scholarly journals Geomagnetic effect of the Albanian earthquake on November 26, 2019

2020 ◽  
Keyword(s):  
Fourier Transform ◽  
Wavelet Transform ◽  
Geomagnetic Field ◽  
Earth Atmosphere ◽  
Period Range ◽  
Magnetohydrodynamic Waves ◽  
Geomagnetic Effect ◽  
The Earth ◽  
S Period ◽  
Atmospheric Gravity

Background. The main cause of geomagnetic disturbances is known to be space sources, processes acting in the solar wind and in the interplanetary medium, as well as falling large celestial bodies. Earthquakes also give rise to geomagnetic effects. In accordance with the systems paradigm, the Earth–atmosphere–ionosphere–magnetosphere system comprises the single system where direct and reverse, positive and negative coupling take place. The mechanism of the earthquake effect on the magnetic field is poorly understood. A rock cracking, a fluctuating movement of fluids in pores, a corona discharge of the high-voltage static charge, etc., are thought to be the processes that give rise to the geomagnetic effect. In the course of earthquakes, seismic, acoustic, atmospheric gravity, and magnetohydrodynamic waves are generated, which provide for coupling between the subsystems in the Earth–atmosphere–ionosphere–magnetosphere system. Purpose of Work. The paper describes the possible response in the level of the geomagnetic field to the earthquake of 26 November 2019 that took place in Albania. Techniques and Methodology. The measurements were taken with the fluxmeter magnetometer at the V. N. Karazin Kharkiv National University Magnetometer Observatory. It delivers 0.5 – 500 pT sensistivity in the 1–1000 s period range over a quite large frequency band of 0.001 to 1 Hz. To study the quasi-periodic processes in detail, the systems spectral analysis of the temporal dependences of the horizontal (H, D) geomagnetic field components has been employed. It includes the short-time Fourier transform, the Fourier transform in a sliding window with a width adjusted to be equal to a fixed number of harmonic periods, and wavelet transform, simultaneously. The wavelet transform employs the Morlet wavelet as a basis function. Results. The quasi-periodic variations in the level of the geomagnetic field observed to appear with a 6 min lag and to last for 70–80 min could be due to the earthquake. These disturbances could be transferred by the magnetohydrodynamic waves. The quasi-periodic variations that were observed to appear with a 97–106 min lag and to last for about 130–140 min were most likely due to the earthquake. They were transferred by the atmospheric gravity waves with a period of 7–14 min. A relative disturbance in the electron density in the atmospheric gravity wave field was observed to be approximately 5.3%. The results obtained from observations of Albanian and Turkish earthquakes show agreement. Conclusions: The magnetic variations in the 1–1000 s period range that were observed to occur before and during the earthquake have been studied.

scholarly journals GEOMAGNETIC EFFECT OF TURKISH EARTHQUAKE OF JANUARY 24, 2020

2020 ◽  
Vol 25 (4) ◽  
pp. 276-289
Author(s):  
Y. Luo ◽  
◽  
L. F. Chernogor ◽  
K. P. Garmash ◽  
◽  
...  
Keyword(s):  
Fourier Transform ◽  
Flash Memory ◽  
Geomagnetic Field ◽  
Temporal Variations ◽  
Fixed Number ◽  
Mhd Waves ◽  
Geomagnetic Disturbances ◽  
Period Range ◽  
Geomagnetic Effect ◽  
S Period

Purpose:The main cause of geomagnetic disturbances are cosmic sources, processes acting in the solar wind and in the interplanetary medium, as well as large celestial bodies entering the terrestrial atmosphere. Earthquakes (EQs) also act to produce geomagnetic effects. In accordance with the systems paradigm, the Earth–atmosphere–ionosphere–magnetosphere system (EAIMS) constitute a unified system, where positive and negative couplings among the subsystems, as well as feedbacks and precondition among the system components take place. The mechanisms for the action of EQs and processes acting in the lithosphere on the geomagnetic field are poorly understood. It is considered that the EQ action is caused by cracking of rocks, fluctuating motion in the pore fluid, static electricity discharges, etc. In the course of EQs, the seismic, acoustic, atmospheric gravity waves (AGWs), and magnetohydrodynamic (MHD) waves are generated. The purpose of this paper is to describe the magnetic effects of the EQ, which took place in Turkey on 24 January 2020. Design/methodology/approach: The measurements are taken with the fluxmeter magnetometer delivering 0.5-500 pT sensitivity in the 1-1000 s period range, respectively, and in a wide enough studied frequency band within 0.001 to 1 Hz. The EM-II magnetometer with the embedded microcontroller digitizes the magnetometer signals and performs preliminary filtering over 0.5 s time intervals, while the external flash memory is used to store the filtered out magnetometer signals and the times of their acquisition. To investigate quasi-periodic processes in detail, the temporal variations in the level of the H and D components of the geomagnetic field were applied to the systems spectral analysis, which makes use of the short-time Fourier transform, the wavelet transform using the Morlet wavelet as a basis function, and the Fourier transform in a sliding window with a width adjusted to be equal to a fixed number of harmonic periods. Findings: The train of oscillations in the level of the D component observed 25.5 h before the EQ on 23 January 2020 is supposed to be associated with the magnetic precursor. The bidirectional pulse in the H component observed on 24 January 2020 could be due to the piston action of the EQ, which had generated an MHD pulse. The quasi-periodic variations in the level of the H and D components of the geomagnetic field, which followed 75 min after the EQ, were caused by a magnetic disturbance produced by the traveling ionospheric disturbances due to the AGWs launched by the EQ. The magnetic effect amplitude was estimated to be close to 0.3 nT, and the quasi-period to be 700-900 s. The amplitude of the disturbances in the electron density in the AGW field was estimated to be about 8 % and the period of 700-900 s. Damping oscillations in both components of the magnetic field were detected to occur with a period of approximately 120 s. This effect is supposed to be due to the shock wave generated in the atmosphere in the course of the EQ. Conclusions: The magnetic variations associated with the EQ and occurring before and during the EQ have been studied in the 1-1000 s period range. Key words: earthquake, fluxmeter magnetometer, quasi-periodic disturbance, seismic wave, acoustic-gravity wave, MHD pulse

scholarly journals Geomagnetic field fluctuations during Chuysk earthquakes on September – October, 2003

2019 ◽  
Keyword(s):  
Geomagnetic Field ◽  
Seismic Waves ◽  
Fluxgate Magnetometer ◽  
Period Range ◽  
National University ◽  
Field Fluctuations ◽  
Band Pass ◽  
S Period ◽  
Negative Links ◽  
Atmospheric Gravity

Urgency. There is an urgent need to study the interactions in the Earth – atmosphere – ionosphere – magnetosphere system. To identify direct and reverse, positive and negative links among the subsystems, sources producing massive releases of energy are commonly used. In this paper, the Chuysk earthquakes whose Richter magnitudes vary from 4.5 to 7.3 are considered as such a source. The aim of this paper is to present the findings of studying a possible response of the geomagnetic field in the 1 – 1000-s period variations to the preparation and occurrence of the Chuysk earthquakes of September – October 2003. Techniques and Methodology. The measurements were carried out using the fluxgate magnetometer located at the V. N. Karazin Kharkiv National University Geomagnetic Observatory. The sensitivity of the magnetometer is 0.5 – 500 pT in the 1 – 1000-s period range. The data processing was performed in three stages. First, the signals from the magnetometer, recorded in relative magnetometer units, were converted into absolute units, taking into account the magnetometer frequency response. Second, band-pass filtering was performed in the 1 – 10-s, 10 – 100-s, and 100 – 1000-s period ranges. Third, a system spectral analysis of time variations in the H- and D-components of the geomagnetic field was undertaken. Results: Forty three minutes and one-hundred-sixty-three minutes prior to the earthquake of Richter magnitude 7.3, quasi-periodic variations of the geomagnetic field were observed. These variations may be an earthquake magnetic precursor, and the mechanism of such a precursor has been described. After the earthquakes of Richter magnitudes 7.3, 6.7, and 7.0, quasi-periodic variations of the geomagnetic field were detected. Such variations may be caused by the perturbation transfer due to seismic waves with speeds in the 1.9 – 5.3-km/s range and owing to atmospheric gravity waves traveling with speeds in the 320- to 670-m/s range. On October 1, 2003, the changes in the character of the variations occurred with time delays of 0 to 5 min. If these variations were associated with earthquakes, the magnetohydrodynamic waves could act as an agent that transferred the disturbances. Conclusions: The moderate earthquakes are determined to be able to cause geomagnetic field disturbances recordable at distances of about 3,500 km from the epicenter.

scholarly journals Dynamic processes in the magnetic field and in the ionosphere during the 30 August–2 September, 2019 geospace storm

2020 ◽  
Author(s):  
Yiyang Luo ◽  
Leonid Chernogor ◽  
Kostiantyn Garmash ◽  
Qiang Guo ◽  
Victor Rozumenko ◽  
...  
Keyword(s):  
Electron Density ◽  
Geomagnetic Field ◽  
Unique Feature ◽  
Recovery Phase ◽  
Radiowave Propagation ◽  
Radio Waves ◽  
Ionospheric Storm ◽  
Period Range ◽  
Multiple Method ◽  
S Period

Abstract. Back at the end of the last century, L. F. Chernogor validated the concept that geospace storms are comprised of synergistically coupled magnetic storms, ionospheric storms, atmospheric storms, and storms in the electric field originating in the magnetosphere, the ionosphere and the atmosphere (i.e., electric storms). Their joint studies require the employment of multiple-method approach to the Sun–interplanetary medium–magnetosphere–ionosphere–atmosphere – Earth system. This study provides general analysis of the 30 August–2 September, 2019 geospace storm, the analysis of disturbances in the geomagnetic field and in the ionosphere, as well as the influence of the ionospheric storm on the characteristics of HF radio waves over the People's Republic of China. A unique feature of the geospace storm under study is its duration, of up to four days. The main results of the study are as follows. The energy and power of the geospace storm have been estimated to be 1.5 PJ and 15 GW, and thus this storm is weak. The energy and power of the magnetic storm have been estimated to be 1.5 PJ and 9 GW, i.e., this storm is moderate, and a unique feature of this storm is the duration of the main phase, of up to two days. The recovery phase also was lengthy, no less than two days. On 31 August 2019 and on 1 September 2019, the variations in the H and D components attained 60–70 nT, while the Z-component variations did not exceed 20 nT. On 31 August 2019 and on 1 September 2019, the level of fluctuations in the geomagnetic field in the 100–1000 s period range increased from from 0.2–0.3 nT to 2–4 nT, while the energy of the oscillations showed a maximum in the 300–400 s to 700–900 s period range. The geospace storm was accompanied by a moderate to strong negative ionospheric storm. During 31 August 2019 and 1 September 2019, the electron density in the ionospheric F region reduced by a factor of 1.4 to 2.4 times as compared to the values on the reference day. The geospace storm gave rise to appreciable disturbances also in the ionospheric E region, as well as in the Es layer. In the course of the ionospheric storm, the altitude of reflection of radiowaves could sharply increase from about 150 km to approximately 300–310 km. The geospace storm was accompanied by the generation of atmospheric gravity waves modulating the ionospheric electron density. For the about 30 min period oscillation, the amplitude of the electron density disturbances could attain about 40 %, while it did not exceed 6 % for the about 15 min period. The results obtained have made a contribution to understanding of the geospace storm physics, to developing theoretical and empirical models of geospace storms, to the acquisition of detailed understanding of the adverse effects that geospace storms have on radiowave propagation and to applying that knowledge to effective forecasting these adverse influences.

scholarly journals Dynamic processes in the magnetic field and in the ionosphere during the 30 August–2 September 2019 geospace storm: influence on high frequency radio wave characteristics

2021 ◽  
Vol 39 (4) ◽  
pp. 657-685
Author(s):  
Yiyang Luo ◽  
Leonid Chernogor ◽  
Kostiantyn Garmash ◽  
Qiang Guo ◽  
Victor Rozumenko ◽  
...  
Keyword(s):  
Radio Wave ◽  
Electron Density ◽  
High Frequency ◽  
Geomagnetic Field ◽  
Recovery Phase ◽  
Radio Waves ◽  
Ionospheric Storm ◽  
Period Range ◽  
Multiple Method ◽  
S Period

Abstract. The concept that geospace storms are comprised of synergistically coupled magnetic storms, ionospheric storms, atmospheric storms, and storms in the electric field originating in the magnetosphere, the ionosphere, and the atmosphere (i.e., electrical storms) was validated a few decades ago. Geospace storm studies require the employment of multiple-method approaches to the Sun–interplanetary medium–magnetosphere–ionosphere–atmosphere–Earth system. This study provides general analysis of the 30 August–2 September 2019 geospace storm, the analysis of disturbances in the geomagnetic field and in the ionosphere, as well as the influence of the ionospheric storm on the characteristics of high frequency (HF) radio waves over the People's Republic of China. The main results of the study are as follows. The energy and power of the geospace storm have been estimated to be 1.5×1015 J and 1.5×1010 W, and thus, this storm is weak. The energy and power of the magnetic storm have been estimated to be 1.5×1015 J and 9×109 W, i.e., this storm is moderate, and a characteristic feature of this storm is the duration of the main phase of up to 2 d. The recovery phase also was lengthy and was no less than 2 d. On 31 August and 1 September 2019, the variations in the H and D components attained 60–70 nT, while the Z-component variations did not exceed 20 nT. On 31 August and 1 September 2019, the level of fluctuations in the geomagnetic field in the 100–1000 s period range increased from 0.2–0.3 to 2–4 nT, while the energy of the oscillations showed a maximum in the 300–400 to 700–900 s period range. During the geospace storm, a moderately to strongly negative ionospheric storm manifested itself by the reduction in the ionospheric F-region electron density by a factor of 1.4 to 2.4 times on 31 August and 1 September 2019, compared to the its values on the reference day. Appreciable disturbances were also observed to occur in the ionospheric E region and possibly in the Es layer. In the course of the ionospheric storm, the altitude of reflection of radio waves could sharply increase from ∼150 to ∼300–310 km. The atmospheric gravity waves generated within the geospace storm modulated the ionospheric electron density; for the ∼30 min period oscillation, the amplitude of the electron density disturbances could attain ∼40 %, while it did not exceed 6 % for the ∼15 min period. At the same time, the height of reflection of the radio waves varied quasi-periodically with a 20–30 km amplitude. The results obtained have made a contribution to the understanding of the geospace storm physics, to developing theoretical and empirical models of geospace storms, to the acquisition of detailed understanding of the adverse effects that geospace storms have on radio wave propagation, and to applying that knowledge to effective forecasting of these adverse influences.

scholarly journals Observation evidences of atmospheric Gravity Waves induced by seismic activity from analysis of subionospheric LF signal spectra

2007 ◽  
Vol 7 (5) ◽  
pp. 625-628 ◽  
Author(s):  
A. Rozhnoi ◽  
M. Solovieva ◽  
O. Molchanov ◽  
P.-F. Biagi ◽  
M. Hayakawa
Keyword(s):  
Gravity Waves ◽  
Fresnel Zone ◽  
Signal Amplitude ◽  
Magnetic Storms ◽  
Frequency Range ◽  
Atmospheric Gravity Waves ◽  
Period Range ◽  
Before And After ◽  
Atmospheric Gravity ◽  
Large Earthquakes

Abstract. We analyze variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms. After 20 s averaging, the frequency range of the analysis is 0.28–15 mHz that corresponds to the period range from 1 to 60 min. Changes in spectra of the LF signal perturbations are found several days before and after three large earthquakes, which happened in November 2004 (M=7.1), August 2005 (M=7.2) and November 2006 (M=8.2) inside the Fresnel zone of the Japan-Kamchatka wavepath. Comparing the perturbed and background spectra we have found the evident increase in spectral range 10–25 min that is in the compliance with theoretical estimations on lithosphere-ionosphere coupling by the Atmospheric Gravity Waves (T>6 min). Similar changes are not found for the periods of magnetic storms.

scholarly journals Introduction to the Special Issue “Radiative Transfer in the Earth Atmosphere”

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 479
Author(s):  
Irina Sokolik
Keyword(s):  
Radiative Transfer ◽  
Earth Atmosphere ◽  
Special Issue ◽  
The Earth ◽  
Radiative Impact ◽  
Different Types ◽  
Recent Developments

This Special Issue aims at addressing the recent developments towards improving our understanding of the diverse radiative impact of different types of aerosols and clouds [...]

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