Quantifying the role of radial diffusion on multi-MeV electron flux variation in the outer radiation belt
Abstract
The radiation belts are highly dynamic regions filled with energetic particles, and understanding the relative effectiveness and contribution of physical mechanisms responsible for their highly dynamic nature is critical due to both scientific interests and practical needs. In particular, as one of the first recognized, important physical mechanisms acting on radiation belt electrons, radial diffusion has received intense attention. Numerous studies have focused on the effect of radial diffusion on radiation belt electrons, though its quantitative contribution to radiation belt electron flux variation is still under considerable debate. In this study, we investigate the periodic flux oscillations of relativistic to ultrarelativistic electrons in the outer radiation belt measured by the REPT instruments on the Van Allen Probes. Through a detailed examination of observed electron phase space densities and ULF waves, we demonstrate that such electron flux oscillation is the microscopic behavior of electron radial diffusion. Combining electron measurements with particle tracing simulation and diffusion modeling, the event-specific radial diffusion coefficients can be derived, and the quantitative role of radial diffusion in radiation belt electron flux variation can be revealed. The results shed more light on radial diffusion as an important physical mechanism of the outer radiation belt electron dynamics.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1072Z