Statistical and Superposed Epoch Studies of Dipolarization Events Using Data from Wind Perigee Passes

Dr. Kristine Sigsbee
Research Associate, National Research Council
NASA, Goddard Space Flight Center

We will present results from a study of magnetic field data from perigee passes of the Wind spacecraft through the magnetotail from 1995 to 2000. Wind spent over 500 hours in the magnetotail during this time period. Based upon a > 15 degree change in magnetic field inclination, a database was compiled of 65 potential dipolarization events in the near magnetotail at distances of -18 RE < XGSM < -6 RE. Most of the dipolarization events were found to occur within a few RE of the neutral sheet. By studying the locations at which magnetic field dipolarizations were observed in the Wind perigee pass data set, we hope to develop a statistical representation of the azimuthal and radial extent of the substorm current wedge. We are currently performing superposed epoch studies to examine the characteristics of dipolarization events and the azimuthal expansion of the substorm current wedge. Our results will be compared to other studies of dipolarizations and the magnetotail current systems.