ARLP051 Propagation de K7RA:
December 10, 2004

Propagation Forecast Bulletin 51 ARLP051
From Tad Cook, K7RA
Seattle, WA December 10, 2004
To all radio amateurs

ARLP051 Propagation de K7RA

This weekend is the ARRL 10-Meter Contest. Conditions aren't great at this point in the solar cycle, but this can be a fun single-band operating activity. Unfortunately, we may see a recurrence of some unsettled to active geomagnetic conditions from the last solar rotation. Predicted planetary A index for December 10-13 is 8, 20, 30 and 12, so that suggests some rough conditions on Sunday. The predicted solar flux for those same days is 85-90, with the values rising gradually and peaking around 105 from December 22-25.

Average daily sunspot numbers for this week were 46, down from 55.1 for the previous week. Average daily solar flux dropped nearly 14 points to 97.

We received mail concerning K5SWW's 10-meter observation of Scandinavian CW signals mentioned in last week's update.

Joe Clayton, W2REH, writes:

"This 'Scandinavian Express' opening is not unusual at all. There were signals here in South Jersey around 2100 Z from SM, OH etc on 10 and 15. Some were a little raspy, suggesting a bit of aurora, I guess. This is a regular opening that we tend to look for in the contests in the afternoon, particularly if someone needs a northern multiplier like JW, or is short a Scandinavian mult on 10 or 15".

Bill Hohnstein, K0HA, of Seward, Nebraska, has been looking at this propagation for the past couple of months by listening for beacons from Scandinavian countries. He copied the OH5RAC beacon on 28.231 MHz at 1957 UTC on November 28. He received an e-mail from beacon operator OH6IY, reporting that Bill's was the first reception report from outside Europe. The beacon operates at 4.5 W using a modified British paging transmitter hooked through 30 meters of RG- 213 to a dipole on a water tower. OH5IY says the radiation toward the US is very low, due to the dipole's orientation and its low height off the tank roof.

OH5IY writes:

"The propagation is 'post-Auroral.' The Au ended here some hours ago, and I am surprised to note the sigs get to USA. The antenna is a dipole with ends pointing to AZ 300 degrees, so there are several minima to the East Coast, but the skewed Au paths have allowed the propagation from the northern lobe to you".

K0HA thinks the propagation from his end may be a first hop via F2, with a trans-equatorial-like spread F-hop after that. Check out his impressive antenna farm by looking him up on the Web site.

John Laney, K4BAI, has noticed the same loud Scandinavian signals on both 10 and 15 meters, often after openings to the rest of Europe have been closed for a couple of hours. He thinks this is more often observed during major DX contests, because more Scandinavian stations may be on during those times.

Chip Margelli, K7JA, writes:

"That's the usual afternoon OH/SM/LA/UA1Z opening that is more commonly observed on 21 MHz. Sometimes it does extend up to 28 MHz, and indeed the Scandinavian side is always in darkness".

Joe Schroeder, W9JUV, says he observed the same propagation, but on both days of the CQ World Wide when he was running QRP. When European signals started to fade, he worked OH, SM and UA1 stations.

W3DF, W9DY, and N5AW also sent in similar remarks about the late 10 meter propagation to Scandinavia.

Ken Brown, N4SO, reminds us that there is a log of current or recent WWV solar flux and mid-latitude K and A index data on the DX Central Web site.

For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page.

Sunspot numbers for December 2 through 8 were 62, 58, 43, 46, 47, 26 and 40, with a mean of 46. The 10.7 cm flux was 105.6, 100.8, 97.4, 95.9, 93.2, 89.7 and 96.5, with a mean of 97. Estimated planetary A indices were 4, 3, 1, 8, 19, 15 and 10, with a mean of 8.6. Estimated mid-latitude A indices were 4, 1, 0, 7, 11, 9 and 9, with a mean of 5.9.