Posted on 08/28/2008 4:28:18 AM PDT by PreciousLiberty
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.
(Excerpt) Read more at icecap.us ...
Thanks!
“I think it may have already bottomed out.”
It has bottomed out (since activity remains very close to zero) but it hasn’t really increased significantly since to signal a true minimum. There was a nice sunspot group that ended 9 days ago, but the Sun has been blank ever since. Possibly more significantly, the solar wind remains at around 300 km/s, about half of historical levels. 10.7 cm flux also remains at solar minimum levels. Latest solar minimum update at spaceweather.com:
Spotless Days
Current Stretch: 9 days
2009 total: 151 days (76%)
Since 2004: 662 days
Typical Solar Min: 485 days
Updated 19 July 2009
Another thought: they may call the minimum based on the moving average formula they use, but there’s no guarantee that the Sun won’t go into another stretch of minimum conditions. Such irregular cycles have been observed historically.
The “spotless day” total for last year was a very high 73%. So far we’re ahead of that rate this year, another thing to watch... We’re past the summer solstice, and heading towards winter still in deep minimum conditions. The Sarychev volcano may also contribute to a cold winter in the northern hemisphere.
On the original “sunspots may vanish by 2015” topic, I’ve not heard anything lately, but that’s such a short time away we’ll all know definitively soon enough. ;-)
2015 is near the next predicted solar maximum, so likely there’ll be no doubt if it happens.
That means I am so glad I kept my Kenwood TS450S all these years and never bought a newer one!
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