Archaeology and CRM gear store : Coronal Mass Ejections - CME's

Coronal Mass Ejections

CME's
Ward Manchester

CORONAL MASS EJECTION SHOCK AND SHEATH STRUCTURES RELEVANT. TO PARTICLE ACCELERATION.

CORONAL MASS EJECTION SHOCK AND SHEATH STRUCTURES RELEVANT. TO PARTICLE ACCELERATION. W. B. Manchester IV, T. I. Gombosi, D. L. De Zeeuw, I. V. Sokolov Coronal Mass Ejection (CME)

A coronal mass ejection (CME) is an ejection of material from the solar corona, observed with a white-light coronagraph.

The material consists of plasma consisting primarily of electrons and protons (in addition to small quantities of heavier elements such as helium, oxygen, and iron), plus the entrained coronal magnetic field. When the ejecta reaches the Earth as an ICME (Interplanetary CME), it may disrupt the Earth's magnetosphere, compressing it on the dayside and extending the nightside tail. When the magnetosphere reconnects on the nightside, it creates trillions of watts of power which is directed back towards the Earth's upper atmosphere. This process can cause particularly strong aurora also known as the Northern Lights (in the Northern Hemisphere) and the Southern Lights (in the Southern Hemisphere).
CME events, along with solar flares, can disrupt radio transmissions, cause power outages (blackouts), and cause damage to satellites and electrical transmission lines. The largest geomagnetic perturbation, resulting presumably from a "prehistoric" CME, coincided with the first-observed solar flare, in 1859. The flare was observed visually by Richard Christopher Carrington and the geomagnetic storm was observed with the recording magnetograph at Kew Gardens. The first detection of a CME was made on December 14, 1971 by R. Tousey (1973) using the 7th Orbiting Solar Observatory (OSO-7).
When the ejecta reaches the Earth as an ICME (Interplanetary CME), it may disrupt the Earth's magnetosphere. Read more about CME's and ICME's by Ward Manchester.
Abstract: GM1.00002 : Three-Dimensional Global Simulations of CME-Driven Shock Waves
Authors:
Ward Manchester
Igor Sokolov
(CSEM, University of Michigan)
Tamas Gombosi
(University of Michigan)
Jozsef Kota
(University of Arizona )
Fast Coronal Mass Ejection (CME) events are characterized by a sudden release of energy and mass from the solar conrona which naturally cause the generation of powerful interplanetary shock waves of a speed ranging from 500 to 3500 km/s. These shock waves are large-scale disturbances to the interplanetary medium that accelerate particles found in gradual solar energetic particle (SEP) events and supra- thermal ions. The acceleration process depends strongly on shock speed and geometry which both exhibit significant temporal and spatial variation. Quantitative studies using global three-dimensional simulations allow to find and predict these complicated magnetic field structures as they propagate from the low corona to 1 AU. Furthermore, we are able to distinguish shock compressed solar wind plasma from CME ejecta in synthetic white-light images which are consistent with coronagraph observations. Capturing such shock is a necessary step in building a quantitative model of SEP acceleration and transport that can be used to forecast and mitigate the radiation hazards for spacecraft.
Titre du document / Document title
Modeling a space weather event from the Sun to the Earth: CME generation and interplanetary propagation
Auteur(s) / Author(s)
MANCHESTER Ward B. (1) ; GOMBOSI Tamas I. (1) ; ROUSSEV Ilia (1) ; RIDLEY Aaron (1) ; DE ZEEUW Darren L. (1) ; SOKOLOV I. V. (1) ; POWELL Kenneth G. (1) ; TOTH Gabor (1 2) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s) (1) Ward Manchester - Center for Space Environment Modeling, University of Michigan, Ann Arbor, Michigan, ETATS-UNIS (2) Department of Atomic Physics, Eotvos University, Budapest, HONGRIE
Abstract
We present a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD) model describing the time-dependent expulsion of a coronal mass ejection (CME) from the solar corona propagating to 1 astronomical unit (AU). The simulations are performed using the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. We begin by developing a global steady-state model of the corona that possesses high-latitude coronal holes and a helmet streamer structure with a current sheet at the equator. The Archimedean spiral topology of the interplanetary magnetic field is reproduced along with fast and slow speed solar wind. Within this model system, we drive a CME to erupt by the introduction of a Gibson-Low magnetic flux rope that is anchored at both ends in the photosphere and embedded in the helmet streamer in an initial state of force imbalance. The flux rope rapidly expands and is ejected from the corona with maximum speeds in excess of 1000 km/s. Physics-based adaptive mesh refinement (AMR) allows us to capture the structure of the CME focused on a particular Sun-Earth line with high spatial resolution given to the bow shock ahead of the flux rope as well as to the current sheet behind. The CME produces a large magnetic cloud at 1 AU (>100 R[?.]) in which Bz undergoes a full rotation from north to south with an amplitude of 20 nT. In a companion paper, we find that the CME is very effective in generating strong geomagnetic activity at the Earth in two ways. First, through the strong sustained southward Bz (lasting more than 10 hours) and, second, by a pressure increase associated with the CME-driven shock that compresses the magnetosphere.
Journal Title
Journal of geophysical research (J. geophys. res.) ISSN 0148-0227
Source
2004, vol. 109, noA2, pp. A02107.1-A02107.15 (39 ref.)
KEYWORDS: Magnetospheric shock wave ; spatial resolution ; refinement ; anchors ; Flux rope ; Magnetic flux ; Interplanetary magnetic field ; topology ; Current sheet ; Helmet streamer ; Coronal hole ; High latitude ; global ; Upwind scheme ; solar wind ; trees ; simulation ; Solar corona ; Coronal mass ejection ; MHD model ; magnetohydrodynamics ; propagation ; Earth ; Sun ; Modeling ;
FRENCH KEYWORDS: Onde choc magnétosphérique ; Résolution spatiale ; Affinement ; Ancrage ; Corde flux ; Flux magnétique ; Champ magnétique interplanétaire ; Topologie ; Couche courant ; Helmet streamer ; Trou coronal ; Haute latitude ; Monde ; Schéma décentré ; Vent solaire ; Arbre ; Simulation ; Couronne solaire ; Ejection masse coronale ; Modèle MHD ; Magnétohydrodynamique ; Propagation ; Planète Terre ; Soleil ; Modélisation ; Mots-clés espagnols /
SPANISH KEYWORDS: Onda choque magnetoesférica ; Afinamiento ; Anclaje ; Cuerda flujo ; Flujo magnético ; Campo magnético interplanetario ; Topología ; Capa corriente ; Helmet streamer ; Agujero coronal ; Alta latitud ; Mundo ; Esquema decentrado ; Viento solar ; Simulación ; Corona solar ; Eyección masa coronal ; Modelo MHD ; Magnetohidrodinámica ; Propagación ; Planeta tierra ; Sol ; Modelización ;