Events of 17 August 2001. I. Development of the loading-unloading phase during the storm

A substorm (storm-time substorm) was observed during the storm conditioned by solar wind parameters (AE max>800 nT). The substorm developed as the “loading-unloading” phase typical of isolated substorms with consecutive growth and expansion phases. There were also differences between the observed event and typical (isolated) substorms. We described a previously unknown fact - two abrupt consecutive onsets of the substorm expansion phase (EP). The first stage (EP-1) was accompanied by current disruption (CD) in the near-Earth tail and generation of field-aligned currents (FACs) of the substorm current wedge (SCW). The second stage (EP-2) involved increase in АЕ, disturbance power in the near-Earth tail, and velocity jump MR-2. We deduced that onsets of EP-1 and EP-2 preceded rapid tailward bursty bulk flows (BBF) of plasma and manifestation of magnetic reconnection (MR) processes in the middle magnetotail. This conclusion contradicts the Outside-In scenario while supporting the Inside-Out scenario and the Global Alfvenic Interaction (GAI).