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The K7RA Solar Update 22 July
Saturday, July 23rd 2011, 3:17 AM EDT
Co2sceptic (Site Admin)
.....There has been quite a bit of news about a predicted grand minima in solar activity. We recently reported on a conference where three lines of evidence were presented, seeming to point to a future disappearance of sunspots, perhaps like the dreaded Maunder Minimum. I am not unbiased in this regard, and like most radio amateurs, yearn for high solar activity. Alas, a return of Solar Cycle 19, the granddaddy of them all, seems elusive. But there is some dissent regarding these predictions of no sunspots, which gives us hope.

On Wednesday, I spoke with Dr. Douglas Biesecker, an astrophysicist at the NOAA Space Environment Center in Boulder. He was mentioned in the Solar Update for June 17, dissenting from the assertion that evidence points toward sunspots disappearing or another Maunder Minimum in our future.

He mentioned something called a Gleissberg Cycle. When we do a really long smoothing of sunspot numbers, the smoothed sunspot numbers we are familiar with -- the data used in those nice graphs of sunspot cycles -- average data over 13 months. So every place you look on the graph doesn’t show the variation that occurred during that month, but instead averages data over more than a year, to smooth out all the noise of daily variations. But what would happen if you smoothed the numbers over a much longer period, say 11 years? Could you find some periodicity that would suggest a cycle of cycles or perhaps predict clusters of decades with low or high solar activity?

Gleissberg cycles suggest a periodicity of about 87 years, and some have studied these to try to predict general levels of solar activity over multiple decades. But if a cycle is 87 years long -- and we only have about 256 years of directly observed solar data -- the most we could look at would be less than three cycles. That isn’t enough data to make even crude speculative projections.


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Doug mentioned what he referred to as an “old NASA axiom,” that goes something like this: “If you can’t see something happen seven times, it isn’t real.”

Doug said he is attending Solar Heliospheric and Interplanetary Environment (SHINE) workshops. At these meetings, participants have been hashing out the evidence for or against a “no Solar Cycle 25” scenario, and discovering some problems with the three lines of evidence pointing toward a disappearance of sunspots. They haven’t reached a consensus, but he believes that positions may be moving away from predicting another Maunder Minimum. On this topic, take a look at this website.

A new issue of WorldRadio is now available. On page 20, you’ll find the monthly Propagation column by Carl Luetzelschwab, K9LA. This time it is titled “Here’s Some Help to Explain Those Unusual QSOs.” Carl looks at propagation that doesn’t seem to be supported by the MUF or general level of solar activity at the time, and offers some interesting ideas on what might really be going on.

If you are fortunate enough to be in Kansas City this weekend, you can catch Carl’s talk on propagation at W0DXCC-2011 on Saturday, July 23. His talk begins at 9:30 AM in the W0JM Room and is called “Our Recent Sunspot Minimum, and the new Sunspot Cycle 24.”

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.

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Source Link: arrl.org
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