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Author: Ehab Mohamed Ali Hussein Hassan Publisher: ISBN: Category : Languages : en Pages : 292
Book Description
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.
Author: Ehab Mohamed Ali Hussein Hassan Publisher: ISBN: Category : Languages : en Pages : 292
Book Description
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.
Author: A. Yoshizawa Publisher: CRC Press ISBN: 1420033697 Category : Science Languages : en Pages : 459
Book Description
Theory and modelling with direct numerical simulation and experimental observations are indispensable in the understanding of the evolution of nature, in this case the theory and modelling of plasma and fluid turbulence. Plasma and Fluid Turbulence: Theory and Modelling explains modelling methodologies in depth with regard to turbulence phenomena a
Author: Loukas Vlahos Publisher: Springer ISBN: 3642002102 Category : Science Languages : en Pages : 332
Book Description
Over the years, many leading European graduate schools in the field of astrophysical and space plasmas have operated within the framework of the research network, "Theory, Observations, and Simulations in Turbulence in Space Plasmas." This text is a set of lectures and tutorial reviews culled from the relevant work of all those schools. It emphasizes applications on solar coronae, solar flares, and the solar wind. In bridging the gap between standard textbook material and state-of-the-art research, this text offers a broad flavor to postgraduate and postdoctoral students just coming to the field. And because of its unique mix, it will also be useful to lecturers looking for advanced teaching material for their seminars and courses.
Author: Henrique Carlotto Aveiro Publisher: ISBN: Category : Languages : en Pages : 284
Book Description
This dissertation describes a theoretical, experimental, and modeling investigation of the plasma irregularities in equatorial spread F (ESF). The primary scientific objective is to evaluate the electrodynamic nature of equatorial F region plasma instabilities. In particular, the difference between two-dimensional and three-dimensional electrodynamic effects on the onset and evolution of equatorial instabilities is investigated. Statistical studies are performed using the Jicamarca Unattended Long Term Investigations of the Ionosphere and Atmosphere (JULIA) radar at Jicamarca. The climatology, persistence, and the correlation with the phase of the moon of equatorial spread F irregularities are evaluated, and different forecasting tools are compared. A three dimensional electrostatic numerical model of the equatorial ionosphere using a finite volume method transport scheme is described. The model incorporates realistic ionospheric conductivities, electric fields, and winds. The model is capable of reproducing the full complement of relevant equatorial F region ionospheric plasma instabilities under realistic conditions, including bottomside shear flow. Of chief importance is the so-called "collisional shear instability" which has come to light recently as a potentially important mechanism in the initiation of ESF. This instability has a faster growth rate than the conventional generalized Rayleigh Taylor (gRT) instability under typical post-sunset conditions. The combination of gRT and CSI produces an instability which develops into an intense ESF event more quickly and with more realistic characteristics than the other two independently in simulations. The model is initialized with data acquired by the C/NOFS satellite, the Jicamarca Radio Observatory, ALTAIR radar, and other ground-based instruments. The forecast potential of the simulation is evaluated through a number of "after the fact" case studies. Various diagnostic codes are used to validate the simulations. To compute the magnetic induction due to ionospheric currents, for example, we solve the partial differencial equation resulting from the Ampère's law for magnetostatics. Airglow emissions corresponding to the sime ulation runs are likewise computed for the 6300-Å (or oxygen red) line. Simulated airglow images are obtained through the integration of the volume emission rates along the camera line of sight. Coherent/incoherent scatter simulations corresponding to the model runs show the typical three stages of ESF evolution, from bottom-type to bottomside to topside ESF. Some of the features that the simulated electron density maps share with ALTAIR scans include westward tilted ascending depletions connected to the bottomside, periodic spacing of 100-200 km in the zonal direction, bifurcation, secondary instabilities growing on the western walls of the primaries, and rates of development. The main goal of these studies has been both to verify the efficacy of the simulation code and its forecast potential while also placing these common but ambiguous diagnostic methods in a formal theoretical/modeling context for the first time.
Author: Massimo Materassi Publisher: Elsevier ISBN: 0128147830 Category : Science Languages : en Pages : 337
Book Description
The Dynamical Ionosphere: A Systems Approach to Ionospheric Irregularity examines the Earth’s ionosphere as a dynamical system with signatures of complexity. The system is robust in its overall configuration, with smooth space-time patterns of daily, seasonal and Solar Cycle variability, but shows a hierarchy of interactions among its sub-systems, yielding apparent unpredictability, space-time irregularity, and turbulence. This interplay leads to the need for constructing realistic models of the average ionosphere, incorporating the increasing knowledge and predictability of high variability components, and for addressing the difficulty of dealing with the worst cases of ionospheric disturbances, all of which are addressed in this interdisciplinary book. Borrowing tools and techniques from classical and stochastic dynamics, information theory, signal processing, fluid dynamics and turbulence science, The Dynamical Ionosphere presents the state-of-the-art in dealing with irregularity, forecasting ionospheric threats, and theoretical interpretation of various ionospheric configurations. Presents studies addressing Earth’s ionosphere as a complex dynamical system, including irregularities and radio scintillation, ionospheric turbulence, nonlinear time series analysis, space-ionosphere connection, and space-time structures Utilizes interdisciplinary tools and techniques, such as those associated with stochastic dynamics, information theory, signal processing, fluid dynamics and turbulence science Offers new data-driven models for different ionospheric variability phenomena Provides a synoptic view of the state-of-the-art and most updated theoretical interpretation, results and data analysis tools of the "worst case" behavior in ionospheric configurations
Author: CAgodi Onwumechikli Publisher: Routledge ISBN: 1351449923 Category : Science Languages : en Pages : 658
Book Description
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.
Author: Ehab Mohamed Ali Hussein Hassan
Author: Ehab Mohamed Ali Hussein Hassan
Author: A. Yoshizawa
Author: Loukas Vlahos
Author: Erhan Kudeki
Author: Henrick Mario Ierkic Vidmar
Author: Henrique Carlotto Aveiro
Author: Institute for Telecommunication Sciences and Aeronomy (U.S.)
Author: Massimo Materassi
Author: Robert Frederick Pfaff
Author: CAgodi Onwumechikli