Using the aa Index Over the Last 14 Solar Cycles to Characterize Extreme Geomagnetic Activity

Abstract Geomagnetic indices are routinely used to characterize space weather event intensity. The DST index is well resolved but is only available over five solar cycles. The aa index extends over 14 cycles but is highly discretized with poorly resolved extremes. We parameterize extreme aa activity...

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Bibliographic Details

Published in:	Geophysical Research Letters
Main Authors:	S. C. Chapman, R. B. Horne, N. W. Watkins
Format:	Article
Language:	English
Published:	Wiley 2020-02-01
Subjects:	space weather aa index Carrington event geomagnetic storm
Online Access:	https://doi.org/10.1029/2019GL086524