Pub Date : 2021-12-31DOI: 10.47774/phag.02.02.2021-3
M. Lyashenko, V. Kolodyazhnyi
Background. Dynamic processes in plasma play a significant role in the formation of the spatial structure of the ionosphere at altitudes above the main ionization maximum. During geomagnetic disturbances, the dynamic mode of the ionospheric plasma noticeably changes, and these changes in the variations in the physical process parameters directly affect the spatial-temporal distribution of the main parameters of the ionosphere. One of the mechanisms affecting the behavior of the dynamic process parameters in the ionosphere is the penetration of electric fields of magnetospheric origin into the mid-latitude ionosphere during magnetic storms. The effects of the electric field, which are practically absent in quiet conditions, during geomagnetic storms lead to an additional transfer of charged particles due to electromagnetic drift. Accounting for these effects in variations in the dynamic process parameters and, as a consequence, in variations in the parameters of the ionosphere, is necessary for a more adequate prediction of the behavior of geospace parameters during geomagnetic disturbances. Development of ionospheric models of the disturbed ionosphere for solving applied problems in the field of radio communication, radio navigation and uninterrupted operation of telecommunication systems for various purposes. The aim of this work is to estimate the magnitude of the zonal component of the electric field in the ionosphere over Kharkiv during a weak magnetic storm on September 25, 2016, as well as to calculate the neutral wind velocity taking into account plasma transport in crossed electric and magnetic fields. Materials and methods. To calculate the parameters of dynamic processes in the ionosphere, the experimental data of the Kharkiv incoherent scatter radar were used. Results. The value of the zonal component of the electric field Ey was calculated during a weak magnetic storm on September 25, 2016. The maximum value of Ey took place around 23:00 EEST on September 25, 2016 and was equal to 5.9 mV/m. Calculated values of particle transfer velocity due to electromagnetic drift vEB during the September 25, 2016 magnetic storm are obtained. Variations in vEB correlate with variations in Ey, and the maximum velocity was –52 m/s. The calculation results showed that during weak magnetic storms (Kp = 4) it is necessary to take into account the plasma transfer due to electromagnetic drift. The contribution of the velocity vEB to the total velocity of charged particle transfer is significant. The neutral (thermospheric) wind velocity vnx is calculated without and taking into account the particle transfer velocity in crossed electric and magnetic fields. Conclusions. As shown by the results of the comparative analysis, taking into account the influence of the electric field made it possible to refine the values of the velocities vnx during a magnetic storm, which, in turn, makes it possible to explain the behavior of the main parameters of the F2 lay
{"title":"Estimation of the Electric Field Zonal Component Value and Particle Transfer Velocity Due To Electromagnetic Drift in the Ionosphere during Magnetic Storm on September 25, 2016 over Kharkiv","authors":"M. Lyashenko, V. Kolodyazhnyi","doi":"10.47774/phag.02.02.2021-3","DOIUrl":"https://doi.org/10.47774/phag.02.02.2021-3","url":null,"abstract":"Background. Dynamic processes in plasma play a significant role in the formation of the spatial structure of the ionosphere at altitudes above the main ionization maximum. During geomagnetic disturbances, the dynamic mode of the ionospheric plasma noticeably changes, and these changes in the variations in the physical process parameters directly affect the spatial-temporal distribution of the main parameters of the ionosphere. One of the mechanisms affecting the behavior of the dynamic process parameters in the ionosphere is the penetration of electric fields of magnetospheric origin into the mid-latitude ionosphere during magnetic storms. The effects of the electric field, which are practically absent in quiet conditions, during geomagnetic storms lead to an additional transfer of charged particles due to electromagnetic drift. Accounting for these effects in variations in the dynamic process parameters and, as a consequence, in variations in the parameters of the ionosphere, is necessary for a more adequate prediction of the behavior of geospace parameters during geomagnetic disturbances. Development of ionospheric models of the disturbed ionosphere for solving applied problems in the field of radio communication, radio navigation and uninterrupted operation of telecommunication systems for various purposes.\u0000\u0000The aim of this work is to estimate the magnitude of the zonal component of the electric field in the ionosphere over Kharkiv during a weak magnetic storm on September 25, 2016, as well as to calculate the neutral wind velocity taking into account plasma transport in crossed electric and magnetic fields.\u0000\u0000Materials and methods. To calculate the parameters of dynamic processes in the ionosphere, the experimental data of the Kharkiv incoherent scatter radar were used.\u0000\u0000Results. The value of the zonal component of the electric field Ey was calculated during a weak magnetic storm on September 25, 2016. The maximum value of Ey took place around 23:00 EEST on September 25, 2016 and was equal to 5.9 mV/m. Calculated values of particle transfer velocity due to electromagnetic drift vEB during the September 25, 2016 magnetic storm are obtained. Variations in vEB correlate with variations in Ey, and the maximum velocity was –52 m/s. The calculation results showed that during weak magnetic storms (Kp = 4) it is necessary to take into account the plasma transfer due to electromagnetic drift. The contribution of the velocity vEB to the total velocity of charged particle transfer is significant. The neutral (thermospheric) wind velocity vnx is calculated without and taking into account the particle transfer velocity in crossed electric and magnetic fields.\u0000\u0000Conclusions. As shown by the results of the comparative analysis, taking into account the influence of the electric field made it possible to refine the values of the velocities vnx during a magnetic storm, which, in turn, makes it possible to explain the behavior of the main parameters of the F2 lay","PeriodicalId":34483,"journal":{"name":"Fizika atmosferi ta geokosmosu","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43314559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.47774/phag.02.02.2021-2
I. Zakharov
Background. In recent decades, new results on the influence of powerful meteorological processes on the ionosphere have been obtained. At the same time, the possibility of tropospheric-ionospheric interaction outside the disturbed periods remains unclear, which is important for assessing the energy of the phenomenon and for modeling the dynamic processes of the lower and upper atmosphere as a single self-organizing system. In this work, for the first time, the possibility of the influence of the lower atmosphere on the median values of ionospheric parameters against the background of processes caused by space weather is considered. Objectives of the work is to search and analyze long-term longitudinal effects of the mid-latitude ionosphere in the winter season and their possible connection with processes in the lower atmosphere. Materials and methods. The studies were carried out using daily data for the winter seasons of 2012 – 2018 at a latitude of 40 °N on the basis of maps of ionospheric total electron content obtained using the global network of navigation satellites and global maps of pressure and temperature of the surface atmosphere. Data on space weather and the magnetosphere (indices of solar and geomagnetic activity) were also used. Statistical analysis methods were used. Results. Significant (up to 40 % of the average level) permanently existing longitudinal extrema of the ionospheric total electron content have been established, which correlate with changes in the pressure and temperature of the surface atmosphere. The relationship is characterized by significant correlation coefficients from +0.34 to +0.48 in the seasons under consideration. The total electron content maxima fall on longitudes with maximum surface atmospheric pressure gradients. The influence of space weather through the mismatch between the geographic and geomagnetic coordinate systems also leads to longitudinal effects in the ionosphere, but without the formation of local extrema. Conclusions. The results obtained indicate the possibility of long-term or continuous interaction of the lower atmosphere with the higher layers of the atmosphere and the ionosphere. Taking into account the constant nature of the longitudinal features of the total electron content, an assumption was made about the important role of stationary planetary waves in the implementation of atmospheric-ionospheric interactions.
{"title":"Influence of Lower Atmosphere on Long-Term Total Electron Content Variations of Mid-latitude Ionosphere in Winter Seasons 2012 – 2018","authors":"I. Zakharov","doi":"10.47774/phag.02.02.2021-2","DOIUrl":"https://doi.org/10.47774/phag.02.02.2021-2","url":null,"abstract":"Background. In recent decades, new results on the influence of powerful meteorological processes on the ionosphere have been obtained. At the same time, the possibility of tropospheric-ionospheric interaction outside the disturbed periods remains unclear, which is important for assessing the energy of the phenomenon and for modeling the dynamic processes of the lower and upper atmosphere as a single self-organizing system. In this work, for the first time, the possibility of the influence of the lower atmosphere on the median values of ionospheric parameters against the background of processes caused by space weather is considered.\u0000\u0000Objectives of the work is to search and analyze long-term longitudinal effects of the mid-latitude ionosphere in the winter season and their possible connection with processes in the lower atmosphere.\u0000\u0000Materials and methods. The studies were carried out using daily data for the winter seasons of 2012 – 2018 at a latitude of 40 °N on the basis of maps of ionospheric total electron content obtained using the global network of navigation satellites and global maps of pressure and temperature of the surface atmosphere. Data on space weather and the magnetosphere (indices of solar and geomagnetic activity) were also used. Statistical analysis methods were used.\u0000\u0000Results. Significant (up to 40 % of the average level) permanently existing longitudinal extrema of the ionospheric total electron content have been established, which correlate with changes in the pressure and temperature of the surface atmosphere. The relationship is characterized by significant correlation coefficients from +0.34 to +0.48 in the seasons under consideration. The total electron content maxima fall on longitudes with maximum surface atmospheric pressure gradients. The influence of space weather through the mismatch between the geographic and geomagnetic coordinate systems also leads to longitudinal effects in the ionosphere, but without the formation of local extrema.\u0000\u0000Conclusions. The results obtained indicate the possibility of long-term or continuous interaction of the lower atmosphere with the higher layers of the atmosphere and the ionosphere. Taking into account the constant nature of the longitudinal features of the total electron content, an assumption was made about the important role of stationary planetary waves in the implementation of atmospheric-ionospheric interactions.","PeriodicalId":34483,"journal":{"name":"Fizika atmosferi ta geokosmosu","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47671022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.47774/phag.02.02.2021-1
Oleksandr Brezgunov, Sergey Brezgunov
The idea of improving the methods of processing the received radio signals under intense noise used in radio communication and radar systems is considered. A method for receiving radio pulses using their autocorrelation functions ACF is presented. It makes it possible to determine the presence of a periodic signal in a mixture with intense noise, the value of the carrier frequency of the radio pulse and the value of its average amplitude. However, to calculate the ACF, many multiplication operations are required, which take much longer than addition operations. It is proposed to use a function similar to the ACF, which by its properties makes it possible to determine the carrier frequency of the radio pulse, the value of its average amplitude, the value of the average amplitude of the noise that distorts the radio pulse. When calculating such a function, the multiplication operations that are in the ACF expression are replaced by the addition operations. However, to obtain such a function, it is not necessary to have signals with a time shift, as in calculating the ACF, but the exact value of the sum of their amplitudes. In this work, this function is called the alternative autocorrelation function AAKF. Shown are the ACF and AAKF images for a radio pulse of long duration, for additive noise, and also for a mixture of a radio pulse and noise. The main properties of the AAKF mixture of a radio pulse and noise relative to the ACF are considered. The forms of AAKF and ACF are different, but their periods are the same. It is shown that a device that allows one to obtain the exact value of signal amplitudes can be constructed according to the scheme of a two-channel "ideal" peak amplitude detector, which is proposed in this work. The possibility of obtaining a periodic AAKF of a mixture of a radio pulse and noise is very briefly considered. It is shown that with the help of periodic AAKF further processing of radio pulses can be done, with additional suppression of the influence of noise. In this case, the shape of the envelope of the periodic AAKF is rectangular. This approach is better suited for processing rectangular radio bursts. To solve this problem, you can use bandpass filtering of periodic AAKF and the operation of inverting the results of calculations. It is emphasized that the considered method for calculating the parameters of the useful signal and noise can be implemented on a modern element base when transferring a signal to an intermediate frequency, but this requires a large time delay in obtaining the results.
{"title":"Alternative Autocorrelation Function for Radio Pulse Processing","authors":"Oleksandr Brezgunov, Sergey Brezgunov","doi":"10.47774/phag.02.02.2021-1","DOIUrl":"https://doi.org/10.47774/phag.02.02.2021-1","url":null,"abstract":"The idea of improving the methods of processing the received radio signals under intense noise used in radio communication and radar systems is considered. A method for receiving radio pulses using their autocorrelation functions ACF is presented. It makes it possible to determine the presence of a periodic signal in a mixture with intense noise, the value of the carrier frequency of the radio pulse and the value of its average amplitude. However, to calculate the ACF, many multiplication operations are required, which take much longer than addition operations. It is proposed to use a function similar to the ACF, which by its properties makes it possible to determine the carrier frequency of the radio pulse, the value of its average amplitude, the value of the average amplitude of the noise that distorts the radio pulse. When calculating such a function, the multiplication operations that are in the ACF expression are replaced by the addition operations. However, to obtain such a function, it is not necessary to have signals with a time shift, as in calculating the ACF, but the exact value of the sum of their amplitudes. In this work, this function is called the alternative autocorrelation function AAKF. Shown are the ACF and AAKF images for a radio pulse of long duration, for additive noise, and also for a mixture of a radio pulse and noise. The main properties of the AAKF mixture of a radio pulse and noise relative to the ACF are considered. The forms of AAKF and ACF are different, but their periods are the same. It is shown that a device that allows one to obtain the exact value of signal amplitudes can be constructed according to the scheme of a two-channel \"ideal\" peak amplitude detector, which is proposed in this work. The possibility of obtaining a periodic AAKF of a mixture of a radio pulse and noise is very briefly considered. It is shown that with the help of periodic AAKF further processing of radio pulses can be done, with additional suppression of the influence of noise. In this case, the shape of the envelope of the periodic AAKF is rectangular. This approach is better suited for processing rectangular radio bursts. To solve this problem, you can use bandpass filtering of periodic AAKF and the operation of inverting the results of calculations. It is emphasized that the considered method for calculating the parameters of the useful signal and noise can be implemented on a modern element base when transferring a signal to an intermediate frequency, but this requires a large time delay in obtaining the results.","PeriodicalId":34483,"journal":{"name":"Fizika atmosferi ta geokosmosu","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41579929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-16DOI: 10.47774/phag.02.01.2021-4
T. Zhivolup, S. Panasenko, O. Koloskov, V. Lisachenko
According to the results of joint ionosonde studies of variations in the ionospheric F2 layer critical frequency over Kharkiv and Tromsø during low solar activity for fall equinox on September 22 – 24, 2020, the features of foF2 variations in middle and low latitudes were investigated for magnetically quiet and magnetically disturbed conditions. On the magnetically quiet day of September 22, 2020, the foF2 values over Kharkiv were found to exceed the foF2 values over Tromsø for the entire time interval of joint observations 02:45 - 16:45 UT. Both over Tromsø and over Kharkiv, a rapid increase in foF2 to its local maximum value was observed after the sunrise. Quasi-periodic variations in foF2 were revealed at high latitudes, which had lower amplitude compared to variations in foF2 over Kharkiv. Over both measuring sites, a pre-sunset local maximum in foF2 was observed. During magnetically disturbed conditions over Tromsø and Kharkiv, quasi-periodic fluctuations in foF2 were observed after the sunrise. Oscillations over Tromsø had lower amplitude than over Kharkiv, and were almost completely suppressed after the onset of a strong magnetic disturbance at high latitudes on September 23, 2020. The foF2 values over Tromsø exceeded its values over Kharkiv in a time interval of 10:45 – 12:15 UT. Comparison of the time variation of foF2 over Tromso on a magnetically quiet day, September 22, 2020, and on a magnetically disturbed day, September 23, 2020, showed that the foF2 value for September 23, 2020 from 10:15 to 15:00 UT exceeded the foF2 values for the same period on September 22, 2020. Comparison of the temporal variations in foF2 over Kharkiv on a magnetically quiet day, September 22, 2020, and on a magnetically disturbed day, September 24, 2020, showed that the foF2 value for September 24, 2020 exceeded its value for September 22, 2020 from 03:00 to 04:45 UT and from 07:00 to 13:00 UT. Magnetic disturbances were found to cause a rapid increase in foF2 values both over Kharkiv and Tromsø, which exceeded foF2 values under magnetically quiet conditions, and also led to a significant increase in the relative amplitudes of traveling ionospheric disturbances over Kharkiv.
{"title":"Joint Ionosonde Studies of F2 Layer Critical Frequency Variations in the Ionosphere Over Kharkiv and Tromsø During Fall Equinox in Quiet and Disturbed Conditions","authors":"T. Zhivolup, S. Panasenko, O. Koloskov, V. Lisachenko","doi":"10.47774/phag.02.01.2021-4","DOIUrl":"https://doi.org/10.47774/phag.02.01.2021-4","url":null,"abstract":"According to the results of joint ionosonde studies of variations in the ionospheric F2 layer critical frequency over Kharkiv and Tromsø during low solar activity for fall equinox on September 22 – 24, 2020, the features of foF2 variations in middle and low latitudes were investigated for magnetically quiet and magnetically disturbed conditions. On the magnetically quiet day of September 22, 2020, the foF2 values over Kharkiv were found to exceed the foF2 values over Tromsø for the entire time interval of joint observations 02:45 - 16:45 UT. Both over Tromsø and over Kharkiv, a rapid increase in foF2 to its local maximum value was observed after the sunrise. Quasi-periodic variations in foF2 were revealed at high latitudes, which had lower amplitude compared to variations in foF2 over Kharkiv. Over both measuring sites, a pre-sunset local maximum in foF2 was observed. During magnetically disturbed conditions over Tromsø and Kharkiv, quasi-periodic fluctuations in foF2 were observed after the sunrise. Oscillations over Tromsø had lower amplitude than over Kharkiv, and were almost completely suppressed after the onset of a strong magnetic disturbance at high latitudes on September 23, 2020. The foF2 values over Tromsø exceeded its values over Kharkiv in a time interval of 10:45 – 12:15 UT. Comparison of the time variation of foF2 over Tromso on a magnetically quiet day, September 22, 2020, and on a magnetically disturbed day, September 23, 2020, showed that the foF2 value for September 23, 2020 from 10:15 to 15:00 UT exceeded the foF2 values for the same period on September 22, 2020. Comparison of the temporal variations in foF2 over Kharkiv on a magnetically quiet day, September 22, 2020, and on a magnetically disturbed day, September 24, 2020, showed that the foF2 value for September 24, 2020 exceeded its value for September 22, 2020 from 03:00 to 04:45 UT and from 07:00 to 13:00 UT. Magnetic disturbances were found to cause a rapid increase in foF2 values both over Kharkiv and Tromsø, which exceeded foF2 values under magnetically quiet conditions, and also led to a significant increase in the relative amplitudes of traveling ionospheric disturbances over Kharkiv.","PeriodicalId":34483,"journal":{"name":"Fizika atmosferi ta geokosmosu","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41687254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-31DOI: 10.47774/phag.01.01.2020-5
V. Pulyaev, L. Emelyanov, A. Miroshnikov
Methodological features of registration and separation of coherent radar reflections from space objects and elements of “space debris” operating in orbit are considered. Registration occurs against the background of signals that are scattering of the probe radio wave on particles of the ionospheric plasma. Methods of how to obtain information about the components of the velocity vector of these objects in near-earth space with the help of specialized ground-based radar facilities are analyzed. Their disadvantage is the unreliable control of weak reflections from the elements of “space debris” if they have a small (up to centimeters) scattering cross section. The authors proposed to use the existing high-energy radar installations. Using the signals after the analog-to-digital conversion generated in quadrature, it is proposed to calculate the phase characteristics of the coherent reflection. The radial velocity of the objects along the radar beam is calculated by isolating the Doppler phase difference and statistically averaging these values in the time of reflection. Similarly, by analyzing the time spent in the radar beam, the velocity component associated with the horizontal movement along the Earth’s surface is calculated. Real examples are given, when in one of the observation sessions on the reflection of a signal from a space object, the phase shift in each of its periods is calculated, and then, using the formula, proposed by the authors, the vertical component of the velocity of this object is calculated. Analyzing the observation time of this object in the beam of the transmitter antenna, an example of the calculation and the component of its horizontal velocity is shown. The block diagram of the radar used to calculate the specified parameters of the movement of space objects is presented. The developed approach is an effective solution of many practical problems in those industries that ensure the operation of spacecraft, ensuring the safety of space stations, optimal placement of objects in orbit, etc. Keywords: Incoherent scatter radar, space objects, coherent reflection, signal phase characteristics, radial and horizontal speed
{"title":"The Speed of Movement of Artificial Space Objects and Its Determination Using Incoherent Scatter Radar","authors":"V. Pulyaev, L. Emelyanov, A. Miroshnikov","doi":"10.47774/phag.01.01.2020-5","DOIUrl":"https://doi.org/10.47774/phag.01.01.2020-5","url":null,"abstract":"Methodological features of registration and separation of coherent radar reflections from space objects and elements of “space debris” operating in orbit are considered. Registration occurs against the background of signals that are scattering of the probe radio wave on particles of the ionospheric plasma. Methods of how to obtain information about the components of the velocity vector of these objects in near-earth space with the help of specialized ground-based radar facilities are analyzed. Their disadvantage is the unreliable control of weak reflections from the elements of “space debris” if they have a small (up to centimeters) scattering cross section. The authors proposed to use the existing high-energy radar installations. Using the signals after the analog-to-digital conversion generated in quadrature, it is proposed to calculate the phase characteristics of the coherent reflection. The radial velocity of the objects along the radar beam is calculated by isolating the Doppler phase difference and statistically averaging these values in the time of reflection. Similarly, by analyzing the time spent in the radar beam, the velocity component associated with the horizontal movement along the Earth’s surface is calculated. Real examples are given, when in one of the observation sessions on the reflection of a signal from a space object, the phase shift in each of its periods is calculated, and then, using the formula, proposed by the authors, the vertical component of the velocity of this object is calculated. Analyzing the observation time of this object in the beam of the transmitter antenna, an example of the calculation and the component of its horizontal velocity is shown. The block diagram of the radar used to calculate the specified parameters of the movement of space objects is presented. The developed approach is an effective solution of many practical problems in those industries that ensure the operation of spacecraft, ensuring the safety of space stations, optimal placement of objects in orbit, etc.\u0000Keywords: Incoherent scatter radar, space objects, coherent reflection, signal phase characteristics, radial and horizontal speed","PeriodicalId":34483,"journal":{"name":"Fizika atmosferi ta geokosmosu","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48895777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-31DOI: 10.47774/phag.01.01.2020-1
L. Chernogor
The purpose of this work is to represent the results of performing regression analysis to fit the distance and the amplitude of the infrasonic signal generated by the explosion of St. Helens volcano, and to estimate a few signal and atmospheric parameters. The pressure amplitude in the explosion wave generated at the beginning of St. Helens volcano eruption was measured at 13 stations in the 0.9 – 39-Mm distance range; based on these data, an attempt has been made to perform a regression analysis to fit amplitude and distance. The regression based on the assumption that the infrasound propagation takes place in a waveguide where it is subject to attenuation is determined to be the most preferable regression. Based on the observations of the shock from the St. Helens volcano eruption, the shock wave energy and mean power have been estimated to be ~1016 J and ~2.3 TW, respectively. Based on the observations of the amplitude and duration of the trains of the infrasonic wave generated by the St. Helens volcano eruption, the infrasonic wave energy and mean power have been estimated to be ~1016 J and ~2 TW, respectively. Both estimates are in good agreement, but they are significantly different from those found in the literature; the latter seem to be overestimated. From the regression expression obtained, the penetration depth of the infrasonic wave is obtained to be about 33 Mm, whereas at other stations this scale length is estimated to be close to 24 Mm. Based on the theoretical dependence of the attenuation coefficient due to atmospheric turbulence, the attenuation length of the infrasound wave has been estimated for infrasound with 10–300-s periods. For 20–300-s periods, this value has been shown to be significantly larger than the values determined from the observations. Other mechanisms for attenuating the infrasonic signal are discussed (the partial radiation of the infrasonic energy through and losses due to the reflection from the waveguide walls). At the same time, the wave attenuation due to their scattering by turbulent fluctuations can be significant for the periods smaller than 20–50 s, depending on the turbulence intensity. Comparison of the regression functions obtained with the corresponding regression expressions for other sources of infrasound waves propagating in the atmosphere has been made. Keywords: volcano eruption, infrasonic wave, shock wave, signal amplitude, regression, signal attenuation
{"title":"Parameters of the Infrasonic Signal Generated in the Atmosphere by a Powerful Volcano Explosion","authors":"L. Chernogor","doi":"10.47774/phag.01.01.2020-1","DOIUrl":"https://doi.org/10.47774/phag.01.01.2020-1","url":null,"abstract":"The purpose of this work is to represent the results of performing regression analysis to fit the distance and the amplitude of the infrasonic signal generated by the explosion of St. Helens volcano, and to estimate a few signal and atmospheric parameters. The pressure amplitude in the explosion wave generated at the beginning of St. Helens volcano eruption was measured at 13 stations in the 0.9 – 39-Mm distance range; based on these data, an attempt has been made to perform a regression analysis to fit amplitude and distance. The regression based on the assumption that the infrasound propagation takes place in a waveguide where it is subject to attenuation is determined to be the most preferable regression. Based on the observations of the shock from the St. Helens volcano eruption, the shock wave energy and mean power have been estimated to be ~1016 J and ~2.3 TW, respectively. Based on the observations of the amplitude and duration of the trains of the infrasonic wave generated by the St. Helens volcano eruption, the infrasonic wave energy and mean power have been estimated to be ~1016 J and ~2 TW, respectively. Both estimates are in good agreement, but they are significantly different from those found in the literature; the latter seem to be overestimated. From the regression expression obtained, the penetration depth of the infrasonic wave is obtained to be about 33 Mm, whereas at other stations this scale length is estimated to be close to 24 Mm. Based on the theoretical dependence of the attenuation coefficient due to atmospheric turbulence, the attenuation length of the infrasound wave has been estimated for infrasound with 10–300-s periods. For 20–300-s periods, this value has been shown to be significantly larger than the values determined from the observations. Other mechanisms for attenuating the infrasonic signal are discussed (the partial radiation of the infrasonic energy through and losses due to the reflection from the waveguide walls). At the same time, the wave attenuation due to their scattering by turbulent fluctuations can be significant for the periods smaller than 20–50 s, depending on the turbulence intensity. Comparison of the regression functions obtained with the corresponding regression expressions for other sources of infrasound waves propagating in the atmosphere has been made.\u0000Keywords: volcano eruption, infrasonic wave, shock wave, signal amplitude, regression, signal attenuation","PeriodicalId":34483,"journal":{"name":"Fizika atmosferi ta geokosmosu","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42701867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-31DOI: 10.47774/phag.01.01.2020-2
O. Levon, I. Domnin
The expediency of using a power active filter in the mode of reactive power compensation of the supply network for the powerful sounding pulses shaper power supply system of the Institute of ionosphere NAS and MES of Ukraine is shown. An analysis of the literature has been carried out, which shows the effectiveness of solving the problem of reactive power compensation, filtering higher harmonics of the power supply network using active filtering of higher harmonics of current or voltage using an additional energy source to obtain a compensating signal in the form of current or voltage. The choice of the power circuit for constructing a power active filter has been made. A voltage inverter on IGBT transistors is used as a power active filter. The basic principles of operation of the power active filter control system are described, which are based on the p-q theory of power and provide for the calculation of instantaneous values of the task currents for each phase of a three-phase power supply system. The work of the Matlab-model of the power supply system of the shaper is shown, the oscillograms of the main energy characteristics of the shaper are given. As a result of using a power active filter, the current of the supply network becomes close to sinusoidal, and the power factor tends to 1. A positive effect on the efficiency of the shaper when the power active filter is included in the supply network is noted, which is due to the efficiency of compensation of the reactive power consumed by the shaper from the supply network. The simulation results are presented, in particular, graphs of reactive power change at the point of connecting the power active filter to the supply network, at different levels of reactive power consumption by the shaper. The results obtained confirmed the possibility of using a power active filter in the mode of reactive power compensation of the supply network when solving the problems of improving the electromagnetic compatibility of powerful sounding pulses shapers with the supply network, reducing losses and increasing the reliability of the shapers. Keywords: active power filter, reactive power control, control systems
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