SSC-excited pulsations recorded near noon on GEOS 2 and on the ground (CDAW 6)

Journal Article · Sat Mar 01 00:00:00 EST 1986 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA091iA03p03089· OSTI ID:5939370

Wedeken, U; Voelker, H; Knott, K; Lester, M

The SSC occurring on March 22, 1979, at 0826 UT had an unusually sharp onset in Scandinavia, in Middle Europe and in experiments on the geostationary satellite GEOS 2, which was near noon, local magnetic time. The ground magnetometer stations showed a small preimpuse which started approx.5 s before the main impulse. Both impulses needed approx.2 s to ''propagate'' from ground stations at L = 6.3-4.6. Search coil magnetometers indicate a very small precursor in northern Finland (Lapprox.4.4-6.0) which started approx.15-20 s before the main impulse. This small precursor also occurred close to the time of the SSC onset at GEOS 2. We interpret this precursor as an effect of precipitating electrons changing the ionospheric conductivity in a localized region. The main impulse triggered damped magnetic pulsations (Psc) with periods near 160 s and 50 s visible in northern Scandinavia and the electric field detector on GEOS 2. Furthermore, the magnetic field and the energetic ions at GEOS observed pulsations with periods near 80 s, but these could only be observed at the northernmost ground stations. There are several indications that the first three harmonics of standing hydromagnetic waves are detected. They may correspond to periodic oscillations of the subsolar point or eigenperiods of the SSC-excited fast mode (compressional cavity resonance). The tentatively identified second harmonic wave (period approx.80 s) is indicative of a bounce resonance of ring current protons. Inside the plasmasphere the dominant period of a superimposed Psc 4 event increased with latitude for the H component indicating several toroidal eigenoscillations.

• Research Organization: Institut fuer Geophysik, Universitaet Goettingen, Federal Republic of Germany
• OSTI ID: 5939370
• Journal Information: J. Geophys. Res.; (United States), Vol. 91:A3
• Country of Publication: United States
• Language: English

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