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The relationship between the background and transient signals in Schumann resonances

June 7, 1999
  |
Conference Paper
Author:
Earle R. Williams
…
Published in:
Proc. 11th Int. Conf. on Atmospheric Electricity, 7-11 June 1999, pp. 758-761.
Topic:
weather
R&D area:
R&D group:

Summary

Two distinct measures of the Earth's Schumann resonances -- the background and the transients -- are studied through comparisons at the mesoscale and at the continental scale. A rough proportionality is shown between the far more abundant afternoon lightning activity and the larger positive mesoscale discharges that make sprites and simultaneously ring the Earth- ionosphere cavity to levels higher than the integration of all other lightnings.
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Summary

Two distinct measures of the Earth's Schumann resonances -- the background and the transients -- are studied through comparisons at the mesoscale and at the continental scale. A rough proportionality is shown between the far more abundant afternoon lightning activity and the larger positive mesoscale discharges that make sprites and...

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The relationship between the background and transient signals in Schumann resonances

Schumann Resonances and the temporal-spatial dynamics of global thunderstorm activity

June 7, 1999
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Conference Paper
Author:
V. Mushtak
…
Published in:
11th Int. Conf. on Atmospheric Electricity, 7-11 June 1999, pp. 698-700.
Topic:
weather
R&D area:
R&D group:

Summary

A two-dimensional computational ELF technique has been applied to interpret variations of peak frequencies of Schumann resosnances (SR) observed at the MIT experimental site (West Greenwich, Rhode Island). The spatial-temporal dynamics of global thunderstorm activity has been simulated on the basis of general meteorological data. It is shown that the proposed models provide a reasonable qualitative agreement between computed and observed variations for SR I to IV. Some inverse task diagrams has been constructed as an instrument for distinguishing between day-to-day thunderstorm scenarios.
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Summary

A two-dimensional computational ELF technique has been applied to interpret variations of peak frequencies of Schumann resosnances (SR) observed at the MIT experimental site (West Greenwich, Rhode Island). The spatial-temporal dynamics of global thunderstorm activity has been simulated on the basis of general meteorological data. It is shown that the...

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Schumann Resonances and the temporal-spatial dynamics of global thunderstorm activity

Comparisons of long-term Schumann resonance records in Europe and North America

June 7, 1999
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Conference Paper
Author:
G. Satori
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Published in:
11th Int. Conf. on Atmos. Electr. 7-11 June 1999, pp. 705-708.
Topic:
electrical engineering
R&D area:
R&D group:

Summary

Two stations at a distance comparable with the wavelength in the Schumann resonance (SR) frequency range, one in Europe (Nagycenk, Hungary) and one in North America (West Greenwich, Rhode Island) have simultaneously monitored the natural vertical electric and horizontal magnetic field components in the frequency range of 3-25 Hz. This is a unique opportunity, as Schumann resonance stations are scarce and even fewer station have records with 5-6 year durations. The main purpose of this paper is to make comparisons in the SR time series measured simultaneously at the two field sites, thereby providing access to global behavior on the seasonal and interannual time scales. The comparative measurements described here point out distinct differences in the nature of convection in South America and in Africa, and reveal new aspects about the behavior of tropical continental convection on the ENS0 time scale.
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Summary

Two stations at a distance comparable with the wavelength in the Schumann resonance (SR) frequency range, one in Europe (Nagycenk, Hungary) and one in North America (West Greenwich, Rhode Island) have simultaneously monitored the natural vertical electric and horizontal magnetic field components in the frequency range of 3-25 Hz. This...

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Comparisons of long-term Schumann resonance records in Europe and North America

Total global lightning inferred from Schumann resonance measurements

December 27, 1998
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Journal Article
Author:
S. J. Heckman
…
Published in:
J. Geophys. Res., Vol. 103, No. D24, 27 December 1998, pp. 31,775-31,779.
Topic:
weather
R&D area:
R&D group:

Summary

Radiation with frequencies of 5-30 Hz is ducted between Earth's surface and ionosphere with little attenuation; at the lowest frequencies, waves travel several times around the Earth before losing most of their energy. Much of this radiation is produced by lightning. Here we assume that all of this radiation is produced by lightning, and attempt to invert the observed and electric and magnetic fields to infer global lightning activity. We show 10 days of inversions. For these 10 days, the inferred average rate of vertical charge transfer squared is only 1.7 105 (ten to the fifth) (Ckm)2/s Other studies suggest that the root mean square moment change of a flash is about 166 Coulomb kilometers. If we naively assume that each of these flashes is composed of four equally sized strokes, then we conclude that our entire observed signal could be produced by only 22 flashes per second.
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Summary

Radiation with frequencies of 5-30 Hz is ducted between Earth's surface and ionosphere with little attenuation; at the lowest frequencies, waves travel several times around the Earth before losing most of their energy. Much of this radiation is produced by lightning. Here we assume that all of this radiation is...

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Total global lightning inferred from Schumann resonance measurements

Total lightning as a severe weather diagnostic in strongly baroclinic systems in Central Florida

September 14, 1998
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Conference Paper
Author:
Earle R. Williams
…
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 643-647.
Topic:
weather
R&D area:
R&D group:

Summary

Severe weather is defined by specific thresholds in wind. hail size and vorticity. All of these phenomena have close physical connections with vertical drafts in deep convection, which are themselves not directly measured with scanning Doppler radars of the NEXRAD type. Cloud electrification and lightning are particularly sensitive to these drafts because they modulate the supply of supercooled water which is the growth agent for the ice particles (ice crystals, graupel and hail) believed essential for electrical charge separation. For these reasons, one can expect correlations at the outset between total lightning activity and the development of severe weather which may aid in the understanding and prediction of these extreme weather conditions. The exploration of these ideas has historically been impeded by lack of good quantitative observations. A recent review of results on severe storm electrification (Williams, 1998) indicates a general absence of cases for which total lightning activity is documented over the lifetime of a severe storm. The recent development of LISDAD (Lightning Imaging Sensor Data Application Display) (Boldi, et aI., 1998) has largely remedied this problem. This paper is concerned with the use of LISDAD to quantify the behavior of total lightning in all types of severe weather, with a focus on a pair of extraordinarily electrified supercells in the Florida dry season.
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Summary

Severe weather is defined by specific thresholds in wind. hail size and vorticity. All of these phenomena have close physical connections with vertical drafts in deep convection, which are themselves not directly measured with scanning Doppler radars of the NEXRAD type. Cloud electrification and lightning are particularly sensitive to these...

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Total lightning as a severe weather diagnostic in strongly baroclinic systems in Central Florida

Total lightning and radar storm characteristics associated with severe storms in Central Florida

September 14, 1998
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Conference Paper
Author:
Steven J. Goodman
…
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 639-642.
Topic:
weather
R&D area:
R&D group:

Summary

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 but not always. Taylor found that 23% of nontornadic storms and I% of non-severe storms had sferics rates comparable to the tornadic storms. MacGorman (1993) found that storms with mesocyclones produced more frequent intracloud (lC) lightning than cloud-ta-ground (CG) lightning. MacGorman (1993) and others suggest that the lightning activity accompanying tornadic storms will be dominated by intracloud lightning- with an increase in intracloud and total flash rates as the updraft increases in depth, size, and velocity. In a recent study, Perez et aI. (1998) found that CG flash rates alone are too variable to be a useful predictor of (F4, F5) tornado formation. Studies of non-tornadic storms have also shown that total lightning flash rates track the updraft, with rates increasing as the updraft intensifies and decreasing rapidly with cessation of vertical growth or downburst onset (Goodman et aI., 1988; Williams et aI., 1989). Such relationships result from the development of mixed phase precipitation and increased hydrometeor collisions that lead to the efficient separation of charge. Correlations between updraft strength and other variables such as cloud-top height, cloud water mass, and hail size have also been observed. In this paper we examine the total lightning activity (with high time resolution), and the associated Doppler radar time history of weaker (FO, Fl) tornadic storms in Florida. Much of the prior work has focused on tornadic supercells in the Great Plains.
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Summary

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 but not always. Taylor found that 23% of nontornadic storms and I% of non-severe storms had sferics rates comparable...

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Total lightning and radar storm characteristics associated with severe storms in Central Florida

The design and evaluation of the Lightning Imaging Sensor Data Applications Display (LISDAD)

September 14, 1998
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Conference Paper
Author:
Robert A. Boldi
…
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 631-634.
Topic:
weather
R&D area:
R&D group:

Summary

The ultimate goal of the LISDAD system is to quantify the utility of total lightning infomation in short-term, severe-weather-forecasting operations. Secondary goals were to collect times series of various storm-cell parameters that relate to storm development and electrification and subsequently make these data available for post-facto analysis. To these ends scientists from NASA, NWS, and MIT/LL organized an effort to study the relationship of lightning and severe-weather on a storm-by-storm, and even cell-by-cell basis for as many storms as possible near Melbourne, Florida. Melbourne was chosen as it offers a unique combination of high probability of severe weather and proximity to major relevant sensors, specifically: NASA's total lightning mapping system at Kennedy Space Center (the LDAR system) at KSC [Lennon and Maier, 1991], a NWS / NEXRAD radar at Melbourne, and a prototype Integrated Terminal Weather System (ITWS), at Orlando. The ITWS system obtains cloud-to-ground lightning information from the National Lightning Detection Network (NLDN) via a link to Lexington, MA, and also uses NSSL's Severe Storms Analysis Package (NSSL / SSAP) to obtain information about various storm-cell parameters
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Summary

The ultimate goal of the LISDAD system is to quantify the utility of total lightning infomation in short-term, severe-weather-forecasting operations. Secondary goals were to collect times series of various storm-cell parameters that relate to storm development and electrification and subsequently make these data available for post-facto analysis. To these ends...

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The design and evaluation of the Lightning Imaging Sensor Data Applications Display (LISDAD)

Observations of total lightning associated with severe convection during the wet season in Central Florida

September 14, 1998
  |
Conference Paper
Author:
Stephen Hodanish
…
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, 635-638.
Topic:
weather
R&D area:
R&D group:

Summary

This paper will discuss findings of a collaborative lightning research project between the Massachusetts Institute of Technology, the National Weather Service (NWS) office in Melbourne (MLB), Florida and the National Aeronautics and Space Administration. In August 1996, NWS MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud to Ground (CG) stroke data from the National Lightning Detection Network (NLDN), and 3D volumetric lightning data collected from the Kennedy Space Centers' Lightning Detection And Ranging (LDAR) system. The two primary objectives of this lightning workstation, called Lightning Imaging Sensor Data Applications Display (L1SDAD), are to: a.) Observe how total lightning relates to severe convective storm morphology over central Florida, and, b.) Compare ground based total lightning data (LDAR) to a satellite based lightning detection system. This presentation will focus on objective #1.
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Summary

This paper will discuss findings of a collaborative lightning research project between the Massachusetts Institute of Technology, the National Weather Service (NWS) office in Melbourne (MLB), Florida and the National Aeronautics and Space Administration. In August 1996, NWS MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud...

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Observations of total lightning associated with severe convection during the wet season in Central Florida

Global validation of single-station Schumann resonance lightning location

May 1, 1998
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Journal Article
Author:
D. J. Boccippio
…
Published in:
J. Atmos. Sol.-Terr. Phys., Vol. 60, No. 7-9., May-June 1998, pp. 701-712.
Topic:
aviation weather
R&D area:
R&D group:

Summary

Global measurements of large, optically bright lightning events from the Optical Transient Detector (OTD) satellite are used to validate estimates of lightning location from single-station Schumann resonance (SR) data. Bearing estimates are obtained through conventional magnetic direction-finding techniques, while source range is estimated from the range-dependent impedance spectrum of an individual SR transients. An analysis of 40 such transients suggests that single-station techniques can locate lightning globally with an accuracy of 1-2 Mm. This is confirmed by further validation at close ranges from flashes detected by the National Lightning Detection Network (NLDN). Observations with both OTD and SR systems may be useful for globally locating lightning with necessary, if not sufficient, characteristics to trigger mesospheric sprites.
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Summary

Global measurements of large, optically bright lightning events from the Optical Transient Detector (OTD) satellite are used to validate estimates of lightning location from single-station Schumann resonance (SR) data. Bearing estimates are obtained through conventional magnetic direction-finding techniques, while source range is estimated from the range-dependent impedance spectrum of an...

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Global validation of single-station Schumann resonance lightning location

Initial comparison of lightning mapping with operational time-of-arrival and interferometric systems

May 27, 1997
  |
Journal Article
Author:
Vladislav Mazur
…
Published in:
J. Geophys. Res., Vol. 102, No. D10, 27 May 1997, pp. 11,071-11,085.
Topic:
weather
R&D area:
R&D group:

Summary

The mapping of lightning radiation sources produced by the operational Time-of-Arrival National Aeronautics and Space Administration/Lightning Detection and Ranging (NASA/LDAR) system is compared with that of the Interferometric French Office National D'Etudes et de Recherches Aerospatiales (ONERA-3D) system. The comparison comprises lightning activity in three Florida storms and also individual flashes in one of these storms. Although limited in scope, the comparison analysis show a significant difference in the representation of lightning radiation by each mapping system. During the duration of a flash, the LDAR data show a continuity in time and a three-dimensional structure of radiation sources. The ONERA-3D radiation source data are more intermittent in time and have a more two-dimensional structure. The distinction between the radiation sources mapped by the two systems is also reflected in the difference between their propagation speeds, 10^4-10^5 m s^-1, estimated by the LDAR system, and 10^7-10^8 m s^-1, estimated by the ONERA-3D system. We infer that this difference occurs because most of the radiation sources mapped with LDAR are associated with virgin breakdown processes typical of slowly propagating negative leaders. On the other hand, most of the radiation sources mapped with ONERA3D are produced by fast intermittent negative breakdown processes typical of dart leaders and K changes as they traverse the previously ionized channels. Thus each operational system may emphasize different stages of the lightning flash, but neither appears to map the entire flash.
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Summary

The mapping of lightning radiation sources produced by the operational Time-of-Arrival National Aeronautics and Space Administration/Lightning Detection and Ranging (NASA/LDAR) system is compared with that of the Interferometric French Office National D'Etudes et de Recherches Aerospatiales (ONERA-3D) system. The comparison comprises lightning activity in three Florida storms and also individual...

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Initial comparison of lightning mapping with operational time-of-arrival and interferometric systems
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