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The plasma turbulence in the equatorial electrojet due to the presence of two different plasma instability mechanisms has been observed and studied for more than seven decades. The sharp density-gradient and large conductivity give rise to gradient-drift and Farley-Buneman instabilities, respectively, of different scale-lengths. A new 2-D fluid model is derived by modifying the standard two-stream fluid model with the ion viscosity tensor and electron polarization drift, and is capable of describing both instabilities in a unified system. Numerical solution of the model in the linear regime demonstrates the capacity of the model to capture the salient characteristics of the two instabilities. Nonlinear simulations of the unified model of the equatorial electrojet instabilities reproduce many of the features that are found in radar observations and sounding rocket measurements under multiple solar and ionospheric conditions. The linear and nonlinear numerical results of the 2-D unified fluid model are found to be comparable to the fully kinetic and hybrid models which have high computational cost and small coverage area of the ionosphere. This gives the unified fluid model a superiority over those models. The distribution of the energy content in the system is studied and the rate of change of the energy content in the evolving fields obeys the law of energy conservation. The dynamics of the ions were found to have the largest portion of energy in their kinetic and internal thermal energy components. The redistribution of energy is characterized by a forward cascade generating small-scale structures. The bracket of the system dynamics in the nonlinear partial differential equation was proved to be a non-canonical Hamiltonian system as that bracket satisfies the Jacobi identity. The penetration of the variations in the interplanetary magnetic and electric fields in the solar winds to the dip equator is observed as a perfect match with the variations in the horizontal components of the geomagnetic and electric fields at the magnetic equator. Three years of concurrent measurements of the solar wind parameters at Advanced Composition Explorer (ACE) and Interplanetary Monitoring Platform (IMP) space missions used to establish a Kernel Density Estimation (KDE) functions for these parameters at the IMP-8 location. The KDE functions can be used to generate an ensemble of the solar wind parameters which has many applications in space weather forecasting and data-driven simulations. Also, categorized KDE functions ware established for the solar wind categories that have different origin from the Sun.
This is the first book to review all the fields of equatorial electrojet phenomena and their relevant theories in one volume. In certain relevant sections, the book discusses both the equatorial electrojet and the world-wide parts of the Sq current systems. Onwumwchili is an internationally known and highly respected expert in the equatorial electrojet field- a brand of geomagnetism.
A computer program which calculates electron and ion densities, ionospheric conductivities, electric fields and currents, and magnetic variations in regions near the magnetic equator is described in detail. It is also explained how this numerical model can be used to deduce F-region vertical plasma drifts in the equatorial ionosphere from observed magnetic variations at ground level. (Author).
A computer simulation accounts for some of the observed features of short wavelength irregularities in the equatorial electrojet. Two dimensional fluid equations for ion number density, velocity, and electrostatic potential are solved in the rest frame of the neutral atmosphere. The initial configuration is gradient-drift unstable. Growth of small amplitude fluctuations agrees with linear theory. When the density fluctuation reaches about 5%, nonlinear effects become noticeable. As the instability grows, the flow becomes similar to 2D turbulence. The late time spectral power decreases as K to the minus 3.5 power in agreement with theory and observations. (Author).