Force balance near an X line along which E (dot) is less than 0

Observations suggest that plasma can occasionally be transferred from closed to open field lines in the Geomagnetic tail during periods when the separatrix between open and closed field lines moves rapidly toward decreasing latitudes. Such transfer would require E (dot) J greater than 0 along the distant tail X line (E being the electric field and J the current density), and it would give important information on the physical processes that occur near an X line. The condition E (dot) J greater than 0 is not allowed in resistive reconnection theory. Collisionless reconnection theory, however, requires a balance between the electric force and a gyroviscous force at an X line but does not necessarily require E (dot) J less than 0. It has been recently shown that gyroviscosity can provide the force required to balance the electric force along an X line having E (dot) J greater than 0