Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) Model - An Unified Concept for Earthquake Precursors Validation

Quasi-electrostatic (QE) fields that temporarily exist at high altitudes following the sudden removal (e.g., by a lightning discharge) of thundercloud charge at low altitudes lead to ambient electron heating (up to ∼5 eV average energy), ionization of neutrals, and excitation of optical emissions in the mesosphere/lower ionosphere. Model calculations predict the possibility of significant (several orders of magnitude) modification of the lower ionospheric conductivity in the form of depletions of electron density due to dissociative attachment to O2 molecules and/or in the form of enhancements of electron density due to breakdown ionization. Results indicate that the optical emission intensities of the 1st positive band of N2 corresponding to fast (∼ 1 ms) removal of 100–300 C of thundercloud charge from 10 km altitude are in good agreement with observations of the upper part (“head” and “hair” [Sentman et al., 1995]) of the sprites. The typical region of brightest optical emission has horizontal and vertical dimensions ∼10 km, centered at altitudes 70 km and is interpreted as the head of the sprite. The model also shows the formation of low intensity glow (“hair”) above this region due to the excitation of optical emissions at altitudes ∼ 85 km during ∼ 500 μs at the initial stage of the lightning discharge. Comparison of the optical emission intensities of the 1st and 2nd positive bands of N2, Meinel and 1st negative bands of , and 1st negative band of demonstrates that the 1st positive band of N2 is the dominating optical emission in the altitude range around ∼70 km, which accounts for the observed red color of sprites, in excellent agreement with recent spectroscopic observations of sprites. Results indicate that the optical emission levels are predominantly defined by the lightning discharge duration and the conductivity properties of the atmosphere/lower ionosphere (i.e., relaxation time of electric field in the conducting medium). The model demonstrates that for low ambient conductivities the lightning discharge duration can be significantly extended with no loss in production of optical emissions. The peak intensity of optical emissions is determined primarily by the value of the removed thundercloud charge and its altitude. The preexisting inhomogeneities in the mesospheric conductivity and the neutral density may contribute to the formation of a vertically striated fine structure of sprites and explain why sprites often repeatedly occur in the same place in the sky as well as their clustering. Comparison of the model results for different types of lightning discharges indicates that positive cloud to ground discharges lead to the largest electric fields and optical emissions at ionospheric altitudes since they are associated with the removal of larger amounts of charge from higher altitudes.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/96JA03528

Sprites produced by quasi-electrostatic heating and ionization in the lower ionosphere

Book on shock waves in collisionless plasmas covering basic equations and classification of shock structures, magnetosonic waves, shocks and solitons, electrostatic shocks and solitons, etc

Shock waves in collisionless plasmas

This is a general review of anomalous resistivity with emphasis on its applicability in space and more specifically on ionospheric plasmas. It is addressed to the general ionospheric community rather than the specialist. Therefore a substantial amount of rigor has been sacrificed in favor of simplified physical pictures. However, several prescriptions are presented, on the basis of which one can compute the anomalous resistivity resulting from each specific mechanism. Following a conceptual discussion of resistivity a general formalism is presented for its computation on the basis of the spectrum of electric field fluctuations. On the basis of this it is shown that stable nonthermal plasmas can at most enhance resistivity by a few percent. The same is true for collisionally driven instabilities. From the current-driven instabilities, only the ion acoustic instability can produce a steady state anomalous resistivity. The rest result in transient resistivity and the appearance of hot electron or ion spots. A more satisfying picture emerges when the low-frequency turbulence that produces resistivity is excited parametrically by a high-frequency instability. The case where such a driver arises from the interaction of precipitating electrons is discussed in detail. Finally, the relevance of the various resistivity mechanisms and their importance in ionospheric electron acceleration is discussed. Although a large number of physical notions are well understood, the efforts toward their incorporation into a gross modeling picture remain embarrassingly small.

/pdf/a-review-of-anomalous-resistivity-for-the-ionosphere-131n90aaqk.pdf

A review of anomalous resistivity for the ionosphere

The interest in relativistic beam-plasma instabilities has been greatly rejuvenated over the past two decades by novel concepts in laboratory and space plasmas. Recent advances in this long-standing field are here reviewed from both theoretical and numerical points of view. The primary focus is on the two-dimensional spectrum of unstable electromagnetic waves growing within relativistic, unmagnetized, and uniform electron beam-plasma systems. Although the goal is to provide a unified picture of all instability classes at play, emphasis is put on the potentially dominant waves propagating obliquely to the beam direction, which have received little attention over the years. First, the basic derivation of the general dielectric function of a kinetic relativistic plasma is recalled. Next, an overview of two-dimensional unstable spectra associated with various beam-plasma distribution functions is given. Both cold-fluid and kinetic linear theory results are reported, the latter being based on waterbag and Maxwell–Juttner model distributions. The main properties of the competing modes (developing parallel, transverse, and oblique to the beam) are given, and their respective region of dominance in the system parameter space is explained. Later sections address particle-in-cell numerical simulations and the nonlinear evolution of multidimensional beam-plasma systems. The elementary structures generated by the various instability classes are first discussed in the case of reduced-geometry systems. Validation of linear theory is then illustrated in detail for large-scale systems, as is the multistaged character of the nonlinear phase. Finally, a collection of closely related beam-plasma problems involving additional physical effects is presented, and worthwhile directions of future research are outlined.

/pdf/multidimensional-electron-beam-plasma-instabilities-in-the-4rrb6d2ux6.pdf

Multidimensional electron beam-plasma instabilities in the relativistic regime

Ion heating by a strong ion‐ion two‐stream instability perpendicular to a magnetic field in the presence of a relatively cold electron background (Te≪miVd2) is considered. The magnetic field strength is such that the ion trajectories are straight, whereas the electrons are bound to the field lines (krLe≪1≪krLi). Theory is presented for both quasilinear and nonlinear stages of the evolution of the system for the case that the instability is electrostatic [(B2/8π) (1+β) >nmiVd2/8] and is compared with a series of computer simulation experiments. It is found that the quasilinear theory gives a fairly accurate description of spatially averaged plasma properties until the ion beams have been sufficiently modulated for ions to be trapped by the waves. In the subsequent nonlinear stage, stabilization occurs when the ion trapping period is equal to the reciprocal growth rate associated with the instability. The directed ion beam energy is mainly converted into random ion energy. The possible role of this instabil...

Heating of Counterstreaming Ion Beams in an External Magnetic Field

Rapid electron heating by two counterstreaming ion beams has been observed in computer experiments. The results are compared with the predictions of quasilinear theory and found to be in substantial agreement.

Electron Heating by Electron-Ion Beam Instabilities

The differences in the ionization rates for RF induced atmospheric breakdown between the analytic formula given by Gurevich et al. [1978] and recent numerical simulations Short et al., 1991; Tsang et al., [1991] were examined and clarified. An updated analytic formula for the ionization rate of air, which includes corrections due to kinetic effects of the electron distribution function, was derived. The formula is valid for arbitrary ratios of RF to electron-neutral collision frequency.

/pdf/ionization-rates-for-atmospheric-and-ionospheric-breakdown-3xtqxrugg7.pdf

Ionization rates for atmospheric and ionospheric breakdown

A comprehensive analysis of the ionization rates of air by RF fields is presented. The analysis relies on a time-dependent code which treats the electron energization with a Fokker-Planck type model and the inelastic energy losses with a multiple time scale technique. Derivation of ionization rates for parameters of interest To D region ionospheric by ground-based RF transmitters with frequency much higher than the electron neutral collision frequency is emphasized. The study provides a physical understanding of the ionization proces and its associated efficiency by combining the computational results with analytic theory. It is shown that for values of quiver energies « I, where I is the ionization potential, the electron production time corresponds to the electron energization time from energies below 2 eV to 20–25 eV. The analytic expressions derived are consistent with the computational results over 6 orders of magnitude in ionization rates and over 2 orders of magnitude in values of 



Power threshold definitions are clarified, and the pitfalls of using fluid descriptions or effective electric field notions are discussed. The paper concludes with an assessment the power requirements for ionization at 70-km ionospheric altitude with RF in the 100–900 MHz frequency range.

RF ionization of the lower ionosphere

A novel method for remote optical diagnostics of the atmosphere at heights 30–60 km is proposed. The method relies on exciting atoms and molecules of minority species by electron impact during and following an ionizing microwave pulse injected from a focused ground-based transmitter. Free electrons produced in the breakdown region are the exciting agents for the atmospheric target molecules. The mixing ratio of the minority species can then be measured by either detecting the direct emission from allowed transitions or by utilizing lidar techniques to measure the excitation level of metastable states. Computer simulations of the intensity of the expected emission, based on kinetic theory of air breakdown, are presented. It is shown that mixing ratios below particle per trillion can be detected using microwave heaters with state of the art effective radiation power and modern detection technology.

/pdf/remote-photometry-of-the-atmosphere-using-microwave-fgmq1xtvit.pdf

R. Shanny

Papers

Heating of Counterstreaming Ion Beams in an External Magnetic Field

Electron Heating by Electron-Ion Beam Instabilities

Ionization rates for atmospheric and ionospheric breakdown

RF ionization of the lower ionosphere

Remote photometry of the atmosphere using microwave breakdown