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The minimal solar activity in 2008–2009 and its implications for long-term climate modeling

Schrijver, C. J. and Livingston, W. C. and Woods, T. N. and Mewaldt, R. A. (2011) The minimal solar activity in 2008–2009 and its implications for long-term climate modeling. Geophysical Research Letters, 38 . Art. no. L06701. ISSN 0094-8276. doi:10.1029/2011GL046658.

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Variations in the total solar irradiance (TSI) associated with solar activity have been argued to influence the Earth's climate system, in particular when solar activity deviates from the average for a substantial period. One such example is the 17th Century Maunder Minimum during which sunspot numbers were extremely low, as Earth experienced the Little Ice Age. Estimation of the TSI during that period has relied on extrapolations of correlations with sunspot numbers or even more indirectly with modulations of galactic cosmic rays. We argue that there is a minimum state of solar magnetic activity associated with a population of relatively small magnetic bipoles which persists even when sunspots are absent, and that consequently estimates of TSI for the Little Ice Age that are based on scalings with sunspot numbers are generally too low. The minimal solar activity, which measurements show to be frequently observable between active-region decay products regardless of the phase of the sunspot cycle, was approached globally after an unusually long lull in sunspot activity in 2008–2009. Therefore, the best estimate of magnetic activity, and presumably TSI, for the least-active Maunder Minimum phases appears to be provided by direct measurement in 2008–2009. The implied marginally significant decrease in TSI during the least active phases of the Maunder Minimum by 140 to 360 ppm relative to 1996 suggests that drivers other than TSI dominate Earth's long-term climate change.

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Mewaldt, R. A.0000-0003-2178-9111
Additional Information:© 2011 American Geophysical Union. Received 4 January 2011; accepted 7 February 2011; published 16 March 2011. The Editor thanks two anonymous reviewers.
Group:Space Radiation Laboratory
Record Number:CaltechAUTHORS:20110404-113008296
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Official Citation:Schrijver, C. J., W. C. Livingston, T. N. Woods, and R. A. Mewaldt (2011), The minimal solar activity in 2008–2009 and its implications for long-term climate modeling, Geophys. Res. Lett., 38, L06701, doi:10.1029/2011GL046658.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23238
Deposited On:19 Apr 2011 18:52
Last Modified:09 Nov 2021 16:12

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