Multipoint Measurements from Substorm Onset to Recovery: The Relation between Magnetic Pulsations and Plasma Sheet Thickening

摘要

Long duration waves in the Pi2 frequency band (6.7 - 22 mHz) were observed by the Air Force Geophysics Laboratory (AFGL) Magnetometer Network during a set of substorms previously analyzed. For these events that on the order of 1 hour after the expansive phase onset of a substorm, there was a sudden appearance of riometer absorption observed at South Pole Station (magnetic latitude about -75 deg) and a reappearance of the plasma sheet as observed in 6-keV electrons by ISEE 1 and 2 satellites at a distance of 15 to 20 R(sub e) in the magnetotail. The wave activity observed at the AFGL stations during these events diminished significantly at approximately the time of the plasma sheet recovery or riometer increase. One explanation for the long duration of these waves is that following substorm onset they are continuously generation in a near-tail reconnection region and then decay when the neutral line moves tailward during the substorm recovery phase. Keywords: Substorms, Magnetospheric substorms, Pi 2 pulsations, Magnetic pulsations. Reprints. (JHD)