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Parameterized lifetime of radiation belt electrons interacting with lower‐band and upper‐band oblique chorus waves
Author(s) -
Gu Xudong,
Shprits Yuri Y.,
Ni Binbin
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl052519
Subject(s) - van allen radiation belt , electron , physics , atomic physics , range (aeronautics) , computational physics , van allen probes , radiation , scattering , plasma , magnetosphere , nuclear physics , materials science , optics , composite material
In order to evaluate the electron lifetimes from quasi‐linear bounce‐averaged diffusion coefficients, a large amount of CPU time is required to compute scattering rates. To reduce computation time, we assume that the electron loss rates are a function of L shell and electron energy, allowing us to derive the parameterization of electron lifetime using a linear regression technique. We also present the parameterizations of lifetimes as a function of electron energy and ratios of plasma frequency to electron gyrofrequency at a fixed L shell. By considering the net loss rates due to lower‐band (0.05–0.5 |Ω ce |) and upper‐band (0.5–0.7 |Ω ce |) chorus waves propagating obliquely with respect to the ambient magnetic field, the parameterizations of electron lifetime for energies between 1 keV and 2 MeV are investigated in the outer radiation belt. The parameterized lifetimes indicate a strong functional dependence on electron energy, L shell, and the level of geomagnetic activity (Kp index), and are also dependent on the ratios of plasma frequency to electron gyrofrequency. During the storm time, the lifetimes for higher energy (>100 keV) electrons range from hours to days in the heart of the radiation belts. In contrast, the lifetimes for lower energy (<100 keV) electrons are mainly in the range from minutes to hours. Such parameterization efforts of radiation belt electron lifetimes are very significant for multi‐dimensional simulations of the dynamics of the radiation belt and ring current electrons.