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Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +3 more
Solar cycle 23 witnessed the most complete set of observations of coronal mass ejections (CMEs) associated with the Ground Level Enhancement (GLE) events. We present an overview of the observed properties of the GLEs and those of the two associated phenomena, viz., flares and CMEs, both being potential sources of particle acceleration. Although we…
Particle Acceleration in the Magnetotail and Aurora
Zelenyi, L. M.; Baker, D. N.; Artemyev, A. V. +3 more
This paper deals with acceleration processes in the magnetotail and the processes that enhance particle precipitation from the tail into the ionosphere through electric fields in the auroral acceleration region, generating or intensifying discrete auroral arcs. Particle acceleration in the magnetotail is closely related to substorms and the occurr…
Magnetic Reconnection in the Solar Wind
Gosling, J. T.
It is only within the last 5 years that we have learned how to recognize the unambiguous signature of magnetic reconnection in the solar wind in the form of roughly Alfvénic accelerated plasma flows embedded within bifurcated magnetic field reversal regions (current sheets). This paper provides a brief overview of what has since been learned about…
Anisotropy in Space Plasma Turbulence: Solar Wind Observations
Horbury, T. S.; Chen, C. H. K.; Wicks, R. T.
The local magnetic field induces many types of anisotropy in plasma turbulence, changing the rate of energy transfer and affecting the propagation of energetic particles. It is challenging to measure this anisotropy in the solar wind due to the limited number of sampling points and measurement difficulties and many aspects remain poorly understood…
Ion Acceleration at the Earth's Bow Shock
Möbius, E.; Scholer, M.; Burgess, D.
The Earth's bow shock is the most studied example of a collisionless shock in the solar system. It is also widely used to model or predict the behaviour at other astrophysical shock systems. Spacecraft observations, theoretical modelling and numerical simulations have led to a detailed understanding of the bow shock structure, the spatial organiza…
What Are Special About Ground-Level Events?. Flares, CMEs, Active Regions and Magnetic Field Connection
Liu, Y.; Nitta, N. V.; Nightingale, R. W. +1 more
Ground level events (GLEs) occupy the high-energy end of gradual solar energetic particle (SEP) events. They are associated with coronal mass ejections (CMEs) and solar flares, but we still do not clearly understand the special conditions that produce these rare events. During Solar Cycle 23, a total of 16 GLEs were registered, by ground-based neu…
Solar Wind Models from the Chromosphere to 1 AU
Velli, Marco; Hansteen, Viggo H.
Recent models of the fast solar wind are characterized by low coronal electron temperatures while proton, α-particle, and minor ion temperatures are expected to be quite high and generally anisotropic, including large temperatures perpendicular to the magnetic field and parallel beams. This entails that the electric field should be relatively unim…
Observational Aspects of Particle Acceleration in Large Solar Flares
Krucker, Säm; Raymond, John C.; Lin, Robert P. +1 more
Solar flares efficiently accelerate electrons to several tens of MeV and ions to 10 GeV. The acceleration is usually thought to be associated with magnetic reconnection occurring high in the corona, though a shock produced by the Coronal Mass Ejection (CME) associated with a flare can also accelerate particles. Diagnostic information comes from em…
LCROSS (Lunar Crater Observation and Sensing Satellite) Observation Campaign: Strategies, Implementation, and Lessons Learned
Terada, Hiroshi; de Pater, Imke; Vilas, Faith +84 more
NASA's LCROSS (Lunar Crater Observation and Sensing Satellite) mission was designed to explore the nature of previously detected enhanced levels of hydrogen near the lunar poles. The LCROSS mission impacted the spent upper stage of the launch vehicle into a permanently shadowed region of the lunar surface to create an ejecta plume. The resultant i…
Scalings, Cascade and Intermittency in Solar Wind Turbulence
Carbone, Vincenzo
Investigating in situ fluctuations in the interplanetary space, offers us a unique challenge to study scaling properties in a turbulent medium which cover a wide range of scales. This includes not only the inertial range, where turbulence can be described within a fluid-like approach, but also the high-frequency region, where a kinetic approach is…