2006

Diendorfer G.: Lightning properties derived from lightning location systems and tower measurements

Invited Talk presented at the 9^th Int. Conference on EMI&EMC (INCEMIC), Bangalore, India, 2006 Cloud-to-ground (CG) lightning parameters and the spatial distribution of lightning flashes are of fundamental interest for the design of lightning protection systems. In the past lightning location systems (LLS) have been installed in many countries around the world and these systems can provide large scale observation of the lightning occurrence together with some additional information about polarity and peak current of the individual strokes.
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Diendorfer G.: Die Blitzentladung als EMV-Störquelle. The Lightning Discharge as an EMC Source

Elektrotechnik & Informationstechnik (e&i), Heft 1/2, 123. Jahrgang, Jänner/Februar 2006 Die jährlichen Schäden an elektronischen Einrichtungen durch die Einwirkungen von direkten bzw. nahen Blitzschlägen sind enorm. Leider gibt es nur sehr vage Schätzungen der Schäden durch Blitzschlag, da diese durch unterschiedlichste Versicherungspakete abgedeckt werden, bzw. daraus resultierende Folgeschäden, wie Betriebsunterbrechungen, oft gar nicht versichert sind. Im Sinne der EMV Grundstruktur Störquelle - Übertragungsweg - Störsenke stellt die Blitzentladung eine natürliche Störquelle dar. Die Eigenschaften dieser Störquelle sind einerseits bestimmt durch die Stromparameter der verschiedenen Blitzstromkomponenten und anderseits durch die Kenngrößen der mit der Entladung verknüpften elektromagnetischen Felder. In den Vorschriften zum Blitzschutz (IEC 62305-3) [3] findet man Kennwerte für die zu erwartenden Blitzströme, IEC 62305-4 [4] behandelt den Schutz von elektrischen und elektronischen Einrichtungen in Gebäuden im Falle eines direkten oder nahen Blitzschlages. In Anlehnung an die zu erwartenden Störgrößen wurden in der Vergangenheit verschiedenste Prüfimpulse für Stossströme und Stoßspannungen entwickelt, die auch zum Teil bei der EMV Prüfung von Geräten zum Einsatz kommen.
Annual costs of damages caused by direct or nearby lightning on electric and electronic infrastructure are enormous. Unfortunately there are only rough estimates of the total costs because they are covered by different insurance packages and often costs for the lightning caused service interruptions are not recorded or insured at all. Lightning is a natural source of current and electromagnetic field in terms of the electromagnetic compatibility concept Source - Coupling Path - Receiver, whose properties are determined by the parameters of the different lightning current components and their corresponding EM fields. In the standard for lightning protection IEC 62305-3 [3] parameters of the lightning current are listed. IEC 62305-4 [4] deals with the protection of electronic equipment in case of a direct or nearby lightning strike. In the past different current and voltage pulses have been specified to simulate the effect of lightning strikes and some of them are also applied in EMC tests.
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Cooray V., G. Diendorfer, C.A. Nucci, D. Pavanello, F. Rachidi, M. Becerra, M. Rubinstein, W. Schulz: On the Effect of the Finite Ground Conductivity on Electromagnetic Field Radiated by Lightning to Tall Towers

28^th International Conference on Lightning Protection (ICLP), Kanazawa, Japan, 2006 In this paper it is shown how the finitely conducting ground modifies the signature of the radiation field of return strokes striking tall towers. Results are presented for different tower heights and for different ground conductivities varying the current risetime in the return stroke model. The results show that the attenuation of the initial peak of the radiation field resulting from the propagation over finitely conducting ground depends strongly on the current risetime, the tower height and the ground conductivity. In general, the attenuation of the radiation field of lightning flashes striking tall towers is larger than that striking flat ground. In the case where the ground conductivity is extremely poor, namely 0.0001 S/m, the attenuation of the peak radiation field may reach as much as 70% in the case of lightning flashes striking a 300-m tall tower.
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Schulz W., G. Diendorfer: Flash Multiplicity and Interstroke Intervals in Austria

28^th International Conference on Lightning Protection (ICLP), Kanazawa, Japan, 2006 In 2003 we have developed a PC based and GPS synchronized field measurement system which is able to measure and store electric field data continuously. This field measurement system is based on a 12 bit digitizing board operated with a sampling rate of 5 MS/s. The board allows to record a maximum of two channels at the same time. Once every second the field data is stored on the hard disc of the PC. Depending on the number of recorded channels (one or two) the size of the file is 10MB or 20MB, respectively [Schulz et al., 2005a]. The main advantage of such a continuous and GPS synchronized field measurement system compared to a triggered system is that it is not suffering from any trigger threshold and dead time and therefore we basically do not miss any events. Consequently this system is ideal
for critical analyzes of data from lightning location systems (LLS). In this paper we will show a comparison of the flash multiplicity and the interstroke interval derived from data from the Austrian LLS ALDIS (Austrian Lightning Detection and Information System) and the data from the new field measurement system. We will further compare the result with parameters previously published in the literature.
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Miki M., T. Shindo, V.A. Rakov, M.A. Uman, G. Diendorfer, M. Mair, F. Heidler, W. Zischank, R. Thottappillil, D. Wang: Characterization of current pulses superimposed on the continuous current in upward lightning initiated from tall objects and in rock

28^th International Conference on Lightning Protection (ICLP), Kanazawa, Japan, 2006 We compare the characteristics of the M components and the initial continuous current pulses (ICC pulses) in natural upward lightning as observed on the Gaisberg tower (100 m), the Peissenberg tower (160 m), and the Fukui chimney (200 m) with their counterparts in rocket-triggered lightning in Florida for the clarification of the mechanism of the ICC pulses. All lightning events analyzed here effectively transported negative charge to ground. The peak, duration, risetime, half peak width and charge transfer of ICC pulses are similar to those of the M components. However, the parameters of the ICC pulses and the M components in Florida rocket-triggered lightning, except for the charge transfer, are different from those in natural upward lightning flashes. Furthermore, optical images of the ICC pulse have been obtained using video cameras. From these results, we discuss the mechanism of the ICC pulses.
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Diendorfer G., H. Pichler, M. Mair: Characteristics of positive upward lightning measured on an instrumented tower

28^th International Conference on Lightning Protection (ICLP), Kanazawa, Japan, 2006 Lightning to elevated towers is mainly upward initiated. We have recorded 9 flashes to an instrumented tower that lowered positive charge to ground and have therefore been initiated by upward negative leaders from the tower top. All these 9 positive flashes occurred during the cold season or winter time (September - March). The observed overall current waveforms typically exhibit a front section with significant pulsing structure lasting for about 2.2 ms (mean). The total flash duration is in the range from 5 to 200 ms (mean 62 ms) and total charge transfer is in the range from 20 to 356 C (mean 128 C). Mean values of the peak current of these leader pulses are in the range of 1.6 to 13.7 kA. For each of the 9 flashes we have determined for the distinct pulses a mean charge transfer of 0.013 C to 0.321 C per pulse. The similarity of negative downward and upward stepped leaders is discussed. PDF File (1,1 MB)

Chum J., F. Jiricek, O. Santolik, M. Parrot, G. Diendorfer, and J. Fiser: Assigning the causative lightning to the whistlers observed on satellites

European Geosciences Union, Annales Geophysicae, 24, 2921-2929, 2006 We study the penetration of lightning induced whistler waves through the ionosphere by investigating the correspondence between the whistlers observed on the DEMETER and MAGION-5 satellites and the lightning discharges detected by the European lightning detection network EUCLID. We compute all the possible differences between the times when the whistlers were observed on the satellite and times when the lightning discharges were detected. We show that the occurrence histogram for these time differences exhibits a distinct peak for a particular characteristic time, corresponding to the sum of the propagation time and a possible small time shift between the absolute time assigned to the wave record and the clock of the lightning detection network. Knowing this characteristic time, we can search in the EUCLID database for locations, currents, and polarities of causative lightning discharges corresponding to the individual whistlers. We demonstrate that the area in
the ionosphere through which the electromagnetic energy induced by a lightning discharge enters into the magnetosphere as whistler mode waves is up to several thousands of kilometres wide.
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Diendorfer G., R. Kaltenböck, M. Mair, H. Pichler: Characteristics of Tower Lightning Flashes in a Winter Thunderstorm and related Meteorological Observations

19^th International Lightning and Detection Conference and  1^st International Lightning Meteorology Conference (ILDC/ILMC), Tucson, Arizona, 2006 In the past a considerable number of papers on winter lightning in the costal area of the Sea of Japan has been published. But very limited information is available about winter lightning characteristics in other regions. Every year a few winter thunderstorms occur over the area of Austria. In this paper we present the analysis of one specific winter thunderstorm with special regard to meteorological aspects and lightning activity. The investigation is limited to the area of Salzburg where several flashes have been recorded at the instrumented tower on Gaisberg, which is located very nearby.
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Campos L. Z. S., M. M. F. Saba, M. G. Ballarotti, O. Pinto Jr., W. Schulz: Characteristics of preliminary Breakdown for first Strokes and subsequent New-Channel Strokes

International Conference on Grounding and Earthing and 2^nd International Conference on Lightning Physics and Effects (GROUND/LPE), Maceió, Brazil, 2006
The aim of this work is to obtain some characteristics of the preliminary breakdown (PB) pulses for negative cloud-to-ground flashes. We present the correlation between the electric field peak of first strokes and subsequent new-channel strokes and the time interval from the beginning of the PB and the stroke event. For this purpose we employed a high-speed observation system (with a time resolution of 1000 frames per second), electric field measurements (flat plate antenna) and data from the Brazilian Lightning Location System - RINDAT. All the measurement systems were synchronized with GPS. All measurements and observations were made in S. José dos Campos (45.864°W; 23.215°S), Brazil. The beginning of the PB pulses could be determined both in the electric field data and in the high-speed video recordings (in which it is possible to observe a low intensity light emission from the cloud). The identification of this instant is a very difficult task in the absence of the images. The electric field peak values of the strokes were all normalized to 100 km, based on the location solution given by RINDAT. An amount of 30 first strokes and 16 subsequent new-channel strokes, all from the same day (March 23rd, 2005), were analyzed, and
their data (PB to stroke time interval versus the inverse of the stroke electric field peak) were plotted. The graph obtained for first strokes showed a linear relationship (correlation coefficient: 0.85). No correlation was found for subsequent new-channel strokes.
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Schulz W., J.-Y. Lojou: Total Lightning Detection Network in Central Europe: The F.L.A.S.H. Project

19^th International Lightning and Detection Conference and  1^st International Lightning Meteorology Conference (ILDC/ILMC), Tucson, Arizona, 2006 In this paper we present the results of a recent study on lightning statistics in Switzerland during an eightyear period from 1999 till 2006, using data from the EUCLID (European Cooperation of Lightning Detection) LLS (Lightning Location System). After a brief presentation of the history of lightning detection in Switzerland, statistics of some salient lightning parameters in Switzerland are presented. It is shown that there is a relatively high lightning activity in Switzerland especially in the Canton of Tessin, located south of the Alps. Additionally, it is found that the lightning flash density in some regions of Switzerland (Tessin) is higher than the maximum lightning flash density in Austria and Germany while the flash median peak current and the number of strokes per flash (flash multiplicity) are similar in the three countries. We observed a significant improvement of network performance from 1999 to 2006.
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