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Ann. Geophys., 24, 3491-3496, 2006
www.ann-geophys.net/24/3491/2006/
© European Geosciences Union 2006
Global manifestations of a substorm onset observed by a multi-satellite and ground station network
H. Wang1,*, S. Y. Ma1, H. Lühr2, Z. X. Liu3, Z. Y. Pu4, C. P. Escoubet5, H. U. Frey6, H. Réme7, and P. Ritter2
1Inst. of Ionosphere and Magnetosphere, LOGEG, CNME; College of Electronic Informatics, Wuhan University, Wuhan 430079, P. R. China
2GeoForschungsZentrum Potsdam, Telegrafenberg 14473 Potsdam, Germany
3Center for Space Science and Applied research, Chinese Academy of Sciences, Beijing, P. R. China
4School of Earth and Space Science, Peking University, Beijing 100871, P. R. China
5ESA/ESTEC (SCI-RSSD), Postbus 299, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands
6Space Sciences Laboratory, University of California, Berkeley, USA
7CESR/CNRS, 31029 Toulouse, France
*now at: University of Michigan, 2455 Hayward Str., Ann Arbor, 48109, USA
Abstract. With a favorable constellation of spacecraft and ground stations,
a study is made on the global manifestations of a substorm onset. The
onset occurred simultaneously and conjugately in both hemispheres,
confirmed by observations of the auroral breakup from IMAGE
FUV-WIC and a sudden intensification of a westward electrojet from
ground-based magnetometers. Concurrently with the onset,
field-aligned and Hall currents in the auroral ionosphere are
observed by CHAMP, which are consistent with the signature of a
Harang discontinuity. Immediately after the onset a magnetic field
dipolarization is clearly observed by Double Star TC-1, located
near the central magnetotail and subsequently, by the Cluster
quartet. The observations can be explained by a dawnward
propagation of the substorm current wedge at a speed of about 300 km/s.
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