J. Space Weather Space Clim.
Volume 2, 2012
|Number of page(s)||9|
|Published online||17 May 2012|
Solar wind drivers of geomagnetic storms during more than four solar cycles
Code 661, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
2 CRESST and Department of Astronomy, University of Maryland, College Park, MD 20742, USA
3 School of Mathematics and Physics, University of Tasmania, Hobart, Tasmania, Australia
* corresponding author: e-mail: email@example.com
Accepted: 24 April 2012
Using a classification of the near-Earth solar wind into three basic flow types: (1) High-speed streams associated with coronal holes at the Sun; (2) Slow, interstream solar wind; and (3) Transient flows originating with coronal mass ejections (CMEs) at the Sun, including interplanetary CMEs and the associated upstream shocks and post-shock regions, we determine the drivers of geomagnetic storms of various size ranges based on the Kp index and the NOAA “G” criteria since 1964, close to the beginning of the space era, to 2011, encompassing more than four solar cycles (20–23). We also briefly discuss the occurrence of storms since the beginning of the Kp index in 1932, in the minimum before cycle 17. We note that the extended low level of storm activity during the minimum following cycle 23 is without precedent in this 80-year interval. Furthermore, the “typical” numbers of storm days/cycle quoted in the standard NOAA G storm table appear to be significantly higher than those obtained from our analysis, except for the strongest (G5) storms, suggesting that they should be revised downward.
Key words: Solar wind / Interplanetary Coronal Mass Ejection (CME) / Storm / Stream / Solar cycle
© Owned by the authors, Published by EDP Sciences 2012
This is an Open Access article distributed under the terms of creative Commons Attribution-Noncommercial License 3.0
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