Relationship Between the Earth’s Radiation Belts and the Atmosphere
Physics, University of Newcastle
Department of Physics, University of Otago
British Antarctic Survey
Last modified: August 1, 2011
The Earth’s radiation belts are two zones between about 1000 and 50,000 km altitude which are home to highly variable populations of high energy (relativistic) electrons and ions. Particles of these energies can (and do) damage spacecraft and other technological assets. The particle fluxes increase rapidly in response to solar events and magnetic storms, but at low altitudes can take weeks to return to background levels. The mechanisms by which particles are accelerated to these energies, and are subsequently lost, are the subject of intense debate. NASA will launch a two-spacecraft mission, Radiation Belt Storm Probes (RBSP), in 2012 specifically to study radiation belt dynamics. However, such missions will still only provide limited spatial coverage. A new global array of low-cost VLF receivers which monitors the amplitude and phase of signals propagating along sub-ionospheric paths from high power communication and navigation transmitters identifies the penetration of high energy radiation belt electrons to low altitudes. Some recent results show that the precipitation of relativistic particles into the atmosphere may be modulated by magnetospheric plasma waves. The particle fluxes may affect atmospheric chemistry, leading to increases in odd nitrogen (NOx) and odd hydrogen (HOx) and stratospheric ozone depletion in polar regions, and provide a possible link between geomagnetic activity and polar surface temperature variability.