February 2011

Propagation Summary During January conditions have remained steady and February should remain the same with the Solar Flux mainly at 82. Apart from a slight fluctuation around 3rd February, the Boulder A index is likely to stay at 5 and the K index at 2. www.wm7d.net/hamradio/solar/27d_forecast.shtml

NASA Sun Spot Number predictions revised yet again.
NASA has revised their Sun Spot prediction once again and it is now at the level of the Maunder Minimum of 1675 -1715 when the climate was much colder. The solar cycle 24 predicted sunspot maximum has been reduced again – predicted peak down to 59 Max. Current prediction for the next sunspot cycle maximum gives a smoothed sunspot number maximum of about 59 in June/July of 2013. We are currently two years into Cycle 24 and the predicted size continues to fall. (NASA Solar Physics, 3 January 2011. http://solarscience.msfc.nasa.gov/predict.shtml )

Cycle 24 Continues “During the course of an approximate eleven year sunspot cycle, the minimum phase, or quiet sun, is generally considered to exist during the time when the smoothed sunspot number (SSN) drops, and remains below 30. The smoothed sunspot number is a monthly index compiled by the Royal Observatory of Belgium for measuring solar cycle progress.
An unbroken string of smoothed sunspot numbers has been recorded since 1750. The present period of quiet sun began as declining Cycle 23 dropped below the SSN 30 level during April, 2005. A period of moderate solar activity is expected for the remainder of 2011, reaching a sunspot count on the order of 60 by year's end. This six-year solar quiet period was the deepest and most persistent recorded in almost two hundred years. It mystified solar scientists, and it is another example of how little is yet known about sunspots and of the nature of the Sun itself.” (George Jacobs WRTH 2011)

Say Goodbye To Sunspots ?“Scientists studying sunspots for the past 2 decades have concluded that the magnetic field that triggers their formation has been steadily declining. If the current trend continues, by 2016 the sun's face may become spotless and remain that way for decades—a phenomenon that in the 17th century coincided with a prolonged period of cooling on Earth.
The last solar minimum should have ended last year, but something peculiar has been happening. Although solar minimums normally last about 16 months, the current one has stretched over 26 months—the longest in a century. One reason, according to a paper submitted to the International Astronomical Union Symposium No. 273, an online colloquium, is that the magnetic field strength of sunspots appears to be waning. “
( http://news.sciencemag.org/sciencenow/2010/09/say-goodbye-to-sunspots.html )

Sunspots may vanish by 2015. By William Livingston, and Matthew Penn.
“We have observed spectroscopic changes in temperature sensitive molecular lines, in the magnetic splitting of an Fe I line, and in the continuum brightness of over 1000 sunspot umbrae from 1990-2005. All three measurements show consistent trends in which the darkest parts of the sunspot umbra have become warmer (45K per year) and their magnetic field strengths have decreased (77 Gauss per year), independently of the normal 11-year sunspot cycle. A linear extrapolation of these trends suggests that few sunspots will be visible after 2015.”
This article can be viewed in PDF format at: http://wattsupwiththat.files.wordpress.com/2008/06/livingston-penn_sunspots2.pdf

Thanks to Ken Fletcher and Mike Terry for this month’s articles. Links to these articles can be found at: www.jameswelsh.org.uk