Response of the radiation belt electron flux to the solar wind velocity: Parameterization by radial distance and energy
Institution:
1. Sarissa Technologies, NASA/Goddard Space Flight Center, USA;2. George Mason University, Department of Computational and Data Sciences, USA;1. Applied Physics Laboratory, Johns Hopkins University, Laurel, USA;2. Space Science Department, The Aerospace Corporation, Chantilly, USA;3. Code 612.3, NASA/GSFC, Greenbelt, MD 20771, USA;1. National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China;2. Chongqing South-to-Thais Environmental Protection Technology Research Institute Co., Ltd., Chongqing 400060, China;3. Hubei HouShui Technology Development Co., Ltd., Wuhan 430000, China;4. School of Environmental and Ecology, Chongqing University, Chongqing 400044, China;1. Hangzhou Institute of Advanced studies, Zhejiang Normal Universtity, 1108 Gengwen Road, Hangzhou 311231, PR China;2. Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road, Dalian 116023, PR China;3. The State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road, Dalian 116023, PR China;1. Center for Degradable and Flame-Retardant Polymeric Materials, College of Chemistry, State Key Laboratory of Polymer Materials Engineering, National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), Sichuan University, Chengdu, 610064, China;2. College of Light Industry, Textile and Food Engineering, Sichuan University, Chengdu, 610064, China;1. Electron Microscopy for Materials Science (EMAT), University of Antwerp, Gronenborgerlaan 171, 2020 Antwerp, Belgium;2. Department of Materials, Oxford University, Parks Road, Oxford OX1 3PH, United Kingdom
Abstract:
The solar wind velocity is the primary driver of the electron flux variability in Earth's radiation belts. The response of the logarithmic flux (“log-flux”) to this driver has been determined at the geosynchronous orbit and at a fixed energy Baker, D.N., McPherron, R.L., Cayton, T.E., Klebesadel, R.W., 1990. Linear prediction filter analysis of relativistic electron properties at 6.6 RE. Journal of Geophysical Research 95(A9), 15,133–15,140) and as a function of L shell and fixed energy Vassiliadis, D., Klimas, A.J., Kanekal, S.G., Baker, D.N., Weigel, R.S., 2002. Long-term average, solar-cycle, and seasonal response of magnetospheric energetic electrons to the solar wind speed. Journal of Geophysical Research 107, doi:10.1029/2001JA000506). In this paper we generalize the response model as a function of particle energy (0.8–6.4 MeV) using POLAR HIST measurements. All three response peaks identified earlier figure prominently in the high-altitude POLAR measurements. The positive response around the geosynchronous orbit is peak P1 (τ=2±1 d; L=5.8±0.5; E=0.8–6.4 MeV), associated with high-speed, low-density streams and the ULF wave activity they produce. Deeper in the magnetosphere, the response is dominated by a positive peak P0 (0±1 d; 2.9±0.5RE; 0.8–1.1 MeV), of a shorter duration and producing lower-energy electrons. The P0 response occurs during the passage of geoeffective structures containing high IMF and high-density parts, such as ICMEs and other mass ejecta. Finally, the negative peak V1 (0±0.5 d; 5.7±0.5RE; 0.8–6.4 MeV) is associated with the “Dst effect” or the quasiadiabatic transport produced by ring-current intensifications. As energies increase, the P1 and V1 peaks appear at lower L, while the Dst effect becomes more pronounced in the region L<3. The P0 effectively disappears for E>1.6 MeV because of low statistics, although it is evident in individual events. The continuity of the response across radial and energy scales supports the earlier hypothesis that each of the three modes corresponds to a qualitatively different type of large-scale electron acceleration and transport.
