Polar Observations of the Near Equatorial Plasma Sheet Near 9 RE: Radial Dynamics

In 2001, 2002 and 2003, the Polar spacecraft probed the near equatorial plasma sheet at 9 RE near local midnight. Often the magnetic field magnitude is very low in this region of space, below 5 nT. A variety of dynamic signatures are seen in the magnetic field including mirror mode waves and sudden recoveries of the field, possibly inward moving compressions, possibly associated with bursty bulk flows. We examine measurements closer to Earth at geosynchronous orbit and farther from Earth (Cluster) to determine the origin of these dynamic compressions in preparation for the THEMIS mission that will probe the region beyond Polar's apogee.