www.ann-geophys.net/25/1001/2007/ © European Geosciences Union 2007

Abstract. A close conjunction of several satellites (LANL, GOES, Polar, Geotail, and Cluster) distributed from the geo-stationary altitude to about 16 RE downstream in the tail oc-curred during substorm activity as indicated by global au-roral imaging and ground-based magnetometer data. This constellation of satellites resembles what is planned for the THEMIS (Time History of Events and Macroscopic Inter-actions during Substorms) mission to resolve the substorm controversy on the location of the substorm expansion onset region. In this article, we show in detail the dipolarization and dynamic changes seen by these satellites associated with two onsets of substorm intensification activity. In particular, we find that dipolarization at ∼16 RE downstream in the tail can occur with dawnward electric field and without plasma flow, just like some near-Earth dipolarization events reported previously. The spreading of substorm disturbances in the tail coupled with complementary ground observations indi-cates that the observed time sequence on the onsets of sub-storm disturbances favors initiation in the near-Earth region for this THEMIS-like conjunction