The reception of over-horizon VHF signal is recently found to be useful for the study of seismo- atmospheric perturbation. So, we have extended our present single path from Chofu to FM Sendai to a nation-wide network. This paper describes our newly established network for reception of over-horizon VHF signals. First, in order to have a triangulation to locate the seismo-atmospheric perturbation for the FM Sendai, we have installed one more station in Kanazawa, to be coordinated with our pre-existing station at Chofu. Other paths are (1) FM Shizuoka to Wakayama and (2) Osaka station to Kagoshima. This VHF system is reported, together with some preliminary results for a recent rather big earthquake (2004 Off Kii-peninsula earthquakes).
{"title":"A network of reception of over-horizon VHF signals associated with earthquakes and some preliminary results","authors":"M. Hayakawa, T. Gotoh, M. Ikeda","doi":"10.1541/JAE.25.19","DOIUrl":"https://doi.org/10.1541/JAE.25.19","url":null,"abstract":"The reception of over-horizon VHF signal is recently found to be useful for the study of seismo- atmospheric perturbation. So, we have extended our present single path from Chofu to FM Sendai to a nation-wide network. This paper describes our newly established network for reception of over-horizon VHF signals. First, in order to have a triangulation to locate the seismo-atmospheric perturbation for the FM Sendai, we have installed one more station in Kanazawa, to be coordinated with our pre-existing station at Chofu. Other paths are (1) FM Shizuoka to Wakayama and (2) Osaka station to Kagoshima. This VHF system is reported, together with some preliminary results for a recent rather big earthquake (2004 Off Kii-peninsula earthquakes).","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121620336","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}
{"title":"RELATION BETWEEN INTERMEDIATE IONS AND METEOROLOGICAL FACTORS","authors":"H. Kojima","doi":"10.1541/JAE.4.49","DOIUrl":"https://doi.org/10.1541/JAE.4.49","url":null,"abstract":"","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133014049","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}
In recent years, it has been reported by many researchers that anomalies of the number of electrons in the ionosphere occur before earthquakes. Because the radio waves used for the global positioning system (GPS) propagate through the ionosphere, it is expected that the anomalies of the ionosphere causes fluctuations of the propagation path and propagation delay, and they result in positioning errors. Therefore, we attempt to predict earthquakes using the GPS positioning errors. In this paper, we discuss the relationship between the GPS positioning errors and earthquakes based on a statistical analysis using the data observed for more than one year.
{"title":"Analysis of the relationship between the earthquake and the GPS positioning error","authors":"Kyohei Takahashi, N. Haga, K. Motojima","doi":"10.1541/JAE.34.41","DOIUrl":"https://doi.org/10.1541/JAE.34.41","url":null,"abstract":"In recent years, it has been reported by many researchers that anomalies of the number of electrons in the ionosphere occur before earthquakes. Because the radio waves used for the global positioning system (GPS) propagate through the ionosphere, it is expected that the anomalies of the ionosphere causes fluctuations of the propagation path and propagation delay, and they result in positioning errors. Therefore, we attempt to predict earthquakes using the GPS positioning errors. In this paper, we discuss the relationship between the GPS positioning errors and earthquakes based on a statistical analysis using the data observed for more than one year.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124520935","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}
M. Hata, I. Takumi, K. Ohta, J. Izutsu, T. Fujii, Tokiyasu Sato, S. Yahashi, N. Watanabe
ELF (30-300 Hz) band three-axial magnetic-flux receiver was developed for detecting electromagnetic-wave precursor of earthquakes and volcanic eruption. The receiver attained a high sensitivity of 0.4pT/√Hz (223Hz) and 4.5 pT/√Hz (17Hz) for the ground based observation of the ambient magnetic flux anomaly. The receiver was extended to detect ultra-low-frequency (ULF) variation (0.1 to 10-7Hz) of crust magnetic flux by through MMD (Modulated Magnetic-flux Detection) reception. It detects the modulated components of the ELF band atmospheric signal which are produced by the crust ULF magnetic-flux variation. The receiver noise due to the artificial noise can be smoothed out from the objective ULF magnetic flux signal by introducing long term integration for the period of 107 seconds of the detected signal. The receiver detected the ULF anomaly of magnetic variation and the Schumann Resonance variation appeared before the two earthquakes of the class M7 occurred in Japan in 2005 and 2007 respectively.
{"title":"Development of ELF Band Receiver of Detecting Extreme Low Frequency Magnetic Flux Variation Due to Earthquakes","authors":"M. Hata, I. Takumi, K. Ohta, J. Izutsu, T. Fujii, Tokiyasu Sato, S. Yahashi, N. Watanabe","doi":"10.1541/JAE.30.37","DOIUrl":"https://doi.org/10.1541/JAE.30.37","url":null,"abstract":"ELF (30-300 Hz) band three-axial magnetic-flux receiver was developed for detecting electromagnetic-wave precursor of earthquakes and volcanic eruption. The receiver attained a high sensitivity of 0.4pT/√Hz (223Hz) and 4.5 pT/√Hz (17Hz) for the ground based observation of the ambient magnetic flux anomaly. The receiver was extended to detect ultra-low-frequency (ULF) variation (0.1 to 10-7Hz) of crust magnetic flux by through MMD (Modulated Magnetic-flux Detection) reception. It detects the modulated components of the ELF band atmospheric signal which are produced by the crust ULF magnetic-flux variation. The receiver noise due to the artificial noise can be smoothed out from the objective ULF magnetic flux signal by introducing long term integration for the period of 107 seconds of the detected signal. The receiver detected the ULF anomaly of magnetic variation and the Schumann Resonance variation appeared before the two earthquakes of the class M7 occurred in Japan in 2005 and 2007 respectively.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"370 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131054846","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}
Kazuhide Nemoto, Kojima Haruna, C. Yoshino, Shu Kaneko, Akitsugu Kitade, K. Hattori, T. Mogi, Toshiharu Konishi
We are developing underground and atmospheric radon observations using an α-ray detector in Chiba-Ibaraki to investigate the relationship between earthquakes and radon emissions from the ground. In this paper, we investigated the relationship between soil radon flux (SRF) and heavy precipitation, and found that SRF was significantly increased by heavy precipitation of 20 mm or more in total for 2 hours. We proposed two types of models, a rainwater load model and a rainwater infiltration model, and it is appropriate for both models to work.
{"title":"Soil radon flux fluctuation near the ground surface:Relationship with heavy precipitation","authors":"Kazuhide Nemoto, Kojima Haruna, C. Yoshino, Shu Kaneko, Akitsugu Kitade, K. Hattori, T. Mogi, Toshiharu Konishi","doi":"10.1541/jae.40.37","DOIUrl":"https://doi.org/10.1541/jae.40.37","url":null,"abstract":"We are developing underground and atmospheric radon observations using an α-ray detector in Chiba-Ibaraki to investigate the relationship between earthquakes and radon emissions from the ground. In this paper, we investigated the relationship between soil radon flux (SRF) and heavy precipitation, and found that SRF was significantly increased by heavy precipitation of 20 mm or more in total for 2 hours. We proposed two types of models, a rainwater load model and a rainwater infiltration model, and it is appropriate for both models to work.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125351729","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}
In non line-of-sight VHF radio wave observation, anomalous propagations due to ionospheric sporadic-E (Es propagation) and tropospheric duct (tropospheric ducting) have been frequently observed. They are known to cause an interference problem in the television, radio broadcasts and wireless communications, so that it is important to understand them. In order to make clear the characteristics of the anomalous propagations, we have observed over-horizon FM radio waves in VHF band for six years in Hiroshima and Aso. For analyses of large amounts of data set observed over years, it is important to classify and extract the radio waves automatically. In this paper, we show a method to classify above two anomalous propagations automatically. Procedures of the method are based on their propagation characteristics and received signal strength. Further the anomalous propagations and broadband noises are separated using dual frequency method. In order to evaluate the method, we examined the occurrence of the Es propagation and tropospheric ducting detected by the above method using the data observed from 2005 to 2010. It was found that the Es propagations were mostly observed in summer season and more frequently observed months in a year were June and July. Further, they were frequently observed from 10 to 12 and from 16 to 18 o’clock in a day. These results had the same tendency as past observations at mid-latitude. On the other hand, the tropospheric ducting was observed from night to morning time in spring and fall at Aso observatory. These results were consistent with past observations of occurrences of inversion layer in the troposphere from fall to spring. In contrast, it was confirmed that there were few tropospheric ducting in summer season while the past observations reported the inversion layer occurred. Since propagation characteristics of the FM radio waves have been clearly shown, it was confirmed that the classification method worked effectively.
{"title":"Observations of anomalous propagation of VHF radio wave due to sporadic-E and tropospheric duct in Hiroshima and Aso","authors":"K. Shin, M. Nishi, Teruaki Yoshida","doi":"10.1541/JAE.32.25","DOIUrl":"https://doi.org/10.1541/JAE.32.25","url":null,"abstract":"In non line-of-sight VHF radio wave observation, anomalous propagations due to ionospheric sporadic-E (Es propagation) and tropospheric duct (tropospheric ducting) have been frequently observed. They are known to cause an interference problem in the television, radio broadcasts and wireless communications, so that it is important to understand them. In order to make clear the characteristics of the anomalous propagations, we have observed over-horizon FM radio waves in VHF band for six years in Hiroshima and Aso. For analyses of large amounts of data set observed over years, it is important to classify and extract the radio waves automatically. In this paper, we show a method to classify above two anomalous propagations automatically. Procedures of the method are based on their propagation characteristics and received signal strength. Further the anomalous propagations and broadband noises are separated using dual frequency method. In order to evaluate the method, we examined the occurrence of the Es propagation and tropospheric ducting detected by the above method using the data observed from 2005 to 2010. It was found that the Es propagations were mostly observed in summer season and more frequently observed months in a year were June and July. Further, they were frequently observed from 10 to 12 and from 16 to 18 o’clock in a day. These results had the same tendency as past observations at mid-latitude. On the other hand, the tropospheric ducting was observed from night to morning time in spring and fall at Aso observatory. These results were consistent with past observations of occurrences of inversion layer in the troposphere from fall to spring. In contrast, it was confirmed that there were few tropospheric ducting in summer season while the past observations reported the inversion layer occurred. Since propagation characteristics of the FM radio waves have been clearly shown, it was confirmed that the classification method worked effectively.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121442297","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}
Tekkan Akashi, H. Ohya, F. Tsuchiya, K. Nozaki, H. Nakata
. We report variation in the D-region ionosphere after the 2015 Nepal earthquake using low-frequency (LF) transmitter signals. The Nepal earthquake (Mw 7.8) occurred at 6:11:26 UT on April 25, 2015. In this study, we used the BPC (China, 68.5 kHz)-Takine (TKN, Japan) LF radio wave propagation path, which has a great circle distance between the epicenter and the LF propagation path of 3,025 km. The observed periods of variation in the LF amplitude and phase were 100-300 s. The observed variation in the LF amplitude and phase was approximately +/-0.1 dB and +/-1°, respectively. The vertical velocity of the ground oscillation near the midpoint of the LF propagation path had a similar period to the LF waves. The Rayleigh wave spread concentrically from the epicenter to the LF path, and then the acoustic waves propagated vertically at the midpoint of the LF path from the Earth’s surface to the D-region ionosphere height. The maximum coherences between the LF amplitude and vertical seismic velocity, and between the LF phase and vertical seismic velocity were 0.90 (period: 146 s) and 0.77 (256 s), respectively, which were both significant at the 95% confidence level. The variation in the LF amplitude and phase was caused by acoustic waves excited by the Rayleigh wave.
{"title":"Variation in the D-region ionosphere after the 2015 Nepal earthquake using LF transmitter signals","authors":"Tekkan Akashi, H. Ohya, F. Tsuchiya, K. Nozaki, H. Nakata","doi":"10.1541/jae.40.1","DOIUrl":"https://doi.org/10.1541/jae.40.1","url":null,"abstract":". We report variation in the D-region ionosphere after the 2015 Nepal earthquake using low-frequency (LF) transmitter signals. The Nepal earthquake (Mw 7.8) occurred at 6:11:26 UT on April 25, 2015. In this study, we used the BPC (China, 68.5 kHz)-Takine (TKN, Japan) LF radio wave propagation path, which has a great circle distance between the epicenter and the LF propagation path of 3,025 km. The observed periods of variation in the LF amplitude and phase were 100-300 s. The observed variation in the LF amplitude and phase was approximately +/-0.1 dB and +/-1°, respectively. The vertical velocity of the ground oscillation near the midpoint of the LF propagation path had a similar period to the LF waves. The Rayleigh wave spread concentrically from the epicenter to the LF path, and then the acoustic waves propagated vertically at the midpoint of the LF path from the Earth’s surface to the D-region ionosphere height. The maximum coherences between the LF amplitude and vertical seismic velocity, and between the LF phase and vertical seismic velocity were 0.90 (period: 146 s) and 0.77 (256 s), respectively, which were both significant at the 95% confidence level. The variation in the LF amplitude and phase was caused by acoustic waves excited by the Rayleigh wave.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122332002","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}
Takahiro Tajiri, T. Morimoto, Y. Nakamura, H. Sakai, Y. Takayanagi, M. Shimizu
Hokuriku region is known to have serious damages to high structures caused by winter thunderstorm. We have been observing winter thunderstorms by LF band receivers since 2016. In the course of observations, lightning discharges with the channel of over 100 km were detected in winter thunderstorm season. Many return strokes were recorded by LLS with these very long lightning channel unlike general lightning discharge in winter thunderstorm season. Moreover, about 60 % of return strokes were positive, and both polarities were detected in 1 flash. This paper reports progress process of lightning discharge with the long channel.
{"title":"A study on progress process of lightning discharge with long lightning channels","authors":"Takahiro Tajiri, T. Morimoto, Y. Nakamura, H. Sakai, Y. Takayanagi, M. Shimizu","doi":"10.1541/jae.40.32","DOIUrl":"https://doi.org/10.1541/jae.40.32","url":null,"abstract":"Hokuriku region is known to have serious damages to high structures caused by winter thunderstorm. We have been observing winter thunderstorms by LF band receivers since 2016. In the course of observations, lightning discharges with the channel of over 100 km were detected in winter thunderstorm season. Many return strokes were recorded by LLS with these very long lightning channel unlike general lightning discharge in winter thunderstorm season. Moreover, about 60 % of return strokes were positive, and both polarities were detected in 1 flash. This paper reports progress process of lightning discharge with the long channel.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115004951","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}
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