BOB BOLDI - Academia.edu (original) (raw)
Papers by BOB BOLDI
Quarterly Journal of the Royal Meteorological Society, 2009
Journal of Geophysical Research, 1999
Ground flashes with positive polarity associated with both sprites and elves excite the Earth... more Ground flashes with positive polarity associated with both sprites and elves excite the Earth's Schumann resonances to amplitudes several times greater than the background resonances. Theoretical predictions for dielectric breakdown in the mesosphere are tested using ELF methods to evaluate vertical charge moments of positive ground flashes. Comparisons of the measured time constants for lightning charge transfer with the electrostatic
This study revisits the sprite polarity paradox, first manifest by observations that exceptional ... more This study revisits the sprite polarity paradox, first manifest by observations that exceptional cloud-to-ground flashes with negative polarity generally did not produce detectable sprites. The paradox is here resolved by the Transient Luminous Event (TLE) known as the halo, which on account of its inferior brightness (0.3 MR versus 1.5 MR) and substantially shorter duration (1 ms versus 10-100 ms) in comparison with the sprite, is not readily detectable in ground-based video cameras with standard field duration (16.7-20 ms). Observations with improved temporal resolution (ISUAL (Imager of Sprites and Upper Atmospheric Lightnings) from space and PIPER (Photometric Imager of Precipitated Electron Radiation) observations from the ground) provide evidence that flashes with negative polarity dominate the global halo population, and that the halo numbers are more than sufficient to account for the previously missing TLEs. The evidence for lightning polarity-dependent TLEs (sprites, positive and halos, negative) is attributable to the well established but incompletely understood contrast in the behavior of negative and positive lightning flashes to ground.
Evidence has accrued that gamma ray bursts detected by the RHESSI (Reuven Ramaty High Energy Sola... more Evidence has accrued that gamma ray bursts detected by the RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) satellite over thunderclouds are associated with lightning (Cummer et al, 2005). These lightning flashes exhibit positive polarity but vertical charge moments substantially less than the empirical threshold for sprites (>500 C-km). Further searches for lightning flashes causal to gamma ray bursts using
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
Science, 1995
In two summertime mesoscale convective systems (MCSs), mesospheric optical sprite phenomena were ... more In two summertime mesoscale convective systems (MCSs), mesospheric optical sprite phenomena were often coincident with both large-amplitude positive cloud-to-ground lightning and transient Schumann resonance excitations of the entire Earth-ionosphere cavity. These observations, together with earlier studies of MCS electrification, suggest that sprites are triggered when the rapid removal of large quantities of positive charge from an areally extensive charge layer stresses the mesosphere to dielectric breakdown.
... Earle Williams* Massachusetts Institute of Technology Y. Hobara University of Sheffield, UK R... more ... Earle Williams* Massachusetts Institute of Technology Y. Hobara University of Sheffield, UK R. Boldi University of Alabama W. Lyons, T. Nelson FMA Research Inc. B. Russell University of Michigan V. Mushtak Massachusetts Institute of Technology G. Satori, J. Bor GGRI, Sopron ...
A number of prior studies have examined the association of lightning activity with the occurrence... more A number of prior studies have examined the association of lightning activity with the occurrence of severe weather and tornadoes, in particular. High flash rates are often observed in tornadic storms (Taylor, 1973; Johnson, 1980; Goodman and Knupp, 1993) but not always. Taylor found that 23% of nontornadic storms and 1% of non-severe storms had sferics rates comparable to the tornadic storms. MacGorman (1993) found that storms with mesocyclones produced more frequent intracloud (IC) lightning than cloud-to-ground (CG) lightning. MacGorman (1993) and others suggest that the lightning activity accompanying tornadic storms will be dominated by intracloud lightningwith an increase in intracloud and total flash rates as the updraft increases in depth, size, and velocity. In a recent study, Perez et al. (1998) found that CG flash rates alone are too variable to be a useful predictor of (F4, FS) tornado formation. Studies of non-tornadic storms have also shown that total lightning flash r...
Journal of Atmospheric and Oceanic Technology, 1988
The structure and operation of a Portable Atmospheric Sampling System (PASS) for measuring trace ... more The structure and operation of a Portable Atmospheric Sampling System (PASS) for measuring trace substances in the remote marine atmosphere are discussed. The PASS includes a walkup sampling tower and several portable electronics and laboratory vans. The system is regulated by an Automatic System for the Control and Logging of Atmospheric Sampling, which monitors local atmospheric parameters and compares them
Sprites have been detected in video camera observations in Niger over mesoscale convective system... more Sprites have been detected in video camera observations in Niger over mesoscale convective systems in Nigeria during the 2006 AMMA campaign. The parent lightning flashes have been detected by multiple ELF receiving stations worldwide. The recorded charge moments of the parent lightning flashes are often in excellent agreement between different receiving sites, and are furthermore consistent with conventional dielectric breakdown in the mesosphere as the origin of the sprites. Analysis of the polarization of the horizontal magnetic field at the distant receivers provides evidence that the departure from linear magnetic polarization at ELF is caused primarily by the day-night asymmetry of the Earth-ionosphere cavity.
Frontiers in Earth Science
The Earth–ionosphere cavity resonator is occupied primarily by the electromagnetic radiation of l... more The Earth–ionosphere cavity resonator is occupied primarily by the electromagnetic radiation of lightning below 100 Hz. The phenomenon is known as Schumann resonances (SR). SR intensity is an excellent indicator of lightning activity and its distribution on global scales. However, long-term measurements from high latitude SR stations revealed a pronounced in-phase solar cycle modulation of SR intensity seemingly contradicting optical observations of lightning from satellite, which do not show any significant solar cycle variation in the intensity and spatial distribution of lightning activity on the global scale. The solar cycle-modulated local deformation of the Earth–ionosphere cavity by the ionization of energetic electron precipitation (EEP) has been suggested as a possible phenomenon that may account for the observed long-term modulation of SR intensity. Precipitating electrons in the energy range of 1–300 keV can affect the Earth–ionosphere cavity resonator in the altitude ran...
Journal of Atmospheric and Solar-Terrestrial Physics
The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous backg... more The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called 'Q-burst' (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of~10-12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as for large transients in the form of global Q-bursts. Mushtak and Williams (2009) describe an effective technique called Isolated Lorentzian (I-LOR), in which, the contributions from local cultural and various other noises are minimized to a great extent. An automated technique based on median filtering of time series data has been developed. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to general negative CG strikes (Huang et al., 1999; Cummer et al., 2006). The global distributions of these Q-bursts have been studied by Huang et al. (1999) Rhode Island, USA by wave impedance methods from single station ELF measurements at Rhode Island, USA and from Japan Hobara et al. (2006). The present work aims to demonstrate the effect of Qbursts on SR background spectra using GPS time-stamped observation of TLEs. It is observed that the Q-bursts selected for the present work do alias the background spectra over a 5-s period, though the amplitudes of these Qbursts are far below the background threshold of 16 Core Standard Deviation (CSD) so that they do not strongly alias the background spectra of 10-12 min duration. The examination of one exceptional Q-burst shows that appreciable spectral aliasing can occur even when 12-min spectral integrations are considered. The statistical result shows that for a 12-min spectrum, events above 16 CSD are capable of producing significant frequency aliasing of the modal frequencies, although the intensity aliasing might have a negligible effect unless the events are exceptionally large (~200 CSD). The spectral CSD methodology may be used to extract the time of arrival of the Q-burst transients. This methodology may be combined with a hyperbolic ranging, thus becoming an effective tool to detect TLEs globally with a modest number of networked observational stations.
Journal of Geophysical Research: Atmospheres
In this paper, we use (1) the 20 year record of Schumann resonance (SR) signals measured at West ... more In this paper, we use (1) the 20 year record of Schumann resonance (SR) signals measured at West Greenwich Rhode Island, USA, (2) the 19 year Lightning Imaging Sensor (LIS)/Optical Transient Detector (OTD) lightning data, and (3) the normal mode equations for a uniform cavity model to quantify the relationship between the observed Schumann resonance modal intensity and the global-average vertical charge moment change M (C km) per lightning flash. This work, by integrating SR measurements with satellite-based optical measurements of global flash rate, accomplishes this quantification for the first time. To do this, we first fit the intensity spectra of the observed SR signals to an eight-mode, three parameter per mode, (symmetric) Lorentzian line shape model. Next, using the LIS/OTD lightning data and the normal mode equations for a uniform cavity model, we computed the expected climatological-daily-average intensity spectra. We then regressed the observed modal intensity values against the expected modal intensity values to find the best fit value of the global-average vertical charge moment change of a lightning flash (M) to be 41 C km per flash with a 99% confidence interval of ±3.9 C km per flash, independent of mode. Mode independence argues that the model adequately captured the modal intensity, the most important fit parameter herein considered. We also tested this relationship for the presence of residual modal intensity at zero lightning flashes per second and found no evidence that modal intensity is significantly different than zero at zero lightning flashes per second, setting an upper limit to the amount of nonlightning contributions to the observed modal intensity. Plain Language Summary This research measures the globally averaged strength of the lightning discharges detected by the LIS/OTD lightning detection satellites. The strength of a lightning discharge is measured by the amount of charge it moves multiplied by the distance it moves this charge. This measure is called the charge moment M with units Coulomb meters (C m). This movement of current produces propagating electromagnetic waves that can be detected all over the Earth in the 5 Hz-55 Hz frequency band. These electromagnetic waves have modal structure called the Schumann resonances. The intensity of these Schumann resonances is directly related to the value of M. We deduce the globally averaged value of M by regressing the expected intensity of these Schumann resonances of against the observed values. The result is that this report finds that the globally averaged value of M is 41.1 ± 3.9.
Journal of Atmospheric and Solar-Terrestrial Physics
Can J Forest Res, 1983
Pinusponderosa Laws. foliage from a relatively nonpolluted area (SO2 ≤ 5.2 μg/m3, annual average)... more Pinusponderosa Laws. foliage from a relatively nonpolluted area (SO2 ≤ 5.2 μg/m3, annual average) was compared with foliage from a more polluted area (75 μg/m3, annual maximum average) over a 6-year period. Total sulfur and fluoride concentrations, frequencies of basal needle injury and healthy needles, and percent needle surface area affected (chlorotic and necrotic) classified as tip necrosis, mottle, and total necrosis were substantially higher at the polluted site and were judged to be sensitive characteristics. Two years following study inception, the first 700 MW of a planned 2100-MW coal-fired electric generating facility began operating in the nonpolluted area. No consistent changes were noted in the foliar characteristics measured in the nonpolluted area since power-plant start-up, and it is concluded that the facility's emissions did not measurably impact the pine ecosystem during the early years of operation.
Quarterly Journal of the Royal Meteorological Society, 2009
Journal of Geophysical Research, 1999
Ground flashes with positive polarity associated with both sprites and elves excite the Earth... more Ground flashes with positive polarity associated with both sprites and elves excite the Earth's Schumann resonances to amplitudes several times greater than the background resonances. Theoretical predictions for dielectric breakdown in the mesosphere are tested using ELF methods to evaluate vertical charge moments of positive ground flashes. Comparisons of the measured time constants for lightning charge transfer with the electrostatic
This study revisits the sprite polarity paradox, first manifest by observations that exceptional ... more This study revisits the sprite polarity paradox, first manifest by observations that exceptional cloud-to-ground flashes with negative polarity generally did not produce detectable sprites. The paradox is here resolved by the Transient Luminous Event (TLE) known as the halo, which on account of its inferior brightness (0.3 MR versus 1.5 MR) and substantially shorter duration (1 ms versus 10-100 ms) in comparison with the sprite, is not readily detectable in ground-based video cameras with standard field duration (16.7-20 ms). Observations with improved temporal resolution (ISUAL (Imager of Sprites and Upper Atmospheric Lightnings) from space and PIPER (Photometric Imager of Precipitated Electron Radiation) observations from the ground) provide evidence that flashes with negative polarity dominate the global halo population, and that the halo numbers are more than sufficient to account for the previously missing TLEs. The evidence for lightning polarity-dependent TLEs (sprites, positive and halos, negative) is attributable to the well established but incompletely understood contrast in the behavior of negative and positive lightning flashes to ground.
Evidence has accrued that gamma ray bursts detected by the RHESSI (Reuven Ramaty High Energy Sola... more Evidence has accrued that gamma ray bursts detected by the RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) satellite over thunderclouds are associated with lightning (Cummer et al, 2005). These lightning flashes exhibit positive polarity but vertical charge moments substantially less than the empirical threshold for sprites (>500 C-km). Further searches for lightning flashes causal to gamma ray bursts using
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
tables, and brief excerpts from this work in scientific and educational works is hereby granted p... more tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use ” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS CopyrightPolicy, available on the AMS Web site located at
Science, 1995
In two summertime mesoscale convective systems (MCSs), mesospheric optical sprite phenomena were ... more In two summertime mesoscale convective systems (MCSs), mesospheric optical sprite phenomena were often coincident with both large-amplitude positive cloud-to-ground lightning and transient Schumann resonance excitations of the entire Earth-ionosphere cavity. These observations, together with earlier studies of MCS electrification, suggest that sprites are triggered when the rapid removal of large quantities of positive charge from an areally extensive charge layer stresses the mesosphere to dielectric breakdown.
... Earle Williams* Massachusetts Institute of Technology Y. Hobara University of Sheffield, UK R... more ... Earle Williams* Massachusetts Institute of Technology Y. Hobara University of Sheffield, UK R. Boldi University of Alabama W. Lyons, T. Nelson FMA Research Inc. B. Russell University of Michigan V. Mushtak Massachusetts Institute of Technology G. Satori, J. Bor GGRI, Sopron ...
A number of prior studies have examined the association of lightning activity with the occurrence... more A number of prior studies have examined the association of lightning activity with the occurrence of severe weather and tornadoes, in particular. High flash rates are often observed in tornadic storms (Taylor, 1973; Johnson, 1980; Goodman and Knupp, 1993) but not always. Taylor found that 23% of nontornadic storms and 1% of non-severe storms had sferics rates comparable to the tornadic storms. MacGorman (1993) found that storms with mesocyclones produced more frequent intracloud (IC) lightning than cloud-to-ground (CG) lightning. MacGorman (1993) and others suggest that the lightning activity accompanying tornadic storms will be dominated by intracloud lightningwith an increase in intracloud and total flash rates as the updraft increases in depth, size, and velocity. In a recent study, Perez et al. (1998) found that CG flash rates alone are too variable to be a useful predictor of (F4, FS) tornado formation. Studies of non-tornadic storms have also shown that total lightning flash r...
Journal of Atmospheric and Oceanic Technology, 1988
The structure and operation of a Portable Atmospheric Sampling System (PASS) for measuring trace ... more The structure and operation of a Portable Atmospheric Sampling System (PASS) for measuring trace substances in the remote marine atmosphere are discussed. The PASS includes a walkup sampling tower and several portable electronics and laboratory vans. The system is regulated by an Automatic System for the Control and Logging of Atmospheric Sampling, which monitors local atmospheric parameters and compares them
Sprites have been detected in video camera observations in Niger over mesoscale convective system... more Sprites have been detected in video camera observations in Niger over mesoscale convective systems in Nigeria during the 2006 AMMA campaign. The parent lightning flashes have been detected by multiple ELF receiving stations worldwide. The recorded charge moments of the parent lightning flashes are often in excellent agreement between different receiving sites, and are furthermore consistent with conventional dielectric breakdown in the mesosphere as the origin of the sprites. Analysis of the polarization of the horizontal magnetic field at the distant receivers provides evidence that the departure from linear magnetic polarization at ELF is caused primarily by the day-night asymmetry of the Earth-ionosphere cavity.
Frontiers in Earth Science
The Earth–ionosphere cavity resonator is occupied primarily by the electromagnetic radiation of l... more The Earth–ionosphere cavity resonator is occupied primarily by the electromagnetic radiation of lightning below 100 Hz. The phenomenon is known as Schumann resonances (SR). SR intensity is an excellent indicator of lightning activity and its distribution on global scales. However, long-term measurements from high latitude SR stations revealed a pronounced in-phase solar cycle modulation of SR intensity seemingly contradicting optical observations of lightning from satellite, which do not show any significant solar cycle variation in the intensity and spatial distribution of lightning activity on the global scale. The solar cycle-modulated local deformation of the Earth–ionosphere cavity by the ionization of energetic electron precipitation (EEP) has been suggested as a possible phenomenon that may account for the observed long-term modulation of SR intensity. Precipitating electrons in the energy range of 1–300 keV can affect the Earth–ionosphere cavity resonator in the altitude ran...
Journal of Atmospheric and Solar-Terrestrial Physics
The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous backg... more The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called 'Q-burst' (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of~10-12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as for large transients in the form of global Q-bursts. Mushtak and Williams (2009) describe an effective technique called Isolated Lorentzian (I-LOR), in which, the contributions from local cultural and various other noises are minimized to a great extent. An automated technique based on median filtering of time series data has been developed. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to general negative CG strikes (Huang et al., 1999; Cummer et al., 2006). The global distributions of these Q-bursts have been studied by Huang et al. (1999) Rhode Island, USA by wave impedance methods from single station ELF measurements at Rhode Island, USA and from Japan Hobara et al. (2006). The present work aims to demonstrate the effect of Qbursts on SR background spectra using GPS time-stamped observation of TLEs. It is observed that the Q-bursts selected for the present work do alias the background spectra over a 5-s period, though the amplitudes of these Qbursts are far below the background threshold of 16 Core Standard Deviation (CSD) so that they do not strongly alias the background spectra of 10-12 min duration. The examination of one exceptional Q-burst shows that appreciable spectral aliasing can occur even when 12-min spectral integrations are considered. The statistical result shows that for a 12-min spectrum, events above 16 CSD are capable of producing significant frequency aliasing of the modal frequencies, although the intensity aliasing might have a negligible effect unless the events are exceptionally large (~200 CSD). The spectral CSD methodology may be used to extract the time of arrival of the Q-burst transients. This methodology may be combined with a hyperbolic ranging, thus becoming an effective tool to detect TLEs globally with a modest number of networked observational stations.
Journal of Geophysical Research: Atmospheres
In this paper, we use (1) the 20 year record of Schumann resonance (SR) signals measured at West ... more In this paper, we use (1) the 20 year record of Schumann resonance (SR) signals measured at West Greenwich Rhode Island, USA, (2) the 19 year Lightning Imaging Sensor (LIS)/Optical Transient Detector (OTD) lightning data, and (3) the normal mode equations for a uniform cavity model to quantify the relationship between the observed Schumann resonance modal intensity and the global-average vertical charge moment change M (C km) per lightning flash. This work, by integrating SR measurements with satellite-based optical measurements of global flash rate, accomplishes this quantification for the first time. To do this, we first fit the intensity spectra of the observed SR signals to an eight-mode, three parameter per mode, (symmetric) Lorentzian line shape model. Next, using the LIS/OTD lightning data and the normal mode equations for a uniform cavity model, we computed the expected climatological-daily-average intensity spectra. We then regressed the observed modal intensity values against the expected modal intensity values to find the best fit value of the global-average vertical charge moment change of a lightning flash (M) to be 41 C km per flash with a 99% confidence interval of ±3.9 C km per flash, independent of mode. Mode independence argues that the model adequately captured the modal intensity, the most important fit parameter herein considered. We also tested this relationship for the presence of residual modal intensity at zero lightning flashes per second and found no evidence that modal intensity is significantly different than zero at zero lightning flashes per second, setting an upper limit to the amount of nonlightning contributions to the observed modal intensity. Plain Language Summary This research measures the globally averaged strength of the lightning discharges detected by the LIS/OTD lightning detection satellites. The strength of a lightning discharge is measured by the amount of charge it moves multiplied by the distance it moves this charge. This measure is called the charge moment M with units Coulomb meters (C m). This movement of current produces propagating electromagnetic waves that can be detected all over the Earth in the 5 Hz-55 Hz frequency band. These electromagnetic waves have modal structure called the Schumann resonances. The intensity of these Schumann resonances is directly related to the value of M. We deduce the globally averaged value of M by regressing the expected intensity of these Schumann resonances of against the observed values. The result is that this report finds that the globally averaged value of M is 41.1 ± 3.9.
Journal of Atmospheric and Solar-Terrestrial Physics
Can J Forest Res, 1983
Pinusponderosa Laws. foliage from a relatively nonpolluted area (SO2 ≤ 5.2 μg/m3, annual average)... more Pinusponderosa Laws. foliage from a relatively nonpolluted area (SO2 ≤ 5.2 μg/m3, annual average) was compared with foliage from a more polluted area (75 μg/m3, annual maximum average) over a 6-year period. Total sulfur and fluoride concentrations, frequencies of basal needle injury and healthy needles, and percent needle surface area affected (chlorotic and necrotic) classified as tip necrosis, mottle, and total necrosis were substantially higher at the polluted site and were judged to be sensitive characteristics. Two years following study inception, the first 700 MW of a planned 2100-MW coal-fired electric generating facility began operating in the nonpolluted area. No consistent changes were noted in the foliar characteristics measured in the nonpolluted area since power-plant start-up, and it is concluded that the facility's emissions did not measurably impact the pine ecosystem during the early years of operation.