scholarly journals Electron Densities and Scale Heights in the Mid-latitude Topside Ionosphere

1967 ◽  
Vol 20 (4) ◽  
pp. 401 ◽  
Author(s):  
PL Dyson
Keyword(s):  
Electron Density ◽  
Northern Hemisphere ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Electron Densities ◽  
Night Time ◽  
Transition Level ◽  
Latitude Region ◽  
Latitudinal Variations

The diurnal and latitudinal variations of electron density and plasma scale height in the topside ionosphere during summer and winter have been calculated from Alouette I ionograms recorded at Woomera. The electron density behaviour is anomalous in that the winter night-time values are generally as large or larger than those occurring during the day. At heights near 1000 km the winter night-time values are greater than those for night-time summer. The behaviour of the scale height is very similar to that reported by others for the mid-latitude region of the northern hemisphere and implies that at night-time the transition level from 0+ to lighter ions occurs at heights of about 550 km in summer and 500 km in winter.

scholarly journals Vertical electron density and topside effective scale height (<I>H</I><sub>T</sub>) variations over the Indian equatorial and low latitude stations

2011 ◽  
Vol 29 (10) ◽  
pp. 1861-1872 ◽  
Author(s):  
K. Venkatesh ◽  
P. V. S. Rama Rao ◽  
P. L. Saranya ◽  
D. S. V. V. D. Prasad ◽  
K. Niranjan
Keyword(s):  
Diurnal Variation ◽  
Electron Density ◽  
Scale Height ◽  
Electron Content ◽  
Iri Model ◽  
Night Time ◽  
Low Latitude ◽  
Density Profiles ◽  
Gps Tec ◽  
Electron Density Profiles

Abstract. Understanding the vertical electron density profile, which is the altitudinal variation of ionospheric electron density distribution is an important aspect for the ionospheric investigations. In this paper, the bottom-side electron density profiles derived from ground based ionosonde data and the ROCSAT-1 in-situ electron density data were used to determine the estimates of the topside electron density profiles using α-Chapman function over an equatorial station Trivandrum (8.47° N, 76.91° E) and a low latitude station Waltair (17.7° N, 83.3° E) in the Indian region. The reconstructed electron density profiles are compared with IRI (2007) model derived vertical electron density profiles which resulted in significant deviations between the two different profiles. Both the reconstructed electron density profiles and the IRI model derived profiles are integrated independently to derive the Total Electron Content (TEC) values which are compared with GPS derived TEC values. TEC values derived from the reconstructed electron density profiles give better estimates with the GPS-TEC compared to those of IRI model derived TEC values. Compared to the GPS-TEC, the IRI model is underestimating the TEC values during day-time and is overestimating during night-time at both the stations. The percentage deviations of IRI derived TEC from GPS-TEC are larger compared to those between reconstructed profile derived TEC and GPS-TEC. F2-layer peak electron density, peak height and electron density at ROCSAT altitudes (≈600 km) are used to derive the effective scale heights (HT) of the topside ionosphere during the period from July 2003 to June 2004. The diurnal and seasonal variations of HT and E×B drift velocities are presented in this paper. The diurnal variation of the effective scale height (HT) shows peak values around noon hours with higher values during day-time and lower values during night-time both at Trivandrum and Waltair. The E×B drift velocities at both the places also have shown a clear diurnal variation with a negative peak around 04:00 LT and maximum during day-time hours. The higher and lower values of HT seem to be associated with positive and negative phases of the E×B drift velocities, respectively.

New topside ionosphere model based on Vary-Chap function using radio occultation and topside sounder data

2020 ◽  
Author(s):  
Mengjie Wu
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Satellite System ◽  
Electron Density Profile ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Ionosphere Model ◽  
Ionospheric Models ◽  
Electron Density Profiles ◽  
Global Navigation Satellite

&lt;p&gt;&lt;span&gt;The Global Navigation Satellite System (GNSS) radio occultation and topside sounder provide materials&amp;#160;for the validation of a mathematical description&amp;#160;of the&amp;#160;topside ionosphere up to satellite altitude. An attempt to represent the topside electron density profile is using &amp;#945;-Chapman function with a continuously varying scale height. In this study, the Vary-Chap scale height profiles are obtained based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) electron density profiles from 1 January 2008 to 31 December 2013 and fitted by a shape function composed of two weighted patterns&amp;#160;representing&amp;#160;the ion and electron&amp;#160;contributions&amp;#160;of lower and higher altitudes. The topside profiles of ISIS-1 data are used to define the transition height of different ions. The associated fitting parameters are analyzed to reveal their temporal and spatial features and variations along with enhancement of solar activity. Their prominent dependence on latitudes, longitudes, the local time, the season, and the solar cycle facilitates modeling of the Vary-Chap scale height in constructing empirical topside ionospheric models.&lt;/span&gt;&lt;/p&gt;

scholarly journals On the link between the topside ionospheric effective scale height and the plasma ambipolar diffusion, theory and preliminary results

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Alessio Pignalberi ◽  
Michael Pezzopane ◽  
Bruno Nava ◽  
Pierdavide Coïsson
Keyword(s):  
Electron Density ◽  
Diffusion Theory ◽  
Vertical Gradient ◽  
Electron Density Profile ◽  
Ambipolar Diffusion ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Effective Parameters ◽  
Analytical Functions ◽  
Vertical Scale

Abstract Over the years, an amount of models relying on effective parameters were implemented in the challenging issue of the topside ionosphere description. These models are based on different analytical functions, but all of them depend on a parameter called effective scale height, that is deduced from topside electron density measurements. As their names state, they are effective in reproducing the topside electron density profile only when applied to the analytical function used to derive them. Then, in principle, they do not have any physical meaning. It is the goal of this paper to mathematically link the effective scale height modeled through the Epstein layer to the vertical scale height theoretically deduced from the plasma ambipolar diffusion theory. Firstly, effective and theoretical scale heights are linked through a mathematical relation by showing that they tend to each other in the topside ionosphere. Secondly, their connection is preliminarily demonstrated by calculating effective scale height values from the entire COSMIC/FORMOSAT-3 radio occultation dataset. Thirdly, a possible connection between the vertical gradient of the topside scale height (as obtained by COSMIC/FORMOSAT-3 satellites) and the electron temperature (as obtained by ESA Swarm B satellite) is studied by highlighting corresponding similarities in the diurnal, seasonal, solar activity, and latitudinal variability.

scholarly journals Looking for a proxy of the ionospheric turbulence with Swarm data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paola De Michelis ◽  
Giuseppe Consolini ◽  
Alessio Pignalberi ◽  
Roberta Tozzi ◽  
Igino Coco ◽  
...  
Keyword(s):  
Electron Density ◽  
Geomagnetic Activity ◽  
Density Fluctuations ◽  
Rate Of Change ◽  
Topside Ionosphere ◽  
Joint Probability Distribution ◽  
Activity Levels ◽  
Scaling Exponents ◽  
Electron Density Fluctuations ◽  
Scaling Features

AbstractThe present work focuses on the analysis of the scaling features of electron density fluctuations in the mid- and high-latitude topside ionosphere under different conditions of geomagnetic activity. The aim is to understand whether it is possible to identify a proxy that may provide information on the properties of electron density fluctuations and on the possible physical mechanisms at their origin, as for instance, turbulence phenomena. So, we selected about 4 years (April 2014–February 2018) of 1 Hz electron density measurements recorded on-board ESA Swarm A satellite. Using the Auroral Electrojet (AE) index, we identified two different geomagnetic conditions: quiet (AE < 50 nT) and active (AE > 300 nT). For both datasets, we evaluated the first- and second-order scaling exponents and an intermittency coefficient associated with the electron density fluctuations. Then, the joint probability distribution between each of these quantities and the rate of change of electron density index was also evaluated. We identified two families of plasma density fluctuations characterized by different mean values of both the scaling exponents and the considered ionospheric index, suggesting that different mechanisms (instabilities/turbulent processes) can be responsible for the observed scaling features. Furthermore, a clear different localization of the two families in the magnetic latitude—magnetic local time plane is found and its dependence on geomagnetic activity levels is analyzed. These results may well have a bearing about the capability of recognizing the turbulent character of irregularities using a typical ionospheric plasma irregularity index as a proxy.

Anomalous features of the electron density in the topside ionosphere

1969 ◽  
Vol 311 (1507) ◽  
pp. 501-516 ◽  
Keyword(s):  
Electron Density ◽  
Power Supply ◽  
Data Rate ◽  
Power Lines ◽  
Topside Ionosphere ◽  
Telemetry Data ◽  
Electron Density And Temperature

The instruments which measure electron density and temperature are quite separate and independent in operation, but on account of the limitations in power supply and telemetry data rate the two experiments share the same power lines and some data channels.

scholarly journals ELECTRON DENSITY STUDIES ON THE REGIOSELECTIVITY OF DEPROTONATION REACTIONS

2014 ◽  
Vol 70 (a1) ◽  
pp. C287-C287
Author(s):  
Juan Van der Maelen ◽  
Javier Cabeza
Keyword(s):  
Electron Density ◽  
Theoretical Calculations ◽  
Density Ratio ◽  
Atomic Charge ◽  
Heterocyclic Ring ◽  
Bond Critical Point ◽  
Electron Densities ◽  
Total Energy Density ◽  
Topological Parameters ◽  
Alkyl Groups

The C-alkyl groups of cationic triruthenium cluster complexes of the type [Ru3(µ-H)(µ-κ2N1,C2-EtnMemPyHk)(CO)10]+ (EtnMemPyHk represents a generic C-alkyl-N-methyl-pyrazium species) have been deprotonated to give kinetic products that contain unprecedented C-alkylidene derivatives and maintain the original edge-bridged decacarbonyl structure. When the starting complexes contain various C-alkyl groups, the selectivity of these deprotonation reactions is related to the atomic charges of the alkyl H atoms, as suggested by DFT/natural-bond orbital (NBO) calculations. Three additional electronic properties of the C-alkyl C-H bonds have also been found to correlate with the experimental regioselectivity since, in all cases, the deprotonated C-H bond has the smallest electron density at the bond critical point (bcp), the greatest Laplacian of the electron density at the bcp, and the greatest total energy density ratio at the bcp (computed by using the quantum theory of atoms in molecules, QTAIM). The kinetic decacarbonyl products evolve, under appropriate reaction conditions that depend upon the position of the C-alkylidene group in the heterocyclic ring, towards face-capped nonacarbonyl derivatives (thermodynamic products). Theoretical calculations support the proposal that the selectivity of these deprotonation reactions is primarily determined by the atomic charge of the alkyl H atoms: the higher the charge the easier the deprotonation when the starting complexes contain various C-alkyl groups. On the other hand, although QTAIM results have been obtained here only from theoretical electron densities for the above clusters, comparisons with local and integral topological parameters derived from both experimental and theoretical electron densities for the related triruthenium complex [Ru3(μ-H)2(μ3-MeImCH)(CO)9] (Me2Im = 1,3-dimethylimidazol-2-ylidene) may easily be made.

scholarly journals Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

1997 ◽  
Vol 15 (8) ◽  
pp. 984-998 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Electron Density ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Atomic Oxygen ◽  
Major Ions ◽  
Integral Intensity ◽  
Rate Coefficients ◽  
Vibrationally Excited ◽  
Vibrational Distribution ◽  
Vibrational Levels

Abstract. This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15–17 February 1967. The major enhancements to the IZMIRAN model developed in this study are the inclusion of He+ ions (three major ions: O+, H+, and He+, and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the diffusion of NO+ and O2+ ions and O(1D) and the revised electron cooling rates arising from their collisions with unexcited N2, O2 molecules and N2 molecules at the first vibrational level. The updated model includes the option to use the models of the Boltzmann or non-Boltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the first five vibrational levels of N2 were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels v > 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N2. It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modelled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N2. The effect of using of the O(1D) diffusion results in the decrease of 4–6% in the calculated integral intensity of the northern hemisphere and 7–13% in the calculated integral intensity of the southern hemisphere. It is found that the modelled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coefficients of O+(4S) ions with the vibrationally excited nitrogen molecules and quenching of O+(2D) by atomic oxygen than the modelled intensities of the northern hemisphere.

scholarly journals Deriving the effective scale height in the topside ionosphere based on ionosonde and satellite in situ observations

2014 ◽  
Vol 119 (10) ◽  
pp. 8472-8482 ◽  
Author(s):  
Libo Liu ◽  
He Huang ◽  
Yiding Chen ◽  
Huijun Le ◽  
Baiqi Ning ◽  
...  
Keyword(s):  
Scale Height ◽  
Topside Ionosphere ◽  
In Situ Observations
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