We examine one well-observed event on November 3, 1997, when clear signatures of intense nose structures were observed during substorm activity on three subsequent inner magnetosphere crossings by Polar and Interball Auroral probe. Tracing particles numerically in stationary electric (Volland-Stern) and magnetic (T96) field models shows that the inward displacement of the intense nose structure in this case could not be formed only by convection in a time-stationary electric field. We add time varying electric and magnetic fields to the tracing procedure which propagate toward the Earth and represent the dipolarization process at a substorm onset. These results show that particles could be moved into the inner magnetosphere within some tens of minutes, consistent with the observations. ¿ 2001 American Geophysical Union