Analysis of the Relationship Between the Solar X-Ray Radiation Intensity and the D-Region Electron Density Using Satellite and Ground-Based Radio Data

2018 ◽  
pp. 669-687
Author(s):  
Aleksandra Nina ◽  
Vladimir M. Čadež ◽  
Jovan Bajčetić ◽  
Srdjan T. Mitrović ◽  
Luka Č. Popović
Keyword(s):  
Electron Density ◽  
Radiation Intensity ◽  
X Ray ◽  
Radio Data ◽  
D Region ◽  
The Relationship

Analysis of the Relationship Between the Solar X-Ray Radiation Intensity and the D-Region Electron Density Using Satellite and Ground-Based Radio Data

Solar Physics ◽  
2018 ◽  
Vol 293 (4) ◽  
Author(s):  
Aleksandra Nina ◽  
Vladimir M. Čadež ◽  
Jovan Bajčetić ◽  
Srdjan T. Mitrović ◽  
Luka Č. Popović
Keyword(s):  
Electron Density ◽  
Radiation Intensity ◽  
X Ray ◽  
Radio Data ◽  
D Region ◽  
The Relationship

scholarly journals Modelling of the Electron Density and Total Electron Content in the Quiet and Solar X-ray Flare Perturbed Ionospheric D-Region Based on Remote Sensing by VLF/LF Signals

2021 ◽  
Vol 14 (1) ◽  
pp. 54
Author(s):  
Aleksandra Nina
Keyword(s):  
Remote Sensing ◽  
Electron Density ◽  
Total Electron Content ◽  
Low Frequency ◽  
Electron Content ◽  
Total Electron ◽  
X Ray ◽  
Causes Of Errors ◽  
D Region ◽  
The Times

Many analyses of the perturbed ionospheric D-region and its influence on the propagation of ground-based and satellite signals are based on data obtained in ionospheric remote sensing by very low/low frequency (VLF/LF) signals. One of the most significant causes of errors in these analyses is the lack of data related to the analysed area and time period preceding the considered perturbation. In this paper, we examine the influence of the estimation of the quiet ionosphere parameters on the determination of the electron density (Ne) and total electron content in the D-region (TECD) during the influence of a solar X-ray flare. We present a new procedure in which parameters describing the quiet ionosphere are calculated based on observations of the analysed area by a VLF/LF signal at the observed time. The developed procedure is an upgrade of the quiet ionospheric D-region (QIonDR) model that allows for a more precise analysis of the D-region intensively perturbed by a solar X-ray flare. The presented procedure is applied to data obtained in ionospheric remote sensing by the DHO signal emitted in Germany and received in Serbia during 30 solar X-ray flares. We give analytical expressions for the dependencies of the analysed parameters on the X-ray flux maximum at the times of the X-ray flux maximum and the most intense D-region perturbation. The results show that the obtained Ne and TECD are larger than in the cases when the usual constant values of the quiet ionosphere parameters are used.

scholarly journals Behaviour of electron content in the ionospheric D-region during solar X-ray flares

2016 ◽  
pp. 11-18 ◽  
Author(s):  
M. Todorovic-Drakul ◽  
V.M. Cadez ◽  
J. Bajcetic ◽  
L.C. Popovic ◽  
D. Blagojevic ◽  
...  
Keyword(s):  
Electron Density ◽  
A Priori ◽  
Low Frequency ◽  
Satellite System ◽  
Electron Content ◽  
High Electron ◽  
Total Electron ◽  
X Ray ◽  
Practical Applications ◽  
D Region

One of the most important parameters in ionospheric plasma research, also having a wide practical application in wireless satellite telecommunications, is the total electron content (TEC) representing the columnal electron number density. The F-region with high electron density provides the biggest contribution to TEC while the relatively weakly ionized plasma of the D-region (60 km { 90 km above Earth's surface) is often considered as a negligible cause of satellite signal disturbances. However, sudden intensive ionization processes, like those induced by solar X-ray flares, can cause relative increases of electron density that are significantly larger in the D-region than in regions at higher altitudes. Therefore, one cannot exclude a priori the D-region from investigations of ionospheric influences on propagation of electromagnetic signals emitted by satellites. We discuss here this problem which has not been sufficiently treated in literature so far. The obtained results are based on data collected from the D-region monitoring by very low frequency radio waves and on vertical TEC calculations from the Global Navigation Satellite System (GNSS) signal analyses, and they show noticeable variations in the D-region's electron content (TECD) during activity of a solar X-ray ?are (it rises by a factor of 136 in the considered case) when TECD contribution to TEC can reach several percent and which cannot be neglected in practical applications like global positioning procedures by satellites.

scholarly journals The estimation of D-region electron densities from riometer data

2003 ◽  
Vol 21 (2) ◽  
pp. 603-613 ◽  
Author(s):  
J. K. Hargreaves ◽  
M. Friedrich
Keyword(s):  
Electron Density ◽  
Time Of Day ◽  
Seasonal Effect ◽  
Auroral Ionosphere ◽  
Radio Waves ◽  
Radio Science ◽  
Direct Measurements ◽  
D Region ◽  
Instruments And Techniques ◽  
The Relationship

Abstract. At high latitude the hard electron precipitation associated with auroral activity is a major source of ionization for the D-region, one consequence being the absorption of radio waves. Direct measurements of the D-region electron density are not readily available, however. This paper investigates the relationship between the electron density at altitudes between 100 and 70 km and the total radio absorption observed with a riometer, with a view to using the latter to predict the former. Tables are given of the median electron density corresponding to 1 dB absorption at 27.6 MHz for each hour of the day, and it is shown that at certain heights the estimates will be accurate to within a factor of 1.6 on 50% of the occasions. A systematic variation with time of day is probably associated with a progressive hardening of the typical electron spectrum during the morning hours. There is also evidence for a seasonal effect possibly due to seasonal variations of the mesosphere.Key words. Ionosphere (auroral ionosphere) – Radio science (ionospheric propagation; instruments and techniques)

Multipole Analysis of the Electron Density in Topaz Using X-ray Diffraction Data

1998 ◽  
Vol 54 (6) ◽  
pp. 774-781 ◽  
Author(s):  
Yu. V. Ivanov ◽  
E. L. Belokoneva ◽  
J. Protas ◽  
N. K. Hansen ◽  
V. G. Tsirelson
Keyword(s):  
Electron Density ◽  
Critical Points ◽  
Diffraction Data ◽  
Closed Shell ◽  
Close Packing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Topological Features ◽  
Type Interaction ◽  
The Relationship

The static deformation electron density, Laplacian of the electron density and critical points in the electron density were analyzed in topaz Al2[SiO4]F2, using high-precision X-ray diffraction data. The electron deformation density, positive values of the Laplacian at (3,−1) bond critical points and the net atomic charges indicate a closed-shell-type interaction in the polyhedra. Anion valence-shell charge depletions are revealed. Maxima in the Laplacian of the electron density are displaced towards the close-packed plane owing to the mutual repulsion of the anion valence shells. The relationship between the topological features of the electron density and the close-packing concept is discussed. Shifts of the critical points from the internuclear vectors reflect the strain in the structure.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

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