The K7RA Solar Update
Again, there were no sunspots this week -- same as we've reported for the last three weeks. In this time of the quiet Sun, spaceweather.com has a new feature keeping track of all these days with no spots. On the left side of the page at below the image of the Sun and the current daily sunspot number, it says "New: Spotless Days." Early on April 9 it said "Current Stretch: 14 days, 2009 total: 89 days (87%), Since 2004: 597 days, Typical Solar Min: 485 days."
But if we show no spots in this bulletin (plus the past three), that accounts for at least 28 days, so why do the new Spotless Days numbers say it has been 14 spotless days since the last sunspot? The last run of sunspots we show is over two days -- March 6-7 -- so through yesterday, April 8, there have been 32 spotless days. If we use their archive feature (look in the upper right side of the page) and go back to March 26, although they shows the sunspot number is zero, the text beneath the Daily Sun image says "A proto-sunspot is struggling to emerge at the circled location." So if no sunspots emerge on April 9, that would account for 14 days since March 26.
Recently, the 45 day forecast for daily solar flux and planetary A index has consistently predicted a solar flux at 70 for every day into the future. The last of these was on March 24. Then on March 25, the prediction was for the solar flux to be at 72 for March 28-31. That changed on March 26, showing solar flux at 72 on March 28-April 2. On March 27, the solar flux rose to 72 (actually 71.6) and the forecast was the same, but extended the 72 number through April 3. Solar flux has not reached 72 since then, but the March 28 forecast extends the reading of 72 through April 4.
On March 29, it extends to April 5, and on March 30, to April 6. On March 31, it extends 72 until April 9 -- three additional days -- but it also shows a new period with a flux of 72, April 23-May 6. April 1 is the same, but April 2 the flux is dropped to 71 for April 3-9. The April 3 prediction gives up on the slightly higher flux values for the near term, but still predicts 72 for April 23-May 6. The forecast remains the same until April 7, when the 72 flux for April 23-May 6 is shortened to April 23-29. So it appears that even these near term predictions for a very small increase in activity are continually revised downward.
In the April 8 forecast, it shows the planetary A index for April 9-10 at 15 and 8, then dropping to 5 until April 21. Early on April 9, we are experiencing the effects of a solar wind stream, and planetary K index rose from 3 to 4 at 0300 UTC.
Sunspot numbers for April 2-8 were 0, 0, 0, 0, 0, 0, and 0 with a mean of 0. The 10.7 cm flux was 70.6, 70.4, 70.1, 70.4, 68.8, 70.2 and 70 with a mean of 70.1. The estimated planetary A indices were 3, 2, 2, 4, 3, 2 and 5 with a mean of 3. The estimated mid-latitude A indices were 0, 2, 0, 3, 2, 2 and 4 with a mean of 1.9. Geophysical Institute Prague predicts quiet to unsettled conditions April 10, quiet April 11-14, quiet to unsettled April 15 and unsettled April 16.
Robin McNeill, ZL4IG, of Invercargill, on New Zealand's South Island, has been on HF for about a year and is another of many new operators I am hearing from who are enjoying HF propagation at the bottom of the sunspot cycle. Robin wrote, "With the sunspots -- and thus the MUF -- as very low as they are, surely this means that 40 meters is currently as good as it ever gets? In fact, shouldn't 40 meters currently be as good as any band ever gets? I base this assertion on the fact that 40 meters is currently very close to the MUF and, as you note in the last Bulletin, there are now few static-causing solar events. But that doesn't explain why only a handful of European superstations and very few others find their signals into ZL for hams like me on 40 meters with modest wire antennas and urban interference, even using the grey line. That said, I have had a handful of QRP SSB QSOs into Europe recently, though I was working hams who have 3-el beams with presumably low-static locations -- one of them, in fact, seemed surprised I was running 5 W PEP and not 500 W PEP output, which surprised us both. Or have I overlooked something?"
Forty meters is a good band right now, but it isn't "as good as any band ever gets." When solar activity returns, the MUF will rise enough to use the 10-20 meter bands, which typically will have less absorption than 40 meters. In addition, the average ham is more likely to have greater antenna efficiency on the higher HF bands. Another factor affecting Robin is that Europe is clear on the other side of the planet from him. From his location to England, the distance is more than 19,000 km (11,000 miles) away. Yet Los Angles is more than 11,500 km (nearly 7200 miles) from him.
If we do some propagation projections using W6ELprop using a smoothed sunspot number of 3 for today, it shows a very narrow period of strong signals over the path to England, from 1900-1930 UTC, when the MUF is 10.9-11.2 MHz. A couple of hours later, the MUF briefly reaches a peak of 14.7 MHz. But for the path to Los Angeles, a 40 percent shorter route, the opening is very strong on 40 meters from 0530-1430 UTC, and then MUF reaches a peak of 22.4 MHz at 2330 UTC. In fact, toward Los Angeles, 20, 17 and 15 meters are good possibilities as well, but not on the path to England.
Another message in, this time from Rich Zwirko, K1HTV, of Amissville, Virginia, about the joys of the extended solar minimum and the resulting quiet geomagnetic field. Rich writes, "I'm now in my fourth month of retirement. I retired after 48 years in broadcasting (the last 28 at the Voice of America). Based on what the 'experts' were saying a number of years ago, I figured that soon after retirement I would be using the F2 layer to add more DX countries to my 148 country total on 50 MHz. Boy, were the experts wrong! Well, as they say, if life hands you lemons, make lemonade. With the extended solar minimum and very low MUF numbers, my lemonade is being made on 160 meters. Shortly after retirement my wife Phyllis (K1WSN) and I moved to a new location in Virginia. The first antenna to go up was a 160 meter inverted-L. At the old Maryland location, I had worked 200 countries on the Topband with 100 W. After six weeks of operating, five new ones have been added to the K1HTV 160 meter low power country total. They include K5D, CP4BT, OA4TT, T2OU and, a few days ago, VK9GMW on Mellish Reef became 160 Meter country #205. So, keep the solar minimum going. We Topband folks are loving it!"
Thanks, Rich. I recall some years ago when our propagation bulletin reported constant geomagnetic storms, week after week. Those in higher latitudes, like much of Canada and especially Alaska, had almost no HF communications as a result. We've almost forgotten what those times were like!
Another great and positive message, forwarded by James Henderson, KF7E, of Queen Creek, Virginia, who said his friend Mickey, K5ML, of Paradise Valley, Arizona, is "clearly an optimist for whom 'the glass is half full,' never half empty. It is a refreshing viewpoint." Mickey lives in a development with a strict homeowner's association and that means No Antennas Allowed. Mickey writes, "Got back on the air in January 2007 after being off the air for more than two decades. I was told that we were at the bottom of the sunspot cycle, but the cycle would be turning up soon. There has been no significant upturn in the cycle since then; however, since getting back on the air using a ground mounted vertical and very low wire antennas, I've worked 206 countries and 39 out of 40 zones. And I know from experience that it's much easier to work DX with a beam or a quad. Like everyone else, I'd like to see the sunspots come back. But the other day, a question popped into my mind: 'When the sunspots return, what am I going to work then that I'm not working now?' We will work DX on higher frequencies more frequently than now, but that's about it. I'm beginning to think all this talk about sunspots is overrated. I'm glad I didn't wait for the sunspots to come back before getting back on the air."
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 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.