Global inospheric effects of the October 1989 geomagnetic storm

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JA02543· OSTI ID:121265

Yeh, K C; Lin, K H; Ma, S Y ^[1]

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1. Univ. of Illinois, Champaign, IL (United States); and others

Based on a large data base from 40 ionosonde stations distributed worldwide and 12 total electron content stations, a case study is made on the global behavior of ionospheric responses to the great magnetic storm of October 1989. The magnetic storm was triggered by a solar flare with the largest class of X13/4B and started with a sudden storm commencement (ssc) at 0917 UT on October 20. After the initial phase the storm underwent two periods of maximum activities in the following 2 days. Low-latitude auroras were sighted and reported in widely separated areas in both northern and southern hemispheres. In response to these magnetic and auroral activities the ionosphere showed remarkable effects. Depending on the local time of ssc occurrence, the ionospheric response differed appreciably. Impressive changes were long-lasting, large-scale effects, such as the severe depressions of foF2 at higher latitudes, the temporary suppression of the equatorial anomaly and large horizontal gradients at certain latitudes. Also observed were positive storm effects of short duration during the post-sunset period in response to the onset of both ssc and main phase of the magnetic storm. These two positive storm effects showed different patterns suggesting different casual mechanisms. In addition, global propagation of large-scale traveling ionospheric disturbances (TIDs) was seen during 2 nights, identified by dramatic rises of h{prime}F with periodic fluctuations. The equatorward propagation velocities of the TIDs varied between 330 m/s and 680 m/s for the east Asia region. 33 refs., 16 figs., 1 tab.

• OSTI ID: 121265
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A4 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
AURORAE
GLOBAL ASPECTS
IONOSPHERE
MAGNETIC STORMS
SOLAR FLARES
TRANSIENTS