daytime TEC Enhancements at Different Longitudinal Sectors During the August 2018 Geomagnetic Storm

Huang

Zhong

et al. 2020

JGR Space Physics

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“…Such a difference between the plasma and the neutral velocity is likely due to the balance with momentum sources other than the ion drag force as discussed in section 4. Mannucci et al (2018) discussed that the difference can be expressed as a relative momentum exchange between ions and neutrals (denoted as the electric field in the ion rest frame). (Figure 3a), the bright discrete auroras were limited to >70°MLAT.…”

Section: 1029/2018ja025457mentioning

confidence: 99%

Mesoscale F Region Neutral Winds Associated With Quasi‐steady and Transient Nightside Auroral Forms

et al. 2018

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High‐latitude neutral winds often circulate in a two‐cell pattern as driven by large‐scale auroral forcing. However, auroral forcing also occurs in various types of mesoscale forms (i.e., tens to hundreds of kilometers in space and a few to tens of minutes in time) and contains more energy input over mesoscale than large scale. A question arises as to whether and how winds respond to the mesoscale forcing. We characterize F region winds associated with various types of auroral forms using scanning Doppler imagers, auroral imagers, and radars. The auroras examined include a quasi‐steady east‐west elongated arc, a quasi‐steady Harang aurora, transient streamers, and a transient substorm westward traveling surge. We find that winds exhibit distinct spatial structures, appearing as channels, vortices, and reversals. Such structures are consistent with the structures of the plasma flows associated with the auroras. Winds exhibit a temporal evolution very similar to the plasma flows and reach maximum perturbations only <~20 min after the flows. The above results suggest that the thermosphere is closely coupled to the ionosphere/magnetosphere through the ion drag force. The <~20‐min time scale can be partially explained by the strong ionization effect associated with the auroras and partially by the fact that the wind perturbations do not approach the flow perturbations but halt at ~20% possibly due to momentum forces other than the ion drag.

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“…• The momentum imparted to the ionospheric plasma creates a velocity difference between the plasma and neutral species, leading to transfer of momentum to the neutral species via collisional processes. The ion-neutral velocity differences lead to the presence of currents and heating in the ionosphere (Vasyliūnas, 2012;Mannucci et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…23is based on momentum considerations, as revealed when derived using the full multi-species plasma equations (Brekke and Rino, 1978;Vasyliunas and Song, 2005;Thayer and Vickrey, 1992). When JH occurs in the absence of an electric field, the currents associated with the heating are generated by ion-neutral velocity differences and not by an electric field (Mannucci et al, 2018;Vasyliūnas 2012;Thayer and Semeter 2004).…”

Section: The Pgr and Joule Heatingmentioning

confidence: 99%

Using the Galilean Relativity Principle to Understand the Physical Basis for Magnetosphere-Ionosphere Coupling Processes

Mannucci

McGranaghan

Meng

et al. 2019

Preprint

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Abstract. We use the Principle of Galilean Relativity (PGR) to gain insight into the physical basis for magnetosphere-ionosphere coupling. The PGR states that the laws of physics are the same in all inertial reference frames, considering relative speeds between such reference frames that are significantly less than the speed of light. The PGR is a limiting case of the principle of Special Relativity, the latter applicable to any relative speeds between two inertial reference frames. Although the PGR has been invoked in past works related to magnetosphere-ionosphere coupling, it has not been fully exploited for the insights it can provide into such topics as large-scale ionospheric convection and high latitude heating. In addition, the difficulties of applying the PGR to electrodynamics has not been covered. The PGR can be used to show that in the high latitude ionosphere there often exists a reference frame where electric fields vanish at lower altitudes where collisions are important (altitudes near ~ 100–120 km). In this reference frame, it is problematic to assert that currents of magnetospheric origin cause horizontal electric fields in the ionosphere, as has been suggested for the causal origin of Subauroral Polarization Stream electric fields. Electric fields have also been invoked as the causal origin of large-scale ionospheric convection, which may be a problematic assertion in certain reference frames. The PGR reinforces the importance of the neutral species and ion-neutral collisions in magnetosphere-ionosphere coupling, which has been noted by several authors using detailed multi-species plasma calculations. A straightforward estimate shows that the momentum carried by electron field aligned currents of magnetospheric origin during disturbed periods is much less than the momentum changes experienced by the neutral species in an Earth-fixed frame. The primary driver of neutral species momentum changes during disturbed periods is the momentum imparted by the solar wind to ionospheric ions resulting from electrodynamic interactions. This is consistent with the idea that electric fields do not lead to large scale ionospheric convection.

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On the role of neutral flow in field-aligned currents

Cited by 6 publications

References 28 publications

Persistence of the Long‐Duration Daytime TEC Enhancements at Different Longitudinal Sectors During the August 2018 Geomagnetic Storm

Persistence of the Long‐Duration Daytime TEC Enhancements at Different Longitudinal Sectors During the August 2018 Geomagnetic Storm

Mesoscale F Region Neutral Winds Associated With Quasi‐steady and Transient Nightside Auroral Forms

Using the Galilean Relativity Principle to Understand the Physical Basis for Magnetosphere-Ionosphere Coupling Processes

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