Dynamic variation and the fast acceleration of particles in Earth's radiation belt  

作　　者：ZONG QiuGang YUAN ChongJing WANG YongFu SU ZhenPeng 

机构地区：[1]Institute of Space Physics and Applied Technology, Peking University [2]Sate Key Laboratory of Space Weather, Chinese Academy of Sciences [3]School of Earth and Space Sciences, University of Science and Technology of China

出　　处：《Science China Earth Sciences》2013年第7期1118-1140,共23页中国科学（地球科学英文版）

基　　金：supported by the National Basic Research Program of China (Grant No. 2012CB825603);the Specialized Research Fund for State Key Laboratories

摘　　要：We have quantitatively investigated the radiation belt's dynamic variations of 1.5-6.0 MeV electrons during 54 CME (coronal mass ejection)-driven storms from 1993 to 2003 and 26 CIR (corotating interaction region)-driven recurrent storms in 1995 by utilizing case and statistical studies based on the data from the SAMPEX satellite. It is found that the boundaries determined by fitting an exponential to the flux as a function of L shell obtained in this study agree with the observed outer and inner boundaries of the outer radiation belt. Furthermore, we have constructed the Radiation Belt Content (RBC) index by integrating the number density of electrons between those inner and outer boundaries. According to the ratio of the maximum RBC index during the recovery phase to the pre-storm average RBC index, we conclude that CME-driven storms produce more relativistic electrons than CIR-driven storms in the entire outer radiation belt, although the relativistic electron fluxes during CIR-related storms are much higher than those during CME-related storms at geosynchronous orbit. The physical radiation belt model STEERB is based on the three-dimensional Fokker-Planck equation and includes the physical processes of local wave-particle interactions, radial diffusion, and adiabatic transport. Due to the limitation of numerical schemes, formal radiation belt models do not include the cross diffusion term of local wave-particle interactions. The numerical experiments of STEERB have shown that the energetic electron fluxes can be overestimated by a factor of 5 or even several orders (depending on the pitch angle) if the cross diffusion term is ignored. This implies that the cross diffusion term is indispensable for the evaluation of radiation belt electron fluxes. Formal radiation belt models often adopt dipole magnetic field; the time varying Hilmer-Voigt geomagnetic field was adopted by the STEERB model, which self-consistently included the adiabatic transport process. The test simulations clearly indicate that the adiabaticWe have quantitatively investigated the radiation belt＇s dynamic variations of 1.5-6.0 MeV electrons during 54 CME （coronal mass ejection）-driven storms from 1993 to 2003 and 26 CIR （corotating interaction region）-driven recurrent storms in 1995 by utilizing case and statistical studies based on the data from the SAMPEX satellite. It is found that the boundaries determined by fitting an exponential to the flux as a function of L shell obtained in this study agree with the observed outer and inner bounda- ries of the outer radiation belt. Furthermore, we have constructed the Radiation Belt Content （RBC） index by integrating the number density of electrons between those inner and outer boundaries. According to the ratio of the maximum RBC index during the recovery phase to the pre-storm average RBC index, we conclude that CME-driven storms produce more relativistic electrons than CIR-driven storms in the entire outer radiation belt, although the relativistic electron fluxes during CIR-related storms are much higher than those during CME-related storms at geosynchronous orbit. The physical radiation belt model STEERB is based on the three-dimensional Fokker-Planck equation and includes the physical processes of local wave-particle interactions, radial diffusion, and adiabatic transport. Due to the limitation of numerical schemes, formal radiation belt models do not include the cross diffusion term of local wave-particle interactions. The numerical experiments of STEERB have shown that the energetic electron fluxes can be overestimated by a factor of 5 or even several orders （depending on the pitch angle） if the cross diffusion term is ignored. This implies that the cross diffusion term is indispensable for the evaluation of radiation belt electron fluxes. Formal radiation belt models often adopt dipole magnetic field; the time varying Hilmer-Voigt geomag- netic field was adopted by the STEERB model, which self-consistently included the adiabatic transport process. The test simu- lations clearly ind

关 键 词：radiation belt killer electrons CME magnetic storm CIR magnetic storm wave-particle interaction ULF wave VLFwave 

分 类 号：P353.7[天文地球—空间物理学]