Numerical study of the auroral particle transport in the polar upper atmosphere  

作　　者：CAI HongTao1,2, MA ShuYing1,2 & PU ZuYin3 1 School of Electronic Information, Wuhan University, Wuhan 430079, China 2 Key Laboratory of Geospace Environment and Geodesy, Ministry of Education of PRC, Wuhan 430079, China 3 School of Earth and Space Sciences, Peking University, Beijing 100871, China 

出　　处：《Science China(Technological Sciences)》2008年第10期1759-1771,共13页中国科学（技术科学英文版）

基　　金：the National Natural Science Foundation of China (Grant Nos. 40404015, 40390150);the Ministry of Science and Technology of PRC (Grant No. 2006BAB18B06) ;Key Lab of Geospace Environment and Geodesy, Ministry of Education of PRC

摘　　要：Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2), to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2 ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2), to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of precipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2 ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that reconstructed from electron density measurements by the radar.

关 键 词：AURORA particle PRECIPITATION POLAR UPPER ATMOSPHERE electron transport equation numerical simulation 

分 类 号：P353[天文地球—空间物理学]