Explosive Magnetotail Activity.

Modes and manifestations of the explosive activity in the Earth's magnetotail, as well as its onset mechanisms and key pre-onset conditions are reviewed. Two mechanisms for the generation of the pre-onset current sheet are discussed, namely magnetic flux addition to the tail lobes, or other high-latitude perturbations, and magnetic flux evacuation from the near-Earth tail associated with dayside reconnection. Reconnection onset may require stretching and thinning of the sheet down to electron scales.

A Case Study of Connection Between Ground Magnetic Field Perturbations and Tail Current Sheet Bursty Flows at = -60 .

We report the first observations that connect a burst of fast flows and Pi2 fluctuations in the midtail current sheet at ~-60 with ground magnetic negative bays and Pi2 pulsations at high latitudes near 70°. Both the flow burst and negative bays occurred around midnight and were isolated and lasted for ~10 min. The flow burst had the characteristics of a low-density plasma bubble.

Tail reconnection triggering substorm onset.

Magnetospheric substorms explosively release solar wind energy previously stored in Earth's magnetotail, encompassing the entire magnetosphere and producing spectacular auroral displays. It has been unclear whether a substorm is triggered by a disruption of the electrical current flowing across the near-Earth magnetotail, at approximately 10 R(E) (R(E): Earth radius, or 6374 kilometers), or by the process of magnetic reconnection typically seen farther out in the magnetotail, at approximately 20 to 30 R(E). We report on simultaneous measurements in the magnetotail at multiple distances, at the time of substorm onset.