The auroral emissions in the upper atmosphere of the polar regions of the Earth are evidence of the capture of energetic particles from the Sun, streaming by the Earth as the solar wind. These auroral emissions, then, are a window to outer space, and can provide us with valuable information about electrodynamic coupling processes between the solar wind and the Earth's ionosphere and upper atmosphere. Studying the physics of these phenomena extends our understanding of our plasma universe. Ground-based remote-sensing techniques, able to monitor continuously the variations in the signatures of aurorae, in combination with in-situ satellite and rocket measurements, promise to advance dramatically our understanding of the physical processes taking place at the interface of the atmospheres of the Earth and the Sun. Decoding their complexity brings us closer to reliable prediction of communication environments, especially at high latitudes. This understanding, in turn, will help us resolve problems of communication and navigation across polar regions.

This volume surveys our current scientific understanding of the terrestrial aurora. It is organized into eleven reviews detailing theoretical and observational aspects of characteristic auroral morphologies, and how these in turn are organized according to local time, latitude, and activity level. Popular descriptions often attribute the aurora to the interaction of charged particles from the solar wind with atoms in the upper atmosphere. In fact, most auroras are not the result of direct entry of solar wind particles. Rather, as detailed in this volume, auroral particle acceleration and generation of auroral forms occur primarily within the magnetosphere. Importantly, many key aspects of the aurora – most notably, the physical mechanisms responsible for the generation of discrete arcs – are still unexplained, and auroral physics continues to be an active area of scientific research. Each review chapter therefore includes a summary of open questions for further investigation. Providing the first comprehensive review of the terrestrial aurora in two decades, this book will aid both active researchers and newcomers interested in understanding the current state of the field. Previously published Space Science Reviews in the Topical Collection "Auroral Physics”

Exploring the processes and phenomena of Earth’s dayside magnetosphere Energy and momentum transfer, initially taking place at the dayside magnetopause, is responsible for a variety of phenomenon that we can measure on the ground. Data obtained from observations of Earth’s dayside magnetosphere increases our knowledge of the processes by which solar wind mass, momentum, and energy enter the magnetosphere. Dayside Magnetosphere Interactions outlines the physics and processes of dayside magnetospheric phenomena, the role of solar wind in generating ultra-low frequency waves, and solar wind-magnetosphere-ionosphere coupling. Volume highlights include: Phenomena across different temporal and spatial scales Discussions on dayside aurora, plume dynamics, and related dayside reconnection Results from spacecraft observations, ground-based observations, and simulations Discoveries from the Magnetospheric Multiscale Mission and Van Allen Probes era Exploration of foreshock, bow shock, magnetosheath, magnetopause, and cusps Examination of similar processes occurring around other planets 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.

The aurora is the most visible manifestation of the connection of the Earth to the space environment and has inspired awe, curiosity, and scientific inquiry for centuries. Recent advances in observing techniques and modeling and theoretical work have revealed new auroral phenomena, provided a better understanding of auroral dynamics, and have led to an enhanced capability for auroral forecasts. This monograph features discussions of: New auroral phenomena due to the ring current ion and polar rain electron precipitation Various auroral forms and hemispheric asymmetry Auroral model development and MHD simulations Application of the auroral observations for radio absorption and scintillation Aurora nowcast and forecast for space weather operations Auroral Dynamics and Space Weather is a valuable contribution for scientists, researchers, space weather operators, and students of Earth's space environment.

These proceedings are based on the invited talks and selected research reports presented at the NATO Advanced Study Institute (ASI) on "POLAR CAP BOUNDARY PHENOMENA" held at Longyearbyen, Svalbard, June 4 - 13, 1997. The role of the polar cap and its boundary is very substantial in solar-terrestrial physics. At this NATO AS! a major change in thinking on the "cusp" precipitation region in the high-latitude days ide upper atmosphere was reflected, at least for intervals when the interplanetary magnetic field (IMF) is directed southward. It is likely that this has implications for northward IMF as well. The change comes from the now almost complete acceptance of the concept of magnetosheath particle entry along open magnetic field lines and the evolution of the precipitation into the upper atmosphere with time elapsed since magnetic reconnection which opened the field line. A key prediction of this view is that the low-latitude boundary layer (LLBL) is on open field lines.

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

Proceedings of the NATO Advanced Research Workshop, Lillehammer, Norway, September 20-24, 1988

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

Nonlinear Wave and Plasma Structures in the Auroral and Subauroral Geospace presents a comprehensive examination of the self-consistent processes leading to multiscale electromagnetic and plasma structures in the magnetosphere and ionosphere near the plasmapause, particularly in the auroral and subauroral geospace. It utilizes simulations and a large number of relevant in situ measurements conducted by the most recent satellite missions, as well as ground-based optical and radar observations to verify the conclusions and analysis. Including several case studies of observations related to prominent geospacer events, the book also provides experimental and numerical results throughout the chapters to further enhance understanding of how the same physical mechanisms produce different phenomena at different regions of the near-Earth space environment. Additionally, the comprehensive description of mechanisms responsible for space weather effects will give readers a broad foundation of wave and particle processes in the near-Earth magnetosphere. As such, Nonlinear Wave and Plasma Structures in the Auroral and Subauroral Geospace Nonlinear Wave and Plasma Structures in the Auroral and Subauroral Geospace is a cutting-edge reference for space physicists looking to better understand plasma physics in geospace. - Presents a unified approach to wave and particle phenomena occurring in the auroral and subauroral geospace - Summarizes the most current theoretical concepts related to the generation of the large-scale electric field near the plasmapause by flows of hot plasma from the reconnection site - Includes case studies of the observations related to the most "famous events during the last 20 years as well as a large number of experimental and numerical results illustrated throughout the text

A comprehensive review of global ionospheric research from the polar caps to equatorial regions It's more than a century since scientists first identified the ionosphere, the layer of the Earth’s upper atmosphere that is ionized by solar and cosmic radiation. Our understanding of this dynamic part of the near-Earth space environment has greatly advanced in recent years thanks to new observational technologies, improved numerical models, and powerful computing capabilities. Ionosphere Dynamics and Applications provides a comprehensive overview of historic developments, recent advances, and future directions in ionospheric research. Volume highlights include: Behavior of the ionosphere in different regions from the poles to the equator Distinct characteristics of the high-, mid-, and low-latitude ionosphere Observational results from ground- and space-based instruments Ionospheric impacts on radio signals and satellite operations How earthquakes and tsunamis on Earth cause disturbances in the ionosphere 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