Effects of Ionospheric Conductance on Magnetosphere-ionosphere Coupling

Effects of Ionospheric Conductance on Magnetosphere-ionosphere Coupling
Author: Ryan Hobson Smith
Publisher:
Total Pages: 196
Release: 2012
Genre:
ISBN:

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As mankind becomes more reliant on space systems and vulnerable to the effects of space weather, creating a comprehensive understanding of the near earth space environment has become increasingly important. Observational data about this environment comes from orbiting satellites or from ground-based measurements. In the statistical analysis of these observations, there is an oft observed and currently unexplained dawn-dusk asymmetry in the flow of plasma through the nightside plasma sheet region of the magnetosphere, as well as in the Alfvénic aurora in the ionosphere. This thesis uses a version of the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) code to examine generation of asymmetry in the magnetosphere-ionosphere system. Controlled simulations using the LFM global model demonstrate that the dawn-dusk asymmetry in plasma sheet flow bursts and Alfvénic auroral power are regulated by the spatial variation in ionospheric conductance. This asymmetry disappears when the conductance is taken to be spatially uniform. Careful examination of currents in the ionosphere shows that the spatial variation in conductance skews the anti-sunward convection of plasma. Analysis indicates that typical distributions of conductance in the ionosphere will induce a clockwise rotation of the convection pattern over the polar cap region. This clockwise rotation causes the closure of open magnetic fiux in the magnetotail to occur preferentially on the duskside, resulting in the observed duskside enhancements in the plasma flow and Alfvénic aurora. Futhermore, non-physical spatial variations in the ionospheric conductance can be used to produce counterclockwise rotations in the convection pattern, leading to increased rates of reconnection and enhancements of plasma flow and Alfvénic aurora on the dawn side of the plasma sheet.

Role of Ionospheric Conductance in Magnetosphere-ionosphere Coupling

Role of Ionospheric Conductance in Magnetosphere-ionosphere Coupling
Author: Tapas Bhattacharya
Publisher:
Total Pages: 354
Release: 2014
Genre: Ionosphere
ISBN:

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Magnetosphere-ionosphere (MI) coupling has been studied for a long time. However, not much work has been done on a systematic understanding of the relation between ionospheric Pedersen conductance, its effect on the evolution and modification of field-aligned currents (FACs), and the influence of conductance and FACs on the formation of parallel electric fields which cause particle precipitation. Though the roles of ionospheric conductance gradients for FACs and parallel electric field evolution are directly related, they are poorly understood. This dissertation advances the understanding of these areas and all results of this study are based on numerical simulations that employ a three-dimensional - two-fluid (ions and neutrals) simulation code. The first part of this dissertation presents a systematic study of the magnetospheric and ionospheric influences on the evolution and modification of FACs with focus on the role of ionospheric Pedersen conductance and its gradients. FACs are typically generated in the magnetosphere and are carried into the ionosphere by Alfvén waves. During their reflection from the ionosphere these FACs are modified depending on the magnitude and distribution of ionospheric conductance. For conductance gradients along the polarization of the wave, strong Pedersen currents can be generated which in turn enhance the FAC as well. The second part of this dissertation addresses the properties and evolution of parallel electric fields in an attempt to better understand the formation of discrete auroral arcs in response to the evolution of FACs for predetermined ionospheric conductance patterns. Frequently, auroral acceleration is believed to occur through U or V shaped potentials. Therefore, this part examines the properties of localized parallel electric fields in a uniform magnetic field. It is demonstrated that localized parallel electric fields generate magnetic flux in the absence of source of free energy. It is also shown that parallel electric fields generated in a FAC in the presence of a (anomalous) resistivity represent a load and can provide physical explanation for the auroral acceleration geometry. The results demonstrate that such electric fields can be significantly enhanced by Alfvén wave reflection where both magnitude and gradients of the ionospheric conductance are important. The strongly enhanced parallel electric field is associated with magnetic reconnection and modifies the FAC system such that thin current layers (with curls and folds) are observed to be embedded in the large scale current system.

Magnetosphere-Ionosphere Coupling

Magnetosphere-Ionosphere Coupling
Author: Y. Kamide
Publisher: Springer Science & Business Media
Total Pages: 279
Release: 2012-12-06
Genre: Science
ISBN: 3642500625

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In the past two decades a succession of direct observations by satellites, and of extensive computer simulations, has led to the realization that the polar ionosphere plays a principal role in large-scale magnetospheric processes - a manifestation of the physics linkage involved in solar-terrestrial interactions. Spatial/temporal variations in high-latitude electromagnetic phenomena, such as dynamic aurorae, electric fields and currents, have proved to be extremely complex. Now the challenge is to comprehend the vast amount of complicated measurements made in this magnetosphere-ionosphere sysstem of the Earth. This book addresses the electrical coupling between the hot, but dilute, magnetospheric plasma and the cold, but dense, plasma in the ionosphere. In five major chapters, this book presents: - basic properties of magnetosphere-ionosphere coupling; - morphology of electric fields and currents at high latitudes; - global modeling of magnetosphere-ionosphere coupling; - modeling of ionospheric electrodynamics; - current issues, such as auroral particle acceleration, substorms, penetration of high-latitude fields into low latitudes.

Space Physics and Aeronomy, Magnetospheres in the Solar System

Space Physics and Aeronomy, Magnetospheres in the Solar System
Author: Romain Maggiolo
Publisher: John Wiley & Sons
Total Pages: 61
Release: 2021-05-04
Genre: Science
ISBN: 1119507529

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An overview of current knowledge and future research directions in magnetospheric physics In the six decades since the term 'magnetosphere' was first introduced, much has been theorized and discovered about the magnetized space surrounding each of the bodies in our solar system. Each magnetosphere is unique yet behaves according to universal physical processes. Magnetospheres in the Solar System brings together contributions from experimentalists, theoreticians, and numerical modelers to present an overview of diverse magnetospheres, from the mini-magnetospheres of Mercury to the giant planetary magnetospheres of Jupiter and Saturn. Volume highlights include: Concise history of magnetospheres, basic principles, and equations Overview of the fundamental processes that govern magnetospheric physics Tools and techniques used to investigate magnetospheric processes Special focus on Earth’s magnetosphere and its dynamics Coverage of planetary magnetic fields and magnetospheres throughout the solar system Identification of future research directions in magnetospheric physics The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about the Space Physics and Aeronomy collection in this Q&A with the Editors in Chief

Cross-Scale Coupling and Energy Transfer in the Magnetosphere-Ionosphere-Thermosphere System

Cross-Scale Coupling and Energy Transfer in the Magnetosphere-Ionosphere-Thermosphere System
Author: Yukitoshi Nishimura
Publisher: Elsevier
Total Pages: 566
Release: 2021-12-07
Genre: Science
ISBN: 0128213736

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Cross-Scale Coupling and Energy Transfer in the Magnetosphere-Ionosphere-Thermosphere System provides a systematic understanding of Magnetosphere-Ionosphere-Thermosphere dynamics. Cross-scale coupling has become increasingly important in the Space Physics community. Although large-scale processes can specify the averaged state of the system reasonably well, they cannot accurately describe localized and rapidly varying structures in space in actual events. Such localized and variable structures can be as intense as the large-scale features. This book covers observations on quantifying coupling and energetics and simulation on evaluating impacts of cross-scale processes. It includes an in-depth review and summary of the current status of multi-scale coupling processes, fundamental physics, and concise illustrations and plots that are usable in tutorial presentations and classrooms. Organized by physical quantities in the system, Cross-Scale Coupling and Energy Transfer in the Magnetosphere-Ionosphere-Thermosphere System reviews recent advances in cross-scale coupling and energy transfer processes, making it an important resource for space physicists and researchers working on the magnetosphere, ionosphere, and thermosphere. Describes frontier science and major science around M-I-T coupling, allowing for foundational understanding of this emerging field in space physics Reviews recent and key findings in the cutting-edge of the science Discusses open questions and pathways for understanding how the field is evolving

Magnetosphere-Ionosphere Coupling in the Solar System

Magnetosphere-Ionosphere Coupling in the Solar System
Author: Charles R. Chappell
Publisher: John Wiley & Sons
Total Pages: 414
Release: 2016-10-31
Genre: Science
ISBN: 1119066778

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Over a half century of exploration of the Earth’s space environment, it has become evident that the interaction between the ionosphere and the magnetosphere plays a dominant role in the evolution and dynamics of magnetospheric plasmas and fields. Interestingly, it was recently discovered that this same interaction is of fundamental importance at other planets and moons throughout the solar system. Based on papers presented at an interdisciplinary AGU Chapman Conference at Yosemite National Park in February 2014, this volume provides an intellectual and visual journey through our exploration and discovery of the paradigm-changing role that the ionosphere plays in determining the filling and dynamics of Earth and planetary environments. The 2014 Chapman conference marks the 40th anniversary of the initial magnetosphere-ionosphere coupling conference at Yosemite in 1974, and thus gives a four decade perspective of the progress of space science research in understanding these fundamental coupling processes. Digital video links to an online archive containing both the 1974 and 2014 meetings are presented throughout this volume for use as an historical resource by the international heliophysics and planetary science communities. Topics covered in this volume include: Ionosphere as a source of magnetospheric plasma Effects of the low energy ionospheric plasma on the stability and creation of the more energetic plasmas The unified global modeling of the ionosphere and magnetosphere at the Earth and other planets New knowledge of these coupled interactions for heliophysicists and planetary scientists, with a cross-disciplinary approach involving advanced measurement and modeling techniques Magnetosphere-Ionosphere Coupling in the Solar System is a valuable resource for researchers in the fields of space and planetary science, atmospheric science, space physics, astronomy, and geophysics. Read an interview with the editors to find out more: https://eos.org/editors-vox/filling-earths-space-environment-from-the-sun-or-the-earth

Magnetosphere-Ionosphere Coupling in the Solar System

Magnetosphere-Ionosphere Coupling in the Solar System
Author: Charles R. Chappell
Publisher: John Wiley & Sons
Total Pages: 786
Release: 2016-09-28
Genre: Science
ISBN: 1119066964

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Over a half century of exploration of the Earth’s space environment, it has become evident that the interaction between the ionosphere and the magnetosphere plays a dominant role in the evolution and dynamics of magnetospheric plasmas and fields. Interestingly, it was recently discovered that this same interaction is of fundamental importance at other planets and moons throughout the solar system. Based on papers presented at an interdisciplinary AGU Chapman Conference at Yosemite National Park in February 2014, this volume provides an intellectual and visual journey through our exploration and discovery of the paradigm-changing role that the ionosphere plays in determining the filling and dynamics of Earth and planetary environments. The 2014 Chapman conference marks the 40th anniversary of the initial magnetosphere-ionosphere coupling conference at Yosemite in 1974, and thus gives a four decade perspective of the progress of space science research in understanding these fundamental coupling processes. Digital video links to an online archive containing both the 1974 and 2014 meetings are presented throughout this volume for use as an historical resource by the international heliophysics and planetary science communities. Topics covered in this volume include: Ionosphere as a source of magnetospheric plasma Effects of the low energy ionospheric plasma on the stability and creation of the more energetic plasmas The unified global modeling of the ionosphere and magnetosphere at the Earth and other planets New knowledge of these coupled interactions for heliophysicists and planetary scientists, with a cross-disciplinary approach involving advanced measurement and modeling techniques Magnetosphere-Ionosphere Coupling in the Solar System is a valuable resource for researchers in the fields of space and planetary science, atmospheric science, space physics, astronomy, and geophysics. Read an interview with the editors to find out more: https://eos.org/editors-vox/filling-earths-space-environment-from-the-sun-or-the-earth

Quasi-Static Modelling of the Ionosphere-Magnetosphere Coupling: Ionospheric Localized Effects

Quasi-Static Modelling of the Ionosphere-Magnetosphere Coupling: Ionospheric Localized Effects
Author:
Publisher:
Total Pages: 9
Release: 2006
Genre:
ISBN:

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The physical processes that take place in the auroral ionosphere (activation of auroral arcs at various spatial scales, plasma irregularities, non-homogeneities of the electric conductivity) are linked with the dynamics of the distant magnetosphere; the same geomagnetic field lines connect the polar ionosphere and the distant magnetosphere. Inside the magnetosphere the plasma parameters (temperature, density, bulk velocity) are non-uniform. We develop a stationary model that predicts the amplitude of the ionospheric perturbations corresponding to magnetospheric sheared flows. In this study we investigate the sheared plasma flows encountered close to the outer magnetospheric boundary layers. The main components of the model are:(i) a kinetic tangential discontinuity that plays the role of a magnetospheric generator; (ii) a current-voltage relationship describing the flux of generator particles precipitating into the ionosphere as well as the flux of the ionospheric outflow and (iii) a simple model of the topside ionosphere. The solution of the current continuity equation at topside ionosphere gives the latitudinal variation of the ionospheric electrostatic potential and of the field aligned potential drop. Our model provides a tool for evaluating the ionospheric effects of a distant dynamic magnetosphere. Ionospheric perturbations (especially conductivity irregularities) constitute a threat for satellite communications (including GPS) as well as for radio-wave navigation systems.

The Magnetotelluric Method

The Magnetotelluric Method
Author: Alan D. Chave
Publisher: Cambridge University Press
Total Pages: 571
Release: 2012-04-26
Genre: Science
ISBN: 1107376971

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The magnetotelluric method is a technique for imaging the electrical conductivity and structure of the Earth, from the near surface down to the 410 km transition zone and beyond. This book forms the first comprehensive overview of magnetotellurics, from the salient physics and its mathematical representation to practical implementation in the field, data processing, modeling and geological interpretation. Electromagnetic induction in 1-D, 2-D and 3-D media is explored, building from first principles, and with thorough coverage of the practical techniques of time series processing, distortion, numerical modeling and inversion. The fundamental principles are illustrated with a series of case histories describing geological applications. Technical issues, instrumentation and field practices are described for both land and marine surveys. This book provides a rigorous introduction to magnetotellurics for academic researchers and advanced students, and will be of interest to industrial practitioners and geoscientists wanting to incorporate rock conductivity into their interpretations.