Effect of self‐absorption on attenuation of lightning and transmitter signals in the lower ionosphere
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Cites methods from "Effect of self‐absorption on attenu..."
...The FDTD model used here was developed in [26] and [27] to simulate the electromagnetic pulse emitted by lightning discharges and its interaction with the lower ionosphere....
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Cites methods from "Effect of self‐absorption on attenu..."
...The electron-neutral collision frequency profile is determined using the method described by Marshall (2014)....
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Cites background from "Effect of self‐absorption on attenu..."
...The heating and ionization associated with elves further affects the propagation of lightning-generated sferics into the magnetosphere by modifying the propagation medium [Marshall, 2014]....
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References
2,633 citations
"Effect of self‐absorption on attenu..." refers methods in this paper
...Mobility, detachment, attachment, ionization, and optical excitation rates all scale with neutral density, which is taken from an MSIS-E-00 profile [Hedin, 1991] at the same time and location....
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2,359 citations
"Effect of self‐absorption on attenu..." refers background or methods in this paper
...A simpler solution is to use a time-domain method that self-consistently updates the electron-neutral collision frequency and electron density during the wave propagation. Self-consistent models of the lightning-ionosphere interaction have existed for some time, beginning with the 1-D formulation of Taranenko et al. [1993a, 1993b]. Two-dimensional and 3-D models have been developed in recent years [Cho and Rycroft, 2001; Nagano et al., 2003; Marshall et al., 2010] and have assessed the chemical effects of lightning in the lower ionosphere through heating, ionization, optical emissions, dissociative attachment, and most recently, associative detachment [Luque and Gordillo-Vázquez, 2011; Liu, 2011; Neubert et al., 2011]. In this paper we use the electromagnetic pulse (EMP) model of Marshall [2012] to calculate wave propagation and nonlinear effects due to lightning and VLF transmitters. The EMP model is a finite-difference time-domain (FDTD) model designed to simulate lightning discharges but is easily modified to simulate a sinusoidal source from a small dipole (similar to a ground-based VLF transmitter). Details on the model formulation can be found in Marshall [2012]. Crucial to this application, the model is cast in spherical coordinates, which inherently accounts for Earth curvature. Arbitrary and inhomogeneous ionosphere, neutral atmosphere, magnetic fields, and ground parameters (conductivity and permittivity) can be included in the model. We calculate nonlinear effects (heating and ionization) in the ionosphere differently for VLF transmitters and for lightning, for reasons that will be explained presently. For lightning, the electron mobility, ionization, attachment, and optical excitation rates are calculated as a function of electric field using BOLSIG+ [Hagelaar and Pitchford, 2005]; the detachment rate is calculated from equation (17) of Neubert et al. [2011]. Figure 1 of Marshall [2012] shows the rates used, which scale with neutral density, as a function of electric field....
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...A simpler solution is to use a time-domain method that self-consistently updates the electron-neutral collision frequency and electron density during the wave propagation. Self-consistent models of the lightning-ionosphere interaction have existed for some time, beginning with the 1-D formulation of Taranenko et al. [1993a, 1993b]. Two-dimensional and 3-D models have been developed in recent years [Cho and Rycroft, 2001; Nagano et al., 2003; Marshall et al., 2010] and have assessed the chemical effects of lightning in the lower ionosphere through heating, ionization, optical emissions, dissociative attachment, and most recently, associative detachment [Luque and Gordillo-Vázquez, 2011; Liu, 2011; Neubert et al., 2011]. In this paper we use the electromagnetic pulse (EMP) model of Marshall [2012] to calculate wave propagation and nonlinear effects due to lightning and VLF transmitters....
[...]
...A simpler solution is to use a time-domain method that self-consistently updates the electron-neutral collision frequency and electron density during the wave propagation. Self-consistent models of the lightning-ionosphere interaction have existed for some time, beginning with the 1-D formulation of Taranenko et al. [1993a, 1993b]. Two-dimensional and 3-D models have been developed in recent years [Cho and Rycroft, 2001; Nagano et al., 2003; Marshall et al., 2010] and have assessed the chemical effects of lightning in the lower ionosphere through heating, ionization, optical emissions, dissociative attachment, and most recently, associative detachment [Luque and Gordillo-Vázquez, 2011; Liu, 2011; Neubert et al., 2011]. In this paper we use the electromagnetic pulse (EMP) model of Marshall [2012] to calculate wave propagation and nonlinear effects due to lightning and VLF transmitters. The EMP model is a finite-difference time-domain (FDTD) model designed to simulate lightning discharges but is easily modified to simulate a sinusoidal source from a small dipole (similar to a ground-based VLF transmitter). Details on the model formulation can be found in Marshall [2012]. Crucial to this application, the model is cast in spherical coordinates, which inherently accounts for Earth curvature. Arbitrary and inhomogeneous ionosphere, neutral atmosphere, magnetic fields, and ground parameters (conductivity and permittivity) can be included in the model. We calculate nonlinear effects (heating and ionization) in the ionosphere differently for VLF transmitters and for lightning, for reasons that will be explained presently. For lightning, the electron mobility, ionization, attachment, and optical excitation rates are calculated as a function of electric field using BOLSIG+ [Hagelaar and Pitchford, 2005]; the detachment rate is calculated from equation (17) of Neubert et al. [2011]. Figure 1 of Marshall [2012] shows the rates used, which scale with neutral density, as a function of electric field. The electron mobility is then inversely related to the electron-neutral collision frequency by νen = qe∕(μeme). The rates are precalculated using BOLSIG+ as a function of electric field and neutral density, so that application in the model is implemented with lookup table interpolation. This method is perfectly valid for either VLF transmitters or lightning, as long as the electron distribution can be assumed to be stationary, which was shown to be true on time scales longer than ∼2 μs by Glukhov and Inan [1996]; this is clearly valid for VLF transmitters operating in the tens of kHz and for most lightning sferics, which have measured rise times of 3−4 μs. However, in our method for calculating the electron mobility, which follows the method of Pasko et al. [1997], we threshold the mobility to a maximum value of 1....
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...A. (2014), Effect of self-absorption on attenuation of lightning and transmitter signals in the lower ionosphere, J....
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...A simpler solution is to use a time-domain method that self-consistently updates the electron-neutral collision frequency and electron density during the wave propagation. Self-consistent models of the lightning-ionosphere interaction have existed for some time, beginning with the 1-D formulation of Taranenko et al. [1993a, 1993b]. Two-dimensional and 3-D models have been developed in recent years [Cho and Rycroft, 2001; Nagano et al., 2003; Marshall et al., 2010] and have assessed the chemical effects of lightning in the lower ionosphere through heating, ionization, optical emissions, dissociative attachment, and most recently, associative detachment [Luque and Gordillo-Vázquez, 2011; Liu, 2011; Neubert et al., 2011]. In this paper we use the electromagnetic pulse (EMP) model of Marshall [2012] to calculate wave propagation and nonlinear effects due to lightning and VLF transmitters. The EMP model is a finite-difference time-domain (FDTD) model designed to simulate lightning discharges but is easily modified to simulate a sinusoidal source from a small dipole (similar to a ground-based VLF transmitter). Details on the model formulation can be found in Marshall [2012]. Crucial to this application, the model is cast in spherical coordinates, which inherently accounts for Earth curvature. Arbitrary and inhomogeneous ionosphere, neutral atmosphere, magnetic fields, and ground parameters (conductivity and permittivity) can be included in the model. We calculate nonlinear effects (heating and ionization) in the ionosphere differently for VLF transmitters and for lightning, for reasons that will be explained presently. For lightning, the electron mobility, ionization, attachment, and optical excitation rates are calculated as a function of electric field using BOLSIG+ [Hagelaar and Pitchford, 2005]; the detachment rate is calculated from equation (17) of Neubert et al. [2011]. Figure 1 of Marshall [2012] shows the rates used, which scale with neutral density, as a function of electric field. The electron mobility is then inversely related to the electron-neutral collision frequency by νen = qe∕(μeme). The rates are precalculated using BOLSIG+ as a function of electric field and neutral density, so that application in the model is implemented with lookup table interpolation. This method is perfectly valid for either VLF transmitters or lightning, as long as the electron distribution can be assumed to be stationary, which was shown to be true on time scales longer than ∼2 μs by Glukhov and Inan [1996]; this is clearly valid for VLF transmitters operating in the tens of kHz and for most lightning sferics, which have measured rise times of 3−4 μs. However, in our method for calculating the electron mobility, which follows the method of Pasko et al. [1997], we threshold the mobility to a maximum value of 1.4856 N∕N0 m2/V/s at low electric fields (modified slightly from the value in Pasko et al. [1997], thanks to updated calculations using BOLSIG+), in order to match the results of BOLSIG+ at higher field values to the maximum mobility at E = 0....
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"Effect of self‐absorption on attenu..." refers methods in this paper
...For all simulations discussed in this paper, we use an International Reference Ionosphere (IRI) model [Bilitza and Reinisch, 2008], computed for 1 January 2011 at midnight local time, 40◦N, 100◦W. (Note that in this paper we restrict our investigation to nighttime propagation; the high electron…...
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