04 December 2011
The K7RA Solar Update
Solar Cycle 24 continues its upturn. We have a new high for the trailing three month daily sunspot number average. Starting with the three month period ending in December 2010 and going through November 2011, they were 30.1, 35.3, 55.7, 72.3, 74.4, 65.9, 61.5, 63, 79.6, 98.6 and 118.8. There hasn’t been a three month period with average daily sunspot numbers above 118.8 since way back in June, July and August 2003, when the average was 121.9. This was as Solar Cycle 23 was declining. The monthly averages of daily sunspot numbers for August-November 2011 were 66, 106.4, 123.6 and 133.1.
Sunspot numbers for November 24-30 were 139, 171, 133, 123, 90, 106 and 111, with a mean of 124.7. The 10.7 cm flux was 137.2, 135.2, 132.8, 135.2, 137.6, 140.6 and 144, with a mean of 137.5. The estimated planetary A indices were 5, 4, 3, 6, 4, 9 and 10, with a mean of 5.9. The estimated mid-latitude A indices were 4, 3, 4, 5, 7, 9 and 9 with a mean of 5.9
The latest forecast from NOAA/USAF has the solar flux on December 2 at 145, 140 on December 3-5, 135 on December 6-7, 140, 150, 150 and 155, on December 8-11, and 160 on December 12-18, and then 155 on December 19-22. The planetary A index on December 2-10 at 8, 8, 7, 8, 8, 5, 5, 8 and 8, and then 5 on December 11-22. Look here for a daily update of this forecast. Geophysical Institute Prague sees unsettled conditions on December 2, quiet to unsettled December 3-5 and quiet conditions December 6-8.
Conditions may not be as quiet as we would like (in terms of geomagnetic disturbances) for the ARRL 160 Meter Contest this weekend, but no major disruptions are anticipated either. Instead of the predicted planetary A index of 8 or 7, we would prefer a forecast with an A index of 5 or lower. With conditions so quiet over the past few years, 160 meter operators had some great conditions to work with. For months at a time, the NOAA/USAF forecast would show a planetary A index of 5 (for some reason it is never predicted lower than that), and mail from 160 meter operators praised the absence of solar activity that most HF operators dreaded.
Although conditions at lower and middle latitudes were fairly quiet, on Wednesday, November 30, polar geomagnetic indices were quite active. You can see it here in the high latitude college A and K index at University of Alaska in Fairbanks. They have a nice web page devoted to geomagnetic activity. They also have a nice Auroral Activity by Solar Rotation display (click on it to make it bigger); each line represents a complete rotation of our Sun, with a range of dates covering 27-28 days. The display shows some recurring activity -- currently you can see a spike of geomagnetic activity from September 26-29 coming around again on October 25. To check the readings on those dates, look at the quarterly records here and here. Historical indices going back to 1994, including sunspot numbers and solar flux, are here.
Daily reports give us some insight into what caused a disturbance on November 30. The report for that day says that “the geomagnetic field reached quiet to active conditions with minor and major storm periods observed at high latitudes. Activity was attributed to a solar sector boundary crossing (SSBC) at approximately 30/0810 UTC, followed by a prolonged period of southward Bz in the interplanetary magnetic field.” For information on what they mean by “solar sector boundary crossing”, click here.
Allen Olender, WA8IWK, of West Bloomfield, Michigan, sent a nice note relating his joy over recent HF conditions: “I’ve spent more CW time on 10 meters working amazing DX in the past two months than I have spent on that band in the past 48 years combined -- all with a mobile antenna in my attic! A great time for our hobby!”
Jeff Hartley, N8II, of Shepherdstown, West Virginia, sent a detailed report on his 10 meter single band effort for the CQ Worldwide CW Contest last weekend: “On Saturday, I turned on the radio at 1130 UTC about 45 minutes before sunrise to find many 10 meter signals. Stations in Africa were S9+, and I quickly logged D4C and C5A. Europeans were louder at about 100 degrees scatter path, but by and large, they were loud enough that they could hear me calling. Right around sunrise the band opened direct path to Europe and I started my best five hours of running Europeans ever, averaging about 130-140 QSOs per hour. Signals from Eastern Europe lasted until around 1500-1530. The Ukrainian turnout was tremendous, as was the activity from Romania and the Czech Republic. Conditions to the Moscow area were okay, but not nearly as good as a month ago. During the weekend, I made 257 QSOs with Germany.
“By about 1715, darkness had pretty well closed the band, except for some loud Spanish, French and Italian stations. Africa and stations very close to the south (Cuba, the Caymans, and Turks and Caicos) to far away were loud. During the contest, I logged Sudan, Mozambique, Morocco, Madeira Islands, The Gambia, Cape Verde Islands, Canary Islands, Liberia, South Africa, Ascension Island, Uganda and Sierra Leone. ZM4T was the first New Zealand station I worked in the 17Z hour, and KG6DX was booming in around 2040 UTC for first QSO of four with Guam; they were uniformly S9+ until about 2300, as was AH0BT. Unfortunately, a really good opening to Japan never materialized, with Saturday being the better day -- I only logged 55 Japanese stations. Surprisingly, In logged three Australian stations in zone 29. Other Pacific DX logged was New Caledonia, Niue, Hawaii, and E51MAN in the Northern Cook Islands. Japanese stations faded out at 2315, and by 2330, the band was nearly dead.
“Sunday, 10 meters was a bit slower to fully open to Europe, but first direct path signals arrived around 1210. I logged UP0L in Kazakhstan via scatter path. I worked my first zone 21s (Qatar and Saudi Arabia) and I was called by VU2KMS in India around 1400. The European opening lingered until around 1900 to very Southern and Western Europe, but QSO volume was minimal past about 1630. I logged OH6AC in Finland close to 1900. I also worked four Icelandic stations, including a mobile, as well as OX3XR in Greenland around 2100. Alaskan stations were loud both days for hours, but not many casual ops from there were active. Around sunset both days was the end of working much of anything to the south. We still have room for improvement (higher solar flux), but 10 and 12 meters have been loads of fun since late September. The ARRL 10 Meter Contest should be a pretty major event on December 10-11.”
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.