R. R. Anderson, D. A. Gurnett, H. Matsumoto, K.
Hashimoto, H. Kojima, G. Rostoker, I. Nagano, Y. Kasaba,
S. Kokubun, T. Yamamoto.
Geophys. Res. Lett., submitted for publication, 1997.
Numerous plasma wave phenomena were detected by GEOTAIL and POLAR related to the solar flare and coronal mass ejection event on April 7, 1997. Type III solar radio bursts were detected at the onset of the flare. Nearly three days later plasma wave features related to the initial interplanetary shock and a magnetic field intensification were observed near Earth. Somewhat sporadic and weak auroral kilometric radiation (AKR) and escaping terrestrial continuum radiation began to be observed as the ejecta approached Earth. On April 11 several substorms occurred as a result of the ejecta reaching the vicinity of the Earth. One substorm immediately followed an abrupt increase in the near-Earth solar wind plasma frequency just preceding the ejecta that engulfed the Earth. Strongly enhanced AKR and Low Frequency bursts were detected simultaneously with substorm expansive phase onsets observed by the CANOPUS photometers and magnetometers. GEOTAIL also detected strongly enhanced escaping terrestrial continuum radiation. The disturbed conditions ended when the ejecta arrived and the interplanetary magnetic field (IMF) near the Earth turned northward. For the following 13-hour period when the IMF Bz remained positive almost no AKR was detected and no significant geomagnetic activity occurred. Strong AKR began again two hours after the IMF turned southward.
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