The K7RA Solar Update


Solar indicators were mixed this week, with the average daily sunspot number down 8.4 points to 84.9, while the average daily solar flux rose 5.9 points to 118.5. Geomagnetic indices were much quieter, with the average planetary A index down 4.7 points to 4.4 and the average mid-latitude A index down 5 points to 3.9. Sunspot numbers for March 7-13 were 80, 59, 63, 89, 105, 95 and 103, with a mean of 84.9. The 10.7 centimeter flux was 113.8, 115, 116.2, 119.2, 119.7, 123 and 122.9, with a mean of 118.5. The estimated planetary A indices were 4, 3, 6, 4, 5, 5 and 4, with a mean of 4.4. The estimated mid-latitude A indices were 2, 3, 6, 3, 4, 6 and 3, with a mean of 3.9.

The predicted solar flux for March 15-17 is 120, then down to 115 on March 18-19, 110 on March 20, 105 on March 21, 95 on March 22-24, 100 on March 25-26, 105 on March 27, 110 on March 28-31, 115 on April 1-3. After that, the solar flux peaks around 120 on April 4-11. The average for the predicted solar flux for the next five days -- March 15-19 -- is 118, right around the average of 118.5 for what we saw this past week. The predicted planetary A index on March 15-16 is 17 and 12, indicating more geomagnetic activity similar to what we saw March 1-2. The predicted planetary A index is 5 on March 17-20, 8 on March 21, 5 on March 22-27, 18 and 10 on March 28-29, and back down to 5 again for March 30-April 16.

At 0600 UTC on March 15, the Australian Space Forecast Centre reported that a sudden impulse of 22 nT (nanotesla) was detected in magnetometers at 0527 UTC. Due to a coronal mass ejection (CME), increased geomagnetic activity is predicted on March 15-16, and minor storm periods at high latitudes are possible. The M1 class solar flare and its accompanying CME were Earth-directed. Both came from sunspot group 1692, right in the center of the visible solar disc viewed from Earth.

In recent online articles about a possible double peak for Solar Cycle 24, it was mentioned that we would see the peak in late 2011 and another in 2013. But I noticed recently that solar physicist Dean Pesnell of NASA is suggesting something different: A peak in late 2013 and another in 2015. Check the last line of the first paragraph of this article posted on the ARRL website on March 14.

Robert Elek, W3HKK, of Johnstown, Ohio, sent these observations about the TX5K operation on Clipperton Island: “Kudos to the ops at TX5K! Their nifty website has a world map, spotting of call signs, almost instantaneous log updates, QSO totals and more. It even lets you see the propagation on a visual basis, call by call. I had not realized TX5K was on the air until the ARRL SSB DX Contest on March 2-3. Post-contest -- and after catching up on my sleep Sunday night and most of Monday -- I turned on the rig right after dinner, and TX5K was everywhere, and with big signals! I worked them on 12, 15, 17, 30, 40 and 160 meters, with many bands on both SSB and CW during an amazing three hour stretch of operating! I worked them so quickly, often on the very first or second call, and it was mind blowing; their pileups were huge. It had to be a miracle of good timing, plus a little experience to boot.”

Brian Alsop, K3KO, of Henderson, North Carolina, commented that “DXers shouldn’t overlook VOACAP while chasing new ones.” He sent a couple of circuit reliability plots from his location to ZL9CI (Campbell Island) and 9M4SLL on Spratly, noting that the times he worked them lined up with the predictions. “I recently downgraded to 500 W, a 2-element tri-bander at 40 feet and a rotary dipole for 30/17/12 meters at 42 feet; I need all the help I can get. Besides the DX cluster, knowing what paths at what time may be possible helps.”

If you’re interested in VOCAP, Carl Luetzelschwab, K9LA, has a VOCAP tutorial on the ARRL website.

Finally, here is a handy tool for converting a street address into latitude/longitude coordinates. This is useful for determining locations for propagation prediction and other programs based on FCC database address records or for your own location.

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.