Acceleration and loss driven by VLF chorus: Van Allen Probes observations and DREAM model results

摘要

For over a decade now we have understood the response of the Earth's radiation belts to solar wind driving are a delicate balance of acceleration and loss processes. Theory has shown that the interaction of relativistic electrons with VLF whistler mode chorus can produce both energization through momentum diffusion and loss through pitch angle diffusion. Recent results from the Van Allen Probes mission has confirmed observationally that chorus can produce both acceleration and loss. The Van Allen Probes satellites are able to measure all the critical particle populations and wave fields with unprecedented precision and resolution but only at the two spacecraft locations. Those spatially-localized observations can be extended globally using three-dimensional diffusion codes such as the DREAM model. We will discuss some of the recent Van Allen Probes observations that firmly demonstrate local acceleration by chorus and losses due to chorus-produced pitch angle scattering (as well as outward radial diffusion). We will look at observational evidence for the complex chain of processes that inject a “seed population”, generate chorus, and ultimately drive radiation belt acceleration and loss. We will also discuss how local satellite observations can be generalized to simulate global dynamics using data-driven input and boundary conditions. RW1/J/IEIE0175/0001