Mechanism of association between Pi2 pulsation and magnetospheric substorm

A long-period Pi 2 associated with a mini-substorm observed by the Japanese satellite JIKIKEN (EXOS-B).

“…3) The present analysis substantiates the plasma-sheet theory (SAITO et al, 1970) that the main component of Pi 2 is related to the field line corresponding not to the plasma pause, but to the plasma sheet.…”

“…The N 140 sec component of the mini-substorm is also recognized clearly in the All substorm is surely associated with Pi-type magnetic pulsation (SAITO, 1969). There is an inverse relation between the Pi 2 period and the substorm magnitude; substorm with the smaller magnitude is associated with Pi 2 with the longer period (SAITO et al, 1968;SAITO et al, 1976). According to the odd-mode model of Pi 2, it has generally two spectral component; one correspond to the temperal odd-mode oscillation of the field line anchoring in the midnight auroral oval KUWASHIMA et al, 1979), and the other to the field line neat the plasmapause (FUKU-NISHI, 1975).…”

“…The simplest one was denot; d by SAITO et al (1976) as minisubstorm based on various kinds of ground-based magnetograms. The purpose of the present study is to analyze the first mini-substorm that has ever been observed by satellites and to interpret its mechanism in relation to the plasmasheet model on Pi 2 type magnetic pulsation.…”

Auroral Observations Using Automatic Optical Instruments: Relations with Multiple Pi 2 Magnetic Pulsations.

“…The Pi 2 pulsations have been considered a sensitive indicator of the onset of the substorm expansion phase (e.g., Saito and Sakurai, 1970;Saito et al, 1976aSaito et al, , 1976b. The observational facts given in this paper suggest that the Pi 2 pulsation is a sensitive indicator of the onset of the sudden brightening and poleward expansion of auroras, even if the Pi 2 onset becomes multiple.…”

The dependence of Pi2 waveforms on periodic velocity enhancements within bursty bulk flows

“…Historically, impulsive ULF waves known as Pi2s, with periods of 40-150 s, have traditionally been used as indicators of substorm onset (e.g., Nose et al, 1998;Saito, 1969;Saito et al, 1976). In this paper we concentrate on the potential process or processes driving impulsive Pi2 ULF waves during substorms, a topic which is still being debated (e.g., Chi et al, 2001;Kepko and Kivelson, 1999;Keiling et al, 2006;Rae et al, 2006;Uozumi et al, 2000).…”