This visualization opens with a full view of the radiation belt of trapped electrons circling Earth. We open a slice of the belts, to display a cross-section for clarity and move the camera to a more equatorial view. Earth rotation and solar motion have been turned off for this visualization to reduce distracting additional motions.
Since their discovery at the dawn of the Space Age, Earth's radiation belts continue to reveal new complex structures and behaviors.
During a particularly intense event in late June 2015, the inner edge of the region of trapped electrons moved closer to Earth. The electrons of interest had energies in excess of a million electron volts (Wikipedia). As the region retreated outward, it left behind a population of high-energy electrons forming another radiation belt inside the L=2 shell (The 'L-shell' value identifies a field line in a magnetic dipole. The numerical value corresponds to the furthest distance from Earth in Earth radii, in this case two Earth radii). This flux of high-energy electrons persisted considerably longer than expected, the relativistic electrons slowly leaking away. It took over a year for the relativistic electron flux in the belt to decline below the level of detectability for the instruments on the Van Allen Probes.
The 3-dimensional radiation belt model in the visualizations above was constructed by propagating electron flux measurements, corresponding to a given time and distance from Earth measured by the Van Allen Probes, along a 3-dimensional structure of magnetic dipole field lines.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 22.214.171.124.0