Characterization of lightning return stroke electric and magnetic fields from simultaneous two‐station measurements

Lin, Yuh-Chieh; Uman, M. A.; Tiller, J. A.; Brantley, R. D.; Beasley, William H.; Krider, E. Philip; Weidman, C. D.

doi:10.1029/jc084ic10p06307

Cited by 252 publications

(183 citation statements)

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“…Also, it has been reported by Lin et al [1979] that the distance-normalized magnitude of vertical electric field is reduced to about 90% and 80% after propagating 50 and 200 km, respectively. Further, it has been reported by Uman et al [1976] that the mean 10-90% risetime of observed vertical electric field is increased by about 1 μs after propagation over 200 km of land with conductivity of 1.4 to 2.8 mS/m.…”

Section: 1002/2015jd023245mentioning

confidence: 99%

FDTD simulation of LEMP propagation over lossy ground: Influence of distance, ground conductivity, and source parameters

2015

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We have computed lightning electromagnetic pulses (LEMPs), including the azimuthal magnetic field H φ , vertical electric field E z , and horizontal (radial) electric field E h that propagated over 5 to 200 km of flat lossy ground, using the finite difference time domain (FDTD) method in the 2-D cylindrical coordinate system. This is the first systematic full-wave study of LEMP propagation effects based on a realistic return-stroke model and including the complete return-stroke frequency range. Influences of the return-stroke wavefront speed (ranging from c/2 to c, where c is the speed of light), current risetime (ranging from 0.5 to 5 μs), and ground conductivity (ranging from 0.1 mS/m to ∞) on H φ , E z , and E h have been investigated. Also, the FDTD-computed waveforms of E h have been compared with the corresponding ones computed using the Cooray-Rubinstein formula. Peaks of H φ , E z , and E h are nearly proportional to the return-stroke wavefront speed. The peak of E h decreases with increasing current risetime, while those of H φ and E z are only slightly influenced by it. The peaks of H φ and E z are essentially independent of the ground conductivity at a distance of 5 km. Beyond this distance, they appreciably decrease relative to the perfectly conducting ground case, and the decrease is stronger for lower ground conductivity values. The peak of E h increases with decreasing ground conductivity. The computed E h /E z is consistent with measurements of Thomson et al. (1988). The observed decrease of E z peak and increase of E z risetime due to propagation over 200 km of Florida soil are reasonably well reproduced by the FDTD simulation with ground conductivity of 1 mS/m.

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Section: 1002/2015jd023245mentioning

confidence: 99%

FDTD simulation of LEMP propagation over lossy ground: Influence of distance, ground conductivity, and source parameters

2015

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“…At these distances, the tortuous model is also able to reproduce another interesting feature of close electric fields, namely a very fast transition in a time interval of a few hundreds of nanoseconds towards a "first peak", followed by a slower increase of the field [38]. The first peak is due to the field radiation component, it is almost independent of the observation point and can be now more easily identified, if compared to closer waveforms.…”

Section: Electric Field E(t)mentioning

confidence: 65%

“…6, are able to reproduce these typical characteristics. As an example, in The field evolution presents both the sharp increase and "humps", but not the "slow front" characteristic; this is probably due to the presence of an upward connecting leader [38] which, as discussed above, is not accounted in the present model, but is typical for triggered channels.…”

Section: Electric Field E(t)mentioning

confidence: 95%

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On the Influence of Channel Tortuosity on Electric Fields Generated by Lightning Return Strokes at Close Distance

Petrarca¹,

Minucci²,

Andreotti³

2017

PIER B

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Abstract-In this paper the results of the estimated electric field associated with tortuous lightning paths at close distance (50 m to 500 m) are shown. Such results are compared with experimental data available in the literature and are illustrated along with a quantitative analysis of the field waveforms and their frequency spectra. The limits of the usual straight-vertical channel assumption and the influence of tortuosity at different azimuth and distances from the lightning channel base are also highlighted.

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“…A typical CG lightning flash is composed by more than one discharge known as return stroke. These individual discharges have a duration of tens of microseconds and they are usually separated in time from 20 ms to 100 ms [29]. The typical waveforms for the electric fields produced by the first return stroke (FRS) and the subsequent return strokes (SRS) that compose a flash are shown in Fig.…”

Section: Typical Waveforms Of Lef Signalsmentioning

confidence: 99%

Local polynomial approximation and intersection of confidence intervals for removing noise of lightning electric field measurements

Rojas

Cortes

Forero-Mejía³

2018

DYNA

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Lightning electric field (LEF) measurements are aperiodic signals characterized by inherent noise of different sources, i.e., it is not possible to register a noise-free signal. In the last decade, the denoising of LEF measurements has been achieved using some time-frequency representations such as short-time Fourier transform (STFT), wavelet transform (WT) and fractional Fourier transform (FRFT) without definitive results. In this paper, a denoising process applied on LEF measurements using the Local Polynomial Approximation (LPA) is proposed. The window size selection is made by combining the LPA with the intersection of confidence intervals (ICI) algorithm. Furthermore, a cross-validation criterion is used to select the optimal value of the threshold parameter in the LPA-ICI denoising method. It is shown that for different signal-to-noise ratio (SNR) values, the proposed method significantly reduces the noise present in the recorded signals. Finally, a discussion about the processed signatures in terms of some lightning electric field temporal features is performed.Keywords: electric field; intersection of confidence intervals; lightning flash; local polynomial approximation; noise reduction.Aproximación local polinomial e intersección de intervalos de confianza para la remoción de ruido en mediciones de campo eléctrico generado por rayos Resumen Las mediciones de campo eléctrico producido por rayos (LEF) son señales aperiódicas caracterizadas por ruido inherente de diferentes fuentes, es decir, no es posible registrar una señal libre de ruido. En la última década, se ha logrado filtrar mediciones de LEF utilizando algunas representaciones tiempo-frecuencia tales como la transformación de Fourier de corto tiempo (STFT), la transformación wavelet (WT) y la transformación de Fourier fraccionaria (FRFT) sin resultados definitivos. En este trabajo, se propone un proceso de eliminación de ruido aplicado a mediciones de LEF usando la aproximación polinomial local (LPA). La selección del tamaño de la ventana se realiza combinando la LPA con el algoritmo de intersección de intervalos de confianza (ICI). Además, un criterio de validación cruzada se utiliza para seleccionar el valor óptimo del umbral en el método de reducción de ruido LPA-ICI. Se muestra que para diferentes valores de relación señal-a-ruido (SNR), el método propuesto reduce significativamente el ruido presente en las señales registradas. Finalmente, se realiza una discusión sobre las señales procesadas en términos de algunas características temporales del campo eléctrico.Palabras clave: aproximación local polinomial; campo eléctrico; intersección de intervalos de confianza; rayos; reducción de ruido.

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Characterization of lightning return stroke electric and magnetic fields from simultaneous two‐station measurements

Cited by 252 publications

References 15 publications

FDTD simulation of LEMP propagation over lossy ground: Influence of distance, ground conductivity, and source parameters

FDTD simulation of LEMP propagation over lossy ground: Influence of distance, ground conductivity, and source parameters

On the Influence of Channel Tortuosity on Electric Fields Generated by Lightning Return Strokes at Close Distance

Local polynomial approximation and intersection of confidence intervals for removing noise of lightning electric field measurements

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