scholarly journals Statistical study of ELF/VLF emissions recorded by a low-altitude satellite during seismic events

1994 ◽  
Vol 99 (A12) ◽  
pp. 23339 ◽  
Author(s):  
Michel Parrot
Keyword(s):  
Statistical Study ◽  
Seismic Events ◽  
Low Altitude ◽  
Vlf Emissions

scholarly journals On the use of ELF/VLF emissions triggered by HAARP to simulate PLHR and to study associated MLR events

2022 ◽  
Vol 74 (1) ◽  
Author(s):  
Michel Parrot ◽  
Frantisěk Němec ◽  
Morris B. Cohen ◽  
Mark Gołkowski
Keyword(s):  
Spectral Analysis ◽  
Time Delay ◽  
High Frequency ◽  
Conjugate Point ◽  
Physical Processes ◽  
Line Radiation ◽  
Harmonic Radiation ◽  
Frequency Spacing ◽  
Low Altitude ◽  
Vlf Emissions

AbstractA spectrogram of Power Line Harmonic Radiation (PLHR) consists of a set of lines with frequency spacing corresponding exactly to 50 or 60 Hz. It is distinct from a spectrogram of Magnetospheric Line Radiation (MLR) where the lines are not equidistant and drift in frequency. PLHR and MLR propagate in the ionosphere and the magnetosphere and are recorded by ground experiments and satellites. If the source of PLHR is evident, the origin of the MLR is still under debate and the purpose of this paper is to understand how MLR lines are formed. The ELF waves triggered by High-frequency Active Auroral Research Program (HAARP) in the ionosphere are used to simulate lines (pulses of different lengths and different frequencies). Several receivers are utilized to survey the propagation of these pulses. The resulting waves are simultaneously recorded by ground-based experiments close to HAARP in Alaska, and by the low-altitude satellite DEMETER either above HAARP or its magnetically conjugate point. Six cases are presented which show that 2-hop echoes (pulses going back and forth in the magnetosphere) are very often observed. The pulses emitted by HAARP return in the Northern hemisphere with a time delay. A detailed spectral analysis shows that sidebands can be triggered and create elements with superposed frequency lines which drift in frequency during the propagation. These elements acting like quasi-periodic emissions are subjected to equatorial amplification and can trigger hooks and falling tones. At the end all these known physical processes lead to the formation of the observed MLR by HAARP pulses. It is shown that there is a tendency for the MLR frequencies of occurrence to be around 2 kHz although the exciting waves have been emitted at lower and higher frequencies. Graphical Abstract

scholarly journals ELF and VLF signatures of sprites registered onboard the low altitude satellite DEMETER

2009 ◽  
Vol 27 (6) ◽  
pp. 2599-2605 ◽  
Author(s):  
J. Błęcki ◽  
M. Parrot ◽  
R. Wronowski
Keyword(s):  
Thunderstorm Activity ◽  
Whistler Wave ◽  
Night Time ◽  
Burst Mode ◽  
The Earth ◽  
Low Latitudes ◽  
Wave Forms ◽  
Low Altitude ◽  
Vlf Emissions ◽  
Cg Lightning

Abstract. We report the observation of ELF and VLF signature of sprites recorded on the low altitude satellite DEMETER during thunderstorm activity. At an altitude of ~700 km, waves observed on the E-field spectrograms at mid-to-low latitudes during night time are mainly dominated by up-going 0+ whistlers. During the night of 20 July 2007 two sprites have been observed around 20:10:08 UT from the observatory located on the top of the mountain Śnieżka in Poland (50°44'09" N, 15°44'21" E, 1603 m) and, ELF and VLF data have been recorded by the satellite at about 1200 km from the region of thunderstorm activity. During this event, the DEMETER instruments were switched in the burst mode and it was possible to register the wave forms. It is shown that the two sprites have been triggered by two intense +CG lightning strokes (100 kA) occurring during the same millisecond but not at the same location. Despite the distance DEMETER has recorded at the same time intense and unusual ELF and VLF emissions. It is shown that the whistler wave propagates from the thunderstorm regions in the Earth-ionosphere guide and enters in the ionosphere below the satellite. They last several tens of milliseconds and the intensity of the ELF waveform is close to 1 mV/m. A particularly intense proton whistler is also associated with these emissions.

scholarly journals A statistical study of the low‐altitude ionospheric magnetic fields over the north pole of Venus

2015 ◽  
Vol 120 (8) ◽  
pp. 6218-6229 ◽  
Author(s):  
T. L. Zhang ◽  
W. Baumjohann ◽  
C. T. Russell ◽  
M. N. Villarreal ◽  
J. G. Luhmann ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Statistical Study ◽  
North Pole ◽  
The North ◽  
Low Altitude

scholarly journals Statistical study of ELF/VLF emissions at subauroral latitudes in Athabasca, Canada

2015 ◽  
Vol 120 (10) ◽  
pp. 8455-8469 ◽  
Author(s):  
Claudia Martinez-Calderon ◽  
Kazuo Shiokawa ◽  
Yoshizumi Miyoshi ◽  
Mitsunori Ozaki ◽  
Ian Schofield ◽  
...  
Keyword(s):  
Statistical Study ◽  
Vlf Emissions

scholarly journals <i>Letter to the Editor</i>A statistical study of the location and motion of the HF radar cusp

2002 ◽  
Vol 20 (2) ◽  
pp. 275-280 ◽  
Author(s):  
T. K. Yeoman ◽  
P. G. Hanlon ◽  
K. A. McWilliams
Keyword(s):  
Solar Wind ◽  
Continuous Monitoring ◽  
Large Scale ◽  
Statistical Study ◽  
Hf Radar ◽  
Auroral Ionosphere ◽  
Cusp Region ◽  
The North ◽  
Low Altitude ◽  
Spacecraft Data

Abstract. The large-scale and continuous monitoring of the ionospheric cusp region offered by HF radars has been exploited in order to examine the statistical location and motion of the equatorward edge of the HF radar cusp as a function of the upstream IMF BZ component. Although a considerable scatter is seen, both parameters have a clear influence from the north-south component of the IMF. Excellent agreement is achieved with previous observations from low altitude spacecraft data. The HF radar cusp region is seen to migrate equatorward at a rate of 0.02° min-1 nT-1 under IMF BZ south conditions, but remains static for IMF BZ north. The motion of the cusp implies an addition of magnetic flux of ~ 2 × 104 Wbs-1 nT-1 under IMF BZ south conditions, equivalent to a reconnection voltage of 20 kV nT-1, which is consistent with previous estimates from case studies on both the dayside and nightside regions.Key words. Ionosphere (auroral ionosphere) – Magnetospheric physics (magnetosphere-ionosphere interaction; solar wind magnetosphere interactions)

scholarly journals Modeling ground deformation associated with the destructive earthquakes occurring on Mt. Etna's southeastern flank in 1984

2016 ◽  
Author(s):  
Flavio Cannavò ◽  
Salvatore Gambino ◽  
Biagio Puglisi ◽  
Rosanna Velardita
Keyword(s):  
Fault Plane ◽  
Ground Deformation ◽  
Fault System ◽  
Seismic Events ◽  
Good Accord ◽  
Mt Etna ◽  
High Hazard ◽  
Low Altitude ◽  
Set Up ◽  
Very High

Abstract. The Timpe Fault System is the source of very shallow but destructive earthquakes that affect several towns and villages on the eastern flank of Mt. Etna (Italy). In 1984, several seismic events, and specifically on October 25, caused one fatality, 12 injuries and produced serious damage in the Zafferana and Acireale territories. This seismicity was mainly related to the activity of the Fiandaca Fault, one of the structures belonging to the Timpe Fault System. We inverted ground deformation data collected by a geodimeter trilateration network set up in 1977 at a low altitude along the eastern side of the volcano in order to define the Timpe Fault System faulting mechanisms linked to the seismicity in 1984. We found that in the May 1980–October 1984 period, the Fiandaca Fault was affected by a strike slip and normal dip slip of about 27 and 23cm. This result is in fairly good accord with field observations of the co-seismic ground ruptures along the fault but it's notably large compared to displacements estimated by seismicity, then suggest ing that most of the slip over the fault plane was aseismic. The results once again confirm how seismicity and in particular ground ruptures represent a very high hazard to the several towns and villages situated along the Fiandaca Fault.

scholarly journals Modeling ground deformation associated with the destructive earthquakes occurring on Mt. Etna's southeastern flank in 1984

2016 ◽  
Vol 16 (11) ◽  
pp. 2443-2453 ◽  
Author(s):  
Flavio Cannavò ◽  
Salvatore Gambino ◽  
Biagio Puglisi ◽  
Rosanna Velardita
Keyword(s):  
Fault Plane ◽  
Ground Deformation ◽  
Strike Slip ◽  
Fault System ◽  
Seismic Events ◽  
Mt Etna ◽  
High Hazard ◽  
Low Altitude ◽  
Set Up ◽  
Very High

Abstract. The Timpe Fault System is the source of very shallow but destructive earthquakes that affect several towns and villages on the eastern flank of Mt. Etna (Italy). In 1984, several seismic events, and specifically on 19 and 25 October, caused one fatality, 12 injuries and produced serious damage in the Zafferana and Acireale territories. This seismicity was mainly related to the activity of the Fiandaca Fault, one of the structures belonging to the Timpe Fault System. We inverted ground deformation data collected by a geodimeter trilateration network set up in 1977 at a low altitude along the eastern side of the volcano in order to define the Timpe Fault System faulting mechanisms linked to the seismicity in 1984. We have found that in the period May 1980–October 1984, the Fiandaca Fault was affected by a strike-slip and normal dip-slip of about 20.4 and 12.7 cm respectively. This result is kinematically consistent with field observations of the coseismic ground ruptures along the fault but it is notably large compared to displacements estimated by seismicity, then suggesting that most of the slip over the fault plane was aseismic. The results once again confirm how seismicity and its relation with ground ruptures and creep displacement represent a very high hazard to the several towns and villages situated along the Timpe Fault System.

scholarly journals Similar behaviors of natural ELF/VLF ionospheric emissions and transmitter signals over seismic Adriatic regions

2008 ◽  
Vol 8 (6) ◽  
pp. 1229-1236 ◽  
Author(s):  
M. Y. Boudjada ◽  
K. Schwingenschuh ◽  
H. K. Biernat ◽  
J. J. Berthelier ◽  
J. Blecki ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Geomagnetic Activity ◽  
Seismic Events ◽  
Electromagnetic Emissions ◽  
Vlf Emissions ◽  
Large Earthquakes ◽  
Key Parameter

Abstract. We report on the analysis of ELF/VLF emissions observed by the Instrument Champ Electrique (ICE) experiment onboard the DEMETER micro-satellite. We consider principally selected seismic events reported by Molchanov et al. (2006). These authors studied the VLF signals radiated by ground transmitters and received on board the DEMETER micro-satellite. They revealed a drop of the signals (scattering spot) connected with the occurrence of large earthquakes. In our investigations, we proceed to a spectral analysis of ICE observations with the aim to find if the natural ionospheric VLF/ELF emissions show, or not, a similar ''drop'' in the intensity as it is the case of the VLF transmitter signal. We combine our results with those of Molchanov et al. (2006), and we discuss the origin of such interesting ionospheric features in the frame of the investigation of the pre-seismic electromagnetic emissions. We show that the geomagnetic activity is a key parameter which could disturb the natural VLF ionospheric emissions, and also the transmitter signal. We find that it is not possible to conclude the presence, or not, of a preseismic effect when the Kp-index is higher than one.

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

Sign in / Sign up

Export Citation Format

Share Document