ARRL

News

The K7RA Solar Update

05/15/2009

After weeks of little or no sunspots, it is nice to have something to report: Following multiple false starts, quick-fading spots and knots of magnetic activity that never progressed into actual darkened sunspots, new sunspot group 1017 emerged on Wednesday, May 13. The daily sunspot number was 12; the next day the size of the group approximately doubled, raising the sunspot number to 18. This is a Solar Cycle 24 sunspot group. A week ago, we expected active regions spotted by the STEREO mission would emerge into sunspots over the weekend, but like many others in the recent past, they faded away. The new sunspot this week emerged a few days later.

Sunspot numbers for May 7 through 13 were 0, 0, 0, 0, 0, 0 and 12 with a mean of 1.7. The 10.7 cm flux was 69.5, 70.8, 72.3, 71.8, 71.9, 73.9 and 73.8 with a mean of 72. The estimated planetary A indices were 10, 13, 6, 4, 4, 2 and 3 with a mean of 6. The estimated mid-latitude A indices were 7, 12, 6, 3, 2, 0 and 2 with a mean of 4.6.

Last week's bulletin showed average daily solar flux at 68.5 -- this week it was 72. The average solar flux for the last three days prior to this bulletin (May 12-14) was 73.9, indicating a further rise. On May 14, the daily predicted 45 day 10.7 cm solar flux from USAF/NOAA was raised to 75 for May 15-21. By the way, we've mentioned in the past that the link to the latest daily forecast is sometimes delayed until after the forecast is put up, and you can hack the URL (Web address) to the next date from the latest available forecast.

Thursdays must be the longest delay between the forecast time and the time the link goes up on the Web. Right now the forecast done at 2059 UTC on May 14 is still not available at 1430 UTC on May 15. But you can click on the latest link, which takes you here and then change the date at the end of the URL to /051445DF.txt, which takes you here. More than 17 hours after it was written, this was still the only way to read Thursday's forecast.

There seems to be more confusion regarding the difference between number of sunspots and the sunspot number. Mike Khokhlov, UA9CIR, of Ekaterinburg in Asiatic Russia, notes that the new Solar Cycle Prediction update for Solar Cycle 24 from NOAA issued a week ago said the cycle may peak four years from now "with a maximum sunspot number of 90." But in other reports, such this was changed to "Solar Cycle 24 will peak in May 2013 with 90 sunspots per day on average." Spaceweather.com got it wrong also, saying, "The panel predicts the upcoming Solar Cycle 24 will peak in May 2013 with 90 sunspots per day, averaged over a month."

Update: Dr Tony Phillips of Spaceweather.com said the error was corrected, but the link should have been changed so that it ends in php instead of htm. Edit that URL and page back and forth to see the difference.

Note that Thursday and Friday of this week had one sunspot group, but the sunspot numbers were 12 and 18. As mentioned in past bulletins, a good explanation for the arcane method for computing daily sunspot number can be found on a NOAA page about the work of Johann Wolf.

The two references above to the "90 sunspots" error were actually widespread. Just Google the phrase "90 sunspots per day" and you will get hundreds of hits. Although NOAA was the source of the original correct information, NOAA News got it wrong here.

Dennis Eksten, W9SS, tried to write in last week, but couldn't find our e-mail address, which is toward the end of each W1AW and ARRL Web site bulletin. Or it should be. I was alarmed to find that it was missing from ARLP019, and I shuddered to think how long the W1AW bulletin had been coming out with no reference for contacting the author. Fortunately, it was only missing last week, and has been reinserted this week. Dennis saw an Associated Press story last weekend titled "Warning: Sunspot Cycle Beginning to Intensify." It was titled differently in different publications (like here -- note that this also has the "90 sunspots per day" error), but Dennis wondered about the geomagnetic storm of 1859 and if it could happen today with the dire results mentioned in the article.

As far as I know, the tales of telegraph wires starting fires and aurora visible around the world were taken from contemporary 19th century accounts and are true. I've heard this story for a long time, and I've seen references to 1859 newspaper accounts. This would make an interesting subject for historical research. The query was passed from W9SS to ARRL Illinois Section Manager Tom Ciciora, KA9QPN, who commented: "We can all pretty much agree that most newspaper accounts of natural phenomena were sensationalized back then in order to assist the fledgling newspaper industry (kind of like now!), but the question bears asking: Is the scenario described even possible?"

We really have no way to predict whether this will happen again, just as we have no way to predict another Solar Cycle 19 or a Maunder Minimum. But the NASA predictions of 4-10 years recovery and trillions of dollars in damages certainly gives one pause for reflection. We do have much more complex and concentrated infrastructure currently, and seem more vulnerable.

This reminds one of the old stories about EMP -- electromagnetic pulse from a nuclear blast -- in warfare, and the vulnerability of solid state vs old vacuum tube technology. In the Cold War, one side felt that their military hardware, in fighter jets for example, with modern solid state electronics was far superior to the other side that may have used older designs with vacuum tubes. But it was pointed out that vacuum tubes are much less vulnerable to an EMP blast. The simpler, hardier design may be superior in a real life battlefield environment that has escalated to the unthinkable level. Thank goodness it was never tested with EMP in a real battle.

Much more to write about on some other topics, but we are out of time.

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 in The ARRL Letter. Check 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.



Back