POLAR CAP CONVECTION DROPOUTS IN SUBSTORMS

At an altitude of about 7RE, on field lines mapping to the central polar cap, the quasi-steady anti-sunward convection shows transient dropouts, labeled "a", "b", and "c". During these events, the Ygse electric field, corresponding to anti-sunward convection drops from 1-2 mV/m to zero or negative values. At the same time, the magnetic field shifts to a less "tailward" direction. We interpret these events as part of the global reconfiguration (dipolarization) associated with substorms.

Last modified: Thu Mar 25 13:28:46 EST 2004