The K7RA Solar Update
Both the averages of daily sunspot numbers and solar flux rose, with the sunspot numbers up nearly 36 points to 93.3, and the solar flux up nearly 12 points to 112.6. The most active geomagnetic day was Friday, March 1, when the planetary A index was 27 and the mid-latitude A index was 23; Alaska’s high latitude College A index was a whopping 64.
Sunspot numbers for February 28-March 6 were 63, 88, 90, 115, 103, 106 and 88, with a mean of 93.3. The 10.7 centimeter flux was 105.5, 112.5, 111, 112, 114.3, 118.4 and 114.3, with a mean of 112.6. The estimated planetary A indices were 7, 27, 12, 7, 4, 4 and 3, with a mean of 9.1. The estimated mid-latitude A indices were 8, 23, 14, 6, 4, 3, and 4, with a mean of 8.9. We generally want to see higher sunspot numbers, but low geomagnetic indices at the same time.
The latest forecast from NOAA/USAF puts the average solar flux for the next five days -- March 9-13 -- at 118.2. The predicted solar flux is 112 and 118 on March 8-9, 120 on March 10-11, 118 on March 12, 115 on March 13-14, 105 on March 15, 95 on March 16-17, 100 on March 18-20, 105 on March 21-24, 110 on March 25 -April 1, and back down to 105 on April 2-5. The predicted planetary A index is 8 on March 8, 5 on March 9, 8 on March 10-12, 5 on March 13-20, 8 on March 21, 5 on March 22-27, then 18, 10, 5 and 10 on March 28-31, and back down to 8 on April 1-4.
The latest solar cycle prediction shows that NASA has revised the forecast downward again. Last month, NASA said that the cycle should peak this fall with a smoothed sunspot number of 69. That was revised down by 3 points, and now NASA says that it will peak at 66. These are international sunspot numbers, which have a lower scale than the Boulder numbers that we use in this bulletin, which run about 35 percent higher.
Many readers wrote in concerning the news about a possible double-peak for the current solar cycle. There seemed to be a peak in activity around the end of 2011, then activity fell off last year. If true, that the cycle will peak this spring or fall, but we don’t seem to be trending toward that activity yet. Click here for a video from NASA explaining this.
If you click here for the latest preliminary report and forecast and turn to page 15, you can check the numbers for the latest prediction from Boulder. It shows a peak in September and October 2013, with solar activity levels about 27 percent higher than we saw last month. The peak in activity at the end of 2011 is represented by the higher numbers (smoothed, so the peak is not pronounced), then gradually declining. The averaging function seems to have moved that peak out to February and March of 2012, but the predicted peak this year is quite a bit higher than the previous peak. Let’s hope that the second peak is indeed much more robust, as predicted.
The forecast from last month shows higher values for the end of 2012, as well as for the first few months of 2013. These reflect estimated future sunspot numbers, which would drag the average down. The numbers for each month are an average for a year’s worth of data: six months forward and six months back. The estimate for March 2013 went from 77 last month to 73 this month. The latest figure represents one more month of real recorded data than last month’s prediction. Note also on the next page that the solar flux prediction shows the peak for that parameter in August 2013.
Julio Medina, NP3CW, of San Juan, Puerto Rico, wrote: “I wanted to let you know that today -- March 1 from 1826-1837 -- I worked VU3WIJ and VU3WII on 20 meter SSB with 5×9 reports both way. I was using a vertical antenna at 10 feet above the ground and 100 W. Both stations had pile ups and they copied my signal very easily.” I replied back to Julio that “On that day, I would expect the band to just begin to open at that time, but signals should reach a peak from 2100-2300.”
Steve Hawkins, NG0G, of Boone, Iowa, wrote: “On March 5 at 2213, I had just worked TX5K (Clipperton Island) on 24 MHz CW. After working TX5K, I stumbled across XT2TT (Burkina Faso) on the same band. Since by then it had been dark in Africa for hours, I was very skeptical and thinking pirate. But I adopted the standard ‘work now, worry later’ mode. I’ll admit it took tweaking everything built into my rig and listening so hard there may have been arcing inside my skull, but I could hear them. I called and worked them about the third call. At first I thought it must be a pirate, as with my wimpy vertical -- and the solar flux as low as it is -- 24 MHz should not be open to Africa from Iowa at 2213. I was astounded when not only did they answer me, but I quickly showed up in their online log. Talking later with a friend, I was reminded that near to the equator, the MUF can be surprisingly high up until midnight.”
Actually, when running the numbers on W6ELprop, propagation over that path at that time on that band is not unusual. I entered 42.07 degrees north, 93.88 degrees west for Steve’s location, and found the XT2TT DXpedition. That page shows a grid square location of IK92fi, so I entered this into the AMSAT grid square conversion tool. This yielded 12.3542 degrees North, 1.54167 degrees West for XT2TT. This turns out to be only 25 miles north of the default Burkina Faso coordinates in W6ELprop.
Based on these coordinates, the station is in the southwest portion of Ouagadougou, Burkina Faso’s capital city. I checked this at 4:17 AM Seattle time today, which is 12:17 PM in Burkina Faso and also 1217 UTC. The path length is 5767 miles (9281 km), and on March 5, W6ELprop shows an opening beginning with a B rating (available 50-75 percent of the time) and signal-to-noise ratio of 40 dB at 1330, changing to an A rating (opening 75-100 percent of the time) by 1430. By 1830, the signal-to-noise ratio is 43 dB and it gradually increases to a peak of 48 dB at 2300. Signals stay at that level, but availability degrades to a B rating at 2330-0000, a C rating (25-50 percent availability) at 0030 and a D rating (1-25 percent) at 0100-0130.
Sunset at XT2TT was 1812 UTC on March 5, and at Steve’s location in Iowa, it was 0006 UTC. So that path opens about 45 minutes after sunrise at Steve’s (1248z), gets better after sunset at XT2TT and finally begins fading around sunset in Iowa. A half hour after sunset in Iowa, that path is done.
Ken Miller, K6CTW, of Rancho Cucamonga, California wrote: “I was up late last night working on the computer and saw that the Clipperton DXpedition was operating on 80 meter CW near the bottom end of the band. Just to satisfy my curiosity, I turned on the 1960s station I’ve restored to see what I could hear. Their signal here in Southern California was 20 over S-9 or better, so I loaded up the rig and gave a call after figuring out where the operator was listening -- he was running Japanese stations. Imagine my amazement when he came back to my call! I am always impressed that the operators at these DXpeditions can sort out a weak signal like mine out of the unbelievable racket. Thanks to them, and also, what a surprise to see how good communications can be on the low bands late at night.”
I'm also home-brewing another improved version VFO using Jim, WA1FFL's DDS unit. This one is a significant upgrade to the unit described in the article.”
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.