Driven reconnection in the earth's magnetotail

In the standard reconnection model, a low flow speed leads to steady reconnection at a distant-tail x-line, but a high flow speed leads to the formation of a near-earth x-line and the onset of an auroral substorm. This paper discusses recent work which suggests that a pile-up of magnetic flux in the earth's magnetotail will occur whenever reconnection is strongly driven by the solar wind and that the near-earth x-line might result from a flux pile-up at the distant-tail x-line.