Magnetospheric Electrodynamics: Energetic Particle Signatures of Geomagnetic Storms and Substorms

Welcome to the Magnetosphere (an introduction).  (schematic drawing or 3-D overview)   Magnetospheric substorms and geomagnetic storms may result in unwanted Space Weather effects. To predict the extent of these effects we must continuously monitor the Sun/solar wind conditions and understand the physical processes behind the dynamic changes that may occur.
 

Magnetospheric substorms are caused by the dynamic response of the magnetosphere to varying solar conditions. The energy input from the solar wind is governed by the orientation of the interplanetary field and as long as the magnetospheric region remains stable energy is stored as magnetic energy. At some critical point the magnetotail becomes unstable and the magnetic energy will be released via the "substorm expansion phase", which  involves:

1. Injection of energetic (tens to hundreds of keV) particles (electrons and ions) to the vicinity of the geostationary orbit.
2. Strong electric currents in the auroral region.
3. Rapid fluctuations and configurational changes of the magnetospheric magnetic field.
    

Geomagnetic storms are large disturbances in the near-Earth environment, which are caused by coherent solar wind and interplanetary field structures that originate from solar disturbances such as coronal mass ejections. These storms are associated with:

1. Major disturbances in the geomagnetic field.
2. Strong increase of energetic (tens to hundreds of keV) ions in the (ring current) region.
3. Occasionally intense fluxes of relativistic (MeV) electrons in the outer van Allen radiation belt.
    

Other Sites:

• Forecasting Geomagnetic Disturbances
• Structures in the Earth's Magnetosphere Boundary Layers
• The Cluster Mission: ESA's Spacefleet to the Magnetosphere
• Polar Plasma Wave Investigation (PWI)

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