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Characteristics of energy transfer of Pi 2 magnetic pulsations: Latitudinal dependence
Author(s) -
Uozumi T.,
Yumoto K.,
Kawano H.,
Yoshikawa A.,
Olson J. V.,
Solovyev S. I.,
Vershinin E. F.
Publication year - 2000
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 - 10.1029/1999gl010767
Subject(s) - substorm , amplitude , physics , latitude , magnetic field , earth's magnetic field , geophysics , astrophysics , atmospheric sciences , magnetosphere , astronomy , quantum mechanics
To investigate the generation and propagation mechanisms of Pi 2 magnetic pulsations, we have analyzed magnetic field data from the 210° magnetic meridian (MM) stations. We used 50 Pi 2 events that were simultaneously observed at seven stations along the 210° MM during January 1995, and focused our analysis on associated magnetic energy, ((Δ H )²+(Δ D )²)/µ 0 . The times when the amplitude of the magnetic energy attained the maximum ( T max ) were compared among these stations. We found that T max has a latitudinal dependence, especially at higher latitudes, which has not been previously reported. At Kotel'nyy (L=8.50) on the poleward side of the auroral region, T max occurred an average of 21 seconds earlier than T max at Guam (L=1.01), and often as much as one minute earlier. The existence of latitudinal variation has implications for interpretation of issues related to timing of substorm onset; it is necessary to consider the global features of Pi 2 events in the study of auroral and magnetospheric substorms.