SB PROP @ ARL $ARLP011 ARLP011 Propagation de K7RA ZCZC AP11 QST de W1AW Propagation Forecast Bulletin 11 ARLP011 >From Tad Cook, K7RA Seattle, WA March 19, 2010 To all radio amateurs
SB PROP ARL ARLP011 ARLP011 Propagation de K7RA On March 6-9 we got a taste of the bad old days from 2008-2009, when there were frequent stretches of zero sunspots. After March 9, activity picked up, and we hope there is no end in sight to the much-welcome sunspots. This week, March 11-17, average daily sunspot numbers increased from the previous period from 12.4 to 29.4. Thursday March 18 had a repeat of Wednesday's sunspot number, 28. We've looked at various moving averages over the past few years to try to smooth out the bumps and spot trends, and another way to look at it would be the trailing 50-day average of daily sunspot numbers, which on March 18 was 27.34. The fifty day period is purely arbitrary. For the eighteenth of each month, going back to April 18, 2009 the trailing 50 day average was 0.48, 2.44, 5.42, 7.4, 3.14, 0.48, 4.42, 7.42, 8.98, 17.44, 26.12 and 27.34. We can see a positive trend there. On March 11 new sunspot group 1055 emerged, which followed the arrival of group 1054 the day prior. 1055 lasted a very brief period, and group 1056 appeared March 17. Today group 1054 is fading over the western limb, and it is hard to tell from the STEREO mission if some of the active magnetic areas just over the horizon are new or returning sunspots, or not even fully formed sunspots at all. One uncertain area looks to be a day or less away, and beyond that, the only thing visible is on the other side of the narrowing unseen area on our Sun's far side. At 1045z Friday morning that blind spot covers less than 11.7% of the Sun's total area. So far in March the average daily sunspot number is 24.2. For all of every month of March since the end of the last century, the average (1999-2009) was 100.5, 203.6, 166.7, 154.3, 119.7, 81, 41, 21.3, 9.8, 15.9, and 0.77. Sobering, isn't it? The Vernal Equinox, marking the beginning of Spring in the Northern Hemisphere and Fall south of the equator occurs tomorrow, March 20 at 1732z, 10:32 AM West Coast Pacific Daylight Time, or 1:32 PM EDT. The weeks prior to and following both the Vernal and Autumnal Equinox are favorable to HF propagation. The latest forecast from Thursday's reading by NOAA and the U.S. Air Force show solar flux remaining in the mid-eighties for the next week, and planetary A index staying around five, until a brief increase to six on March 28-29. Geophysical Institute Prague sees quiet conditions for all of March 19-25. A few comments this week from readers: "I am fortunate to have #1 DXCC but in recent years have concentrated on 6 meters and the low bands, with lots needed on 17m and above. The last month has shown a great improvement in my new ones, with one on 17m, 3 on 15m, 13 on 12m and two new ones on 10m (5N and IS0). Lots more to go for this OT. 73, Pat, W5OZI." Mark Lunday, WD4ELG Greensboro, NC - FM06be, wrote, "0300 UTC on 15 Mar, 2 hours after local sunset, I worked ZK3YA and FO8RZ on 12 meters. Makes me wonder if the activity is as much a function of the perception of conditions (which makes amateurs go on the higher bands) as opposed to the conditions themselves. It's not THAT far into the cycle yet, but everyone is itching to get on 15, 12, and 10 meters." W3HKK in Johnstown, Ohio wrote, "Tuning around on 160 the evening of March 14 showed exceptionally strong SSB signals into Ohio from Virginia and the Carolinas, with very low band noise. Didn't think much of it until the next morning at 1045z when I again heard booming SSB signals from the early morning 160 meter crowd. So I tuned down to CW, and low and behold heard KL7RA (Kenai, Alaska) calling CQ, and then a sked in 9 land, for over half an hour, working assorted east coast stations along the way. His signals were a solid 569. Not many takers but he was there to be had." A note before closing, in case anyone is confused, when we say 1030z that is the same as 1030 UTC or 1030 Greenwich Mean Time. It is also the same as 3:30 AM Pacific Daylight Time or 6:30 AM Eastern Daylight Time. If you would like to make a comment or have a tip for our readers, email the author at, k...@arrl.net. For more information concerning radio propagation, see the ARRL Technical Information Service web page 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/. Instructions for starting or ending email distribution of this bulletin are at http://www.arrl.org/w1aw.html#email. Sunspot numbers for March 11 through 17 were 31, 36, 32, 30, 28, 21, and 28 with a mean of 29.4. 10.7 cm flux was 84.2, 89.6, 91.8, 89.4, 86.4, 85.2, and 86.7 with a mean of 87.6. Estimated planetary A indices were 9, 9, 4, 6, 3, 4 and 7 with a mean of 6. Estimated mid- latitude A indices were 9, 6, 2, 2, 2, 3 and 5 with a mean of 4.1. NNNN /EX ----------------------------------------------------------- To unsubscribe or subscribe to this list. Please send a message to imail...@njdxa.org In the message body put either unsubscribe dx-news or subscribe dx-news This is the DX-NEWS reflector sponsored by the NJDXA http://njdxa.org -----------------------------------------------------------