Medium-scale wave-like irregularities of electron density and electron temperature in the upper ionosphere at subauroral and high latitudes during different phases of the magnetic storm of January 1974

1992 ◽  
Vol 70 (7) ◽  
pp. 582-594 ◽  
Author(s):  
M. Förster ◽  
M. N. Fatkullin ◽  
N. A. Gasilov ◽  
U. Schwarz
Keyword(s):  
Electron Temperature ◽  
Magnetic Storm ◽  
Electron Density ◽  
Geomagnetic Storm ◽  
Temperature Fluctuations ◽  
Magnetic Disturbance ◽  
High Latitudes ◽  
Medium Scale ◽  
Main Ionospheric Trough ◽  
Upper Ionosphere

Data obtained aboard the INTERCOSMOS-10 satellite during different phases of the geomagnetic storm in the last week of January, 1974, are used for the investigation of medium-scale wave-like irregularities of electron density and electron temperature in the upper ionosphere (altitudes from about 800 to about 1400 km) for high and subauroral latitudes. Daytime and nighttime conditions are analysed in detail. It is shown that independent of local time and of the degree of magnetic disturbance the spectra of medium-scale electron-density and electron-temperature fluctuations reveal equal characteristic wavelengths of l ≈ 130–150, 150–200, 210–240, 250–320, 340–400 km and so on. During nighttime conditions in the region of the main ionospheric trough the fluctuations of electron density (at the equatorward wall of the trough) and of electron temperature at the bottom of the trough) are separated in space. Later on it is shown that the intensity of the fluctuations of electron density and electron temperature at high and subauroral latitudes is dependent on the phase of magnetic storm.

Plasmaspheric response to the geomagnetic storm period March 20–23, 1990, observed by the ACTIVNY (MAGION-2) satellite

1992 ◽  
Vol 70 (7) ◽  
pp. 569-574 ◽  
Author(s):  
M. Förster ◽  
N. Jakowski ◽  
A. Best ◽  
J. Smilauer
Keyword(s):  
Magnetic Storm ◽  
Electron Density ◽  
Geomagnetic Storm ◽  
Joule Heating ◽  
Growth Phase ◽  
Langmuir Probe ◽  
Atomic Oxygen ◽  
Scale Height ◽  
Ionospheric Response ◽  
Increased Pressure

Langmuir probe data obtained during the storm period March 20–23, 1990, on board the MAGION-2 subsatellite of the ACTIVNY experiment are analyzed to study the plasmaspheric and ionospheric response to a magnetic storm. The data indicate a well-pronounced equatorward edge of the electron density trough in the afternoon (18:15 LT) at about 800 km height that moves towards lower latitudes during the course of the storm. It is interesting to note that the electron density inside the plasmasphere is increased by more than 20% in the morning shortly after sunrise (07:30 LT). This is due to enhanced O+ densities in the lower plasmasphere during the growth phase of the geomagnetic storm as measured by the ion mass spectrometer NAM-5 onboard the main satellite. It is suggested that the source for the increased density is thermospheric Joule heating at auroral latitudes with a commensurate increase in thermospheric pressure. This increased pressure causes the local thermosphere to expand both upward and equatorward. The increased atomic-oxygen scale height coupled with equatorward motion of fhermospheric perturbations results in an increased O density and resulting O+ density within the lower plasmasphere. The observations indicate a storm-induced compression of the plasmasphere that favourizes an enhanced outflow of plasma into the ionosphere leading to an increased nighttime F2-layer ionization and a depletion of the plasmasphere during the following hours.

Studying the Ionospheric Responses Induced by a Geomagnetic Storm in September 2017 with Multiple Observations in America

2020 ◽  
Author(s):  
Yang Liu ◽  
Zheng Li ◽  
Jinling Wang
Keyword(s):  
Electron Density ◽  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Ionospheric Irregularities ◽  
Electron Content ◽  
High Latitudes ◽  
Total Electron ◽  
Multiple Observations ◽  
The Usa ◽  
Plasma Depletions

<p>A series of studies have suggested that a geomagnetic storm can accelerate the formation of plasma depletions and the generation of ionospheric irregularities. Using observation data from the Continuously Operating Reference Stations (CORS) network in the USA, the responses of the ionospheric total electron content (TEC) to the geomagnetic storm on September 8, 2017 are studied in detail. A mid-latitude trough was discovered from 01:00 UT to 06:00 UT in the USA with a length exceeding 5000 km. The probable causes are the combination of a classic negative storm response with increments in the neutral composition and the expansion of the auroral oval, pushing the mid-latitude trough equatorward.  Super-scale plasma depletion was observed by SWARM data accompanied by the expansion of mid-latitude trough. Both PPEF from high latitudes and pole-ward neutral wind are responsible for the large-scale ionospheric irregularities. Medium-scale travelling ionospheric disturbances (MSTID) with wavelengths of 600–700 km were generated accompanied by a drop and perturbation in the electron density. The intensity of the MSTID fluctuations reached over 2.5 TECU, which were discovered by filtering the differential TEC. The evolution of plasma depletions were associated with the MSTID propagating from high latitudes to low latitudes. SWARM spaceborne observations also showed a drop in the electron density from 10<sup>5</sup> to 10<sup>3</sup> compared to the background values at 28° N, 96° W, and 25° N, 95° W. This research investigates super-scale plasma depletions generated by geomagnetic storms using both CORS GNSS and spaceborne observations. The proposed work is valuable for better understanding the evolution of ionospheric depletions during geomagnetic storms.</p>

Topside observation of electron density variations (G-condition) at times of low magnetic activity

1969 ◽  
Vol 47 (23) ◽  
pp. 2683-2689 ◽  
Author(s):  
L. Herzberg ◽  
G. L. Nelms ◽  
P. L. Dyson
Keyword(s):  
Electron Temperature ◽  
Observational Data ◽  
Electron Density ◽  
Path Length ◽  
Gradual Increase ◽  
Magnetic Activity ◽  
Scale Height ◽  
Magnetic Disturbance

The so-called G-condition of the ionosphere (foF2 < foF1, with normal foF1) is investigated from the topside with the Alouette II satellite. In the absence of a severe magnetic disturbance, the condition is occasionally observed over a path length of the order of a thousand kilometers. In this case, one observes a characteristic development: in the F2 region at the levels below about 1000 km there is a systematic decrease of electron density to about one-half the original value, followed by a gradual increase to normal, and at the levels above about 1000 km there is a corresponding increase, followed by a decrease back to normal. This variation in electron density is accompanied, at levels below 2000 km, by significant increases in scale height. Cylindrical electrostatic probes carried on the satellite show, at the same time, increases in electron temperature. Possible interpretations of the observational data are discussed.

scholarly journals Temperature Fluctuations in PN

1993 ◽  
Vol 155 ◽  
pp. 188-188
Author(s):  
Ruth Gruenwald ◽  
Sueli M. Viegas
Keyword(s):  
Electron Temperature ◽  
Observational Data ◽  
Electron Density ◽  
Temperature Fluctuation ◽  
Planetary Nebulae ◽  
Temperature Fluctuations ◽  
Emission Lines ◽  
Mean Square ◽  
The Mean

For planetary nebulae, empirical abundances can be obtained from the observed emission-lines as long as the electron density, the electron temperature, and the ionization corrections factor are determined. However, due to temperature fluctuations in the emitting gas, the evaluation of the temperature from the observational data is strongly dependent on the method used. The temperature fluctuation is usually characterized by the mean square temperature fluctuation, t2 (Peimbert and Costero, 1969 — PC).

scholarly journals The formation of electron-temperature hot spots in the main ionospheric trough by the internal processes

1996 ◽  
Vol 14 (8) ◽  
pp. 816-825 ◽  
Author(s):  
G. I. Mingaleva ◽  
V. S. Mingalev
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
High Latitude ◽  
Hot Spots ◽  
Electron Gas ◽  
Three Dimensional ◽  
Neutral Atmosphere ◽  
F Region ◽  
Main Ionospheric Trough ◽  
High Latitude Ionosphere

Abstract. A mathematical model of the convecting high-latitude ionosphere is described which produces three-dimensional distributions of electron density, positive-ion velocity and electron and ion temperatures at the F-layer altitudes. The results of simulation of the behaviour of the high-latitude ionosphere, in particular, the heat regime of the F-layer, are presented and analysed. From our study, it was found that electron-temperature hot spots in the main ionospheric trough can arise owing to internal ionospheric processes, and not due to effects of any external causes. Three conditions, to be satisfied simultaneously, are necessary for the formation of the considered electron-temperature hot spots: first, low values of electron density; second, solar illumination of the upper F region and darkness of the lower F region; third, low values of neutral-component densities. These conditions are valid in the main ionospheric trough near the terminator on the nightside when the density of the neutral atmosphere is not high. The physical processes which lead to the formation of the electron-temperature hot spots are the heat transfer from the upper into the lower F region, the reduced heat capacity of electron gas and the weakened cooling of electron gas due to inelastic collisions with neutral atoms and molecules. Also investigated is the influence of seasonal and solar-activity variations on the efficiency of the identified mechanism responsible for the formation of the electron temperature peaks in the main ionospheric trough by the internal processes.

scholarly journals Observation of a Critical Gradient Threshold for Electron Temperature Fluctuations in the DIII-D Tokamak

2013 ◽  
Vol 110 (4) ◽  
Author(s):  
J. C. Hillesheim ◽  
J. C. DeBoo ◽  
W. A. Peebles ◽  
T. A. Carter ◽  
G. Wang ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Temperature Fluctuations

scholarly journals Comparison of the measured and modelled electron densities and temperatures in the ionosphere and plasmasphere during 20-30 January, 1993

2000 ◽  
Vol 18 (10) ◽  
pp. 1257-1262 ◽  
Author(s):  
A. V. Pavlov ◽  
T. Abe ◽  
K.-I. Oyama
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Electron Temperature ◽  
Field Line ◽  
Electron Density ◽  
Magnetic Field Line ◽  
New Approach ◽  
Additional Heating ◽  
Vibrational Levels ◽  
The Magnetic Field

Abstract. We present a comparison of the electron density and temperature behaviour in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite with numerical model calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere during the geomagnetically quiet and storm period on 20–30 January, 1993. We have evaluated the value of the additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the daytime plasmasphere region above 5000 km along the magnetic field line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite within the Millstone Hill magnetic field flux tube in the Northern Hemisphere. The additional heating brings the measured and modelled electron temperatures into agreement in the plasmasphere and into very large disagreement in the ionosphere if the classical electron heat flux along magnetic field line is used in the model. A new approach, based on a new effective electron thermal conductivity coefficient along the magnetic field line, is presented to model the electron temperature in the ionosphere and plasmasphere. This new approach leads to a heat flux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasmasphere found for the first time here allow the model to accurately reproduce the electron temperatures observed by the instruments on board the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The effects of the daytime additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modified electron heat flux is used. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at the first vibrational levels of N2 and O2 and the second level of O2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The resulting effect of N2(v > 0) and O2(v > 0) on NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 1.5. The modelled electron temperature is very sensitive to the electron density, and this decrease in electron density results in the increase of the calculated daytime electron temperature up to about 580 K at the F2 peak altitude giving closer agreement between the measured and modelled electron temperatures. Both the daytime and night-time densities are not reproduced by the model without N2(v > 0) and O2(v > 0), and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement.Key words: Ionosphere (ionospheric disturbances; ionosphere-magnetosphere interactions; plasma temperature and density)  

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