scholarly journals Three‐Dimensional and Trans‐Hemispheric Changes in Ionospheric Electron Density Caused by the Great Solar Eclipse in North America on 21 August 2017

2018 ◽  
Vol 45 (20) ◽  
Author(s):  
Liming He ◽  
Kosuke Heki ◽  
Lixin Wu
Keyword(s):  
North America ◽  
Electron Density ◽  
Solar Eclipse ◽  
Three Dimensional ◽  
Ionospheric Electron Density

scholarly journals Evidence of gravity waves into the atmosphere during the March 2006 total solar eclipse

2007 ◽  
Vol 7 (3) ◽  
pp. 7603-7624 ◽  
Author(s):  
C. S. Zerefos ◽  
E. Gerasopoulos ◽  
I. Tsagouri ◽  
B. Psiloglou ◽  
A. Belehaki ◽  
...  
Keyword(s):  
Electron Density ◽  
Gravity Waves ◽  
Solar Eclipse ◽  
Ozone Layer ◽  
Total Solar Eclipse ◽  
Electron Content ◽  
Supersonic Speed ◽  
Ionospheric Electron Density ◽  
Total Electron ◽  
Phase Spectra

Abstract. This study aims at testing the hypothesis according to which the movement of the moon's shadow sweeping the ozone layer at supersonic speed during a solar eclipse creates gravity waves in the atmosphere. An experiment was conducted to study fluctuations of the ozone layer, the Ionosonde Total Electron Content (ITEC) and the peak electron density height (hmF2) in the ionosphere, as well as at a number of other parameters before, during and after the total solar eclipse. We found the existence of dominant oscillations with periods ranging between 30–40 min in most of the parameters. Cross-spectrum analyses between total ozone and various atmospheric parameters resulted to statistically significant square coherences between the observed oscillations, while the respective phase spectra show that the perturbation originates in the stratosphere and reaches the various layers at speeds around 20 km min−1. Additional evidence supporting these findings was provided by the amplitude of the oscillations in the ionospheric electron density, which increased upwards from 160 to 220 km height.

scholarly journals Numerical simulation of oblique ionospheric heating by powerful radio waves

2018 ◽  
Vol 36 (3) ◽  
pp. 855-866
Author(s):  
Moran Liu ◽  
Chen Zhou ◽  
Xiang Wang ◽  
Bin Bin Ni ◽  
Zhengyu Zhao
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Oblique Incidence ◽  
Three Dimensional ◽  
Radio Waves ◽  
Powerful Radio ◽  
Ionospheric Electron Density ◽  
Ionospheric Heating ◽  
Tracing Algorithm ◽  
Electron Density And Temperature

<p><strong>Abstract.</strong> In this paper, we investigate the ionospheric heating by oblique incidence of powerful high-frequency (HF) radio waves using three-dimensional numerical simulations. The ionospheric electron density and temperature perturbations are examined by incorporating the ionospheric electron transport equations and ray-tracing algorithm. The energy distribution of oblique incidence heating waves in the ionosphere is calculated by the three-dimensional ray-tracing algorithm. The calculation takes into consideration the electric field of heating waves in the caustic region by the plane wave spectral integral method. The simulation results show that the ionospheric electron density and temperature can be disturbed by oblique incidence of powerful radio waves, especially in the caustic region of heating waves. The oblique ionospheric heating with wave incidence parallel and perpendicular to the geomagnetic field in the mid-latitude ionosphere is explored by simulations, results of which indicate that the ionospheric modulation is more effective when the heating wave propagates along the magnetic field line. Ionospheric density and temperature striations in the caustic region due to thermal self-focusing instability are demonstrated, as well as the time evolution of the corresponding fluctuation spectra.</p>

scholarly journals Three-dimensional ionospheric electron density structure of the Weddell Sea Anomaly

2009 ◽  
Vol 114 (A2) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. H. Lin ◽  
J. Y. Liu ◽  
C. Z. Cheng ◽  
C. H. Chen ◽  
C. H. Liu ◽  
...  
Keyword(s):  
Electron Density ◽  
Three Dimensional ◽  
Weddell Sea ◽  
Density Structure ◽  
Ionospheric Electron Density ◽  
Weddell Sea Anomaly

scholarly journals Early VLF perturbations observed in association with elves

2006 ◽  
Vol 24 (8) ◽  
pp. 2179-2189 ◽  
Author(s):  
Á. Mika ◽  
C. Haldoupis ◽  
T. Neubert ◽  
H. T. Su ◽  
R. R. Hsu ◽  
...  
Keyword(s):  
North America ◽  
Electron Density ◽  
Lower Ionosphere ◽  
The United States ◽  
Low Light ◽  
Ionospheric Electron Density ◽  
Large Dataset ◽  
Transient Luminous Events ◽  
Theoretical Predictions ◽  
Great Circle Path

Abstract. VLF remote sensing is used to detect lower-ionospheric electron density changes associated with a certain type of transient luminous events known as elves. Both ground- and satellite-based observations of elves are analysed in relation to VLF data acquired at various receiver sites in Europe, the United States and Antarctica. Ground-based observations were performed during the EuroSprite2003 campaign, when five elves were captured by low-light cameras located in the Pyrenees. Analysis of VLF recordings from Crete shows early VLF perturbations accompanying all of the elves. A large dataset consisting of elves captured by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) payload on Taiwan's FORMOSAT-2 satellite over Europe and North America has also been analysed. Early/fast VLF perturbations were found to accompany some of the elves observed over Europe. However, no VLF perturbations were detected in relation to the elves observed by ISUAL over North America. The present analysis – based on the largest database of optical elve observations used for VLF studies so far – constitutes evidence of processes initiated by the lightning EMP (electromagnetic pulse) causing electron density changes in the lower ionosphere in line with theoretical predictions. It also proves that sub-ionospheric electron density changes associated with elves can intrude to lower heights and thus perturb VLF transmissions. The possibility of VLF detection, however, depends on several factors, e.g., the distance of the elve from the receiver and the transmitter–receiver great circle path (GCP), the altitude of the ionised region and the characteristics of the VLF transmitter, as well as the EMP energy, which occasionally may be sufficient to cause optical emissions but not ionisation.

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