J. Space Weather Space Clim.
Volume 3, 2013
Space Weather and Challenges for Modern Society
|Number of page(s)
|05 July 2013
Solar activity – past, present, future
W.W. Hansen Experimental Physics Laboratory, Stanford University, CA 94305, California, USA
* Corresponding author: email@example.com
Accepted: 30 April 2013
As our civilization depends increasingly on space-borne assets and on a delicate and vulnerable earth-bound infrastructure, solar activity and its potential impact becomes of increasing importance and relevance. In his famous paper on the Maunder Minimum, Eddy (1976) introduced the notion that the Sun is a variable star on long time scales. After the recent decade of vigorous research based on cosmic ray and sunspot data as well as on geomagnetic activity, an emerging consensus reconstruction of solar wind magnetic field strength has been forged for the last century. The consensus reconstruction shows reasonable agreement among the various reconstructions of solar wind magnetic field the past ~ 170 years. New magnetic indices open further possibilities for the exploitation of historic data. The solar wind is a direct result of solar magnetic activity providing an important link to the effects on the Earth’s environment. Reassessment of the sunspot series (no Modern Grand Maximum) and new reconstructions of Total Solar Irradiance also contribute to our improved knowledge (or at least best guess) of the environment of the Earth System, with obvious implications for management of space-based technological assets or, perhaps, even climate. Several lines of evidence suggest that the Sun is entering a period of low activity, perhaps even a Grand Minimum. Average space weather might be “milder” with decreased solar activity, but the extreme events that dominate technological effects are not expected to disappear. Prediction of solar activity has a poor track record, but the progression of the current Cycle 24 is in accordance with its behavior predicted from the evolution of the solar polar fields, so perhaps there is hope.
Key words: solar activity / cycle prediction / time variation / historical data / solar wind
Details of the analyses and related talks and papers can be found at http://www.leif.org/research
© L. Svalgaard et al., Published by EDP Sciences 2013
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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