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Timing of magnetic reconnection initiation during a global magnetospheric substorm onset
Author(s) -
Baker D. N.,
Peterson W. K.,
Eriksson S.,
Li X.,
Blake J. B.,
Burch J. L.,
Daly P. W.,
Dunlop M. W.,
Korth A.,
Donovan E.,
Friedel R.,
Fritz T. A.,
Frey H. U.,
Mende S. B.,
Roeder J.,
Singer H. J.
Publication year - 2002
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 - 10.1029/2002gl015539
Subject(s) - substorm , magnetic reconnection , physics , geophysics , plasma sheet , geostationary orbit , field line , magnetosphere , astrophysics , magnetic field , satellite , astronomy , quantum mechanics
We have used a unique constellation of Earth‐orbiting spacecraft and ground‐based measurements in order to study a relatively isolated magnetospheric substorm event on August 27, 2001. Global ultraviolet images of the northern auroral region established the substorm expansion phase onset at 0408:19 (±1 min) UT. Concurrent measurements from the GOES‐8, POLAR, LANL, and CLUSTER spacecraft allow us to construct a timeline which is consistent with magnetic reconnection on the closed field lines of the central plasma sheet near X GSM ∼ −18 R E some 7 minutes prior to the near‐earth and auroral region times of substorm expansion phase onset. This suggests that magnetic reconnection (i.e., the substorm neutral line) in this case formed in the mid‐tail region substantially before current disruption, field dipolarization near geostationary orbit, or auroral substorm onsets occurred. Thus, the magnetic reconnection process is interpreted as the causative driver of dissipation in this well‐observed case.