Analyses of Schumann resonance spectra from Kolkata and their possible interpretations
01 Aug 2009-
TL;DR: In this article, the amplitude and frequency fluctuations along with some aspects of Schumann Resonance (SR) during the period are investigated and the variation of global thunderstorm activity as inferred from monthly intensity fluctuations of global SR signals over Kolkata and Modra (Latitude 48.61oN) is presented and the observed difference has been interpreted.
Abstract: The paper deals with the study of Schumann resonance data set recorded at Kolkata (Latitude 22.56oN). The results of analyses are confined to a period of one year (January to December 2000). The amplitude and frequency fluctuations along with some aspects of Schumann resonances (SR) during the period are investigated. The variation of global thunderstorm activity as inferred from monthly intensity fluctuations of global SR signals over Kolkata and Modra (Latitude 48.61oN) is presented and the observed difference has been interpreted.
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TL;DR: In this article, a review on ULF, ELF and VLF signals within the waveguide in terms of different geophysical and extra-terrestrial events like lightning, earthquakes, Leonid meteor shower, solar flares, solar eclipse, geomagnetic storms, and TLEs etc.
Abstract: The space between the two spherical conducting shells, Earth surface and the lower boundary of the ionosphere, behaves as a spherical cavity in which some electromagnetic signals can propagate a long distance and is called Earth-ionosphere waveguide. Through this waveguide ultra low frequency (ULF), extremely low frequency (ELF) and very low frequency (VLF) signals can propagate efficiently with low attenuation. Resonances which occur for ELF waves due to round-the-world propagation interfering with $2n \pi $
phase difference are called Schumann resonances. Lightnings are the main sources of energy continuously producing these electromagnetic radiations from the troposphere. Some fixed frequency signals are also transmitted through the waveguide from different stations for navigation purposes. The intensity and phase of these signals at a particular position depend on the waveguide characteristics which are highly influenced by different natural events. Thus the signatures of different geophysical and extra-terrestrial events may be investigated by studying these signals through proper monitoring of the time series data using suitable techniques. In this article, we provide a review on ULF, ELF and VLF signals within the waveguide in terms of different geophysical and extra-terrestrial events like lightning, earthquakes, Leonid meteor shower, solar flares, solar eclipse, geomagnetic storms, and TLEs etc.
6 citations
TL;DR: In this paper, the amplitude and frequency of the first resonant mode of the Earth-ionosphere waveguide were examined using an induction magnetometer, which was operated from the Indian Antarctic station, Maitri (708°S, 117°E).
Abstract: Schumann resonances (SRs) are the AC components of the global electric circuit and are excited by the lightning activity within the Earth-ionosphere waveguide An induction magnetometer, which was operated from the Indian Antarctic station, Maitri (708°S, 117°E), served to examine the SR parameters, namely the amplitude and frequency, in the north-south (H NS ) and east-west (H EW ) magnetic components The analysis for the first resonant mode presented in this work reveals a strong UT variation in its amplitude in seasonal as well as yearly timescales The NS amplitude reveals a semi-diurnal variation with peaks at ~1000 and ~2100 UT, whereas the EW amplitude exhibits a strong diurnal variation with a pronounced peak at 1600 UT The diurnal curves for the frequency for both components are similar in nature to those for the amplitude, but for a time shift The diurnal trend in the amplitude is retained irrespective of seasons, whereas significant difference are noticed in the frequency behaviour between the summer and winter seasons, especially in the EW component The observed diurnal variation in the SR intensity is explained in terms of the dominant thunderstorm activity centred over the three convectively active regions: Asia/Maritime Continent (Indonesia), South America and Africa The diurnal variation in frequency depends not only on the location of the thunderstorm region with respect to the observer, but also on the ionospheric day/night conditions and the Earth-ionosphere cavity thickness
6 citations
TL;DR: In this paper, the seasonal variations of global thunderstorm activity, effective source distance and level of lightning were analyzed for two periods; first from 01 April, 2007 to 31 March, 2008 (period-I), and then from 01 March, 2011 to 29 February, 2012 (period II) which correspond to pre and post periods of solar cycle minimum of 2008-2009.
Abstract: Employing a set of 3-component search coil magnetometer, Schumann resonance studies have been in progress at Agra (Geograph. lat. 27.2°N, long. 78°E), India since 01 April, 2007. We have analysed the data for two periods; first from 01 April, 2007 to 31 March, 2008 (period-I), and then from 01 March, 2011 to 29 February, 2012 (period-II) which correspond to pre and post periods of solar cycle minimum of 2008-2009. From the diurnal variation of first mode intensity and frequency, we study the seasonal variations of global thunderstorm activity, effective source distance and level of lightning during both the periods. We show that world thunderstorm activity shifts to summer in the northern hemisphere as the effective source distance approaches close to the observer, and the level of intense lightning shifts from the month of July, 2007 in period-I to August, 2011 in period-II. This is supported by Lightning Imaging Sensor (LIS) satellite data also. A possible explanation in terms of increasing solar activity is suggested.
4 citations
01 May 2017
TL;DR: In this article, the characteristics of Schumann resonance (SR) have been studied at a low latitude station Agra (Geograph. lat. 27.2 o N, long. 78 o E), India and the results obtained during two periods (01 April, 2007-31 March, 2008 and 01 March, 2011-29 February, 2012) corresponding to pre and post period of solar cycle minimum (SCM) of 2008-2009 are compared.
Abstract: The characteristics of Schumann resonance (SR) have been studied at a low latitude station Agra (Geograph. lat. 27.2 o N, long. 78 o E), India and the results obtained during two periods (01 April, 2007-31 March, 2008 and 01 March, 2011-29 February, 2012) corresponding to pre and post period of solar cycle minimum (SCM) of 2008-2009 are compared. Our results show that (i) there is a shift in the (ii) peak thunderstorm activity from the month of July in the pre-SCM to August in post-SCM, (iii) the first mode frequency increases with the increasing SCM, and there are distinct drops in the frequency range dF 1 in the months of August and December, 2012 corresponding to effective lightning areas during the post-SCM. We also study the seasonal variation of first mode SR frequency and show theoretically it’s dependence on source-observer distance.
4 citations
TL;DR: In this article, the Schuman Resonance (SR) power varies with respect to the receiver position and the lightning centers, commonly referred as source-observer distance, and the electric and magnetic components of SR intensity vary with the spatial shifts of the thunderstorm regions under El Nino and La Nina conditions.
Abstract: Discrete spectra of frequencies at 8, 14, 20, 26, … Hz are generated by electromagnetic emission from lightning sources and can be regarded as excitation of AC global circuit. These electromagnetic emissions originating within the Earth-ionosphere waveguide occur in the ULF, ELF and VLF frequency ranges. These include Schuman Resonances (SR), ELF-VLF sferics, sprites etc. During 1990s and later, the scenario with these sub-ionospheric ELF SR waves changed and several new aspects emerged. The SR power varies with respect to the receiver position and the lightning centers, commonly referred as source-observer distance. Both electric and magnetic components of SR intensity vary with the spatial shifts of the thunderstorm regions under El-Nino and La-Nina conditions. The magnitude of the lightning in the lower atmospheric region varies with time of the day. The electromagnetic waves thus generated at SR frequencies resonate due to multiple reflections in the Earth-ionosphere cavity. The total signal may be dependent on the waves from the different lightning sources. In this context, different groups of researchers throughout the globe are working and published few interesting results. In this work, few results of different observatories are discussed. Also, an attempt was made to detect experimentally the discrete signals at Kolkata (Lat. 22.56° N, Long. 88.5° E) from the year 1999. Some frequency changes in the peak values are observed in the recorded data which may be attributed to uncertainty arising from spatial distribution of lightning sources exciting the Schuman Resonance modes. Some of those results are also presented in this paper.
2 citations
Cites background or methods or result from "Analyses of Schumann resonance spec..."
...7, at different times showed amplitude and frequency f luctuations which are due to the f luctuations of the causes producing such signals spectra from the middle ionosphere (De et al., 2009; De, 2007)....
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...The recorded Schumann resonance spectra over Kolkata GEOMAGNETISM AND AERONOMY Vol. 59 No. 8 on April 12, 2000 (De et al., 2009) experience variations in Schumann frequencies which is shown in Fig....
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...8 on April 12, 2000 (De et al., 2009) experience variations in Schumann frequencies which is shown in Fig....
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...are compared with the variations over the same season of the year 2006 at Moshiri, Japan (De et al., 2009; Sekiguchi et al., 2008) are depicted in Fig....
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...Variations of the peak frequency of the first SR mode for the spring season (March to May) recorded at Kolkata in the year 2000 GNETISM AND AERONOMY Vol. 59 No. 8 2019 are compared with the variations over the same season of the year 2006 at Moshiri, Japan (De et al., 2009; Sekiguchi et al., 2008) are depicted in Fig....
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References
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TL;DR: The Schumann resonance, a global electromagnetic phenomenon, is shown to be a sensitive measure of temperature fluctuations in the tropical atmosphere, which increases nonlinearly with temperature in the interaction between deep convection and ice microphysics.
Abstract: The Schumann resonance, a global electromagnetic phenomenon, is shown to be a sensitive measure of temperature fluctuations in the tropical atmosphere. The link between Schumann resonance and temperature is lightning flash rate, which increases nonlinearly with temperature in the interaction between deep convection and ice microphysics.
453 citations
240 citations
TL;DR: In this article, a detailed study of the distribution of global midnight lightning from 60 deg S to 60 deg N for 365 consecutive days is reported. The period covered is from September 1, 1977, to August 31, 1978.
Abstract: A detailed study is reported of the distribution of global midnight lightning from 60 deg S to 60 deg N for 365 consecutive days. The period covered is from September 1, 1977, to August 31, 1978. More than 32,000 lightning locations obtained from DMSP photographic data are plotted with an accuracy of 100 km. The locations are in good agreement with features of the general circulation. Land-ocean lightning ratios vary from 2.2 (September) to 4.2 (July) with a mean of 3.2. If these values are corrected for the earth's land-ocean area ratio of 1/2.4, the land-ocean lightning ratios range from 5.3 (September) to 10 (July) with a mean of 7.7.
205 citations
TL;DR: In this paper, the authors reviewed the observational and theoretical work on the low-frequency electromagnetic oscillations of the earth-ionosphere cavity, known as the Schumann resonances, and introduced additional theoretical considerations to allow the models to incorporate the asymmetries of the actual cavity.
Abstract: The observational and theoretical work on the low-frequency electromagnetic oscillations of the earth-ionosphere cavity, known as the Schumann resonances, is reviewed. Additional theoretical considerations are introduced to allow the models to incorporate the asymmetries of the actual cavity. These models are used to explain the observed variations of the power and of the apparent frequency of the resonant modes. The theoretical studies show that the structure of the low D or C region of the ionosphere is critical to these resonances, and the observed frequencies must rule out certain proposed ionospheric models. The perturbations of the cavity are also studied, and comparisons are made between different types of perturbations. The resonance data from July 9, 1962, are used to confirm the tremendous extent of the ionospheric perturbations caused by the Starfish high-altitude nuclear explosion. The possible effects of natural perturbations are also examined.
204 citations
TL;DR: On a clear day, there is a downward electric field of 100 to 300 volts/meter at Earth's surface, although this field is not noticeable in daily life as discussed by the authors. But the field is there.
Abstract: On a clear day, there is a downward electric field of 100 to 300 volts/meter at Earth's surface, although this field is not noticeable in daily life. That is, one does not encounter a 1 kV potential difference when getting into a car on an upper floor in a parking garage, and electrocution is not the major hazard associated with jumping out of trees. The major reason why we don't notice the fair‐weather field is that virtually everything is a good conductor compared to air. Objects such as tree trunks and our bodies are excellent ionic conductors that short out the field and keep us from noticing it. But the field is there.
154 citations