An FDTD Model for Low and High Altitude Lightning-Generated EM Fields

Hu, Wenyi; Cummer, S. A.

doi:10.1109/tap.2006.874336

Cited by 125 publications

(139 citation statements)

References 37 publications

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“…They represent lightning channel as a 10 m vertical current source, simulate a realistic nonflat ground geometry with 10 m × 10 m cubic cells, and employ a 7 km × 4 km × 7 km moving domain within a 7 km × 28 km × 7 km computation volume. Haddad et al [2012] computed vertical electric field waveforms at distances ranging from 100 to 400 km using an FDTD model of VLF propagation in the Earth-ionosphere waveguide [Hu and Cummer, 2006].…”

Section: Baba and Rakovmentioning

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: Baba and Rakovmentioning

confidence: 99%

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

2015

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“…The nature of this technique inherently measures the average D-layer properties along the source-receiver path and would be difficult to use for finer spatial resolution. With a similar frequency-domain analysis but a different VLF propagation model [Hu and Cummer, 2006], Han and Cummer [2010] reported the variations of nighttime D-layer height for a number of storms.…”

Section: Introductionmentioning

confidence: 99%

High temporal and spatial-resolution detection of D-layer fluctuations by using time-domain lightning waveforms

Lay

Shao

2011

J. Geophys. Res.

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[1] This paper presents a new method for probing ionospheric D-layer fluctuations with time-domain very-low and low-frequency (VLF/LF) lightning waveforms detected several hundred kilometers away from lightning storms. The technique compares the amplitude and the time delay between the direct ground wave and the first-hop ionospheric reflection of the lightning signal to measure the apparent D-layer reflectivity and height. This time-domain technique allows a higher time and spatial resolution measurement of the D-layer fluctuations compared to previously reported frequency-domain techniques. For a region near a nighttime thunderstorm, results demonstrate that the apparent reflectivity and height exhibit significant variation on spatial scales of tens of kilometers and over time periods of hours. The range of the reflectivity variation was observed as large as 100% away from the averaged reflectivity for some localized regions, and the height varies by as much as 5% (4 km). The time scales and propagation velocities of the fluctuations appear to be consistent with signatures of atmospheric gravity waves at D-layer altitudes, and the direction of the fluctuation propagation suggests that the gravity waves are originated from the storm. Superimposed on the fluctuations, a general decreasing trend (by ∼4-8 km) in reflection height over the nighttime is observed. In some localized ionosphere regions, apparent splitting of the D-layer by 2-4 km is observed to last a short time period of about 10 min.

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“…Though in case of magnetized plasma, due to the complexity of the applied numerical scheme the stability analysis is rather arduous. It has been found empirically that the stability requirement in case of non-magnetized plasma is still valid for the magnetized case [12]. There is however no analytical proof.…”

Section: Reliability Of the Numerical Resultsmentioning

confidence: 99%

An analysis of the hybrid finite-difference time-domain scheme for modeling the propagation of electromagnetic waves in cold magnetized toroidal plasma

Surkova¹,

Pavlenko²,

Oost³

et al. 2014

Phys. Scr.

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To explore the behavior of electromagnetic waves in cold magnetized plasma, a three-dimensional cylindrical hybrid finite-difference time-domain (FDTD) model is developed. The full discrete dispersion relation is derived and compared to the exact solutions. We establish an analytical proof of stability in the case of nonmagnetized plasma. We demonstrate that in the case of nonmagnetized cold plasma the maximum stable Courant number of the hybrid method coincides with the vacuum Courant condition. In the case of magnetized plasma the stability of the applied numerical scheme is investigated by numerical simulation. In order to determine the utility of the applied difference scheme we complete the analysis of the numerical method demonstrating the limit of the reliability of the numerical results.

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An FDTD Model for Low and High Altitude Lightning-Generated EM Fields

Cited by 125 publications

References 37 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

High temporal and spatial-resolution detection of D-layer fluctuations by using time-domain lightning waveforms

An analysis of the hybrid finite-difference time-domain scheme for modeling the propagation of electromagnetic waves in cold magnetized toroidal plasma

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