Propagation de K7RA

Sunspot numbers and solar flux both increased this week, but just barely. Average daily sunspot numbers rose five points to 19.6, while average daily solar flux rose one point to 75.8.

Values are expected to stay about the same over the next week. In fact, the U.S. Air Force predicts an even 75 for solar flux over the next 30 days. Geomagnetic activity should remain quiet. Geophysical Institute Prague agrees with outlook, predicting quiet to unsettled conditions for today, March 2, quiet conditions on March 3-5, and unsettled on March 6-7. The Air Force predicts 5 for the planetary A
index from March 2-5, 10 for March 6, and back to 5 after that.

You'll note when there is geomagnetic activity (see
http://www.sec.noaa.gov/ftpdir/indices/DGD.txt) that often the planetary A and K index will be higher than the mid-latitude numbers. Since most of us live at middle latitudes, a quiet number for the planetary A index means quiet conditions for us as well. On the last day of February, a solar wind stream caused a rise in geomagnetic activity. You can see on the above URL that the planetary A index was 23, Alaska's College A index was 38, but the mid-latitude A index was only 12.

In February we had low sunspot numbers, appropriate for the bottom of the solar cycle. The average daily sunspot number for February was just 17.3. The only months with lower average daily sunspot numbers in the past year were October (14.7) and February 2006 (5.3). Monthly averages of daily sunspot numbers for February 2006 through February 2007 were 5.3, 21.3, 55.2, 39.6, 24.4, 22.6, 22.8, 25.2, 14.7, 31.5, 22.2, 28.2 and 17.3. Monthly averages of daily solar flux for the same period were 76.5, 75.5, 88.9, 80.9, 76.5, 75.8, 79, 77.8, 74.3, 86.3, 84.4, 83.5 and 77.7.

This month just might be the bottom of the cycle. View the table at http://sec.noaa.gov/ftpdir/weekly/Predict.txt, and you'll see that the predicted smoothed sunspot number for March 2007 is 11.3, and it rises after that through the end of the year.

This weekend is the ARRL International DX SSB Contest, and
conditions will probably not be bad, at least no big geomagnetic storms should occur. While there isn't much sunspot activity, our local star isn't devoid of spots. Currently sunspot 944 faces us from the center of the visible solar disk.

Eric Owen, KD4MZM of Sarasota, Florida sent a URL for a web page devoted to 10-meter beacons at, http://10mbeacons.com/. Here you can check loggings for 10-meter beacons, and leave your own feedback as well for any you hear. There is also a list of links to individual beacon web sites, and a beacon-chat area. Eric runs a beacon on 28.277 MHz.

In case you thought HF radio is no fun at the bottom of the solar cycle, Aki, JA2UOZ, Aki, of Nagoya, Japan writes that he operates with only one-half watt transmitter power and dipole antennas. Currently he is trying for DXCC on 17 meters and higher at the bottom of the solar cycle.
He outlines his personal challenge at,
http://www.k4.dion.ne.jp/~jq2uoz/sub1.html, and some of his recent contest logs at, http://www.k4.dion.ne.jp/~
jq2uoz/sub7.html.

If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL Technical Information Service at,
http://www.arrl.org/tis/info/propagation.html.

For a detailed explanation of the numbers used in this bulletin see, http://www.arrl.org/tis/info/k9la-prop.html.

An archive of past propagation bulletins is at, http://www.arrl.org/w1aw/prop/.

Monthly propagation charts between four USA regions and twelve overseas locations are at, http://www.arrl.org/qst/propcharts/.

Sunspot numbers for February 22 through 28 were 25, 22, 11, 12, 22, 23 and 22 with a mean of 19.6. 10.7 cm flux was 75.5, 75.1, 75.5, 76.6, 75.4, 74.8, and 75.8, with a mean of 75.5. Estimated planetary A indices were 2, 2, 1, 3, 4, 12 and 23 with a mean of 6.7. Estimated mid-latitude A indices were 2, 2, 2, 4, 4, 7 and 12, with a mean of 4.7.

Source: The American Radio Relay League

• All propagation reports can be found at:
http://www.southgatearc.org/propagation