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The K7RA Solar Update


The average daily sunspot numbers were up nearly 24 points this week to 50, while the average daily solar flux rose more than 9 points to 89.5. The lagging three month average of daily sunspot numbers was down 3.5 points from last month’s average of the previous three months. The three month moving average of daily sunspot numbers -- ending on June through December -- was 16.2, 20.4, 23.2, 28.9, 33, 35.6 and 32.1. Sunspot numbers for December 30-January 5 were 24, 23, 65, 38, 51, 54 and 50, with a mean of 43.6. The 10.7 cm flux was 82.9, 90.9, 91, 91.1, 92.1, 90.6 and 87.7, with a mean of 89.5. The estimated planetary A indices were 5, 4, 3, 3, 4, 4 and 2, with a mean of 3.6. The estimated mid-latitude A indices were 4, 2, 2, 3, 3, 3 and 2, with a mean of 2.7.

The latest forecast from NOAA/USAF for the near term has a solar flux of 88 on January 7, 86 on January 8-9, 84 on January 10, 82 on January 11, 80 on January 12-15 and 78 on January 16-18, 80 again on January 19-25, 88 on January 26-30, and 90 on January 31 through February 2.  The planetary A index is predicted at 7 on January 7, 10 on January 8-10, 8 on January 11 and 5 on January 12-19. The geomagnetic prediction from Geophysical Institute Prague is quiet to unsettled January 7, unsettled January 8-9, quiet to unsettled January 10 and quiet January 11-13.

Yekta Gursel, KJ6DRO, alerted us to an article in the February 2011 issue of Sky & Telescope titled “The Perfect Solar Superstorm.” You can read most of it online here. Click on “Preview” if you are not a subscriber. Your local library may also provide online access to the magazine. The article begins on page 28.

David Moore -- who is not a radio amateur but has a keen interest in all things solar -- sent a link to a National Science Foundation article on why the corona of the sun is millions of degrees hotter than the surface.

Ken Lappe, W1YO, of Leesburg, Florida, is puzzled by the lack of HF DX during this time when we have sunspot activity.  He wrote, “The past few days -- January 3, 4 and 5, the sunspot number has been in the 50 range and the solar flux in the low 90s with very low A and K indices. All indications suggest at least fair conditions on the higher bands, but this is not the case. Yes, we hear some sporadic-E at times and some trans-equatorial propagation at times on 12 and 10 meters. But otherwise the bands are dead, or so it seems. ZL4WW was weak here in Central Florida on 12 meters yesterday around 1900, but nothing else was heard. Even 17 meters has been quiet in the afternoon and nothing special in the mornings. So, the question is: If we have sunspots and solar flux and quiet As and Ks, where is the DX?”

It may just be a combination of seasonal winter conditions and sunspot activity not high enough to support much long distance propagation. A look at a propagation program, such as W6ELprop, is instructive. Using a predicted smoothed sunspot number of 39 for January 5 (see here then go to page 11 of the January 4 edition for the source) from Ken’s Florida location to New Zealand, 12 meters looks marginal, and 17 meters looks good over that path, but only from 0200-0500. Look a few months ahead to April, and with a smoothed sunspot number of 51, conditions look considerably better. Now 12 meters opens 1930-0300, and 17 meters is open during Ken’s local evening until 0530. But perhaps Ken is accustomed to better HF openings at this time of year with this level of solar activity. In that case, I don’t know.

Walt Knodle of Bend, Oregon, wrote that on January 2, he had “an interesting experience on 40 meters, interesting because of the timing relative to reading an article by K9LA on skew paths in the January 2011 World Radio Online. That article was directed toward 160 meter propagation, but seemed appropriate for conditions on 40 meters today. While listening for VU2GSM, I noticed his signal was stronger along the long path than the short path. However, the LP was almost entirely in daylight so something else was at play. In swinging the beam toward the LP, I could hear Kanti’s signal pass through a very definite peak between the SP and LP headings. The best heading was directly SW of my QTH and along the grey line. Assuming a refraction point near the equator, this would follow Carl’s example from the WRO article and implicate the equatorial ionization anomaly. One side benefit of the skew path was that it placed the Chinese OTH radar at 90 deg. to my beam heading.”

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.




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