2011

Zhou, H., G. Diendorfer, R. Thottappillil, H. Pichler, M. Mair: Upward Positive Lightning Flashes Observed from the Gaisberg Tower from 2000 – 2009

3^rd International Symposium on Winter Lightning (ISWL), Sapporo, Japan, 2011 In this paper, we report the measured current characteristics of positive lightning discharges observed from the Gaisberg Tower (GBT) in Austria from 2000 to 2009. Based on the recorded current waveforms, a total of 26 flashes were identified as upward positive discharges initiated by an upward negative leader from the top of the GBT, consisting of initial stage current only, without any leader-return-stroke sequences. No downward positive flashes containing microsecond-scale current waveforms of return strokes were observed. The occurrence of upward positive flashes accounts for 4% (26/652) of the total number of recorded flashes at the GBT during the 10-year observation period. Nineteen (73%) out of the 26 flashes occurred during non-convective or cold season (September- March). Median values of flash peak current, flash duration, flash charge transfer, and flash action integral were determined as 5.2 kA, 82 ms, 58 C and 0.16×103 A2s, respectively. Narrow current pulses of high repetition rate, different from normal initial continuous current (ICC) pulses typical for upward negative flashes, were found during the initial portion of the ICC for these upward positive flashes. Based on simultaneous current and electric field measurements at a distance of 170 m from the GBT these pulses are inferred to be associated with the stepping process of the upward propagating negative leaders initiated from the tower top. PDF File (284 KB)

Diendorfer, G., H. Zhou, H. Pichler: Review of 10 years of lightning measurement at the Gaisberg Tower in Austria

3^rd International Symposium on Winter Lightning (ISWL), Sapporo, Japan, 2011 First instrumentation for lightning measurements at the Gaisberg Tower (GBT) has been installed in 1998. During the 10-years period from 2000 – 2009 a total of 652 lightning events have been recorded. Fast majority of the lightning to the GBT was upward initiated and only very few records are candidates for downward flashes when the recorded current waveform is used for discrimination between upward and downward lightning. Most of the lightning to the GBT (about 60%) is observed during cold season, comparable to winter lightning in Japan. 3% (21/652) of the flashes were bipolar and 4% (26/652) were positive. Maximum measured charge transfer to ground in a single flash was 546 C. 10 out of the 652 flashes (1.5 %) transferred charge values exceeding 300 C and all those events occurred during cold season. Median peak current of return strokes following the initial continuing current is 9.2 kA and similar to values observed in triggered lightning and to peak current estimates for subsequent strokes from lightning location systems. PDF File (1,6 MB)

Campos L.Z.S., M.M.F. Saba, C. Schumann, W. Schulz: Characterization of M Components in Positive Lightning from High-Speed Video and Electric Field Data

3^rd International Symposium on Winter Lightning (ISWL), Sapporo, Japan, 2011 Recent high-speed video experiments have indicated that positive cloud-to-ground lightning (+CG) might present M components during their continuing current period [1]. As only optical data were available, their results consisted mainly on occurrence- and time-related parameters and their statistical distribution. In the present work we address this issue by extending those investigations through the addition of simultaneous slow and fast electric field data (obtained through the use of capacitive antennas) to the high-speed camera recordings (obtained by two different cameras, Red Lake Motion Scope 8000S and Photron Fastcam 512 PCI, operating at frame rates ranging from 1000 or 8000 frames per second). Through the use of an algorithm previously developed by the authors [1-2] we were able to plot luminosity-versus-time curves of each continuing current recorded by the cameras. Once an individual M component is identified in this luminosity data, it is possible to find the electric field change it has produced and that could be measured by the antennas. By using a simple electrostatic model it is possible to estimate the peak current and total charge transfer to ground of each M component observed from the slow electric field data. These intensity-related parameters can be also be correlated to occurrence- and time-related parameters such as duration, elapsed time since the return stroke and time interval between successive M components, making it possible to see at which periods of a continuing current M components can be more or less intense. This type of data is very relevant for both engineering applications (such as EMC studies [3]) and scientific research (especially sprite initiation [4] and the bidirectional leader model for lightning [5]). PDF File (471 KB)

Schuhmann C., M.M.F. Saba, L.Z.S. Campos, R.B.G. da Silva, W. Schulz: Leader Characteristics in Positive Cloud-to-Ground Lightning Flashes

3^rd International Symposium on Winter Lightning (ISWL), Sapporo, Japan, 2011 Past results from streak photographs by Berger and Vogelsanger [1] show that there may be no steps on the positive leader propagation. Steps in positive leader propagation have never been observed by high speed cameras with frame rates up to 8000 frames per second [2]. However some other studies found pulses on the electric field during the progression of the leader toward ground that could indicate the presence of steps in the leader propagation. Hojo et al. [3] observed electric field leader pulses in 26-30% of their cases, with mean time interval of about 17µs (ranging from 3 µs  to 31 µs ). Proctor [4] observed two out of 175 flashes in South Africa that show pulses on the leader. Cooray and Lundquist [5] reported step pulses within a mean time interval of 26µs for positive lighting in Sweden. This work presents high-speed video camera and electric field measurements of downward leaders in positive cloud-to-ground lightning in Brazil. Several cases were analyzed and the percentage of leaders containing pulses is reported. PDF File (234 KB)

Campos L.Z.S., M. M. F. Saba, W. Schulz, O. Pinto Jr.: Observations of natural cloud-to-ground lightning leaders from simultaneous high-speed video recordings and electric field measurements

14^th International Conference on Atmospheric Electricity (ICAE), Rio de Janeiro, Brazil, 2011 The aim of this investigation is to analyze the phenomenology of positive and negative (stepped-, dart- and recoil) leaders observed in natural lightning from simultaneous high-speed video recordings and electric field measurements. For that intent we have used two different high-speed cameras (obtained by two different cameras, Red Lake Motion Scope 8000S and Photron Fastcam 512 PCI, operating at frame rates ranging from 1000 or 8000 frames per second) and two different types of electric field sensors (slow and fast) in addition to data from a lightning locating system (BrasilDat). All the instruments were GPS time synchronized in order to avoid ambiguities in the analysis and allow us to estimate the peak current of and the distance to each flash that was detected by BrasilDat. From these data it is possible to calculate the two-dimensional speed of each observed leader, allowing us to obtain its statistical distribution along with its correlation to other characteristics of the associated flash, such as return stroke peak current, interstroke interval and presence and duration of continuing current after the return stroke initiated by the leader. Also, the availability of electric field data makes it possible to correlate it to the optical characteristics of each leader type, providing us new insights on the microphysics of these phenomena. In the analyzed dataset, the speeds of positive leaders and negative dart-leaders follow a lognormal distribution at the 0.05 level (according to the Shapiro-Wilk test), while the negative stepped leaders have a similar distribution even though according to a relatively weaker test (Kolmogorov-Smirnov). Unfortunately, due to the range of frame rates reached by the used cameras, only the minimum propagation speeds could be estimated in the recoil leaders that were observed. PDF File (428 KB)

Schuhmann C., M.M.F. Saba, W. Schulz, R.G.B. da Silva: Electric field waveforms of positive return strokes

14^th International Conference on Atmospheric Electricity (ICAE), Rio de Janeiro, Brazil, 2011 Positive flashes are usually composed of a single stroke. A large fraction of the positive cloud-to-ground (+CG) flashes (81%) produces just a single-stroke, and the average multiplicity is only 1.2 strokes per flash. Almost all (~95%) subsequent strokes in multiple-stroke +CG flashes create a new ground termination [Saba et. al. 2010]. In the present work we combine high-speed video recordings (obtained by two different cameras, Red Lake Motion Scope 8000S and Photron Fastcam 512 PCI, operating at frame rates ranging from 1000 or 8000 frames per second) with fast electric field measurements (obtained through the use of flat plate antennas) to investigate the characteristics of the electric field changes produced by leader pulses and return stroke in positive flashes. PDF File (410 KB)

Diendorfer, G.: Lightning Initiated from Tall Structures – a Review

11^th International Symposium on Lightning Protection (SIPDA), Fortaleza, Brazil. (invited), 2011 Current parameters of tower triggered lightning are of interest for the lightning protection of high objects, such as wind turbines. Initiation conditions of upward lightning are still subject of ongoing research and probably needs consideration of local conditions. In this paper results of measurements of upward lightning from the Gaisberg Tower (GBT) in Austria are summarized and compared with some other measurements on towers or rocket-triggered lightning. Upward lightning initiated by a positive upward leader is the most common type (93%) of lightning observed at the GBT, nevertheless 3% of the discharges are bipolar and 4% of the tower flashes are lowering positive charge to ground. Positive flashes are initiated by a negatively charged leader and short current pulses associated with the stepping leader process are observed. No PDF Download Download Link

Zhou, H., G. Diendorfer, R. Thottappillil, H. Pichler, M. Mair: Close Electric Field Changes Associated with Upward-Initiated Lightning at the Gaisberg Tower

11^th International Symposium on Lightning Protection (SIPDA), Fortaleza, Brazil. (invited), 2011 We examine in detail the simultaneous lightning current waveforms, close electric field changes, and lighting location system data for upward lightning discharges initiated from the Gaisberg Tower (GBT) from 2005 to 2009. Out of 205 upward flashes, we find that most of upward flashes (179/205 or 87%) are initiated at the tower top without any nearby preceding discharge activity, 26 flashes (13%) are initiated by nearby triggering lightning discharges, including 10 positive cloud-to-ground lightning, 1 negative cloud-to-ground lightning, and 15 cloud discharges. The possible reasons for self-triggered upward flashes dominating at the GBT would be the field enhancement due to the Gaisberg Mountain above 800 m of the surrounding terrain of the city of Salzburg and low cloud base during cold season. No PDF Download Download Link

Romero, C., M. Paolone, F. Rachidi, M. Rubinstein, A. Rubinstein, G. Diendorfer, W. Schulz, M. Bernardi, C. A. Nucci: Preliminary Comparison of Data from the Säntis Tower and the EUCLID Lightning Location System

11^th International Symposium on Lightning Protection (SIPDA), Fortaleza, Brazil, 2011 In this paper, direct lightning current measurements obtained on the Säntis Tower from June 1st, 2010 to May 31st, 2011 are used to evaluate the ability of the EUCLID lightning detection network to detect this type of lightning triggered by a tall tower in terms of detection efficiency, location accuracy and peak current estimates. The Säntis Tower is a 124-meter tall tower sitting on the top of the Säntis Mountain (2500 m) in Switzerland. The tower has been instrumented to measure waveforms of the lightning current and of its time derivative. In the considered period, 57 flashes were recorded at the Säntis Tower out of which 15 were of positive polarity. The data have been correlated to EUCLID data by comparing the time-stamps provided by the GPS time references. The flash detection efficiency for negative flashes is estimated to be 93%. The median value of the location error is 126 m. The EUCLID peak current estimates were on average significantly larger than the measured current. The measurements include four typical positive flashes, which were successfully detected by EUCLID. The location errors for the positive events ranged from 1 to 3 km, with a median of 959 m. No PDF Download Download Link

Birkl, J., T. Böhm, E. Schulzhenko, P. Zahlmann G. Diendorfer, H. Pichler: Comparative Lightning Current Measurements on Gaisberg Tower

11^th International Symposium on Lightning Protection (SIPDA), Fortaleza, Brazil, 2011 Comparison measurements with a mobile lightning current detection system and measuring station used for scientific purposes were carried out. The mobile system including sensors, data acquisition and transmission are described. The lightning current parameters recorded during comparative measurements are analyzed. The results are in line with the lightning current statistics. Mainly upward initiated flashes were measured. No PDF Download Download Link

Smorgonskiy, A., F. Rachidi, M. Rubinstein, G. Diendorfer, W. Schulz, N. Korovkin: A New Method for the Estimation of the Number of Upward Flashes from Tall Structures

11^th International Symposium on Lightning Protection (SIPDA), Fortaleza, Brazil, 2011 A new method to estimate the number of upward flashes from tall structures is presented. The method is based on the analysis of the data provided by lightning location systems (LLS) and thus could be applied for any tall structure located in the region covered by a LLS. About 80 tall objects in Europe with heights ranging from 100 m to 300 m were selected for the analysis. LLS data for a period of 10 years on flashes within circles of 8 km around each object were exported from the EUCLID network database and analyzed. The number of upward flashes for each considered structure was estimated and the obtained results were compared with those calculated using the empirical formula of Eriksson. For towers located on hilly terrain, the physical height of the structure was replaced by ist effective height determined according to the IEC recommendation. The obtained results follow the trend predicted by Eriksson’s formula. However, significant dispersion is observed. This dispersion might be attributed essentially to meteorological and geological factors associated with different objects. No PDF Download Download Link

Diendorfer, G., H. Zhou, R. Thottappillil, H. Pichler: Review of Upward Positive and Bipolar Lightning Flashes at the Gaisberg Tower

7^th Asia-Pacific International Conference on Lightning (APL), Chengdu, China. (invited), 2011 First instrumentation for lightning measurements at the Gaisberg Tower (GBT) has been installed in 1998. During the 10-years period from 2000 – 2009 a total of 652 lightning events have been recorded. Vast majority of the lightning to the GBT was upward initiated and only one record is a candidate for a downward flash when the recorded current waveform is used for discrimination between upward and downward lightning. 3% (21/652) of the flashes were bipolar and about the same number of 4% (26/652) were positive. 73% of positive and 63% of bipolar lightning was triggered by the GBT during cold season in Austria. No PDF Download Download Link

Zhou, H., G. Diendorfer, R. Thottappillil, H. Pichler, M. Mair: Mixed Mode of Charge Transfer to Ground for Initial Continuous Current Pulses in Upward Lightning

7^th Asia-Pacific International Conference on Lightning (APL), Chengdu, China, 2011 In this paper, we discuss properties of initial continuous current (ICC) pulses superimposed on the slow varying initial stage current in upward flashes initiated from the Gaisberg Tower (GBT) based on simultaneous current, near/far electric field measurements. ICC pulses are usually associated with M-component mode of charge transfer to ground, if only one branch of the lightning channel is active. However, there are several cases in which ICC pulses involve a predominantly leader/return-stroke mode of charge transfer to ground in a new channel that connects to the old channel carrying continuous current. With the help of high-speed video camera records, we find that this mixed mode of charge transfer for ICC pulses, leader-return stroke in one channel and continuous current in another channel, occurring simultaneously during the initial stage current in upward lightning from tall towers is very common. This is in contrast to triggered-lightning where usually only one channel is dominant and ICC pulses are associated predominantly with M-component mode of charge transfer. Also, ICC pulses with mixed-mode of charge transfer have shorter risetimes, larger peaks, and shorter half-peak widths. No PDF Download Download Link

Smorgonskyi, A., F. Rachidi, M. Rubinstein, G. Diendorfer, W. Schulz: On Lightning Incidence to Tall Structures

7^th Asia-Pacific International Conference on Lightning (APL), Chengdu, China, 2011 We compare in this paper direct measurements obtained at Tower 1 on Mount San Salvatore (Switzerland) and the Gaisberg Tower (Austria). They are situated in similar topographical environment but in different lightning activity
zones. Direct measurements of lightning currents on these two towers have revealed a major difference in terms of the number of downward flashes. While Berger and co-workers obtained a significant number of downward flashes, more recent observations on Gaisberg and Peissenberg Towers were essentially composed of upward flashes. We use in this paper a new method to estimate the proportion of upward/downward flashes to a given tower, based on data from lightning location systems. The analysis using the proposed method explains the discrepancy in terms of the measured number of downward flashes in Gaisberg and in Monte San Salvatore. PDF File (429 KB)

Fiser J., J. Chum, G. Diendorfer, M. Parrot, O. Santolik: An Investigation of Whistler Intensities above Thunderstorms

Union Radio-Scientifique Internationale (URSI), General Assembly, Istanbul, Turkey, 2011 We study a penetration of whistlers to the ionosphere. We developed an automatic method for assigning causative lightning to fractional-hop whistlers observed on the DEMETER satellite. Processing data from 364 passes of the satellite over Europe, we found that at nighttime, a mean whistler intensity is approximately three times larger than at daytime. A maximum of whistler intensity is shifted approximately one degree from the satellite magnetic footprint owing to the oblique propagation. Calculations of wave attenuation made using IRI2007 and MSIS models show very similar result in a ratio of nighttime and daytime intensities. No PDF Download Download Link

Zhou, H., G. Diendorfer, R. Thottappillil, H. Pichler, and M. Mair: Characteristics of upward bipolar lightning flashes observed at the Gaisberg Tower

Journal of Geophysical Research: Atmospheres, 116, D13106, doi:10.1029/2011JD015634, 2011 We analyze current records for 21 upward initiated bipolar lightning flashes observed at the Gaisberg Tower (GBT) in Austria from 2000 to 2009. A bipolar lightning flash occurrence of 3% (21/652) is found during the 10‐year observation period. Thirteen (62% or 13/21) of them occurred in nonconvective season (September–March). On the basis of the classification suggested by Rakov and Uman (2003), 13 (62%) of the 21 bipolar flashes belong to Type 1 associated with a polarity reversal during the initial stage (IS) current, five belong to Type 2 associated with different polarities of the IS current and the following return strokes, one belongs to Type 3 associated with
return strokes of opposite polarity following the IS, and two of them are not assigned.
We also find that the initial polarity reversal from negative to positive occurs more often (76% or 16/21) than that from positive to negative within a bipolar flash, in agreement with observations in other studies. The geometric mean (GM) and arithmetic mean (AM) of the total absolute charge transfer are 99.5 C and 125 C, with the GM and AM total flash duration of 320 ms and 396 ms, respectively. From simultaneous current and high‐speed video measurements of one bipolar flash, within the field of view, the positive charge was transferred along one branch initially, followed by the negative charge transfer after cessation of the luminosity for 142 ms, while the other two branches connected to the main channel always contributed to the negative charge transfer during the whole process. No PDF Download Download Link

Zhou, H., G. Diendorfer, R. Thottappillil, H. Pichler: Fair-weather Atmospheric Electric Field Measurements at the Gaisberg Mountain in Austria

Progress In Electromagnetics Research Symposium (PIERS) Proceedings, Marrakesh, Morocco, 2011 A field mill (FM) has been permanently operated at a distance of about 170m from the Gaisberg Tower (GBT) in Austria since several years. The electric field measurements suffer from field enhancement due to its location on a 4-m tall metal platform near the tower which itself is located on a 1280 meter high mountain. A special measuring campaign was conducted to determine the fair-weather atmospheric electric field at the Gaisberg Mountain on June 24th, 2010. The main objectives of this campaign were to calibrate the field mill in order to infer the relation between the electric fields at the tower tip and the ground level measured by the field mill under thunderstorm conditions. Besides the permanent field mill near the tower, two Campbell Scientific CS100 electric field meters were used during this campaign, and distances between each other were determined by using the Global Positioning System (GPS). Overall we determined an enhancement factor of 2.75 due to the mountain itself with reference to the mountains surrounding terrain. A field enhancement factor of 7.81 was obtained for the permanently installed field mill at the measurement platform next to the GBT with reference to the undisturbed electric field at the mountain top close to the platform at ground level. The electric field near the tower (distances about the tower height of 100 m) was smaller than the field measured at larger distance from the Tower. This observation was possibly caused by a shadowing effect of the tower. PDF File (278 KB)

Birkl, J., T. Böhm, E. Shulzhenko, P. Zahlmann, G. Diendorfer, H. Pichler: Mobiles Messsystem zur Blitzstromerfassung

Elektrotechnik und Automation (ETZ), Heft 7, 2011 Weltweit wurden in den vergangenen Jahrzehnten Blitzstrommessungen zur wissenschaftlichen Grundlagenforschung an verschiedenen Blitzmess-stationen durchgeführt. Bedingt durch den wissenschaftlichen Ansatz dieser Untersuchungen sind deren Messsysteme technisch sehr aufwendig und somit nur bedingt für einen mobilen Einsatz an wechselnden Standorten geeignet. Das in diesem Beitrag vorgestellte mobile Blitzstromerfassungssystem erlaubt hingegen Messungen an unterschiedlichen Standorten und Anlagen, zum Beispiel Windenergieanlagen, Telekommunikationstürmen oder hohen Bürogebäuden. Die Erfassung und Bewertung von tatsächlich stattgefundenen Blitzeinschlägen in solchen Anlagen ermöglicht es beispielsweise, die Notwendigkeit von Wartungsmaßnahmen nach Blitzeinschlägen zu bewerten. PDF File (1,8 MB)

Schulz W.: Performance Evaluations of the European Lightning Location System EUCLID

6^th European Conference on Severe Storms (ECSS), Palma de Mallorca, Balearic Islands, Spain, 2011 In 2001 several countries (Austria, France, Germany, Italy, Norway and Slovenia) started a cooperation called EUCLID (EUropean Cooperation for LIghtning Detection). It is the goal of this cooperation to provide European wide lightning data with nearly homogeneous quality. Subsequently also Spain, Portugal, Finland and Sweden joined EUCLID. The EUCLID cooperation is special in the sense that the individual partners are highly motivated to run their individual networks with state-of-the-art lightning sensors. All the partners employ dedicated technicians to supervise and maintain the network and to react fast in case of sensor or communication problems. As of August 2011 the EUCLID network employs 142 sensors, 4 LPATS III, 13 LPATS IV, 1 SAFIR, 16 IMPACT, 42 IMPACT ES/ESP and 66 LS7000 sensors (oldest to newest), all operating over the same frequency range with individually-calibrated gains and sensitivities.  Data from all of these sensors are processed in real-time using a single common central processor, which also produces daily performance analyses for each of the sensors. This assures that the resulting data are as consistent as possible throughout Europe. In fact, the Europe-wide data produced by EUCLID is frequently of higher quality than the data produced by individual country networks, due to the implicit redundancy produced by shared sensor information.  Further, this cooperation also acts as a platform for exchange of knowledge related to lightning location technology. Since the beginning of the cooperation the performance of the EUCLID network has been steadily improved, e.g. with improved location algorithms, with newer sensor technology and by adapting sensor positions because of bad sites.  Over the next 1-2 years, at least 15 of the older sensors are expected to be upgraded to the newest (LS700x) instruments. To compare the estimated performance to real values several measurement campaigns were carried out in Europe, e.g. in Slovenia where LLS data was compared to data from GPS synchronized flash counters installed on mobile phone towers [1] – [2], in France where video surveys were used to determine the actual network performance of the French lightning location system [3]. In the presentation detailed performance results from a comparison with direct lightning current measurements on a tower and from video and E-field measurements in Austria will be provided. REFERENCES

1. Djurica V., Kosmač J.: LLS Accuracy improvements by measurements collected by the RLDN, 19th International Lightning Detection Conference, Tucson, USA, 2006.
2. Djurica V., G. Milev , J. Kosmač: Lightning location networks performance validation with RLDN, 16th International Symposium on High Voltage Engineering, South Africa, 2009.
3. Berger, G. and S. Pedeboy: Comparison between real CG flashes and CG flashes detected by a lightning detection network, ICOLSE, Blackpool, 2003.

Schulz W., H. Pichler, G. Diendorfer: Überprüfung der Performance des österreichischen Blitzortungssystems ALDIS und Ausblick auf weitere Verbesserungen

Meteorologentag, 2011 Das österreichische Blitzortungssystem ALDIS ist seit fast 20 Jahren in Betrieb und während dieser Zeit wurde das System immer wieder verbessert. Speziell das Upgrade der Sensoren im Jahr 2005 und die Verbesserungen im Ortungsalgorithmus der letzten Jahre machen eine neuerliche Überprüfung der Performance notwendig. Die wichtigsten Performance Parameter eines Blitzortungssystems sind die Detection Efficiency, die Ortungsgenauigkeit, die Genauigkeit der Blitzstromamplituden-bestimmung und die Zuverlässigkeit der Klassifizierung der einzelnen Entladungen als Wolke-Erde Entladung oder Wolkenentladung. Um alle diese Performance Parameter zu überprüfen, sind vom Blitzortungssystem völlig unabhängige Messungen notwendig. Aus diesem Grund  wurden von ALDIS in den letzten Jahren sowohl Blitzstrommessungen am ORS Sendemast am Gaisberg als auch  Video- und E-Feldmessungen an mehreren Orten Ostösterreichs durchgeführt. Im unserem Beitrag möchten wir die Resultate dieser Messungen präsentieren und einen Ausblick auf weitere Verbesserungen in den nächsten Jahren geben.

Prinz T., W. Spitzer, C. Neuwirth, W. Schulz, G. Diendorfer, A. Keul: GIS Analysis of Austrian-Bavarian Cloud-to-Ground Lightning Data

6^th European Conference on Severe Storms (ECSS), Palma de Mallorca, Balearic Islands, Spain, 2011 Based on lightning records provided by the Austrian Lightning Detection and Information System (ALDIS), the cloud-to-ground (CG) lightning structure was analyzed. The cross-border study site covers an area of 40,000 square kilometres encompassing the Austrian Federal province of Salzburg and south-east Bavaria, Germany. From 1998 to 2009 about 1 million CG lightning flashes occurred in the area populated by roughly 1.3 million inhabitants. In order to analyze CG lightning activity fine-grain concerning the spatiotemporal distribution of lightning occurrence and the coherence between lightning activity and topographic properties, a geographic information system (GIS) was used. Furthermore, a cross-border approach for the derivation of hazard zones as an indicator for the optimization of preventive measures was developed. Consequently, the results of this study can be used as a decision support for lightning prevention, risk management, spatial planning and civil protection. PDF File (430 KB)

Spitzer W., W. Schulz, T. Prinz und A. Keul: GIS-basierte Methode zur genaueren Schätzung der Blitzdichte

Symposium und Fachmesse für Angewandte Geoinformatik (AGIT), Salzburg, Austria, 2011 Karten zur Blitzdichte sind eine international übliche Darstellungsform der Blitzhäufigkeit und dienen u.a. der Abschätzung des Blitzrisikos und in weiterer Folge der Auswahl geeigneter Schutzmaßnahmen. Blitzortungssysteme erfassen die Koordinaten von Blitzentladungen und damit die Grundlage zur Berechnung der Blitzdichte. Die räumliche Genauigkeit jeder einzelnen Blitzortung wird dabei quantifiziert. Herkömmliche Methoden zur Punktdichteschätzung berücksichtigen die Ortungsgenauigkeit meist nur mit pauschalen Annahmen für alle Punkte, obwohl die Genauigkeit der Blitzortung stark variiert. Der gegenständliche Beitrag stellt mit der probabilistischen Blitzdichte eine innovative GIS-basierte Methode zur Schätzung der Blitzdichte unter Berücksichtigung der individuellen Ortungsgenauigkeit vor und vergleicht diese mit etablierten Methoden der Blitzdichteschätzung. PDF File (696 KB)

Smorgonskiy A., F. Rachidi, M. Rubinstein, G. Diendorfer, W. Schulz: On the proportion of upward flashes to lightning research towers

7^th Asia-Pacific International Conference on Lightning (APL), Chengdu, China, 2011 We compare in this paper direct measurements obtained at the Towers on Mount San Salvatore (Switzerland) and the Gaisberg Tower (Austria). They are situated in similar topographical environments but in different lightning activity zones. Direct measurements of lightning currents on these towers have revealed a major difference in terms of the number of downward flashes. While Berger and co-workers obtained a significant number of downward flashes, more recent observations on the Gaisberg and Peissenberg Towers were essentially composed of upward flashes. We use in this paper a new method to estimate the proportion of upward/downward flashes to a given tower, based on the data from lightning location systems. The analysis using the proposed method explains the discrepancy in terms of the measured number of downward flashes in Gaisberg Tower and in Monte San Salvatore Tower No PDF Download Download Link

Mosaddeghi A., A. Shoory, F. Rachidi, M. Rubinstein, G. Diendorfer, H. Pichler, D. Pavanello: Lightning Return Strokes to Tall Towers: Ability of Engineering Models to Reproduce Nearby Electromagnetic Fields

Union Radio-Scientifique Internationale (URSI), General Assembly, Istanbul, Turkey, 2011 We present measurements of nearby vertical and horizontal electric fields from leaders and return strokes
associated with lightning strikes to the 100-m tall Gaisberg Tower in Austria obtained in 2007 and 2008. The fields were measured at a distance of about 20 m from the tower’s vertical axis. Simultaneously with the fields, return-stroke currents were also measured at the top of the tower. The measured data are used to test engineering models for the return stroke. In general, the agreement between measured waveforms and model-predicted ones are satisfactory. No PDF Download Download Link