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Occurrence of EMIC Waves in the Magnetosphere According to Their Distance to the Magnetopause
Author(s) -
Grison B.,
Santolík O.,
Lukačevič J.,
Usanova M. E.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090921
Subject(s) - magnetopause , magnetosphere , physics , geophysics , emic and etic , magnetosheath , noon , computational physics , earth radius , solar wind , local time , population , astrophysics , atmospheric sciences , magnetic field , statistics , demography , mathematics , quantum mechanics , sociology , anthropology
Wave growth of electromagnetic ion cyclotron (EMIC) emissions observed in the outer magnetosphere is mainly controlled by compression events resulting from solar wind dynamic pressure pulses. During such events wave growth is expected to be maximum close to the magnetopause. In previous studies, distribution of EMIC waves was analyzed according to their distance from the Earth, which is inadequate for studying the magnetopause region. We map a data set of EMIC waves observed by Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft according to their distance from case‐by‐case modeled magnetopause. EMIC occurrence rate is found to be maximum within two Earth radii from the magnetopause and then it linearly decreases with an increasing distance, especially close to the local noon. Asymmetries between the morning and evening magnetic sectors are explained by asymmetries in the upstream conditions and by the presence of another EMIC population of a different origin.