Dependence of pitch‐angle scattering rates and loss timescales on the magnetic field model

Abstract

Radiation belt diffusion codes require, as inputs, precomputed scattering rates, which are currently bounce‐averaged in the dipole magnetic field. We present the results of computations of the bounce‐averaged quasi‐linear pitch‐angle diffusion coefficients of relativistic electrons for various distances and two MLT in the Tsyganenko 89c magnetic field model. The coefficients were computed for quiet and storm‐time conditions. We compare scattering rates bounce‐averaged in a non‐dipole field model with those in the dipole field. We demonstrate that on the day side the effects of taking into account a realistic magnetic field are negligible at distances less than six Earth radii. On the night side diffusion coefficients may significantly depend on the assumed field model. Pitch‐angle scattering rates calculated in the non‐dipole field can explain the often observed night‐side chorus induced precipitation. The physical explanation for the changes of pitch‐angle scattering rates with the field model is presented and discussed.