Open AccessPropagation of the preliminary reverse impulse of sudden commencements to low latitudes
Author(s) -
Chi P. J.,
Russell C. T.,
Raeder J.,
Zesta E.,
Yumoto K.,
Kawano H.,
Kitamura K.,
Petrinec S. M.,
Angelopoulos V.,
Le G.,
Moldwin M. B.
Publication year - 2001
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001ja900071
Subject(s) - ionosphere , latitude , magnetosphere , impulse (physics) , wavefront , physics , geophysics , middle latitudes , low latitude , geology , geodesy , atmospheric sciences , plasma , optics , quantum mechanics
It has been thought that the preliminary reverse impulse (PRI) of the sudden commencements (SC) phenomena occurs simultaneously on the ground at different locations. A popular explanation is that the PRI propagates through the Earth‐ionosphere waveguide at the 35 ground magnetometer stations during the SC event on September 24, 1998, and found clear differences in the arrival time of PRI. We calculated the MHD wave propagation time from the location of the first compression of the magnetosphere to the low‐latitude ground stations and found good agreement with the observed PRI arrival times. Our calculation also indicates that the wavefront is seriously distorted by the inhomogeneity of the magnetosphere and the small difference in PRI arrival time between high‐latitude and low‐latitude observations cannot be an indicator of a super‐Alfvenic propagation. We also found implications that high‐latitude PRIs can be induced by the vortex of ionospheric currents at nearby latitudes, and the motion of the current vortex can affect the arrival time of high‐latitude PRIs.