The K7RA Solar Update
This bulletin is coming out a day ahead of normal schedule due to the Christmas holiday on Friday. ARRL Headquarters closes early today for Christmas Eve at 1900 UTC.
Many of us are nearly giddy with joy over the recent steady increase in sunspot activity that seems long overdue. Average daily sunspot numbers rose more than 10 points this week compared to last -- from 21.1 to 31.4! The monthly average daily sunspot numbers for September, October and November were 6.6, 7 and 7.7, so this is quite a large jump. Sunspot numbers for December 17-23 were 24, 20, 43, 42, 42, 26 and 23, with a mean of 31.4. The 10.7 cm flux was 86.9, 84.2, 81.7, 83.7, 82.7, 82.2 and 78.4, with a mean of 82.8. The estimated planetary A indices were 1, 2, 1, 1, 1, 2 and 2, with a mean of 1.4. The estimated mid-latitude A indices were 2, 2, 0, 2, 1, 2 and 3, with a mean of 1.7.
Five new sunspot groups have emerged since December 9 -- three of those over the past week, on December 19 and 20 -- groups 1035 and 1036 on December 19 and 1037 on December 20. Today, a new sunspot appears to be forming and you can see it via the Solar Terrestrial Relations Observatory. Look for that bright spot in our Sun's southern hemisphere, around -65 to -70 degrees longitude. If we consider there are 12 of these 30 degree segments on the spinning Sun seen on the STEREO Web site, and considering a complete solar rotation takes about 27.5 days, each 30 degree segment passes over the horizon in about 2.3 days, or every 55 hours. We can't tell if every bright spot beyond the horizon is formed into a sunspot, but we can roughly calculate how long it takes for a particular area of interest to rotate into view. Right now on early Thursday morning, December 24, I can see an active area (number 1035) around +115 degrees longitude or so, about 25 degrees over the horizon. We can roughly assume that it is about 155 degrees longitude away from its reappearance at the -90 degree longitude horizon on the other side. This should be about 11-12 days from now. Of course, we do not know if activity in this area will increase or decrease in the next couple of weeks.
If you go here, we see a prediction for December 24 (in the December 23 forecast) showing predicted solar flux values of 76, 74 and 72 for December 24-26, continuing at 72 until January 4, around the time this region reemerges, when it rises to 75, then 77 for January 5-6, then 80 on January 7-9 and 85 for January 10-18. We also see steady quiet geomagnetic conditions with planetary A index rising slightly to 7, just for December 27-28. Or course, this could be wrong. Note that in the December 16-19 forecasts, the expected planetary A index for December 20 was 15. Our data shows that the planetary A index for that day was only 1.
The winter solstice occurred on Monday, December 21 at 1747 UTC in the northern hemisphere and days are gradually growing longer. Spring equinox is only 179 days from today.
We've had reports from Robert Elek, W3HKK, of Johnstown, Ohio, in two recent bulletins, and again he comes through with some interesting observations. Bob reports that John, ON4BW (Jean-Michel Debroux in Braine l'Alleud, Belgium), is running 600 W to a 4 element 40 meter Yagi at 70 feet and blasting a strong signal into North America during his mid-day, around 1100 UTC. Braine l'Alleud is about 10 miles south of Brussels. You can see a nice photo of ON4BW and the big antenna here.
Bob says, "Time and time again, strong signals are heard from Europe 2-3 hours past their sunrise here in Ohio, during the so called dog-days of winter. The combination of a broadcast-station-free segment of 40 meters and growing global wealth have 40 meter Yagis popping up all over the 7.125-7.200 SSB band segment, with corresponding big sigs from around the globe. If you haven't been on 40 SSB for a few years, you will be surprised at how much 40 sounds like 20 meters used to sound. And, it only takes one Yagi to make the circuit, so give them a call. W3HKK is using 100 W to a quarter wave ground plane just off the ground, with 6 radials. A reminder: This is the time to hear polar stations, northern and southern latitudes. Antarctica, KC4AAC, was heard just above the noise near 7.170 SSB, around 0100 UTC on December 20. Oleg, UU9JX/MM, was worked from the Magellan Straits on 10.110 MHz at about the same time. Strong LU stations are regulars on 40 SSB in the evening. Plus OX and TF have been worked in recent weeks with big signals."
On December 18, Bob reported that it was "another interesting Friday night on 40 SSB. At times during the evening, the band sounds pretty quiet. More stateside signals are being heard with the recent rise in sunspots. And a fair number of Central American and Caribbean stations come and go. But if you poke around, the juicy DX is there loud and clear. I2VRN is a beacon, and several EAs also 59+ are heard. A pair of A71 stations (A71EM, Juma, and A71FJ, Jamil) were taking turns working DX on 7.130 MHz with signals around 5×9 from 0400-0445 UTC. 4L4TL joined in for a while. Juma noted they were more than 2 hours past their sunrise and still the DX kept coming. Juma and Jamil are a couple of very nice guys looking to spread A71 contacts around to any takers. A71 activity on 40 meters has been almost daily all this week, through December 19. Then, tuning up into the 7.135-7.155 MHz range, at least eight ZS stations were heard working stateside, or ragchewing in a morning ZS roundtable, at 0400-0430 UTC. Again it was at least one hour past their sunrise. ZS3D has been heard in Ohio on a nightly basis with signals between 57 and 59+10 running 500 W to a 2 element hex beam."
Dick Grubb, W0QM, of Boulder, Colorado, used to work at the NOAA Space Weather Prediction Center. He sent along an article he scanned from the current issue of Space Weather, the International Journal of Research and Applications from the American Geophysical Union. Titled "Slow Start to Solar Cycle Tied to Sluggish Interior Stream," it explains there is a slow moving river of gas deep inside the Sun which may be the reason for the scarcity of sunspots and late start to the current solar cycle. Sonograms show it is currently moving much slower than normal. The currents typically take 6-8 years to move from the poles to equator as they spiral east to west, and for this cycle it is taking 1-2 years longer. When the stream reaches 22 degrees latitude, a new crop of sunspots and new solar cycle appears. The jet stream has finally reached critical latitudes for sunspot development, and we should look forward to a quick uptick in activity. Solar activity is now expected to peak in May 2013.
The same publication announces a Space Weather Forecasting Contest. Unfortunately, they do not allow individual entrants without affiliation to some educational or research institution, but the criteria (high school students, researchers, grad students, alumni and such) look pretty broad, so perhaps individuals may enter after all. Probably most of us are at least alumni of some high school, correct? You can see details here.
The new issue of WorldRadio Online is out. Check pages 22-24 for Carl Luetzelschwab's, K9LA, excellent monthly propagation feature, this month titled, "Is There a Most Advantageous Band and 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 each Thursday 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.