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

Aoki, Masanori; Baba, Yoshihiro; Rakov, Vladimir A.

doi:10.1002/2015jd023245

Cited by 14 publications

(12 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They studied influences of the return‐stroke speed (ranging from c /2 to c ), current risetime (ranging from 0.5 to 5 μs), and ground conductivity (ranging from 0.1 mS/m to ∞) on electric and magnetic field waveforms. Aoki et al () disregarded the presence of conducting atmosphere, because they only considered the ground wave.…”

Section: Introductioncontrasting

confidence: 74%

“…Qin et al (2017) concluded that their model is adequate for predicting lightning sky waves in VLF/LF bands at distances up to 1,000 km. Aoki, Baba, and Rakov (2015) examined propagation of vertical electric field, azimuthal magnetic field, and horizontal (radial) electric field over 5 to 200 km of flat lossy ground, using the FDTD method in the 2-D cylindrical coordinate system. In contrast to previous FDTD studies, their model employed a travelingwave-type return-stroke model and covered nearly complete return-stroke frequency bandwidth.…”

Section: Introductionmentioning

confidence: 99%

“…They studied influences of the return-stroke speed (ranging from c/2 to c), current risetime (ranging from 0.5 to 5 μs), and ground conductivity (ranging from 0.1 mS/m to ∞) on electric and magnetic field waveforms. Aoki et al (2015) disregarded the presence of conducting atmosphere, because they only considered the ground wave. Somu et al (2015) examined ionospheric reflections in wideband (16 Hz to at least 10 MHz) lightning electric field waveforms recorded at 50 to 330 km from the lightning channel.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

FDTD Modeling of LEMP Propagation in the Earth‐Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

et al. 2017

Self Cite

View full text Add to dashboard Cite

The finite difference time domain (FDTD) method in the 2‐D cylindrical coordinate system was used to compute the nearly full‐frequency‐bandwidth vertical electric field and azimuthal magnetic field waveforms produced on the ground surface by lightning return strokes. The lightning source was represented by the modified transmission‐line model with linear current decay with height, which was implemented in the FDTD computations as an appropriate vertical phased‐current‐source array. The conductivity of atmosphere was assumed to increase exponentially with height, with different conductivity profiles being used for daytime and nighttime conditions. The fields were computed at distances ranging from 50 to 500 km. Sky waves (reflections from the ionosphere) were identified in computed waveforms and used for estimation of apparent ionospheric reflection heights. It was found that our model reproduces reasonably well the daytime electric field waveforms measured at different distances and simulated (using a more sophisticated propagation model) by Qin et al. (2017). Sensitivity of model predictions to changes in the parameters of atmospheric conductivity profile, as well as influences of the lightning source characteristics (current waveshape parameters, return‐stroke speed, and channel length) and ground conductivity were examined.

show abstract

Section: Introductioncontrasting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

FDTD Modeling of LEMP Propagation in the Earth‐Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…These choices were made considering that ground wave features are sharper than those of sky waves, and therefore, ground wave signals require higher-frequency components to adequately reconstruct their features. Lowpass filtering to an upper frequency response of 700 kHz maintains all the observed salient features of the time domain ground wave that has had its high-frequency content attenuated in propagating over 209 km of Florida soil [e.g., Uman et al, 1976;Aoki et al, 2015;Jiang et al, 2016]. In our data, the received ground wave 10-90% risetime exceeds 1 μs, similar to the experimental over-ground data of Uman et al [1976] for natural subsequent strokes recorded at 200 km in Florida, whereas natural subsequent stroke ground waves propagating over salt water of relatively high conductivity, expected to produce significantly less propagation attenuation, exhibit submicrosecond risetimes [Weidman and Krider, 1980].…”

Section: Electric Field Measurement 209 Km South (Uf Station)mentioning

confidence: 99%

Triggered lightning sky waves, return stroke modeling, and ionosphere effective height

et al. 2017

View full text Add to dashboard Cite

Ground waves and sky waves measured 209 km and 250 km south of six triggered lightning flashes containing 30 strokes that occurred in the half‐hour before sunset on 27 August 2015 are presented and analyzed. We use a cross‐correlation technique to find the ionospheric effective reflection height and compare our results to previous techniques that calculate effective height based on the time delay between ground wave and sky wave time domain features. From the first flash to the last flash there is, on average, a 1.6 km increase in effective ionospheric height, whereas no change in effective ionospheric height can be discerned along the individual strokes of a given flash. We show to what extent the triggered lightning radiation source can be described (using channel‐base current, channel geometry, and channel luminosity versus time and height) and speculate that a well‐characterized source could allow a more accurate determination of the electromagnetic fields radiated toward the ionosphere than has been done to date. We show that both channel geometry and the change in return stroke current amplitude and waveshape with channel height (inferred from measured channel luminosity versus height and time) determine the waveshape of the ground wave (and presumably the upward propagating wave that results in the sky wave) and that the waveshape of the ground wave does not appear to be related to the current versus time waveform measured at the channel base other than a roughly linear relationship between the two peak values.

show abstract

“…Recent studies show that the amplitude and phase perturbation for VLF signals have a complicated relationship with the ionospheric

D

region parameters. The propagation of the VLF signal between the Earth ground surface and the lower ionosphere can be affected by many factors, such as the propagation distances (Aoki et al, ; Azadifar et al, ; Tran et al, ), the attenuation due to the ground conductivity (Aoki et al, ; Tran et al, ), the electron and neutral particle densities (Lay and Shao, ; Lay et al, ; Marshall, ), the Earth curvature (Tran et al, ) and the presence of the geomagnetic field (Lay et al, ; Shao et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Propagation Effects of Lightning Electromagnetic Fields Over Mountainous Terrain in the Earth‐Ionosphere Waveguide

Luque

Rachidi

et al. 2019

JGR Atmospheres

View full text Add to dashboard Cite

In this paper, a full‐wave two‐dimensional Finite‐Difference‐Time‐Domain model is developed to evaluate the propagation effects of lightning electromagnetic fields over mountainous terrain in the Earth‐ionosphere waveguide. In the model, we investigate the effect of the Earth‐ionosphere waveguide structure and medium parameters, including the effect of the ionospheric cold plasma characteristics, the effect of the Earth curvature, and the propagation effects over mountainous terrain. For the first time, the obtained results are validated against simultaneous experimental data consisting of lightning currents measured at the Säntis Tower and electric fields measured in Neudorf, Austria, located at 380‐km distance from the tower. It is shown that both the time delays and amplitudes of the lightning electromagnetic fields at 380‐km distance can be strongly affected by the ionospheric electron density profile, the mountainous terrain, and the Earth curvature. After taking into account the effect of the irregular terrain between the Säntis Tower and the field measurement station, the vertical electric fields calculated by using our model are found to be in good agreement with the corresponding measured cases occurred in both daytime and nighttime. The ideal approximation used in either the classical solutions or the simplified models might lead to inaccuracies in the estimated reflection height. Furthermore, we discuss the sensitivity of our results by considering different return stroke models, as well as different typical values of the return stroke speed and of the ground conductivity.

show abstract

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

Cited by 14 publications

References 40 publications

FDTD Modeling of LEMP Propagation in the Earth‐Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

FDTD Modeling of LEMP Propagation in the Earth‐Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

Triggered lightning sky waves, return stroke modeling, and ionosphere effective height

The Propagation Effects of Lightning Electromagnetic Fields Over Mountainous Terrain in the Earth‐Ionosphere Waveguide

Contact Info

Product

Resources

About