The K7RA Solar Update
Spaceweather.com reports that a CME has been coming toward us since July 30, when a magnetic filament erupted on our Sun. It may sideswipe our magnetic field on Saturday, August 2, and there is a 30 percent chance of geomagnetic storms in polar regions.
Right now there are plenty of sunspots, but they are magnetically weak.
Since July 24, the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, Canada, has been experiencing some serious computer network issues, so we do not have a source for the 10.7 centimeter solar flux values resolved to one-tenth of a point. This is not a serious problem, except those of us who archive the values like to see the values in a consistent format. We can still get the flux values resolved to whole integers from NOAA.
These numbers appear at the end of the weekly bulletin. For those who archive the values, when Penticton site gets back online, you will be able to correct the values from these usual sources — Spaceweather.ca and Geomagnetism Canada.
The official flux number is the daily local noon value, which is at 2000 UTC. When the system comes back online, you should see solar flux readings after July 23. NOAA has always presented these as whole integers, and for the past week the noon flux has been supplied via a daily phone call to Boulder from Penticton.
Using the flux values rounded to whole integers makes little difference. For example, rounding to whole integers would change the average solar flux in ARLP027 from 129.5 to 129.6, and in ARLP028 it does not change the average at all.
There were were no zero-sunspot days over the past week, so the average daily sunspot number rose from 25.9 in the July 17-23 period to 107.7 this week. Average daily solar flux rose from 90.3 to a more robust 125. Solar flux on Thursday, July 31 was 156.
July ended yesterday, so we can look at recent averages. The average daily sunspot number for July was 113.6, up from 107.8 for June. The 3-month moving averages of daily sunspot numbers for the past year are 85.6, 77.4, 91.2, 102.9, 123.7, 123.3, 138.5, 146.4, 148.2, 129.6, 118.4, and 112.8.
Predicted solar flux for the near term is 160 on August 1-2, 150 on August 3, 145 on August 4-6, then 140, 120, 110, 105, 100 and 95 on August 7-12, 90 on August 13-15, 95 on August 16-17, 100 on August 18, and 105 on August 19-21.
From July 21-27 the flux value predicted for August 18 was only 85, but that was revised back to 100 on July 28, the same value predicted from July 13-20 (for August 18. Is that as clear as mud?)
Predicted planetary A index is 5, 8, 14, 10, and 8 on August 1-5, then 5, 8, 6, 5 and 8 on August 6-10, 5 on August 11-21, then 8, 5, 12 and 10 on August 22-25, and 5 on August 26-31.
FK Janda, OK1HH, predicts mostly quiet geomagnetic conditions on August 1, quiet to unsettled for August 2-3, quiet to active on August 4, quiet to unsettled for August 5-6, quiet on August 7, quiet to active on August 8, active to disturbed on August 9, quiet to active for August 10-11, quiet for August 12-15, mostly quiet on August 16, quiet for August 17-18, mostly quiet for August 19-20, quiet on August 21, quiet to unsettled on August 22, quiet to active for August 23, and active to disturbed on August 24.
Scott Bidstrup, TI3/W7RI, commented, “You wrote: ‘No sunspots? Sky and Telescope recommends observing faculae.
“There's actually a good reason for hams to do so. Faculae actually appear fairly bright in the 304 angstrom wavelength images of the Sun. When they are large and numerous, even in the absence of significant sunspots, they can contribute significantly to the 304 angstrom ultraviolet that causes about half of our F2 ionization. So when the sunspots are low, but the propagation isn't all that bad, it's a good bet that a lot of faculae are present on the solar disk.
“You can easily see if this is the case in the 304 angstrom image of the sun, which can be found on my propagation web page. The 304 angstrom image is the upper right in the group of four solar images (the image can be viewed full size by right-clicking the image and selecting ‘view image’ from the drop-down menu). Sunspots normally appear as a bright, white spot in this image, but faculae appear as bright orange areas surrounding the sunspots, much brighter than the background granulation around them. The faculae may not be as bright as the sunspots, but they make up for that in a much larger area on the solar surface.
“While the faculae don't show up quite as well in the 195 angstrom image from the STEREO B spacecraft beacon, the green image just below the 304 angstrom image on my page, it will give you an idea of what faculae as well as active regions are about to rotate into view. So it can be useful to watch these images to get an idea of what is coming up — particularly for a contest weekend. It can help in planning band strategies.”
Tomas Hood, NW7US, the propagation editor for CQ and several other magazines, is publishing cool propagation and space weather information throughout each day on his Space Weather and Radio Propagation page on Facebook.
These posts include current images from the Solar Dynamics Observatory (SDO) instruments that watch the Sun 24/7, daily space weather and radio propagation conditions and forecasts, plus educational tidbits that can enhance your understanding of this exciting topic. Anyone who has a Facebook account can “Like” and have notifications turned on, so that they can see alerts when these page posts are made. Speaking of educational material, check out the self-study course that Tomas offers.
For more information concerning radio propagation, see the ARRL Technical Information Service. For an explanation of the numbers used in this bulletin, see this article. There is an archive of past propagation bulletins. More good information and tutorials on propagation are here.
Sunspot numbers for July 24 through 30 were 55, 65, 76, 110, 143, 160, and 145, with a mean of 107.7. 10.7 cm flux was 104, 107, 117, 121, 132, 142, and 152, with a mean of 125. Estimated planetary A indices were 5, 6, 7, 5, 9, 4, and 5, with a mean of 5.9. Estimated mid-latitude A indices were 6, 9, 9, 6, 12, 6, and 7, with a mean of 7.9.