SUBSTORM EVENT ON NOVEMBER 24, 1996
Prepared by V.A.Stepanov, A.A.Petrukovich, Yu.I.Galperin, V.A.Sergeev, Yu.I.Yermolaev, L.M.Zelenyi, R.A.Kovrazhkin
|21:10 UT||Start of the growth phase|
|21:10 - 22:00 UT||Pronounced plasma sheet thinning (Bz decrease)|
|21:48 UT||Localized activation (pseudobreakup?) - see below|
|22:25 - 22:27 UT||Onset of the expansion phase|
|23:07 UT||Start of recovery, pressure minimum|
|22:25 UT||Breakup at Amderma|
|Start of sharp plasmasheet pressure increase (by GEOTAIL)|
|22:27 UT||Breakup at other stations (IMAGE, Dixon, Leirvogur, Niemegk)|
|Plasmasheet pressure maximum (by GEOTAIL)|
Activation At 21:45 UT
During the growth phase, an interesting feature was
detected in the solar wind: a small perturbation in Bz near the
21:25 UT (change from -5.5 to 0 nT), also seen in the plasma
parameters. According to the WIND position (Xgsm = 72
Re, Ygsm = -18 Re) and particle velocities,
time delay needed to take into account solar wind travelling time is
approximately 18 minutes.
The LANL-080 picture shows the electron intensity profiles at the geosynchronous orbit. A small dip indicated by the black line is most probably caused by the magnetic field decrease, unfortunately unsupported by the onboard magnetometer measurements because of their absence.
Magnetometers data from some ground stations could be seen here. The pseudobreakup at 21:48 UT, probably related to the observed IMF disturbance, is indicated by the left black line. The look of these magnetograms imply that there was a current between Tromso and Kiruna.
The INTERBALL Auroral probe particle detectors observed a particle burst inside the Northern Polar Cap. ION particle spectrometer data are presented here separately for electrons and ions. It is seen that particle energy lies below 1 keV.
The INTERBALL Tail probe ELECTRON particle spectrometer data snapshot taken in the North Lobe shows a burst of electrons of 1 keV and below, rather isotropic, but somewhat like counterstreaming at 143 eV energy. CORALL particle spectrometer data detected 1 keV ions.
The INTERBALL Tail probe detected ion burst a minute later than its subsatellite MAGION-4 (top panel), located 2000 km earthward from the Tail probe. On the bottom panel there is a Tail probe plasma flux, on the middle panel - MAGION-4 plasma flux.
It should be pointed that Auroral and Tail probes detected particles of almost the same energy. Here is a picture representing the respective positions of the satellites in GSE coordinate system. The field lines on which Auroral and Tail probes were located, being traced to 100 km altitude, appear to have a very close position in the ILAT-MLT frame, and close to the IMAGE longitude.
We are grateful to S.Perraut and T.Bosinger for valuable comments during the discussion.