Wavelet analysis of lightning return stroke

Miranda, F.J.

doi:10.1016/j.jastp.2008.04.008

Cited by 31 publications

(15 citation statements)

References 20 publications

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“…A further limitation of the work performed here was the time resolution of the cosmic ray data (5 min) that prevented us from going to higher frequencies, as these are known to exist in atmospheric electric fields (see e.g., Miranda, 2008).…”

Section: Discussionmentioning

confidence: 99%

Signatures of thunderstorms in the variations of the secondary cosmic rays registered in Mexico City

Alvarez-Castillo

Galicia

2010

Journal of Atmospheric and Solar-Terrestrial Physics

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Section: Discussionmentioning

confidence: 99%

Signatures of thunderstorms in the variations of the secondary cosmic rays registered in Mexico City

Alvarez-Castillo

Galicia

2010

Journal of Atmospheric and Solar-Terrestrial Physics

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“…The arrangement composed by the antenna, the short coaxial cable and the electronic circuit works as a passband filter with a cut-off frequency of 11.8 MHz, which is enough to study lightnings because this range of frequencies covers the bandwidth in which most of the spectrum of the return strokes is found (some hundreds of kHz) [3,12]. A complete description of the measuring system and the electronic circuit, including its calibration process, can be reviewed in [33].…”

Section: Measuring Systemmentioning

confidence: 99%

“…Because of the limitations of FT and STFT (loss of resolution in time or frequency), new signal processing methods have been proposed. Wavelet transform (WT) has been used for different purposes in the study of lightning activity, including noise reduction and frequency anlaysis [3,8,12]. The major disadvantages of WT are the complexity of calculations, the sensitivity to some noise levels, and the dependence of its accuracy on the selected wavelet base (mother) function [8,12].…”

Section: Introductionmentioning

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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“…To understand the temporal features of the frequency content of the different events of lightning wavelet transform has been used in this study. The wavelet transforms have been used in various geophysical studies in the 1990s (Torrence and Compo, 1998), however they have not been widely used in the analysis of lightning electromagnetic fields except for Miranda (2008), Sheshyekani et al (2006), Santamaria et al (2009), Xueqiang et al (2009) and Nedjah et al (2010 for different purposes in the field of lightning activities. Using wavelet transform one is able to determine the dominant modes of variability and how those modes vary in time (Torrence and Compo, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…In this study, out of various wavelets, Derivative of Gaussian (DOG) wavelet was chosen though the type of wavelet function is not critical for the computation of wavelet power spectrum (Miranda, 2008). Nevertheless, the DOG is the real valued wavelet and captures both the positive and negative oscillations of the time series as separate peaks in wavelet power (Torrence and Compo, 1998).…”

Section: Introductionmentioning

confidence: 99%