Author: Allison Jaynes
Publisher: Elsevier
ISBN: 0128133996
Category : Science
Languages : en
Pages : 346
Book Description
The Dynamic Loss of Earth's Radiation Belts: From Loss in the Magnetosphere to Particle Precipitation in the Atmosphere presents a timely review of data from various explorative missions, including the Van Allen Probes, the Magnetospheric Multiscale Mission (which aims to determine magnetopause losses), the completion of four BARREL balloon campaigns, and several CubeSat missions focusing on precipitation losses. This is the first book in the area to include a focus on loss, and not just acceleration and radial transport. Bringing together two communities, the book includes contributions from experts with knowledge in both precipitation mechanisms and the effects on the atmosphere. There is a direct link between what gets lost in the magnetospheric radiation environment and the energy deposited in the layers of our atmosphere. Very recently, NASA's Living With a Star program identified a new, targeted research topic that addresses this question, highlighting the timeliness of this precise science. The Dynamic Loss of Earth's Radiation Belts brings together scientists from the space and atmospheric science communities to examine both the causes and effects of particle loss in the magnetosphere. - Examines both the causes and effects of particle loss in the magnetosphere from multiple perspectives - Presents interdisciplinary content that bridges the gap, through communication and collaboration, between the magnetospheric and atmospheric communities - Fills a gap in the literature by focusing on loss in the radiation belt, which is especially timely based on data from the Van Allen Probes, the Magnetospheric Multiscale Mission, and other projects - Includes contributions from various experts in the field that is organized and collated by a clear-and-consistent editorial team
The Dynamic Loss of Earth's Radiation Belts
Author: Allison Jaynes
Publisher: Elsevier
ISBN: 0128133996
Category : Science
Languages : en
Pages : 346
Book Description
The Dynamic Loss of Earth's Radiation Belts: From Loss in the Magnetosphere to Particle Precipitation in the Atmosphere presents a timely review of data from various explorative missions, including the Van Allen Probes, the Magnetospheric Multiscale Mission (which aims to determine magnetopause losses), the completion of four BARREL balloon campaigns, and several CubeSat missions focusing on precipitation losses. This is the first book in the area to include a focus on loss, and not just acceleration and radial transport. Bringing together two communities, the book includes contributions from experts with knowledge in both precipitation mechanisms and the effects on the atmosphere. There is a direct link between what gets lost in the magnetospheric radiation environment and the energy deposited in the layers of our atmosphere. Very recently, NASA's Living With a Star program identified a new, targeted research topic that addresses this question, highlighting the timeliness of this precise science. The Dynamic Loss of Earth's Radiation Belts brings together scientists from the space and atmospheric science communities to examine both the causes and effects of particle loss in the magnetosphere. - Examines both the causes and effects of particle loss in the magnetosphere from multiple perspectives - Presents interdisciplinary content that bridges the gap, through communication and collaboration, between the magnetospheric and atmospheric communities - Fills a gap in the literature by focusing on loss in the radiation belt, which is especially timely based on data from the Van Allen Probes, the Magnetospheric Multiscale Mission, and other projects - Includes contributions from various experts in the field that is organized and collated by a clear-and-consistent editorial team
Publisher: Elsevier
ISBN: 0128133996
Category : Science
Languages : en
Pages : 346
Book Description
The Dynamic Loss of Earth's Radiation Belts: From Loss in the Magnetosphere to Particle Precipitation in the Atmosphere presents a timely review of data from various explorative missions, including the Van Allen Probes, the Magnetospheric Multiscale Mission (which aims to determine magnetopause losses), the completion of four BARREL balloon campaigns, and several CubeSat missions focusing on precipitation losses. This is the first book in the area to include a focus on loss, and not just acceleration and radial transport. Bringing together two communities, the book includes contributions from experts with knowledge in both precipitation mechanisms and the effects on the atmosphere. There is a direct link between what gets lost in the magnetospheric radiation environment and the energy deposited in the layers of our atmosphere. Very recently, NASA's Living With a Star program identified a new, targeted research topic that addresses this question, highlighting the timeliness of this precise science. The Dynamic Loss of Earth's Radiation Belts brings together scientists from the space and atmospheric science communities to examine both the causes and effects of particle loss in the magnetosphere. - Examines both the causes and effects of particle loss in the magnetosphere from multiple perspectives - Presents interdisciplinary content that bridges the gap, through communication and collaboration, between the magnetospheric and atmospheric communities - Fills a gap in the literature by focusing on loss in the radiation belt, which is especially timely based on data from the Van Allen Probes, the Magnetospheric Multiscale Mission, and other projects - Includes contributions from various experts in the field that is organized and collated by a clear-and-consistent editorial team
Dynamics of the Earth's Radiation Belts and Inner Magnetosphere
Author: Danny Summers
Publisher: John Wiley & Sons
ISBN: 1118704371
Category : Science
Languages : en
Pages : 782
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 199. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere draws together current knowledge of the radiation belts prior to the launch of Radiation Belt Storm Probes (RPSP) and other imminent space missions, making this volume timely and unique. The volume will serve as a useful benchmark at this exciting and pivotal period in radiation belt research in advance of the new discoveries that the RPSP mission will surely bring. Highlights include the following: a review of the current state of the art of radiation belt science; a complete and up-to-date account of the wave-particle interactions that control the dynamical acceleration and loss processes of particles in the Earth's radiation belts and inner magnetosphere; a discussion emphasizing the importance of the cross-energy coupling of the particle populations of the radiation belts, ring current, and plasmasphere in controlling the dynamics of the inner magnetosphere; an outline of the design and operation of future satellite missions whose objectives are to discover the dominant physical processes that control the dynamics of the Earth's radiation belts and to advance our level of understanding of radiation belt dynamics ideally to the point of predictability; and an examination of the current state of knowledge of Earth's radiation belts from past and current spacecraft missions to the inner magnetosphere. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere will be a useful reference work for the specialist researcher, the student, and the general reader. In addition, the volume could be used as a supplementary text in any graduate-level course in space physics in which radiation belt physics is featured.
Publisher: John Wiley & Sons
ISBN: 1118704371
Category : Science
Languages : en
Pages : 782
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 199. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere draws together current knowledge of the radiation belts prior to the launch of Radiation Belt Storm Probes (RPSP) and other imminent space missions, making this volume timely and unique. The volume will serve as a useful benchmark at this exciting and pivotal period in radiation belt research in advance of the new discoveries that the RPSP mission will surely bring. Highlights include the following: a review of the current state of the art of radiation belt science; a complete and up-to-date account of the wave-particle interactions that control the dynamical acceleration and loss processes of particles in the Earth's radiation belts and inner magnetosphere; a discussion emphasizing the importance of the cross-energy coupling of the particle populations of the radiation belts, ring current, and plasmasphere in controlling the dynamics of the inner magnetosphere; an outline of the design and operation of future satellite missions whose objectives are to discover the dominant physical processes that control the dynamics of the Earth's radiation belts and to advance our level of understanding of radiation belt dynamics ideally to the point of predictability; and an examination of the current state of knowledge of Earth's radiation belts from past and current spacecraft missions to the inner magnetosphere. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere will be a useful reference work for the specialist researcher, the student, and the general reader. In addition, the volume could be used as a supplementary text in any graduate-level course in space physics in which radiation belt physics is featured.
Dayside Magnetosphere Interactions
Author: Qiugang Zong
Publisher: John Wiley & Sons
ISBN: 1119509629
Category : Science
Languages : en
Pages : 324
Book Description
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. Find out more about this book from this Q&A with the editors
Publisher: John Wiley & Sons
ISBN: 1119509629
Category : Science
Languages : en
Pages : 324
Book Description
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. Find out more about this book from this Q&A with the editors
The Van Allen Probes Mission
Author: Nicola Fox
Publisher: Springer
ISBN: 9781489978707
Category : Science
Languages : en
Pages : 0
Book Description
Documents the science, the mission, the spacecraft and the instrumentation on a unique NASA mission to study the Earth’s dynamic, dangerous and fascinating Van Allen radiation belts that surround the planet This collection of articles provides broad and detailed information about NASA’s Van Allen Probes (formerly known as the Radiation Belt Storm Probes) twin-spacecraft Earth-orbiting mission. The mission has the objective of achieving predictive understanding of the dynamic, intense, energetic, dangerous, and presently unpredictable belts of energetic particles that are magnetically trapped in Earth’s space environment above the atmosphere. It documents the science of the radiation belts and the societal benefits of achieving predictive understanding. Detailed information is provided about the Van Allen Probes mission design, the spacecraft, the science investigations, and the onboard instrumentation that must all work together to make unprecedented measurements within a most unforgiving environment, the core of Earth’s most intense radiation regions. This volume is aimed at graduate students and researchers active in space science, solar-terrestrial interactions and studies of the upper atmosphere. Originally published in Space Science Reviews, Vol. 179/1-4, 2013.
Publisher: Springer
ISBN: 9781489978707
Category : Science
Languages : en
Pages : 0
Book Description
Documents the science, the mission, the spacecraft and the instrumentation on a unique NASA mission to study the Earth’s dynamic, dangerous and fascinating Van Allen radiation belts that surround the planet This collection of articles provides broad and detailed information about NASA’s Van Allen Probes (formerly known as the Radiation Belt Storm Probes) twin-spacecraft Earth-orbiting mission. The mission has the objective of achieving predictive understanding of the dynamic, intense, energetic, dangerous, and presently unpredictable belts of energetic particles that are magnetically trapped in Earth’s space environment above the atmosphere. It documents the science of the radiation belts and the societal benefits of achieving predictive understanding. Detailed information is provided about the Van Allen Probes mission design, the spacecraft, the science investigations, and the onboard instrumentation that must all work together to make unprecedented measurements within a most unforgiving environment, the core of Earth’s most intense radiation regions. This volume is aimed at graduate students and researchers active in space science, solar-terrestrial interactions and studies of the upper atmosphere. Originally published in Space Science Reviews, Vol. 179/1-4, 2013.
Space Physics and Aeronomy, Magnetospheres in the Solar System
Author: Romain Maggiolo
Publisher: John Wiley & Sons
ISBN: 1119507529
Category : Science
Languages : de
Pages : 61
Book Description
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
Publisher: John Wiley & Sons
ISBN: 1119507529
Category : Science
Languages : de
Pages : 61
Book Description
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
Dynamics of the Earth's Radiation Belts and Inner Magnetosphere
Author: Danny Summers
Publisher: American Geophysical Union
ISBN: 9780875904894
Category : Science
Languages : en
Pages : 450
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 199. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere draws together current knowledge of the radiation belts prior to the launch of Radiation Belt Storm Probes (RPSP) and other imminent space missions, making this volume timely and unique. The volume will serve as a useful benchmark at this exciting and pivotal period in radiation belt research in advance of the new discoveries that the RPSP mission will surely bring. Highlights include the following: a review of the current state of the art of radiation belt science; a complete and up-to-date account of the wave-particle interactions that control the dynamical acceleration and loss processes of particles in the Earth's radiation belts and inner magnetosphere; a discussion emphasizing the importance of the cross-energy coupling of the particle populations of the radiation belts, ring current, and plasmasphere in controlling the dynamics of the inner magnetosphere; an outline of the design and operation of future satellite missions whose objectives are to discover the dominant physical processes that control the dynamics of the Earth's radiation belts and to advance our level of understanding of radiation belt dynamics ideally to the point of predictability; and an examination of the current state of knowledge of Earth's radiation belts from past and current spacecraft missions to the inner magnetosphere. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere will be a useful reference work for the specialist researcher, the student, and the general reader. In addition, the volume could be used as a supplementary text in any graduate-level course in space physics in which radiation belt physics is featured.
Publisher: American Geophysical Union
ISBN: 9780875904894
Category : Science
Languages : en
Pages : 450
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 199. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere draws together current knowledge of the radiation belts prior to the launch of Radiation Belt Storm Probes (RPSP) and other imminent space missions, making this volume timely and unique. The volume will serve as a useful benchmark at this exciting and pivotal period in radiation belt research in advance of the new discoveries that the RPSP mission will surely bring. Highlights include the following: a review of the current state of the art of radiation belt science; a complete and up-to-date account of the wave-particle interactions that control the dynamical acceleration and loss processes of particles in the Earth's radiation belts and inner magnetosphere; a discussion emphasizing the importance of the cross-energy coupling of the particle populations of the radiation belts, ring current, and plasmasphere in controlling the dynamics of the inner magnetosphere; an outline of the design and operation of future satellite missions whose objectives are to discover the dominant physical processes that control the dynamics of the Earth's radiation belts and to advance our level of understanding of radiation belt dynamics ideally to the point of predictability; and an examination of the current state of knowledge of Earth's radiation belts from past and current spacecraft missions to the inner magnetosphere. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere will be a useful reference work for the specialist researcher, the student, and the general reader. In addition, the volume could be used as a supplementary text in any graduate-level course in space physics in which radiation belt physics is featured.
Waves, Particles, and Storms in Geospace
Author: Georgios Balasis
Publisher: Oxford University Press
ISBN: 0198705247
Category : Science
Languages : en
Pages : 467
Book Description
The book presents an overview of the complex interplay of particles, fields, waves and currents in geospace, with an emphasis on wave-particle interactions and radiation belt dynamics.
Publisher: Oxford University Press
ISBN: 0198705247
Category : Science
Languages : en
Pages : 467
Book Description
The book presents an overview of the complex interplay of particles, fields, waves and currents in geospace, with an emphasis on wave-particle interactions and radiation belt dynamics.
Solar and Space Physics
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309313953
Category : Science
Languages : en
Pages : 37
Book Description
In 2010, NASA and the National Science Foundation asked the National Research Council to assemble a committee of experts to develop an integrated national strategy that would guide agency investments in solar and space physics for the years 2013-2022. That strategy, the result of nearly 2 years of effort by the survey committee, which worked with more than 100 scientists and engineers on eight supporting study panels, is presented in the 2013 publication, Solar and Space Physics: A Science for a Technological Society. This booklet, designed to be accessible to a broader audience of policymakers and the interested public, summarizes the content of that report.
Publisher: National Academies Press
ISBN: 0309313953
Category : Science
Languages : en
Pages : 37
Book Description
In 2010, NASA and the National Science Foundation asked the National Research Council to assemble a committee of experts to develop an integrated national strategy that would guide agency investments in solar and space physics for the years 2013-2022. That strategy, the result of nearly 2 years of effort by the survey committee, which worked with more than 100 scientists and engineers on eight supporting study panels, is presented in the 2013 publication, Solar and Space Physics: A Science for a Technological Society. This booklet, designed to be accessible to a broader audience of policymakers and the interested public, summarizes the content of that report.
Ring Current Investigations
Author: Vania K. Jordanova
Publisher: Elsevier
ISBN: 0128155728
Category : Science
Languages : en
Pages : 334
Book Description
Ring Current Investigations offers a comprehensive description of ring current dynamics in the Earth's magnetosphere as part of the coupled magnetosphere-ionosphere system. In order to help researchers develop a deeper understanding of the fundamental physics of geomagnetic storms, it includes a detailed description of energetic charged particles injection, trapping, and loss. It reviews historical and recent advances in observations, measurements, theory and simulations of the inner magnetosphere and its coupling to the ionosphere and other surrounding plasma populations. In addition, it compares the physics of ring currents at other strongly magnetized planets in the solar system, specifically Jupiter, Saturn, Uranus and Neptune, with the ring current system at Earth. Providing a description of the most important space weather effects driven by inner magnetospheric energetic particles during geomagnetic storms and present capabilities for their nowcast and forecast, Ring Current Investigations is an important reference for researchers in geophysics and space science, especially related to plasma physics, the ionosphere and magnetosphere, solar-terrestrial relations, and spacecraft anomalies. - Includes an appendix with links to downloadable video clips, illustrating features of ring current and geomagnetic storm dynamics - Provides overview of existing state-of-the-art numerical models and links for open-source code downloads - Offers guidance on how to develop numerical models within the context of the present-day understanding
Publisher: Elsevier
ISBN: 0128155728
Category : Science
Languages : en
Pages : 334
Book Description
Ring Current Investigations offers a comprehensive description of ring current dynamics in the Earth's magnetosphere as part of the coupled magnetosphere-ionosphere system. In order to help researchers develop a deeper understanding of the fundamental physics of geomagnetic storms, it includes a detailed description of energetic charged particles injection, trapping, and loss. It reviews historical and recent advances in observations, measurements, theory and simulations of the inner magnetosphere and its coupling to the ionosphere and other surrounding plasma populations. In addition, it compares the physics of ring currents at other strongly magnetized planets in the solar system, specifically Jupiter, Saturn, Uranus and Neptune, with the ring current system at Earth. Providing a description of the most important space weather effects driven by inner magnetospheric energetic particles during geomagnetic storms and present capabilities for their nowcast and forecast, Ring Current Investigations is an important reference for researchers in geophysics and space science, especially related to plasma physics, the ionosphere and magnetosphere, solar-terrestrial relations, and spacecraft anomalies. - Includes an appendix with links to downloadable video clips, illustrating features of ring current and geomagnetic storm dynamics - Provides overview of existing state-of-the-art numerical models and links for open-source code downloads - Offers guidance on how to develop numerical models within the context of the present-day understanding
The THEMIS Mission
Author: James L. Burch
Publisher: Springer Science & Business Media
ISBN: 0387898204
Category : Science
Languages : en
Pages : 575
Book Description
J.L. Burch·V. Angelopoulos Originally published in the journal Space Science Reviews, Volume 141, Nos 1–4, 1–3. DOI: 10.1007/s11214-008-9474-5 © Springer Science+Business Media B.V. 2008 The Earth, like all the other planets, is continuously bombarded by the solar wind, which is variable on many time scales owing to its connection to the activity of the Sun. But the Earth is unique among planets because its atmosphere, magnetic eld, and rotation rates are each signi cant, though not dominant, players in the formation of its magnetosphere and its reaction to solar-wind inputs. An intriguing fact is that no matter what the time scale of solar-wind variations, the Earth’s response has a de nite pattern lasting a few hours. Known as a magnetospheric substorm, the response involves a build-up, a crash, and a recovery. The build-up (known as the growth phase) occurs because of an interlinking of the geom- netic eld and the solar-wind magnetic eld known as magnetic reconnection, which leads to storage of increasing amounts of magnetic energy and stress in the tail of the mag- tosphere and lasts about a half hour. The crash (known as the expansion phase) occurs when the increased magnetic energy and stresses are impulsively relieved, the current system that supports the stretched out magnetic tail is diverted into the ionosphere, and bright, dynamic displays of the aurora appear in the upper atmosphere. The expansion and subsequent rec- ery phases result from a second magnetic reconnection event that decouples the solar-wind and geomagnetic elds.
Publisher: Springer Science & Business Media
ISBN: 0387898204
Category : Science
Languages : en
Pages : 575
Book Description
J.L. Burch·V. Angelopoulos Originally published in the journal Space Science Reviews, Volume 141, Nos 1–4, 1–3. DOI: 10.1007/s11214-008-9474-5 © Springer Science+Business Media B.V. 2008 The Earth, like all the other planets, is continuously bombarded by the solar wind, which is variable on many time scales owing to its connection to the activity of the Sun. But the Earth is unique among planets because its atmosphere, magnetic eld, and rotation rates are each signi cant, though not dominant, players in the formation of its magnetosphere and its reaction to solar-wind inputs. An intriguing fact is that no matter what the time scale of solar-wind variations, the Earth’s response has a de nite pattern lasting a few hours. Known as a magnetospheric substorm, the response involves a build-up, a crash, and a recovery. The build-up (known as the growth phase) occurs because of an interlinking of the geom- netic eld and the solar-wind magnetic eld known as magnetic reconnection, which leads to storage of increasing amounts of magnetic energy and stress in the tail of the mag- tosphere and lasts about a half hour. The crash (known as the expansion phase) occurs when the increased magnetic energy and stresses are impulsively relieved, the current system that supports the stretched out magnetic tail is diverted into the ionosphere, and bright, dynamic displays of the aurora appear in the upper atmosphere. The expansion and subsequent rec- ery phases result from a second magnetic reconnection event that decouples the solar-wind and geomagnetic elds.