Statistical Distributions of Lightning Currents Associated With Upward Negative Flashes Based on the Data Collected at the Säntis (EMC) Tower in 2010 and 2011

Romero, C.; Rachidi, Farhad; Paolone, Mario; Rubinstein, Marcos

doi:10.1109/tpwrd.2013.2254727

Cited by 59 publications

(33 citation statements)

References 17 publications

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“…It is worth noting that the number of pulses per flash (multiplicity) for upward flashes measured at Säntis has a median value of about 8 [ Romero et al ., ], which is about twice as high as the multiplicity of downward flashes [CIGRE WG C4.407 Report 549, ]. This might explain the obtained high value for the EUCLID efficiency in detecting Säntis flashes, despite the fact that upward flashes do not have first strokes.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the performance characteristics of the European Lightning Detection Network EUCLID in the Alps region for upward negative flashes using direct measurements at the instrumented Säntis Tower

et al. 2016

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In this paper, we present a performance analysis of the European Cooperation for Lightning Detection (EUCLID) lightning detection network using data obtained on lightning currents measured at the Säntis Tower (located in northeastern of Switzerland) from June 2010 to December 2013. In the considered period of analysis, a total number of 269 upward negative flashes were recorded at the Säntis Tower. The performance of the EUCLID lightning detection network is evaluated in terms of detection efficiency, location accuracy, and peak current estimates for upward flashes. Excluding flashes containing only an initial continuous current with no superimposed pulses exceeding 2 kA, the flash detection efficiency for upward flashes is estimated to be 97%. The recorded flashes contained a total of 2795 pulses (including return strokes and International Conference on Communications pulses characterized by risetimes lower than 8 μs and peaks greater than 2 kA). The overall pulse detection efficiency was found to be 73%. For pulses with peak values higher than 5 kA, the pulse detection efficiency was found to be about 83%. Peak current estimates provided by the EUCLID network were found to be significantly larger than their directly measured counterparts. This overestimation might be attributed to the enhancement of the radiated electromagnetic fields associated with the presence of the tower and the mountain. The median of the absolute distance error, defined as the median distance between the Säntis Tower location and the EUCLID's stroke locations, was found to be 186 m, the majority of large location errors being associated with measured current peaks lower than 10 kA. The analysis revealed also that the location accuracy of the EUCLID network improved significantly in 2013 as a result of an upgrade in the location algorithms to take into account propagation effects.

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Section: Resultsmentioning

confidence: 99%

Evaluation of the performance characteristics of the European Lightning Detection Network EUCLID in the Alps region for upward negative flashes using direct measurements at the instrumented Säntis Tower

et al. 2016

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“…The adopted value for the ground reflection coefficient is 0.8. Assuming a channel impedance of about 0.5 to 2.5 kΩ (Rakov, ), this would correspond to a grounding impedance of about 50 to 300 Ω, which is reasonable considering the rocky terrain at the summit of the Säntis mountain (with a resistivity as high as 10 kΩ.m (Romero et al, )). The velocities for the M‐component pulse and M‐component‐type ICC pulse are in the range of typical speeds for M components (Jordan et al, ; Rakov et al, ).…”

Section: Comparison Between Model‐predicted Fields and Observationsmentioning

confidence: 99%

Electromagnetic Fields Associated With the M‐Component Mode of Charge Transfer

Rachidi

Azadifar

et al. 2019

JGR Atmospheres

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In upward flashes, charge transfer to ground largely takes place during the initial continuous current (ICC) and its superimposed pulses (ICC pulses). ICC pulses can be associated with either M‐component or leader/return‐stroke‐like modes of charge transfer to ground. In the latter case, the downward leader/return stroke process is believed to take place in a decayed branch or a newly created channel connected to the ICC‐carrying channel at relatively short distance from the tower top, resulting in the so‐called mixed mode of charge transfer to ground. In this paper, we study the electromagnetic fields associated with the M‐component charge transfer mode using simultaneous records of electric fields and currents associated with upward flashes initiated from the Säntis Tower. The effect of the mountainous terrain on the propagation of electromagnetic fields associated with the M‐component charge transfer mode (including classical M‐component pulses and M‐component‐type pulses superimposed on the initial continuous current) is analyzed and compared with its effect on the fields associated with the return stroke (occurring after the extinction of the ICC) and mixed charge transfer modes. For the analysis, we use a 2‐Dimentional Finite‐Difference Time Domain method, in which the M‐component is modeled by the superposition of a downward current wave and an upward current wave resulting from the reflection at the bottom of the lightning channel (Rakov et al., 1995, https://doi.org/10.1029/95JD01924 model) and the return stroke and mixed mode are modeled adopting the MTLE (Modified Transmission Line with Exponential Current Decay with Height) model. The finite ground conductivity and the mountainous propagation terrain between the Säntis Tower and the field sensor located 15 km away at Herisau are taken into account. The effects of the mountainous path on the electromagnetic fields are examined for classical M‐component and M‐component‐type ICC pulses. Use is made of the propagation factors defined as the ratio of the electric or magnetic field peak evaluated along the mountainous terrain to the field peak evaluated for a flat terrain. The velocity of the M‐component pulse is found to have a significant effect on the risetime of the electromagnetic fields. A faster traveling wave speed results in larger peaks for the magnetic field. However, the peak of the electric field appears to be insensitive to the M‐component wave speed. This can be explained by the fact that at 15 km, the electric field is still dominated by the static component, which mainly depends on the overall transferred charge. The contribution of the radiation component to the M‐component fields at 100 km accounts for about 77% of the peak electric field and 81% of the peak magnetic field, considerably lower compared to the contribution of the radiation component to the return stroke fields at the same distance. The simulation results show that neither the electric nor the magnetic field propagation factors are very sensitive to the risetimes of...

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“…More details on the measurement sensors and instrumentation system can be found in [28] and [29]. In 2013-2014, a certain number of updates were made to the overall measuring system, which are described in [30].…”

Section: A Current Measuement System At the Säntis Towermentioning

confidence: 99%

On Lightning Electromagnetic Field Propagation Along an Irregular Terrain

Azadifar

Rachidi

et al. 2016

IEEE Trans. Electromagn. Compat.

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Abstract-In this paper, we present a theoretical analysis of the propagation effects of lightning electromagnetic fields over a mountainous terrain. The analysis is supported by experimental observations consisting of simultaneous records of lightning currents and electric fields associated with upward negative lightning flashes to the instrumented Säntis tower in Switzerland. The propagation of lightning electromagnetic fields along the mountainous region around the Säntis tower is simulated using a full-wave approach based on the finite-difference time-domain method and using the two-dimensional topographic map along the direct path between the tower and the field measurement station located at about 15 km from the tower. We show that, considering the real irregular terrain between the Säntis tower and the field measurement station, both the waveshape and amplitude of the simulated electric fields associated with return strokes and fast initial continuous current pulses are in excellent agreement with the measured waveforms. On the other hand, the assumption of a flat ground results in a significant underestimation of the peak electric field. Finally, we discuss the sensitivity of the obtained results to the assumed values for the return stroke speed and the ground conductivity, the adopted return stroke model, as well as the presence of the building on which the sensors were located.

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Statistical Distributions of Lightning Currents Associated With Upward Negative Flashes Based on the Data Collected at the Säntis (EMC) Tower in 2010 and 2011

Cited by 59 publications

References 17 publications

Evaluation of the performance characteristics of the European Lightning Detection Network EUCLID in the Alps region for upward negative flashes using direct measurements at the instrumented Säntis Tower

Evaluation of the performance characteristics of the European Lightning Detection Network EUCLID in the Alps region for upward negative flashes using direct measurements at the instrumented Säntis Tower

Electromagnetic Fields Associated With the M‐Component Mode of Charge Transfer

On Lightning Electromagnetic Field Propagation Along an Irregular Terrain

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