Reconciliation of the substorm onset determined on the ground and at the Polar spacecraft

P. K Toivanen; D. N Baker; A Keiling; J. R Wygant; C. A Kletzing; W. K Peterson; H. J Singer; N. E Turner; X LI; K Kauristie; M Syrjäsuo; A Viljanen; T. I Pulkkinen

doi:10.1029/2000GL000099

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Reconciliation of the substorm onset determined on the ground and at the Polar spacecraft

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Reconciliation of the substorm onset determined on the ground and at the Polar spacecraft

P. K Toivanen, D. N Baker, A Keiling, J. R Wygant, C. A Kletzing, W. K Peterson, H. J Singer, N. E Turner, X LI, K Kauristie, …

Geophysical research letters, Vol.28(1), pp.107-110

2001

DOI: 10.1029/2000GL000099

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Abstract

An isolated substorm on Oct. 17, 1997 during a close conjunction of the Polar spacecraft and the ground-based MIRACLE network is studied in detail. We identify signatures of substorm onset in the plasma sheet midway between the ionosphere and the equatorial plasma sheet, determine their timing relative to the ground signatures, and discuss their counterparts on the ground and in the equatorial plasma sheet. The substorm onset is determined as the negative bay onset at 2040:42(±5 sec) UT coinciding with the onset of auroral precipitation, energization of plasma sheet electrons at Polar, and strong magnetic field variations perpendicular to the ambient field. Such accurate timing coincidence is consistent with the Alfvén transit time between Polar and the ionosphere. Furthermore, the timing of other field and particle signatures at Polar showed clear deviations from the onset time (±2 min). This suggests that the sequence of these signatures around the onset time can be used to validate the signatures predicted by various substorm onset models.

Earth, ocean, space

Exact sciences and technology

External geophysics

Magnetic storms, substorms

Physics of the magnetosphere

Details

Title: Subtitle: Reconciliation of the substorm onset determined on the ground and at the Polar spacecraft
Creators: P. K Toivanen - Laboratory for Atmospheric and Space Physics
D. N Baker - Laboratory for Atmospheric and Space Physics
A Keiling - University of Minnesota
J. R Wygant - University of Minnesota
C. A Kletzing - University of Iowa
W. K Peterson - Lockheed Martin Space Science Laboratory, Palo Alto
H. J Singer - National Oceanic and Atmospheric Administration
N. E Turner - Laboratory for Atmospheric and Space Physics
X LI - Laboratory for Atmospheric and Space Physics
K Kauristie - Finnish Meteorological Institute
M Syrjäsuo - Finnish Meteorological Institute
A Viljanen - Finnish Meteorological Institute
T. I Pulkkinen - Finnish Meteorological Institute
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.28(1), pp.107-110
Publisher: American Geophysical Union
DOI: 10.1029/2000GL000099
ISSN: 0094-8276
eISSN: 1944-8007
Language: English
Date published: 2001
Academic Unit: Physics and Astronomy
Record Identifier: 9984199829802771

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