Role of inductive electric fields and currents in dynamical ionospheric situations

Abstract. We study the role of ionospheric induction in different commonly observed ionospheric situations. These include an intensifying electrojet, westward travelling surge (WTS) and Ω-band. We use data based, realistic models for these phenomena and calculate the inductive electric fields that are created due to the temporal variations of ionospheric currents. The ionospheric induction problem is solved using a new calculation technique that can handle non-uniform, time-dependent conductances and electric fields of any geometry. We find that in some situations inductive effects are not negligible and the ionospheric electric field is not a pure potential field, but has a significant induced rotational part. In the WTS and Ω-band models the induced electric field is concentrated in a small area, where the time derivatives are largest. In the electrojet model the induced field is significant over a large part of the jet area. In these examples the induced electric field has typical values of few mV/m, which amounts to several tens of percents of the potential electric field present at the same locations. The induced electric field is associated with ionospheric and field aligned currents (FAC), that modify the overall structure of the current systems. Especially the induced FAC are often comparable to the non-inductive FAC, and may thus modify the coupling between the ionosphere and magnetosphere in the most dynamical situations. We also present some examples with very simple ionospheric current systems, where the effect of different ionospheric parameters on the induction process is studied.

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Spatial distribution of conductances and currents associated with a north-south auroral form during a multiple-substorm period

Annales Geophysicae ◽

10.1007/s00585-999-1385-6 ◽

1999 ◽

Vol 17 (11) ◽

pp. 1385-1396 ◽

Cited By ~ 24

Author(s):

O. Amm ◽

A. Pajunpää ◽

U. Brandström

Keyword(s):

Electric Field ◽

Electric Fields ◽

Method Of Characteristics ◽

Auroral Ionosphere ◽

Hall Conductance ◽

Similarities And Differences ◽

Ground Magnetic ◽

Ionospheric Electric Field ◽

Electric Fields And Currents ◽

Field Disturbance

Abstract. Using the method of characteristics to invert ground-based data of the ground magnetic field disturbance and of the ionospheric electric field, we obtain spatial distributions of ionospheric conductances, currents, and field-aligned currents (FACs) associated with a north-south auroral form that drifts westwards over northern Scandinavia around 2200 UT on December 2, 1977. This auroral form is one in a sequence of such north-south structures observed by all-sky cameras, and appears 14 min after the last of several breakups during that extremely disturbed night. Our analysis shows that the ionospheric Hall conductance reaches values above 200 S in the center of the form, and upward flowing FACs of up to 25 µA/m2 are concentrated near its westward and equatorward edge. The strong upward flowing FACs are fed by an area of more distributed, but still very strong downward-flowing FACs northeastward of the auroral form. In contrast to the conductances, the electric field is only slightly affected by the passage of the form. We point out similarities and differences of our observations and results to previously reported observations and models of 'auroral fingers', 'north-south aurora', and 'auroral streamers' which are suggested to be ionospheric manifestations of bursty bulk flows in the plasma sheet.Key words. Ionosphere (auroral ionosphere; electric fields and currents) · Magnetospheric physics (magnetosphere · ionosphere interactions)

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The response of the azimuthal component of the ionospheric electric field to auroral arc brightening

Annales Geophysicae ◽

10.1007/s00585-000-0065-3 ◽

2000 ◽

Vol 18 (1) ◽

pp. 65-73 ◽

Cited By ~ 2

Author(s):

V. Safargaleev ◽

W. Lyatsky ◽

N. G. Gazey ◽

P. N. Smith ◽

V. Kriviliov

Keyword(s):

Electric Field ◽

External Electric Field ◽

Electric Fields ◽

Short Circuit ◽

Ionospheric Irregularities ◽

Azimuthal Component ◽

Ionospheric Electric Field ◽

Auroral Phenomena ◽

Electric Fields And Currents ◽

East West

Abstract. We have analyzed the response of azimuthal component of the ionospheric electric field to auroral arc activity. We have chosen for analysis three intervals of coordinated EISCAT and TV observations on 18 February, 1993. These intervals include three kinds of arc activity: the appearance of a new auroral arc, the gradual brightening of the existing arc and variations of the arc luminosity. The arcs were mostly east-west aligned. In all cases, the enhancement of arc luminosity is accompanied by a decrease in the westward component of the ionospheric electric field. In contrast, an increase of that component seems to be connected with arc fading. The observed response is assumed to have the same nature as the "short circuit" of an external electric field by the conductor. The possible consequence of this phenomenon is discussed..Keywords. Ionosphere (electric fields and currents; ionospheric irregularities) · Magnetospheric physics (auroral phenomena)

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Elucidating the Influence of Electric Fields toward CO2 Activation on YSZ (111)

Catalysts ◽

10.3390/catal11020271 ◽

2021 ◽

Vol 11 (2) ◽

pp. 271

Author(s):

Nisa Ulumuddin ◽

Fanglin Che ◽

Jung-Il Yang ◽

Su Ha ◽

Jean-Sabin McEwen

Keyword(s):

Electric Field ◽

Electric Fields ◽

Heterogeneous Catalysts ◽

Co2 Reduction ◽

Total Density ◽

Reverse Water Gas Shift ◽

High Thermodynamic Stability ◽

Shift Reaction ◽

Water Gas

Despite its high thermodynamic stability, the presence of a negative electric field is known to facilitate the activation of CO2 through electrostatic effects. To utilize electric fields for a reverse water gas shift reaction, it is critical to elucidate the role of an electric field on a catalyst surface toward activating a CO2 molecule. We conduct a first-principles study to gain an atomic and electronic description of adsorbed CO2 on YSZ (111) surfaces when external electric fields of +1 V/Å, 0 V/Å, and −1 V/Å are applied. We find that the application of an external electric field generally destabilizes oxide bonds, where the direction of the field affects the location of the most favorable oxygen vacancy. The direction of the field also drastically impacts how CO2 adsorbs on the surface. CO2 is bound by physisorption when a +1 V/Å field is applied, a similar interaction as to how it is adsorbed in the absence of a field. This interaction changes to chemisorption when the surface is exposed to a −1 V/Å field value, resulting in the formation of a CO3− complex. The strong interaction is reflected through a direct charge transfer and an orbital splitting within the Olatticep-states. While CO2 remains physisorbed when a +1 V/Å field value is applied, our total density of states analysis indicates that a positive field pulls the charge away from the adsorbate, resulting in a shift of its bonding and antibonding peaks to higher energies, allowing a stronger interaction with YSZ (111). Ultimately, the effect of an electric field toward CO2 adsorption is not negligible, and there is potential in utilizing electric fields to favor the thermodynamics of CO2 reduction on heterogeneous catalysts.

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Electric potential differences across auroral generator interfaces

Annales Geophysicae ◽

10.5194/angeo-31-251-2013 ◽

2013 ◽

Vol 31 (2) ◽

pp. 251-261 ◽

Cited By ~ 11

Author(s):

J. De Keyser ◽

M. Echim

Keyword(s):

Electric Field ◽

High Altitude ◽

Electric Fields ◽

Electric Potential ◽

Equilibrium Configuration ◽

Potential Difference ◽

Field Profile ◽

Electric Potential Difference ◽

Electric Field Profile

Abstract. Strong localized high-altitude auroral electric fields, such as those observed by Cluster, are often associated with magnetospheric interfaces. The type of high-altitude electric field profile (monopolar, bipolar, or more complicated) depends on the properties of the plasmas on either side of the interface, as well as on the total electric potential difference across the structure. The present paper explores the role of this cross-field electric potential difference in the situation where the interface is a tangential discontinuity. A self-consistent Vlasov description is used to determine the equilibrium configuration for different values of the transverse potential difference. A major observation is that there exist limits to the potential difference, beyond which no equilibrium configuration of the interface can be sustained. It is further demonstrated how the plasma densities and temperatures affect the type of electric field profile in the transition, with monopolar electric fields appearing primarily when the temperature contrast is large. These findings strongly support the observed association of monopolar fields with the plasma sheet boundary. The role of shear flow tangent to the interface is also examined.

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Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

Annales Geophysicae ◽

10.5194/angeo-22-511-2004 ◽

2004 ◽

Vol 22 (2) ◽

pp. 511-525 ◽

Cited By ~ 12

Author(s):

K. Oksavik ◽

F. Søraas ◽

J. Moen ◽

R. Pfaff ◽

J. A. Davies ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Broad Band ◽

Spectral Width ◽

Hf Radar ◽

Optical Data ◽

Low Energy Electrons ◽

Field Lines ◽

Auroral Phenomena ◽

Electric Fields And Currents

Abstract. In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finland spectral width enhancements and ground-based optical data from Svalbard during a meridional crossing of the cusp. The observed 630nm rayed arc (Type-1 cusp aurora) is associated with stepped cusp ion signatures. Simultaneous counterstreaming low-energy electrons on open magnetic field lines lead us to propose that such electrons may be an important source for rayed red arcs through pitch angle scattering in collisions with the upper atmosphere. The observed particle precipitation and electric field turbulence are found to be nearly collocated with the equatorward edge of the optical cusp, in a region where CUTLASS Finland also observed enhanced spectral width. The electric field turbulence is observed to extend far poleward of the optical cusp. The broad-band electric field turbulence corresponds to spatial scale lengths down to 5m. Therefore, we suggest that electric field irregularities are directly responsible for the formation of HF radar backscatter targets and may also explain the observed wide spectra. FAST also encountered two narrow highly structured field-aligned current pairs flowing near the edges of cusp ion steps. Key words. Ionosphere (electric fields and currents). Magnetosphere physics (magnetopause, cusp, and boundary layers; auroral phenomena)

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A statistical study of intense electric fields at 4−7 R<sub><i>E</i></sub> geocentric distance using Cluster

Annales Geophysicae ◽

10.5194/angeo-23-2579-2005 ◽

2005 ◽

Vol 23 (7) ◽

pp. 2579-2588 ◽

Cited By ~ 8

Author(s):

T. Johansson ◽

T. Karlsson ◽

G. Marklund ◽

S. Figueiredo ◽

P.-A. Lindqvist ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Time Distribution ◽

Statistical Study ◽

Auroral Oval ◽

Field Structure ◽

Geocentric Distance ◽

Using Data ◽

Auroral Phenomena ◽

Current Systems

Abstract. Intense high-latitude electric fields (>150 mV/m mapped to ionospheric altitude) at 4–7 RE geocentric distance have been investigated in a statistical study, using data from the Cluster satellites. The orbit of the Cluster satellites limits the data collection at these altitudes to high latitudes, including the poleward part of the auroral oval. The occurrence and distribution of the selected events have been used to characterize the intense electric fields and to investigate their dependance on parameters such as MLT, CGLat, altitude, and also Kp. Peaks in the local time distribution are found in the evening to morning sectors but also in the noon sector, corresponding to cusp events. The electric field intensities decrease with increasing latitude in the region investigated (above 60 CGLat). A dependence on geomagnetic activity is indicated since the probability of finding an event increases up to Kp=5–6. The scales sizes are in the range up to 10 km (mapped to ionospheric altitude) with a maximum around 4–5km, consistent with earlier findings at lower altitudes and Cluster event studies. The magnitudes of the electric fields are inversely proportional to the scale sizes. The type of electric field structure (convergent or divergent) is consistent with the FAC direction for a subset of events with electric field intensities in the range 500–1000 mV/m and with clear bipolar signatures. The FAC directions are also consistent with the Region 1 and NBZ current systems, the latter of which prevail only during northward IMF conditions. For scale sizes less than 2 km the majority of the events were divergent electric field structures. Both converging and diverging electric fields were found throughout the investigated altitude range (4–7 RE geocentric distance). Keywords. Magnetospheric physics (Electric fields; Auroral phenomena; Magnetosphere-ionosphere interactions)

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The dawn and dusk electrojet response to substorm onset

Annales Geophysicae ◽

10.1007/s00585-000-1097-4 ◽

2000 ◽

Vol 18 (9) ◽

pp. 1097-1107 ◽

Cited By ~ 7

Author(s):

E. Borälv ◽

P. Eglitis ◽

H. J. Opgenoorth ◽

E. Donovan ◽

G. Reeves ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Information Transfer ◽

Neutral Line ◽

Substorm Onset ◽

Model Case ◽

Onset Timing ◽

Storms And Substorms ◽

Electric Fields And Currents ◽

Substorm Onsets

Abstract. We have investigated the time delay between substorm onset and related reactions in the dawn and dusk ionospheric electrojets, clearly separated from the nightside located substorm current wedge by several hours in MLT. We looked for substorm onsets occurring over Greenland, where the onset was identified by a LANL satellite and DMI magnetometers located on Greenland. With this setup the MARIA magnetometer network was located at dusk, monitoring the eastward electrojet, and the IMAGE chain at dawn, for the westward jet. In the first few minutes following substorm onset, sudden enhancements of the electrojets were identified by looking for rapid changes in magnetograms. These results show that the speed of information transfer between the region of onset and the dawn and dusk ionosphere is very high. A number of events where the reaction seemed to preceed the onset were explained by either unfavorable instrument locations, preventing proper onset timing, or by the inner magnetosphere's reaction to the Earthward fast flows from the near-Earth neutral line model. Case studies with ionospheric coherent (SuperDARN) and incoherent (EISCAT) radars have been performed to see whether a convection-induced electric field or enhanced conductivity is the main agent for the reactions in the electrojets. The results indicate an imposed electric field enhancement.Key words: Ionosphere (auroral ionosphere; electric fields and currents) - Magnetospheric physics (storms and substorms)

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Role of filament plasma remnants in ICMEs leading to geomagnetic storms

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313011708 ◽

2013 ◽

Vol 8 (S300) ◽

pp. 493-494 ◽

Cited By ~ 1

Author(s):

Rahul Sharma ◽

Nandita Srivastava ◽

D. Chakrabarty

Keyword(s):

Electric Field ◽

Geomagnetic Storms ◽

Interplanetary Coronal Mass Ejections ◽

Plasma Dynamics ◽

Terrestrial Magnetosphere ◽

Auroral Substorms ◽

Polarity Reversals ◽

Ionospheric Electric Field ◽

Filament Plasma

AbstractWe studied three interplanetary coronal mass ejections associated with solar eruptive filaments. Filament plasma remnants embedded in these structures were identified using plasma, magnetic and compositional signatures. These features when impacted the Earth's terrestrial magnetosphere - ionosphere system, resulted in geomagnetic storms. During the main phase of associated storms, along with high density plasma structures, polarity reversals in the Y-component (dawn-to-dusk) of the interplanetary electric field seem to trigger major auroral substorms with concomitant changes in the polar ionospheric electric field. Here, we examine the cases where plasma dynamics and magnetic structuring in the presence of the prompt penetration of the electric field into the equatorial ionosphere affected the space weather while highlighting the complex geomagnetic storm-substorm relationship.

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Multi-instrument observations of the electric and magnetic field structure of omega bands

Annales Geophysicae ◽

10.1007/s00585-000-0099-6 ◽

2000 ◽

Vol 18 (1) ◽

pp. 99-110 ◽

Cited By ~ 14

Author(s):

J. A. Wild ◽

T. K. Yeoman ◽

P. Eglitis ◽

H. J. Opgenoorth

Keyword(s):

Electric Fields ◽

Time Resolution ◽

Recovery Phase ◽

High Time ◽

High Time Resolution ◽

Band Formation ◽

Vhf Radar ◽

E Region ◽

Ionospheric Electric Field ◽

Electric Fields And Currents

Abstract. High time resolution data from the CUTLASS Finland radar during the interval 01:30-03:30 UT on 11 May, 1998, are employed to characterise the ionospheric electric field due to a series of omega bands extending ~5° in latitude at a resolution of 45 km in the meridional direction and 50 km in the azimuthal direction. E-region observations from the STARE Norway VHF radar operating at a resolution of 15 km over a comparable region are also incorporated. These data are combined with ground magnetometer observations from several stations. This allows the study of the ionospheric equivalent current signatures and height integrated ionospheric conductances associated with omega bands as they propagate through the field-of-view of the CUTLASS and STARE radars. The high-time resolution and multi-point nature of the observations leads to a refinement of the previous models of omega band structure. The omega bands observed during this interval have scale sizes ~500 km and an eastward propagation velocity ~0.75 km s-1. They occur in the morning sector (~05 MLT), simultaneously with the onset/intensification of a substorm to the west during the recovery phase of a previous substorm in the Scandinavian sector. A possible mechanism for omega band formation and their relationship to the substorm phase is discussed..Key words. Ionosphere (auroral ionosphere; electric fields and currents) · Magnetospheric physics (magnetosphere-ionosphere interactions)

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Can Electric Fields Drive Chemistry for an Aqueous Microdroplet?

10.21203/rs.3.rs-550908/v1 ◽

2021 ◽

Author(s):

Hongxia Hao ◽

Itai Leven ◽

Teresa Head-Gordon

Keyword(s):

Electric Field ◽

Electric Fields ◽

Water Droplet ◽

Reaction Rates ◽

Surface Reactivity ◽

Bulk Solution ◽

Excess Charge ◽

Electronic Effects ◽

Rate Acceleration

Abstract Reaction rates of common organic reactions have been reported to increase by one to six orders of magnitude in aqueous microdroplets compared to bulk solution, but the reasons for the rate acceleration are poorly understood. We investigate the role of electric fields at water droplet surfaces that might explain the promotion of unusual reactive chemistry, along with changes in electric field profiles as a function of excess charge to model the electrospray fragmentation process. We find that electric field alignments along free O-H bonds at the surface yield field strength distributions that are ~30 MV/cm larger on average than that found for O-H bonds in the interior of the water droplet, consistent with greater surface reactivity. We emphasize the importance of both nuclear and electronic effects at the surface, and the non-linear coupling of intramolecular solute polarization with intermolecular solvent modes, as a necessary feature for predicting the higher field strengths at water droplet surfaces.

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