The quiet sun (continued)

April 3, 2009 at 2:13 pm | Posted in Uncategorized | Leave a comment
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NASA’s position seems to be changing. A couple of days ago they put out this about the Solar minimum. There is a very healthy discussion of this on wattsupwiththat , but I’d like to add a few points of my own, expanding on points from within the press release.

I suppose the first point is that the report is authored by someone other than NASA’s usual expert trotted out on these occasions, David Hathaway.  Instead it’s authored by Dr Tony Phillips, who looks after the site updated daily by NASA.  Hathaway is quoted, butjust saying that “It’s the quietest sun for almost a century”  Looking at a previous presentation by Hathaway, there was an expectation, in early 2007, that the next cycle, cycle 25, would be weaker than 24, see this presentation powerpoint presentation. In fact he points out within the same presentation that the methodology used by another US Scientist, Dikpati, may be flawed.  In fact, reading between lines, to me it seems that the presentation, taken as a whole points to a lower Cycle24 than originally indicated.

Secondly, of the points made, in order of importance, the drop in extreme UV of 5% means that the amount of heat received, and aborbed by the planet stands out.  UV radiation is almost completely absorbed by the atmosphere, and is turned into heat, a drop of 5% in the extreme UV range doesn’t mean that the temperature of the planet will drop by 5%, but probably does mean that there will be a cooling trend of about 1.25 to 2.00 degrees across the planet.  There will still be individual variations where places may get warmer, but the overall trend is down.

Solar Wind pressure is also at a 50 year low, this allows more Galactic Cosmic Rays to hit our lower atmosphere.  That produces more clouds, more clouds mean a higher albedo, more sunlight is reflected, and until the sun picks up, we have the possibility of a viscious circle, with Cold having a positive feedback loop established.

Hathaway’s comment “Since the Space Age began in the 1950s, solar activity has been generally high,” notes Hathaway. “Five of the ten most intense solar cycles on record have occurred in the last 50 years. We’re just not used to this kind of deep calm.” is most instructive.  The whole Global warming hype has been with us for about half of that time.  In other data, a drop of  0.1 C can be seen at each Solar Minimum, but the minima of the last few cycleshave been very short before the sun ramped back up with lots of spots, yet even in those minima we see a global drop in temperature, so where do we go with a long minimum?  Just hope it isn’t a Dalton or Maunder length of time or things could get tricky.

Further updates later


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