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Analytical Fast Magnetosonic Wave Model Based on Observations of Van Allen Probe
Author(s) -
Yao Fei,
Yuan Zhigang,
Yu Xiongdong,
Wang Dedong,
Ouyang Zhihai
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028527
Subject(s) - plasmasphere , amplitude , physics , van allen probes , computational physics , earth's magnetic field , van allen radiation belt , magnetosphere , magnetic field , optics , quantum mechanics
Based on observations of Van Allen Probe‐A during the period from 19 September 2012 to 28 February 2016, the relations of the fast magnetosonic (MS) wave amplitude B w with kp index, the wave normal angle ( WNA ), and the wave normalized frequency ( norF ) are presented. Then, we establish an analytical regression model for MS wave amplitude as a function of geomagnetic storm activity (presented by kp index), L ‐shell ( L ), magnetic local time ( MLT ), magnetic latitude ( λ ), and the characteristics of MS wave, that is, wave norF and WNA . From the analytical B w models, we found MS wave amplitude B w has a positive relation with the intensity of geomagnetic activities both inside and outside the plasmapause, while the B w can reach higher values inside the plasmapause than it does outside the plasmapause as the kp index increases. The B w distribution on the norF demonstrates that most of the wave energies are concentrated on the lower harmonics part, which results from the excitation mechanism of MS waves. In addition, the B w distribution on the WNA shows that the waves with larger normal angles have higher values of wave amplitude. Our analytic MS wave model agrees with the observed distribution in 3‐D space of L , MLT , and λ well with high value of determine coefficient R 2 . The extended λ dimension will help us to calculate the more accurate bounced averaged diffusion coefficients during particles transit time.