Spacecraft Charging at Geosynchronous Orbit and Large Scale Electric Fields in the High Latitude Ionosphere.

1981 ◽  
Author(s):  
Joan Feynman ◽  
William J. Burke
Keyword(s):  
Electric Fields ◽  
High Latitude ◽  
Large Scale ◽  
Geosynchronous Orbit ◽  
Spacecraft Charging ◽  
High Latitude Ionosphere

scholarly journals The dayside high-latitude trough under quiet geomagnetic conditions: Radio tomography and the CTIP model

2005 ◽  
Vol 23 (4) ◽  
pp. 1199-1206 ◽  
Author(s):  
S. E. Pryse ◽  
K. L. Dewis ◽  
R. L. Balthazor ◽  
H. R. Middleton ◽  
M. H. Denton
Keyword(s):  
High Latitude ◽  
Large Scale ◽  
Physical Models ◽  
Physical Processes ◽  
Winter Solstice ◽  
Ion Density ◽  
Plasma Production ◽  
Radio Tomography ◽  
High Latitude Ionosphere

Abstract. The dayside high-latitude trough is a persistent feature of the post-noon wintertime auroral ionosphere. Radio tomography observations have been used to map its location and latitudinal structure under quiet geomagnetic conditions (Kp≤2) near winter solstice. The trough is also a clear feature in the ion density distribution of the Coupled Thermosphere-Ionosphere-Plasmasphere model (CTIP) under similar geophysical conditions. Comparisons of the measured and modelled distributions show that the plasma production equatorward of the trough is mainly controlled by solar radiation, but there are also other processes maintaining the equatorward trough-wall that are open to debate. The poleward trough-wall is produced by particle precipitation, but the densities are significantly overestimated by the model. At the trough minimum the observed densities are consistent with low nighttime densities convecting sunward to displace the higher daytime densities, but this is not borne out by the CTIP model. The study shows the potential of combining radio tomography and modelling to interpret the balance of the physical processes responsible for large-scale structuring of the high-latitude ionosphere, and highlights the role of tomographic imaging in validating and developing physical models.

scholarly journals The relationship between electric fields, conductances and currents in the high-latitude ionosphere: a statistical study using EISCAT data

1999 ◽  
Vol 17 (1) ◽  
pp. 43-52 ◽  
Author(s):  
J. A. Davies ◽  
M. Lester
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
High Latitude ◽  
Statistical Study ◽  
Field Vector ◽  
Relative Contribution ◽  
High Latitude Ionosphere ◽  
The Times ◽  
The Relationship ◽  
Uhf Radar

Abstract. The relationship between electric fields, height-integrated conductivities and electric currents in the high-latitude nightside electrojet region is known to be complex. The tristatic nature of the EISCAT UHF radar facility provides an excellent means of exploring this interrelationship as it enables simultaneous estimates to be made of the full electric field vector and the ionospheric Hall and Pedersen conductances, further allowing the determination of both field-perpendicular electric current components. Over 1300 h of common programme observations by the UHF radar system provide the basis of a statistical study of electric fields, conductances and currents in the high-latitude ionosphere, from which preliminary results are presented. Times at which there is significant solar contribution to the ionospheric conductances have been excluded by limiting the observations according to solar zenith angle. Initial results indicate that, in general, the times of peak conductance, identified from the entire set of EISCAT observations, do not correspond to the times of the largest electric field values; the relative contribution of ionospheric conductance and electric field to the electrojet currents therefore depends critically on local time, a conclusion which corroborates work by previous authors. Simultaneous measurements confirm a tendency for a decrease in both Hall and Pedersen conductances to be accompanied by an increase in the electric field, at least for moderate and large electric field value, a tendency which is also identified to some extent in the ratio of the conductances, which acts as an indicator of the energy of precipitating particles.Key words. Ionosphere (auroral ionosphere; electric fields and currents)

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

2019 ◽  
Author(s):  
Anthony J. Mannucci ◽  
Ryan McGranaghan ◽  
Xing Meng ◽  
Bruce T. Tsurutani ◽  
Olga P. Verkhoglyadova
Keyword(s):  
Reference Frame ◽  
Electric Fields ◽  
High Latitude ◽  
Large Scale ◽  
Reference Frames ◽  
Physical Basis ◽  
Neutral Species ◽  
Ionospheric Convection ◽  
Galilean Relativity ◽  
Primary Driver

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.

scholarly journals Equatorial electrojet as part of the global circuit: a case-study from the IEEY

1998 ◽  
Vol 16 (6) ◽  
pp. 698-710 ◽  
Author(s):  
A. T. Kobea ◽  
C. Amory-Mazaudier ◽  
J. M. Do ◽  
H. Lühr ◽  
E. Houngninou ◽  
...  
Keyword(s):  
Electric Field ◽  
Geomagnetic Storm ◽  
Electric Fields ◽  
High Latitude ◽  
Large Scale ◽  
Equatorial Electrojet ◽  
Doppler Frequency ◽  
Time Interval ◽  
Ground Field ◽  
Equatorial Latitude

Abstract. Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY) experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ) to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

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