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Author: Meghan R. Mella Publisher: ISBN: Category : Languages : en Pages : 314
Book Description
Two auroral sounding rocket case studies, one in the dayside and one in the nightside, explore aspects of poleward boundary aurora. The nightside sounding rocket, Cascades-2 was launched on 20 March 2009 at 11:04:00 UT from the Poker Flat Research Range in Alaska, and flew across a series of poleward boundary intensifications (PBIs). Each of the crossings have fundamentally different in situ electron energy and pitch angle structure, and different ground optics images of visible aurora. The different particle distributions show signatures of both a quasistatic acceleration mechanism and an Alfvénic acceleration mechanism, as well as combinations of both. The Cascades-2 experiment is the first sounding rocket observation of a PBI sequence, enabling a detailed investigation of the electron signatures and optical aurora associated with various stages of a PBI sequence as it evolves from an Alfvénic to a more quasistatic structure. The dayside sounding rocket, Scifer-2 was launched on 18 January 2008 at 7:30 UT from the Andoya Rocket Range in Andenes, Norway. It flew northward through the cleft region during a Poleward Moving Auroral Form (PMAF) event. Both the dayside and the nightside flights observe dispersed, precipitating ions, each of a different nature. The dispersion signatures are dependent on, among other things, the MLT sector, altitude, source region, and precipitation mechanism. It is found that small changes in the shape of the dispersion have a large influence on whether the precipitation was localized or extended over a range of altitudes. It is also found that a single Maxwellian source will not replicate the data, but rather, a sum of Maxwellians of different temperature, similar to a Kappa distribution, most closely reproduces the data. The various particle signatures are used to argue that both events have similar magnetospheric drivers, that is, Bursty Bulk Flows in the magnetotail.
Author: Meghan R. Mella Publisher: ISBN: Category : Languages : en Pages : 314
Book Description
Two auroral sounding rocket case studies, one in the dayside and one in the nightside, explore aspects of poleward boundary aurora. The nightside sounding rocket, Cascades-2 was launched on 20 March 2009 at 11:04:00 UT from the Poker Flat Research Range in Alaska, and flew across a series of poleward boundary intensifications (PBIs). Each of the crossings have fundamentally different in situ electron energy and pitch angle structure, and different ground optics images of visible aurora. The different particle distributions show signatures of both a quasistatic acceleration mechanism and an Alfvénic acceleration mechanism, as well as combinations of both. The Cascades-2 experiment is the first sounding rocket observation of a PBI sequence, enabling a detailed investigation of the electron signatures and optical aurora associated with various stages of a PBI sequence as it evolves from an Alfvénic to a more quasistatic structure. The dayside sounding rocket, Scifer-2 was launched on 18 January 2008 at 7:30 UT from the Andoya Rocket Range in Andenes, Norway. It flew northward through the cleft region during a Poleward Moving Auroral Form (PMAF) event. Both the dayside and the nightside flights observe dispersed, precipitating ions, each of a different nature. The dispersion signatures are dependent on, among other things, the MLT sector, altitude, source region, and precipitation mechanism. It is found that small changes in the shape of the dispersion have a large influence on whether the precipitation was localized or extended over a range of altitudes. It is also found that a single Maxwellian source will not replicate the data, but rather, a sum of Maxwellians of different temperature, similar to a Kappa distribution, most closely reproduces the data. The various particle signatures are used to argue that both events have similar magnetospheric drivers, that is, Bursty Bulk Flows in the magnetotail.
Author: Eileen MacKenzie Publisher: ISBN: Category : Auroras Languages : en Pages : 52
Book Description
The orbiting HiLat satellite launched in 1983 offered an opportunity for studying ionospheric scintillation parameters in relation to in-situ measurements of ionization density, drift velocity, field-aligned current, and particle precipitation during the sunspot minimum period. This report discusses results of a morphological study based on observations of scintillations and total electron content (TEC) at the auroral oval station at Tromso, Norway, during the period Dec 1983 - Oct 1985. The geometrical enhancement of scintillations observed during alignment of the propagation with the local magnetic L-shell is shown to be the most consistent and conspicuous feature of scintillations in the nighttime auroral oval. The dynamics of the spatial and temporal extent of this region are illustrated in the invariant latitude/magnetic local time grid. Steepening of phase spectral slope in the geometrical enhancement region is indicative of the presence of L-shell aligned sheet-like irregularities at long scale lengths. The seasonal variation of TEC determined from the differential Doppler measurements of HiLat transmissions is discussed in relation to the in-situ density measurements at 830 km. The results are also used to illustrate the dependence of ionospheric structure parameters on short-term variability of solar activity during the sunspot minimum period. This study provides an insight into the nature of magnetospheric coupling with the ionosphere at high latitudes.
Author: Yongliang Zhang Publisher: John Wiley & Sons ISBN: 1118978722 Category : Science Languages : en Pages : 324
Book Description
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.
Author: Anders Omholt Publisher: ISBN: Category : Languages : en Pages : 16
Book Description
Research in the following areas is summarized: rapid movements of auroral rays, construction and application of a four channel photometer for auroral research; current densities in visual aurora; temperature measurements; relation between auroral luminosity and ionospheric absorption; studies of the hydrogen line emissions; very low frequency emissions from aurora.
Author: Chao Huang Publisher: John Wiley & Sons ISBN: 1119507553 Category : Science Languages : en Pages : 47
Book Description
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
Author: Andreas Keiling Publisher: John Wiley & Sons ISBN: 1118671538 Category : Science Languages : en Pages : 794
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 197. Many of the most basic aspects of the aurora remain unexplained. While in the past terrestrial and planetary auroras have been largely treated in separate books, Auroral Phenomenology and Magnetospheric Processes: Earth and Other Planets takes a holistic approach, treating the aurora as a fundamental process and discussing the phenomenology, physics, and relationship with the respective planetary magnetospheres in one volume. While there are some behaviors common in auroras of the different planets, there are also striking differences that test our basic understanding of auroral processes. The objective, upon which this monograph is focused, is to connect our knowledge of auroral morphology to the physical processes in the magnetosphere that power and structure discrete and diffuse auroras. Understanding this connection will result in a more complete explanation of the aurora and also further the goal of being able to interpret the global auroral distributions as a dynamic map of the magnetosphere. The volume synthesizes five major areas: auroral phenomenology, aurora and ionospheric electrodynamics, discrete auroral acceleration, aurora and magnetospheric dynamics, and comparative planetary aurora. Covering the recent advances in observations, simulation, and theory, this book will serve a broad community of scientists, including graduate students, studying auroras at Mars, Earth, Saturn, and Jupiter. Projected beyond our solar system, it may also be of interest for astronomers who are looking for aurora-active exoplanets.
Author: Jules Aarons Publisher: ISBN: Category : Languages : en Pages : 21
Book Description
In order to study the dynamics of ionospheric F-layer irregularities at latitudes below the auroral oval, radio, optical, and incoherent scatter observations were initiated primarily in the region of 75 degrees W longitude. In addition earlier observations including in-situ satellite measurements were used, The principal conclusions were first that the sub-auroral ionospheric observations could be understood by correlating F-layer irregularities with ring current intensities as measured by Dst, the magnetic field measurement made near the magnetic equator. Sub-auroral irregularities which affect HF communications and over the horizon observations last over several nights while the ring current recovers from an injection of ions during a magnetic storm. The second conclusion made possible from local observations of Stable Auroral Red (SAR) Arcs and by Millstone Hill incoherent scatter data is that the weaker SAR Arcs detected are important in determining the physics of the generation of these emissions.
Author: James L. Burch Publisher: Springer Science & Business Media ISBN: 9401142335 Category : Science Languages : en Pages : 509
Book Description
IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) is the first NASA MIDEX mission and the first mission dedicated to imaging the Earth's magnetosphere. This volume offers detailed descriptions of the IMAGE instrumentation and of the image inversion techniques used to interpret the data. Also included are chapters on the IMAGE science objectives, the spacecraft design and capabilities, science and mission operations, and the processing and distribution of IMAGE's nonproprietary data products.
Author: Meghan R. Mella
Author: Meghan R. Mella
Author: Eileen MacKenzie
Author: Yongliang Zhang
Author: 
Author: Anders Omholt
Author: Chao Huang
Author: Andreas Keiling
Author: Costel Bunescu
Author: Jules Aarons
Author: James L. Burch