Open AccessIncorporating spectral characteristics of Pc5 waves into three‐dimensional radiation belt modeling and the diffusion of relativistic electrons
Author(s) -
Perry K. L.,
Hudson M. K.,
Elkington S. R.
Publication year - 2005
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004ja010760
Subject(s) - physics , van allen radiation belt , van allen probes , electron , computational physics , diffusion , ultra low frequency , spectral density , earth's magnetic field , magnetic field , dipole , wave power , pitch angle , geosynchronous orbit , magnetosphere , geophysics , power (physics) , satellite , nuclear physics , statistics , mathematics , quantum mechanics , astronomy , thermodynamics
The influence of ultralow frequency (ULF) waves in the Pc5 frequency range on radiation belt electrons in a compressed dipole magnetic field is examined. This is the first analysis in three dimensions utilizing model ULF wave electric and magnetic fields on the guiding center trajectories of relativistic electrons. A model is developed, describing magnetic and electric fields associated with poloidal mode Pc5 ULF waves. The frequency and L dependence of the ULF wave power are included in this model by incorporating published ground‐based magnetometer data. It is demonstrated here that realistic spectral characteristics play a significant role in the rate of diffusion of relativistic electrons via drift resonance with poloidal mode ULF waves. Radial diffusion rates including bounce motion show a weak pitch angle dependence for α eq ≥ 50° (λ ≤ 20°) for a power spectral density which is L ‐independent. The data‐based model for greater power at higher L values yields stronger diffusion at α eq = 90°. The L 6 dependence of the diffusion coefficient which is obtained for a power spectral density which is L ‐independent is amplified by power spectral density which increases with L . During geomagnetic storms when ULF wave power is increased, ULF waves are a significant driver of increased fluxes of relativistic electrons inside geosynchronous orbit. Diffusion timescales obtained here, when frequency and L dependence comparable to observations of ULF wave power are included, support this conclusion.