What's Up With the Sun?

NASA/Hathaway’s updated solar cycle prediction – smallest in 100 years

The current prediction for Sunspot Cycle 24 gives a smoothed sunspot number maximum of about 60 in the Spring of 2013. We are currently over three years into Cycle 24. The current predicted size makes this the smallest sunspot cycle in about 100 years.

The prediction method has been slightly revised. The previous method found a fit for both the amplitude and the starting time of the cycle along with a weighted estimate of the amplitude from precursor predictions (polar fields and geomagnetic activity near cycle minimum). Recent work [see Hathaway Solar Physics; 273, 221 (2011)] indicates that the equatorward drift of the sunspot latitudes as seen in the Butterfly Diagram follows a standard path for all cycles provided the dates are taken relative to a starting time determined by fitting the full cycle. Using data for the current sunspot cycle indicates a starting date of May of 2008. Fixing this date and then finding the cycle amplitude that best fits the sunspot number data yields the current (revised) prediction.

This matters if you believe that the sunspot cycle strongly effects the earth's climate.  Evidence suggests that in the past, the low sunspot cycles of the Maunder and Dalton minimums coincide with periods of cool average climate on Earth. Recent progression of the cycle suggests that the sun may be going into a minimum now, which may rival the Dalton minimum, and may reach the low levels seen in the Maunder minimum.

A mechanism for the relationship between the sunspot cycle has been proposed.  The solar magnetic field (also tied to sunspots) deflects cosmic rays from earth.  Cosmic rays, in turn, ionize atoms in the Earth's atmosphere, and help to seed clouds.  Thus, periods of low sunspots correlate to greater cloudiness, high albedo, and lower temperatures on Earth.

So far, every revision of the next solar cycle has been downward.  Will they earth's climate cool as solar activity recedes?  Stay tuned for further developments:

Previous posts on the solar cycle/climate link:

Japanese Scientists Warm of Cooling Climate 
A View from the Beach: Ain't No Sunspots...
Solar Magnetic Activity Linked to Climate Via Cosmic Rays
Solar Breakdown - AAS Predicts Solar Minimum
CERN Head Censors Scientific Thinking
Dalton or Maunder?
CERN Study Finds-Climate Cosmic Ray Link 



Found at Watts Up With That.