The K7RA Solar Update
Here are some yearly averages that we have neglected at the beginning of the year. These are the average daily sunspot numbers for whole calendar years, from 1994-2011: 48.1, 28.7, 13.2, 30.7, 88.7, 136.3, 173, 170.3, 176.7, 109.2, 68.6, 48.9, 26.1, 12.8, 4.7, 5.1, 25.5 and 29.9. You can see from these numbers that the minimum between Solar Cycles 22-23 -- centered around 1996 -- was over quickly. But the next minimum before Solar Cycle 24 -- centered around 2008-2009 -- was much longer. In 2011, we were back near the levels we saw in 2006, 1997 and 1995. Also note that from 2009-2010, the average daily sunspot number increased by 400 percent (multiplied five times), but from 2010-2011, it moved up only 17.3 percent.
The three-month moving averages of daily sunspot numbers -- centered on January-December 2011 -- are 35.3, 55.7, 72.3, 74.4, 65.9, 61.5, 63, 79.6, 98.6, 118.8, 118.6 and 110. The value centered on December 2011 is the average of the daily sunspot numbers from November 1, 2011-January 31, 2012. The value centered on November 2011 includes all daily sunspot numbers from October 1-December 31, 2011.
Sunspot numbers for January 26-February 1 were 55, 39, 34, 74, 76, 71 and 85, with a mean of 62. The 10.7 cm flux was 128.2, 141.7, 114.5, 109.8, 114.4, 116.5 and 117.5, with a mean of 120.4. The estimated planetary A indices were 6, 7, 5, 5, 6, 3 and 5, with a mean of 5.3. The estimated mid-latitude A indices were 5, 6, 6, 5, 5, 2 and 5, with a mean of 4.9. Over the past reporting week -- January 26-February 1 -- the average daily sunspot number declined nearly 37 points to 62, while the average daily solar flux was off nearly 21 points to 120.4. On February 2, the sunspot number and total area of sunspot regions was the same as February 1. From February 1-2, the noon flux measurement moved from 117.5 to 118.
The predicted solar flux for the near term is 120 on February 2-5, 110 on February 6-9, 150 on February 10, 155 on February 11-13, 150 on February 14-19, and then 145 on February 20-23. The forecast in mid-January for flux levels at 165 on February 17-21 are but a distant memory.
Unfortunately, for some reason, the predictions updated for Thursday were not yet available early Friday, February 3, so the numbers in the previous paragraph were not updated since Wednesday, February 1. But you can still get the latest prediction here.
The 20 point difference in predicted solar flux should be a noticeable difference. Although this is not an accurate prediction method, for comparative purposes, I ran a W6ELprop forecast for February 19 from the center of the USA to Hungary, with a solar flux of 145 and then again at 165. On the higher frequencies in particular, paths would not be as reliable nor openings as long as with the higher value.
There is a new updated NASA prediction (issued early this morning) for the peak of the current Solar Cycle; the previous update was on January 3. There is no archive of past predictions online, but I can tell you that the prediction for the peak of Solar Cycle 24 is still for a smoothed international sunspot number of 96, but it has moved from February 2013 to late 2013. NASA gives a detailed explanation of the models they use for predicting the peak of the cycle, and you can read it all here. Also see this graph at for a revised solar flux prediction.
Shortly after the last bulletin was released on Friday, January 27, a powerful X-class solar flare was released at 1837 UTC, but it was not Earth-directed.
In case you missed it last week, Science Friday on NPR ran a fascinating story on space weather, and they spoke with astronomer David Hathaway of NASA and astrophysicist Doug Biesecker of NOAA. They mention ham radio and effects on shortwave radio propagation, and Biesecker gives a fascinating account of Carrington’s observation of a solar flare and how it caused the great magnetic storm of September 2, 1859, in which aurora was observed worldwide.
We received a nice note from Ed Richmond, W4YO, of Harbor Island, South Carolina (EM92): “The evening of Friday, January 27 into the 28th was extraordinary here. At about 0145, I came into the shack to take a last check on band activity before hitting the big switch, checked the DX cluster for activity on 6 meters and saw a whole lot of TEP activity. I turned on my rig and immediately heard ZP6CW weakly calling CQ. I called him with no luck. Tuning around, I heard a bunch of Brazilian and Argentinean stations. Wow! My first experience with transequatorial propagation after four years of being on the band! I heard PY1ZV calling CQ, called him and he came back to me! Next it was LU1FAM, followed by LU5FF, PY2 XB, ZP5SNA and CX9AU. The amazing thing about it is that my station runs a barefoot FT920 with an indoor dipole beneath the roof at about 35 feet. I was so juiced for the rest of the evening, I couldn't fall asleep until after midnight!”
A week ago (January 27), Julio Medina, NP3CW, of San Juan, Puerto Rico, sent a message about some 6 meter excitement: “Today at 1913, I worked HK0NA (Malpelo Island) on 50.110 MHz. The signal was 5×9 +30 dB in FK68, and had good propagation with him for about two hours. I also had good propagation to the USA, Panama, Trinidad and Tobago, China and Cuba. We had tropo and sporadic-E and I also saw television from Cuba. This is a new country for me on 6 meters.”
The outlook for the week is low solar activity. When looking at STEREO on Friday morning, I see little activity, save for a bright, complex geomagnetic signature at 180 degrees longitude on the far side of our Sun from Earth.
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.