2007

Manoochehrnia P., F. Rachidi, M. Rubinstein, W. Schulz:
Lightning Statistics in Switzerland

IX International Symposium on Lightning Protection (SIPDA), Foz do Iguaçu, Brazil, 2007

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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Pichler H., M. Mair, G. Diendorfer:
Correlated current and far field records from lightning discharges to the Gaisberg Tower

IX International Symposium on Lightning Protection (SIPDA), Foz do Iguaçu, Brazil, 2007

Simultaneous measurements of lightning current and associated radiated fields from tower lightning are of fundamental interest for various reasons in lightning research. These data can be used for the evaluation of return stroke models or to investigate the so called tower effect when lightning hits an elevated object [1].

In this paper we show first results of simultaneously measured far-field waveforms at a distance of 78.8 km together with the corresponding current pulses measured at the top of the instrumented Gaisberg tower in Austria. We have analyzed the Ep/Ip ratios separately for two distinct groups of current pulses observed at the tower, the so called á-pulses, which are superimposed on the initial continuing current and the â-pulses, which occur after the initial continuing current. It is generally accepted, that â-pulses are assumed to be most comparable to subsequent strokes in flashes to ground.

Based on the available experimental data we determined a field enhancement factor of 1.6 compared to the predicted transmission line model Ep/Ip ratio. This observation is comparable to results with triggered lightning data [2] and agrees with a calculated enhancement factor for an “electrically short tower” in [1].

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Diendorfer G.:
Lightning Location System (LLS)

IX International Symposium on Lightning Protection (SIPDA), Foz do Iguaçu, Brazil, 2007

Nowadays various techniques are employed to locate lightning activity over large areas. Electric and/or magnetic field sensors in the VLF, LF and VHF frequency ranges measure the lightning radiated electromagnetic fields. For locating ground strike points magnetic direction finding (MDF), time-of-arrival (TOA), or a combination of both (MDF+TOA) is employed. Major difference between those techniques is the minimum number of sensor required to calculate a stroke location. Network configuration (mean baseline between sensors, network geometry) and the type of sensors employed strongly affect the achievable detection efficiency (DE) and the resulting peak current distribution. Normally it is the strokes with small peak currents that are missed by lower DE networks and this results in a bias of the peak current distribution to higher values. In this paper we present some results of model calculations and performance evaluation of a LLS based on directly measured lightning to an instrumented tower in Austria.

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Filho A.O., W. Schulz, M. M. F. Saba, O. Pinto Jr., M. G. Ballarotti:
First and subsequent stroke electric field peaks in negative cloud-to-ground lightning

IX International Symposium on Lightning Protection (SIPDA), Foz do Iguaçu, Brazil, 2007

In this paper we show details about the relationship between first and subsequent stroke electric field peak in negative cloud-to-ground lightning in Brazil.
A field measurement campaign during summer 2006 in Brazil collected electric field data with a GPS synchronized fast electric field flat-plate antenna. The data analysis shows that the ratio between first stroke fields and subsequent stroke fields in Brazil and in Austria is smaller than in Florida and that the ratio which is including single strokes, differs significantly even between Austria and Brazil. We further found that 38.2% of the flashes in Brazil had at least one subsequent stroke peak field greater than the first stroke peak field.

PDF File (796 KB)

Filho O. A., W. Schulz, M. M. F. Saba, O. Pinto Jr., M. G. Ballarotti:
The relationship between first and subsequent stroke electric field peak in negative cloud-to-ground lightning

13th International Conference on Atmospheric Electricity (ICAE), Beijing, China, 2007

In this paper we show details about the relationship between first and subsequent stroke electric field peak in negative cloud-to-ground lightning in Brazil. A field measurement campaign during summer 2006 in Brazil collected electric field data with a GPS synchronized fast electric field flat-plate antenna. The data analysis shows that the ratio between first stroke fields and subsequent stroke fields in Brazil and in Austria is smaller than in Florida and that the ratio which is including single strokes, differs significantly even between Austria and Brazil. We further found that 38.2% of the flashes in Brazil had at least one subsequent stroke peak field greater than the first stroke peak field.

PDF File (167 KB)

Montanyà J., S. Soula, G. Diendorfer, G. Solà, D. Romero:
Analysis of the Altitude of the Isotherms and the Electrical Charge for Flashes that Struck the Gaisberg Tower

13th International Conference on Atmospheric Electricity (ICAE), Beijing, China, 2007

The features of lightning flashes occurring on tall structures can give some valuable information about their initiation, especially the cases of upward flashes for lightning protection of tall structures such as wind-turbines. More than 300 flashes which struck the Gaisberg tower (Austria) have been analyzed in order to investigate differences in occurrence conditions between winter and summer. More flashes struck the tower in winter unlike the Austrian lightning activity is much lower during this season. These winter flashes deposit to ground more electrical charge than summer ones. The median values of the -10 ºC isotherm altitudes during winter are 2-km lower than during summer. This difference would produce stronger electric fields at ground level which could favor the triggering of upward flashes.

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Kleiter I., R. Luerding, G. Diendorfer, H. Rek, U. Bogdahn, B. Schalke:
A lightning strike to the head causing a visual cortex defect with simple and complex visual hallucinations

Journal of Neurology, Neurosurgery & Psychiatry (JNNP), 78;423-426, doi:10.1136/jnnp.2006.097642, 2007

The case of a 23-year-old mountaineer who was hit by a lightning strike to the occiput causing a large central visual field defect and bilateral tympanic membrane ruptures is described. Owing to extreme agitation, the patient was set to a druginduced coma for 3 days. After extubation, she experienced simple and complex visual hallucinations for several days, but otherwise recovered largely. Neuropsychological tests revealed deficits in fast visual detection tasks and non-verbal learning, and indicated a right temporal lobe dysfunction, consistent with a right temporal focus on electroencephalography. Four months after the accident, she developed a psychological reaction consisting of nightmares with reappearance of the complex visual hallucinations and a depressive syndrome. Using the European Cooperation for Lightning Detection network, a meteorological system for lightning surveillance, the exact geographical location and nature of the lightning flash were retrospectively retraced.

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