scholarly journals Algorithm for numerical simulation of electron density and stochastically convecting high latitude ionosphere

2021 ◽  
Vol 2131 (2) ◽  
pp. 022013
Author(s):  
G Vlaskov
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Electron Density ◽  
Large Scale ◽  
Ionospheric Plasma ◽  
Auroral Zone ◽  
Polar Ionosphere ◽  
Magnetospheric Convection ◽  
The Monte Carlo Method ◽  
High Latitude Ionosphere

Abstract The problem of modeling the inhomogeneities of the electron density in the polar ionosphere at the level of the F - layer is considered. It is known that the distribution of ionospheric plasma changes under the action of the electric field of large-scale magnetospheric convection. Since the electric field undergoes significant fluctuations in the auroral zone, it is proposed to use the Monte Carlo method to solve this problem, simulating the process of plasma motion, like the Wiener one with deterministic drift.

scholarly journals Observing the north polar ionosphere on 30 October 2003 by GPS imaging and IS radars

2006 ◽  
Vol 24 (1) ◽  
pp. 107-113 ◽  
Author(s):  
C. Stolle ◽  
J. Lilensten ◽  
S. Schlüter ◽  
Ch. Jacobi ◽  
M. Rietveld ◽  
...  
Keyword(s):  
Time Series ◽  
Electron Density ◽  
Large Scale ◽  
Electron Content ◽  
Polar Ionosphere ◽  
Storm Main Phase ◽  
The North ◽  
F Region ◽  
Longitudinal Band ◽  
North Polar

Abstract. The evening of 30 October 2003 was subject to a major storm main phase. For this time, we combine large-scale electron content maps from GPS imaging with time series of electron density and temperature of two EISCAT radars in Tromsø and Svalbard and the Sondrestrom radar, for observing the north polar ionosphere. The GPS assimilations resulted in the image of the electron content trace of an anti-sunward polar Tongue Of Ionisation (TOI) consecutively to 20:00 UT. In combination with the radar observations we concluded that the TOI persisted during the whole period of continuous southward IMF Bz until about 22:40 UT while its largest extension toward the nightside auroral region was found between 21:00-22:00 UT. A typical F region electron temperature of ~2000 K and the plasma velocity of ~800 ms-1 support its convective origin from the dayside mid-latitudes. Due to the structured appearance of the electron content distribution and the radar electron density time series we believe that discrete plasma patches formed inside the anti-sunward drift pattern. After two large oscillations of the IMF Bz the nightside plasma density was observed to re-enhance after 23:00 UT along a longitudinal band below 70 N. Coinciding electron temperatures of ~2000 K suggest again the convective nature of the plasma, while a modified convection pattern is expected.

scholarly journals Comparison of large-scale Birkeland currents determined from Iridium and SuperDARN data

2006 ◽  
Vol 24 (3) ◽  
pp. 941-959 ◽  
Author(s):  
D. L. Green ◽  
C. L. Waters ◽  
B. J. Anderson ◽  
H. Korth ◽  
R. J. Barnes
Keyword(s):  
Electric Field ◽  
Large Scale ◽  
Radar Data ◽  
Space Environment ◽  
Near Earth Space ◽  
Radar Network ◽  
High Latitude Ionosphere ◽  
Ionospheric Electric Field ◽  
Birkeland Currents

Abstract. The Birkeland currents, J||, electrically couple the high latitude ionosphere with the near Earth space environment. Approximating the spatial distribution of the Birkeland currents may be achieved using the divergence of the ionospheric electric field, , assuming zero conductance gradients such that . In this paper, electric field data derived from the Super Dual Auroral Radar Network (SuperDARN) are used to calculate , which is compared with the Birkeland current distribution derived globally from the constellation of Iridium satellites poleward of 60° magnetic latitude. We find that the assumption of zero conductance gradients is often a poor approximation. On the dayside, in regions where the SuperDARN electric field is constrained by radar returns, the agreement in the locations of regions of upward and downward current between and J|| obtained from Iridium data is reasonable with differences of less than 3° in the latitudinal location of major current features. It is also shown that away from noon, currents arising from conductance gradients can be larger than the component. By combining the estimate in regions of radar coverage with in-situ estimates of conductance gradients from DMSP satellite particle data, the agreement with the Iridium derived J|| is considerably improved. However, using an empirical model of ionospheric conductance did not account for the conductance gradient current terms. In regions where radar data are sparse or non-existent and therefore constrained by the statistical potential model the approximation does not agree with J|| calculated from Iridium data.

scholarly journals Effect of double layers on magnetosphere–ionosphere coupling

1987 ◽  
Vol 5 (2) ◽  
pp. 351-366 ◽  
Author(s):  
Robert L. Lysak ◽  
Mary K. Hudson
Keyword(s):  
Wave Propagation ◽  
Electric Field ◽  
Double Layer ◽  
Large Scale ◽  
Debye Length ◽  
Plasma Temperature ◽  
Auroral Zone ◽  
Alfven Wave ◽  
Scale Model ◽  
Double Layers

The earth's auroral zone contains dynamic processes occurring on scales from the length of an auroral zone field line (about 10RE) which characterizes Alfven wave propagation to the scale of microscopic processes which occur over a few Debye lengths (less than 1 km). These processes interact in a time-dependent fashion since the current carried by the Alfven waves can excite microscopic turbulence which can in turn provide dissipation of the Alfven wave energy. This review will first describe the dynamic aspects of auroral current structures with emphasis on consequences for models of microscopic turbulence. In the second part of the paper a number of models of microscopic turbulence will be introduced into a large scale model of Alfven wave propagation to determine the effect of various models on the overall structure of auroral currents. In particular, we will compare the effect of a double layer electric field which scales with the plasma temperature and Debye length with the effect of anomalous resistivity due to electrostatic ion cyclotron turbulence in which the electric field scales with the magnetic field strength. It is found that the double layer model is less diffusive than the resistive model leading to the possibility of narrow, intense current structures.

scholarly journals Field-aligned currents and ionospheric parameters deduced from EISCAT radar measurements in the post-midnight sector

2002 ◽  
Vol 20 (9) ◽  
pp. 1335-1348 ◽  
Author(s):  
M. Sugino ◽  
R. Fujii ◽  
S. Nozawa ◽  
T. Nagatsuma ◽  
S. C. Buchert ◽  
...  
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Electric Fields ◽  
Large Scale ◽  
Radar Data ◽  
Temporal Variations ◽  
Dark Spot ◽  
Ionospheric Conductivity ◽  
Eiscat Radar ◽  
Transmitting Antenna

Abstract. Attempting to derive the field-aligned current (FAC) density using the EISCAT radar and to understand the role of the ionosphere on closing FACs, we conducted special radar experiments with the EISCAT radar on 9 October 1999. In order to derive the gradient of the ionospheric conductivity (grad S) and the divergence of the electric field (div E) nearly simultaneously, a special experiment employed an EISCAT radar mode which let the transmitting antenna sequentially point to four directions within 10 min; two pairs of the four directions formed two orthogonal diagonals of a square.  Our analysis of the EISCAT radar data disclosed that SP div E and E · grad SP produced FACs with the same direction inside a stable broad arc around 05:00 MLT, when the EISCAT radar presumably crossed the boundary between the large-scale upward and downward current regions. In the most successfully observed case, in which the conductances and the electric field were spatially varying with little temporal variations, the contribution of SP div E was nearly twice as large as that of E · grad SP . On the other hand, the contribution of (b × E) · grad SH was small and not effective in closing FACs. The present EISCAT radar mode along with auroral images also enables us to focus on the temporal or spatial variation of high electric fields associated with auroral arcs. In the present experiment, the electric field associated with a stable arc was confined in a spatially restricted region, within ~ 100 km from the arc, with no distinct depletion of electron density. We also detected a region of the high arc-associated electric field, accompanied by the depletion of electron density above 110 km. Using auroral images, this region was identified as a dark spot with a spatial scale of over 150 × 150 km. The dark spot and the electron depletion were likely in existence for a limited time of a few minutes.Key words. Ionosphere (auroral ionosphere; electric fields and currents; particle precipitation)

scholarly journals Polar observations of electron density distribution in the Earth’s magnetosphere. 2. Density profiles

2002 ◽  
Vol 20 (11) ◽  
pp. 1725-1735 ◽  
Author(s):  
H. Laakso ◽  
R. Pfaff ◽  
P. Janhunen
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Auroral Zone ◽  
Polar Cap ◽  
Geomagnetic Disturbances ◽  
Activity Data ◽  
Density Peaks ◽  
Spacecraft Potential ◽  
Order Of Magnitude ◽  
Auroral Phenomena

Abstract. Using spacecraft potential measurements of the Polar electric field experiment, we investigate electron density variations of key plasma regions within the magnetosphere, including the polar cap, cusp, trough, plasmapause, and auroral zone. The statistical results were presented in the first part of this study, and the present paper reports detailed structures revealed by individual satellite passes. The high-altitude (> 3 RE) polar cap is generally one of the most tenuous regions in the magnetosphere, but surprisingly, the polar cap boundary does not appear as a steep density decline. At low altitudes (1 RE) in summer, the polar densities are very high, several 100 cm-3 , and interestingly, the density peaks at the central polar cap. On the noonside of the polar cap, the cusp appears as a dense, 1–3° wide region. A typical cusp density above 4 RE distance is between several 10 cm-3 and a few 100 cm-3 . On some occasions the cusp is crossed multiple times in a single pass, simultaneously with the occurrence of IMF excursions, as the cusp can instantly shift its position under varying solar wind conditions, similar to the magnetopause. On the nightside, the auroral zone is not always detected as a simple density cavity. Cavities are observed but their locations, strengths, and sizes vary. Also, the electric field perturbations do not necessarily overlap with the cavities: there are cavities with no field disturbances, as well as electric field disturbances observed with no clear cavitation. In the inner magnetosphere, the density distributions clearly show that the plasmapause and trough densities are well correlated with geomagnetic activity. Data from individual orbits near noon and midnight demonstrate that at the beginning of geomagnetic disturbances, the retreat speed of the plasmapause can be one L-shell per hour, while during quiet intervals the plasmapause can expand anti-earthward at the same speed. For the trough region, it is found that the density tends to be an order of magnitude higher on the day-side (~1 cm-3) than on the nightside (~0.1–1 cm-3), particularly during low Kp.Key words. Magnetospheric physics (auroral phenomena; plasmasphere; polar cap phenomena)

scholarly journals An extended TRANSCAR model including ionospheric convection: simulation of EISCAT observations using inputs from AMIE

2005 ◽  
Vol 23 (2) ◽  
pp. 419-431 ◽  
Author(s):  
P.-L. Blelly ◽  
C. Lathuillère ◽  
B. Emery ◽  
J. Lilensten ◽  
J. Fontanari ◽  
...  
Keyword(s):  
Large Scale ◽  
Frictional Heating ◽  
Polar Ionosphere ◽  
Energy Inputs ◽  
Early Afternoon ◽  
High Latitude Ionosphere ◽  
Field Lines ◽  
Moment Approach ◽  
The Magnetic Field ◽  
Good Agreement

Abstract. The TRANSCAR ionospheric model was extended to account for the convection of the magnetic field lines in the auroral and polar ionosphere. A mixed Eulerian-Lagrangian 13-moment approach was used to describe the dynamics of an ionospheric plasma tube. In the present study, one focuses on large scale transports in the polar ionosphere. The model was used to simulate a 35-h period of EISCAT-UHF observations on 16-17 February 1993. The first day was magnetically quiet, and characterized by elevated electron concentrations: the diurnal F2 layer reached as much as 1012m-3, which is unusual for a winter and moderate solar activity (F10.7=130) period. An intense geomagnetic event occurred on the second day, seen in the data as a strong intensification of the ionosphere convection velocities in the early afternoon (with the northward electric field reaching 150mVm-1) and corresponding frictional heating of the ions up to 2500K. The simulation used time-dependent AMIE outputs to infer flux-tube transports in the polar region, and to provide magnetospheric particle and energy inputs to the ionosphere. The overall very good agreement, obtained between the model and the observations, demonstrates the high ability of the extended TRANSCAR model for quantitative modelling of the high-latitude ionosphere; however, some differences are found which are attributed to the precipitation of electrons with very low energy. All these results are finally discussed in the frame of modelling the auroral ionosphere with space weather applications in mind.

scholarly journals Electric Field Multifractal Features in the High-Latitude Ionosphere: CSES-01 Observations

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 646
Author(s):  
Giuseppe Consolini ◽  
Virgilio Quattrociocchi ◽  
Giulia D’Angelo ◽  
Tommaso Alberti ◽  
Mirko Piersanti ◽  
...  
Keyword(s):  
Electric Field ◽  
Geomagnetic Field ◽  
Three Dimensional ◽  
Auroral Region ◽  
Polar Ionosphere ◽  
Polar Cap ◽  
High Latitude Ionosphere ◽  
Field Fluctuations ◽  
Spatio Temporal ◽  
Multifractal Nature

In the polar ionosphere, the electric field is characterized by broadband and power law spectral densities at small/short spatio-temporal scales, which support a possible turbulent nature of the electric field fluctuations. Here, we investigate the multifractal character of the full three-dimensional electric field in the polar ionosphere as recorded on board the first Chinese Seismo-Electromagnetic Satellite (CSES-01). The results of our analysis prove a clear different degree of multifractality of the electric field fluctuations approaching either the polar cap trailing edge or the auroral region. The observed differences in the multifractal character are interpreted in terms of the different natures of the particle precipitation in the polar cap and in the auroral region. A possible link between the multifractal nature of electric field fluctuations, parallel to the geomagnetic field, and filamentation of field aligned currents (FACs) is established.

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