. Fractal analysis has been applied to the ultra-low frequency (ULF) magnetic time series data to study the critical behaviour of impending earthquake preparation zone. Burlaga Klein method has been adapted. The ULF time series data have been prepared from the routine recordings of ULF magnetic field emissions at Agra station in India with the help of 3-component search coil magnetometers for the month of September 2013 in which two large earthquakes of magnitudes M=7.4 and 6.8 occurred in Pakistan. The two important parameters namely fractal dimension D and fractal exponent β are calculated which are found to vary abnormally before the occurrence of earthquakes. From a detailed amplitude-time analysis of ULF data precursory period of anomalies in amplitude has been found of the order of 16 days. The fractal dimension and fractal exponent show complementary behaviour with each other and they are found to vary abnormally around the observed precursory period in the normal analysis of the data. This month is free from geomagnetic disturbances and hence the analysis is not contaminated from the effects of such disturbances.
{"title":"Fractal analysis of Ultra Low Frequency magnetic field emissions observed at Agra associated with two major earthquakes occurred in Pakistan","authors":"Swati, Birbal Singh, D. Pundhir, Y. Hobara","doi":"10.1541/jae.39.1","DOIUrl":"https://doi.org/10.1541/jae.39.1","url":null,"abstract":". Fractal analysis has been applied to the ultra-low frequency (ULF) magnetic time series data to study the critical behaviour of impending earthquake preparation zone. Burlaga Klein method has been adapted. The ULF time series data have been prepared from the routine recordings of ULF magnetic field emissions at Agra station in India with the help of 3-component search coil magnetometers for the month of September 2013 in which two large earthquakes of magnitudes M=7.4 and 6.8 occurred in Pakistan. The two important parameters namely fractal dimension D and fractal exponent β are calculated which are found to vary abnormally before the occurrence of earthquakes. From a detailed amplitude-time analysis of ULF data precursory period of anomalies in amplitude has been found of the order of 16 days. The fractal dimension and fractal exponent show complementary behaviour with each other and they are found to vary abnormally around the observed precursory period in the normal analysis of the data. This month is free from geomagnetic disturbances and hence the analysis is not contaminated from the effects of such disturbances.","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":"129345247","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}
A. Nickolaenko, M. Hayakawa, Y. Galuk, I. Kudintseva
. In a recent paper by McCormick and Cohen (2021), the new vertical profiles were discussed of electron density in the D/E region of ionosphere that accounts for the observations of VLF atmospherics (sferics). In the present paper, we use a typical profile from this paper and apply the classical profile of electron effective collision frequency for obtaining the conductivity of middle atmosphere. This air conductivity profile is compared then with those matching the Schumann resonance observations. By using this novel conductivity model, we compute the propagation parameters of ELF-VLF modes in the Earth–ionosphere cavity with the help of full-wave solution. An emphasis is made on the comparison of Schumann resonance spectra found for the existing and the novel profiles. The multi-mode full-wave solutions allowed us to compute the wide-band complex spectra of vertical electric and horizontal magnetic field components by using the classical modal expansions. Finally, the pulsed waveforms were calculated using the Fourier transform of complex ELF/VLF spectra, which belong to typical slow tail atmospherics (sferics). The conclusion is made that the profile by McCormick and Cohen underestimates the radio wave attenuation only at ELF, so that relevant data predicts somewhat higher peak frequencies and Q-factors of Schumann resonance.
{"title":"Application of McCormick-Cohen Model for Computing ELF/VLF Atmospherics","authors":"A. Nickolaenko, M. Hayakawa, Y. Galuk, I. Kudintseva","doi":"10.1541/jae.41.30","DOIUrl":"https://doi.org/10.1541/jae.41.30","url":null,"abstract":". In a recent paper by McCormick and Cohen (2021), the new vertical profiles were discussed of electron density in the D/E region of ionosphere that accounts for the observations of VLF atmospherics (sferics). In the present paper, we use a typical profile from this paper and apply the classical profile of electron effective collision frequency for obtaining the conductivity of middle atmosphere. This air conductivity profile is compared then with those matching the Schumann resonance observations. By using this novel conductivity model, we compute the propagation parameters of ELF-VLF modes in the Earth–ionosphere cavity with the help of full-wave solution. An emphasis is made on the comparison of Schumann resonance spectra found for the existing and the novel profiles. The multi-mode full-wave solutions allowed us to compute the wide-band complex spectra of vertical electric and horizontal magnetic field components by using the classical modal expansions. Finally, the pulsed waveforms were calculated using the Fourier transform of complex ELF/VLF spectra, which belong to typical slow tail atmospherics (sferics). The conclusion is made that the profile by McCormick and Cohen underestimates the radio wave attenuation only at ELF, so that relevant data predicts somewhat higher peak frequencies and Q-factors of Schumann resonance.","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":"131162628","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}
Adi Zomer, C. Price, L. Alperovich, M. Finkelstein, M. Merzer
. Since 2003 continuous measurements of natural ultra low frequency (ULF) magnetic fields have been made in the southern region of Israel. An analysis of the diurnal cycle over 21 months was made in order to examine the daily behavior of the ULF magnetic field amplitude. A comparison of the ULF magnetic field measurements and the time of local sunrise shows a sharp daily rise in amplitude that starts about 2 hours before sunrise, reaching a peak just after the terminator crossing. On the other hand, across the sunset terminator there is no parallel sharp decrease, but only a steady decrease, which is seen normally during the day. As a result no significant sunset effect can be observed from the ULF amplitude measurements. A possible explanation of this asymmetric behavior can be the recombination time difference between sunrise and sunset in the ionospheric terminator. The amplitude changes at dawn were also better observed in the East-West (EW) component than in the North-South (NS) or Vertical components of the magnetic field, possibly due to North-South currents along the ionospheric terminator. The regularity of these diurnal changes may allow us not only to monitor ionospheric currents along the terminator using ground based measurements, but also to define a polarization of the initial MHD-wave incident on the ionosphere.
{"title":"ULF amplitude observations at the dawn/dusk terminators","authors":"Adi Zomer, C. Price, L. Alperovich, M. Finkelstein, M. Merzer","doi":"10.1541/jae.28.21","DOIUrl":"https://doi.org/10.1541/jae.28.21","url":null,"abstract":". Since 2003 continuous measurements of natural ultra low frequency (ULF) magnetic fields have been made in the southern region of Israel. An analysis of the diurnal cycle over 21 months was made in order to examine the daily behavior of the ULF magnetic field amplitude. A comparison of the ULF magnetic field measurements and the time of local sunrise shows a sharp daily rise in amplitude that starts about 2 hours before sunrise, reaching a peak just after the terminator crossing. On the other hand, across the sunset terminator there is no parallel sharp decrease, but only a steady decrease, which is seen normally during the day. As a result no significant sunset effect can be observed from the ULF amplitude measurements. A possible explanation of this asymmetric behavior can be the recombination time difference between sunrise and sunset in the ionospheric terminator. The amplitude changes at dawn were also better observed in the East-West (EW) component than in the North-South (NS) or Vertical components of the magnetic field, possibly due to North-South currents along the ionospheric terminator. The regularity of these diurnal changes may allow us not only to monitor ionospheric currents along the terminator using ground based measurements, but also to define a polarization of the initial MHD-wave incident on the ionosphere.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"51 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":"133873816","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":"DIRECTION FINDING OF WHISTLERS AND CAUSATIVE LIGHTNING","authors":"K. Ohta, T. Tomomatsu, M. Hayakawa, S. Shimakura","doi":"10.1541/JAE.10.89","DOIUrl":"https://doi.org/10.1541/JAE.10.89","url":null,"abstract":"","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"7 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":"123979230","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}
One important issue in aviation weather is how to reduce lightning strikes to aircrafts. One of our previous researches confirmed that detection of aircraft lightning potential areas by using the vertical integrated weather radar reflectivity and the reflectivity at the altitude of -10 degree Celsius air temperature is feasible. Once the aircraft lightning potential areas are detected, they can be avoided by operating aircrafts so that aircraft lightning strikes can be reduced. In this study, we have improved the detection method by adding weather radar echo top heights and aircraft altitudes into consideration. Our results showed that with this new detection method the false alarm rate can be reduced by a few tens of percentage points.
{"title":"Aircraft Lightning Potential Area Detection Enhanced by Echo Top Height and its Evaluation with Winter Lightning Cases","authors":"E. Yoshikawa, Shoichi Horishita, T. Ushio","doi":"10.1541/JAE.39.70","DOIUrl":"https://doi.org/10.1541/JAE.39.70","url":null,"abstract":"One important issue in aviation weather is how to reduce lightning strikes to aircrafts. One of our previous researches confirmed that detection of aircraft lightning potential areas by using the vertical integrated weather radar reflectivity and the reflectivity at the altitude of -10 degree Celsius air temperature is feasible. Once the aircraft lightning potential areas are detected, they can be avoided by operating aircrafts so that aircraft lightning strikes can be reduced. In this study, we have improved the detection method by adding weather radar echo top heights and aircraft altitudes into consideration. Our results showed that with this new detection method the false alarm rate can be reduced by a few tens of percentage points.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"1 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":"121326214","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}
Lotfy Elbaghdady, A. Allam, T. Ushio, Z. Kawasaki, M. Ragab
. Broadband radio interferometers have been developed to locate the sources of VHF/UHF radiation from lightning discharges in three spatial dimensions (3D) and time. In a previous work, a VHF broadband digital interferometer has been used to estimate the 3D lightning location from only one site. In order to study the accuracy of this algorithm, a cross check of one site 3D VHF broadband digital interferometer with Phased Array Radar (PAR) system will be introduced in this paper. In August 18, 2012, VHF pulses from lightning flashes have been recorded by VHF digital broadband interferometer LIB site located in Nara, Japan. On the same day the precipitation profile has been recorded using Phased Array RADAR (PAR) located in Osaka University. The 3D locations of four flashes are compared with the PAR horizontal and Range-Height Indicator RHI scan images. This comparison introduced a good correlation between 3D VHF broadband digital interferometer algorithm and the precipitation profiles recorded by PAR.
{"title":"Correlated One Site Three Dimensions VHF Broadband Digital Interferometer algorithm and Phased Array Radar (PAR) Observations","authors":"Lotfy Elbaghdady, A. Allam, T. Ushio, Z. Kawasaki, M. Ragab","doi":"10.1541/JAE.34.27","DOIUrl":"https://doi.org/10.1541/JAE.34.27","url":null,"abstract":". Broadband radio interferometers have been developed to locate the sources of VHF/UHF radiation from lightning discharges in three spatial dimensions (3D) and time. In a previous work, a VHF broadband digital interferometer has been used to estimate the 3D lightning location from only one site. In order to study the accuracy of this algorithm, a cross check of one site 3D VHF broadband digital interferometer with Phased Array Radar (PAR) system will be introduced in this paper. In August 18, 2012, VHF pulses from lightning flashes have been recorded by VHF digital broadband interferometer LIB site located in Nara, Japan. On the same day the precipitation profile has been recorded using Phased Array RADAR (PAR) located in Osaka University. The 3D locations of four flashes are compared with the PAR horizontal and Range-Height Indicator RHI scan images. This comparison introduced a good correlation between 3D VHF broadband digital interferometer algorithm and the precipitation profiles recorded by PAR.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"66 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":"116223999","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}
We have observed over-horizon FM broadcasting waves at Niijima for the purpose of clarifying some relationships between earthquake activities and the propagations of over-horizon FM waves. We have monitored 81.3MHz, 79.2MHz and 82.1MHz FM broadcasting waves, from Tokyo, Shizuoka and Hamamatsu, respectively, at Niijima. The period of the observation was for 3 years from January 2005 to December 2007. From observational results, it was found that the received levels of three FM broadcasting waves had seasonal variations in their fluctuations; the fluctuation levels in summer season were larger than those in winter. And the fluctuation levels were positively correlated with the temperature and the water vapor pressure, and were negatively correlated with the atmospheric pressure and the wind speed. In the observation period, one big earthquake with seismic intensity of 4 and three earthquakes with seismic intensity of 3 were observed near the propagation path of the FM broadcasting from Tokyo. By comparing the fluctuation levels of FM waves with the seismic intensities, it was found that there was little correlation between them. It is reasonable to consider that the received level fluctuations are mainly caused by meteorological conditions not by earthquakes. It was concluded that affections of meteorological conditions should be considered to observe seismic activities through over-horizon FM broadcasting waves.
{"title":"Seasonal variations of over-horizon propagation characteristics of FM broadcasting waves","authors":"T. Higashi, K. Shin, M. Nishi, Teruaki Yoshida","doi":"10.1541/JAE.29.105","DOIUrl":"https://doi.org/10.1541/JAE.29.105","url":null,"abstract":"We have observed over-horizon FM broadcasting waves at Niijima for the purpose of clarifying some relationships between earthquake activities and the propagations of over-horizon FM waves. We have monitored 81.3MHz, 79.2MHz and 82.1MHz FM broadcasting waves, from Tokyo, Shizuoka and Hamamatsu, respectively, at Niijima. The period of the observation was for 3 years from January 2005 to December 2007. From observational results, it was found that the received levels of three FM broadcasting waves had seasonal variations in their fluctuations; the fluctuation levels in summer season were larger than those in winter. And the fluctuation levels were positively correlated with the temperature and the water vapor pressure, and were negatively correlated with the atmospheric pressure and the wind speed. In the observation period, one big earthquake with seismic intensity of 4 and three earthquakes with seismic intensity of 3 were observed near the propagation path of the FM broadcasting from Tokyo. By comparing the fluctuation levels of FM waves with the seismic intensities, it was found that there was little correlation between them. It is reasonable to consider that the received level fluctuations are mainly caused by meteorological conditions not by earthquakes. It was concluded that affections of meteorological conditions should be considered to observe seismic activities through over-horizon FM broadcasting waves.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"629 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":"123274382","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}
:Earlier measurements at Karymshino observatory (Kamchatka peninsula, Russia) indicated that there appeared electromagnetic radiation in the frequency range of ULF-ELF a few days before earthquakes (EQs). It was shown that its combined characteristics of the ratio of the field components and the dispersion of field ellipticity were most sensitive to this radiation. We have also shown its high efficiency as an EQ precursor. Here we have tried to estimate its reliability by using the data from an induction magnetometer at another observatory Moshiri in Japan. The data of five weeks in February-March 2007 were analyzed and as a result, reliable precursors were found for four most significant EQ events in the vicinity of the observatory.
{"title":"Estimation of the Efficiency of Combined Characteristics of ULF-ELF Fields as a Precursor to Earthquakes Based on the Observations in February-March 2007 in Moshiri","authors":"M. Hayakawa, A. Schekotov, Y. Hobara","doi":"10.1541/JAE.32.35","DOIUrl":"https://doi.org/10.1541/JAE.32.35","url":null,"abstract":":Earlier measurements at Karymshino observatory (Kamchatka peninsula, Russia) indicated that there appeared electromagnetic radiation in the frequency range of ULF-ELF a few days before earthquakes (EQs). It was shown that its combined characteristics of the ratio of the field components and the dispersion of field ellipticity were most sensitive to this radiation. We have also shown its high efficiency as an EQ precursor. Here we have tried to estimate its reliability by using the data from an induction magnetometer at another observatory Moshiri in Japan. The data of five weeks in February-March 2007 were analyzed and as a result, reliable precursors were found for four most significant EQ events in the vicinity of the observatory.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"91 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":"123834074","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}
This study examined the relationships of precipitation rate and wind gust intensity to lightning activity in Japan by using data recorded at ~1,000 automatic weather stations and a lightning detection network at 10 minute intervals for three years from June 2009 to May 2012. The relationships were evaluated by correlation analyses in 11 climatologically distinct areas of Japan. To investigate the frequency of simultaneous occurrences of precipitation, gusts, and lightning activity, observations were subjectively divided into four categories, based on their distributions in a plot of precipitation and gust data versus lightning activity. There were weak positive correlations between cloud-to-ground (CG) lightning activity and precipitation rate in summer, except in northern Japan, but no significant correlations between CG lightning activity and precipitation rate in winter. High precipitation rate was associated with 5%–40% of occurrences of high lightning activity, suggesting that lightning activity has only limited application as an indicator of high precipitation rate in summer. There were no significant correlations of lightning activity with wind gusts in summer or winter in any of the 11 areas. Only 0%–11% of occurrences of high lightning activity were accompanied by strong gusts in winter, indicating that lightning activity is not a useful indicator of strong wind gusts in winter.
{"title":"Statistical Relationships of Precipitation Rate and Wind Gust Intensity to Lightning Activity in Japan","authors":"S. Hayashi","doi":"10.1541/JAE.35.43","DOIUrl":"https://doi.org/10.1541/JAE.35.43","url":null,"abstract":"This study examined the relationships of precipitation rate and wind gust intensity to lightning activity in Japan by using data recorded at ~1,000 automatic weather stations and a lightning detection network at 10 minute intervals for three years from June 2009 to May 2012. The relationships were evaluated by correlation analyses in 11 climatologically distinct areas of Japan. To investigate the frequency of simultaneous occurrences of precipitation, gusts, and lightning activity, observations were subjectively divided into four categories, based on their distributions in a plot of precipitation and gust data versus lightning activity. There were weak positive correlations between cloud-to-ground (CG) lightning activity and precipitation rate in summer, except in northern Japan, but no significant correlations between CG lightning activity and precipitation rate in winter. High precipitation rate was associated with 5%–40% of occurrences of high lightning activity, suggesting that lightning activity has only limited application as an indicator of high precipitation rate in summer. There were no significant correlations of lightning activity with wind gusts in summer or winter in any of the 11 areas. Only 0%–11% of occurrences of high lightning activity were accompanied by strong gusts in winter, indicating that lightning activity is not a useful indicator of strong wind gusts in winter.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"54 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":"124162411","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}
S. Yoshida, M. Akita, Y. Nakamura, T. Morimoto, T. Ushio, Z. Kawasaki, Daohong Wang, N. Takagi
Six initial continuing current (ICC) pulses contained in upward negative lightning were studied. We classified these ICC pulses into two types according to current pulse shapes.The type 1 ICC pulses had a short geometric mean (GM) of 10-90% risetimes of 8.9 μs, while the type 2 ICC pulses had a long GM of 10-90% risetimes of 55 μs. We found that the type 1 ICC pulses had preceding negative leaders which were connected to the channel of the existing ICC. These negative leaders caused the current increases of the ICC pulses by creating the conducting channels. The height of the space charges transferred by the fast rise ICC pulse is estimated to be about 700 m above sea level at most.
{"title":"Evidence of negative leaders prior to fast rise ICC pulses of upward lightning","authors":"S. Yoshida, M. Akita, Y. Nakamura, T. Morimoto, T. Ushio, Z. Kawasaki, Daohong Wang, N. Takagi","doi":"10.1541/JAE.29.13","DOIUrl":"https://doi.org/10.1541/JAE.29.13","url":null,"abstract":"Six initial continuing current (ICC) pulses contained in upward negative lightning were studied. We classified these ICC pulses into two types according to current pulse shapes.The type 1 ICC pulses had a short geometric mean (GM) of 10-90% risetimes of 8.9 μs, while the type 2 ICC pulses had a long GM of 10-90% risetimes of 55 μs. We found that the type 1 ICC pulses had preceding negative leaders which were connected to the channel of the existing ICC. These negative leaders caused the current increases of the ICC pulses by creating the conducting channels. The height of the space charges transferred by the fast rise ICC pulse is estimated to be about 700 m above sea level at most.","PeriodicalId":274637,"journal":{"name":"Journal of atmospheric electricity","volume":"1 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":"128217497","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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