The K7RA Solar Update
The average daily sunspot numbers declined 12 points to 38 during the past week, compared to the previous week, December 30 through January 5, when the average was exactly 50. Sunspot numbers for January 6-12 were 28, 52, 52, 50, 35, 26 and 23, with a mean of 38. The 10.7 cm flux was 86.8, 86.4, 84.8, 82.7, 83.3, 82.6 and 80, with a mean of 83.8. The estimated planetary A indices were 8, 11, 7, 5, 5, 5 and 6, with a mean of 6.7. The estimated mid-latitude A indices were 9, 10, 6, 4, 4, 5 and 6, with a mean of 6.3.
The average daily solar flux declined by nearly 6 points to 83.8. The latest forecast shows solar flux at 80 on January 14-15, 78 on January 16-21, back to 80 on January 22-25, 82 on January 26, 88 on January 27-30 and 89 on January 31. The same forecast has planetary A index for January 14 at 8, January 15 at 7 and January 16-31 at 5. Geophysical Institute Prague sees unsettled geomagnetic conditions on January 14-15, quiet to unsettled January 16, unsettled January 17-18, quiet to unsettled January 19 and quiet on January 20.
The STEREO mission’s coverage of the entire Sun is nearly complete, with continuous images showing more than 99.2 percent of our nearest star. By Sunday evening in North America, the project will have passed 99.34 percent coverage. The black band of unseen area is now just a tiny sliver, and magnetically active areas over the entire Sun may now be observed live from any place with an internet connection at any time of the day or night.
In last week’s bulletin, we discussed W1YO’s comments on HF propagation. This prompted a question from Howard Lester, N7SO, of Schuylerville, New York. He thought it would be more instructive if we intended to illustrate seasonal variation by using the same sunspot number for the April prediction as for the January prediction. That is true, but since the prediction engine is based on a statistical model that employs the predicted smoothed sunspot number (not the latest actual sunspot number), I thought it would be interesting to use the official smoothed prediction from NOAA to illustrate how conditions might actually play out. Thus we changed two variables, the date and sunspot number. It is important to keep in mind that the smoothed sunspot number for January is predicted as well, because it uses about a year of data to arrive at the number. We know what the last six months of data are, but the component that makes up the next six months is predicted, and currently unknown. So in order to know the true smoothed sunspot number, you need to go back at least six months.
In last week’s bulletin we used the table on page 11 of the document here. In that table, all of the smoothed sunspot numbers from January 2009 through June 2010 are known quantities. Each month after June 2010 uses a declining number of months of known data. July 2010 uses 11 months of known data, and one month (January 2011) of predicted data. August 2010 uses 10 months of known data, and two months (January-February 2011) of predicted data and so on.
How do past predicted smoothed numbers compare with the ones we now know for sure? The first six months of 2010 have known smoothed sunspot numbers of 9, 11, 12, 14, 16 and 16. If we go back two months to the first week in November, the numbers for the same months track closely -- 9, 11, 12, 14, 16 and 19). Of course, going back two months, the only months the smoothed sunspot number is not known for sure are May and June 2010.
Every time we step back a month, the series diverges a little more from the actual outcome. Here we see October’s projection for those months, and it is 9, 11, 12, 15, 18, and 21. Go back and it is now 9, 11, 13, 16, 19 and 22 for September. In August, we see 9, 11, 14, 17, 20 and 23. In July, we see variation all the way back to January, at 10, 13, 15, 18, 21 and 24. You can see now why forecasts for the increase of this solar cycle keep getting scaled back to track actual outcomes more closely.
W1YO commented this week that Solar Cycle 24 is different: “It's slow to climb and the effects of high SSNs and solar flux are not long lasting. I have been through five solar cycles and this one is not normal.”
Larry Godek, W0OGH, of Gilbert, Arizona commented on 6 meters in the New Year: “January 11 just after midnight UTC, I worked ZL1RS on 6 meter CW, followed by VK3OT then ZL2TPY on SSB, followed by VK4MA back on CW. What a surprise opening that was! Hopefully this is leading us into a very good January VHF contest weekend coming up soon. Neither high power nor big antenna systems are needed for these QSOs. I only have 100 W and a 5 element Yagi at 40 feet fed with 1/2 inch hard-line. Signals were very easily copyable without wearing cans.”
Jon Jones, N0JK, in Lawrence, Kansas (EM28), reported that he made his his first 6 meter QSO -- and first QSO of the New Year 2011 -- with XE2OR/m. “Rafael was mobile in the rare grid DL97 and worked at 2330 on January 9 on 50.125 MHz via E-skip. He was strong with considerable fading signals. I heard him work a few other zeros and N5JEH in New Mexico also spotted him.”
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 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.