ZCZC AP44
QST de W1AW
Propagation Forecast Bulletin 44 ARLP044
From Tad Cook, K7RA
Seattle, WA October 29, 2004
To all radio amateurs
SB PROP ARL ARLP044
ARLP044 Propagation de K7RA
This week has been fantastic for HF propagation, with a sun peppered with spots, and best of all, no geomagnetic upsets. This is an unusual combination, to have geomagnetic indices so low while sunspot numbers are up. What could be better, just ahead of the CQ World Wide DX SSB Contest this weekend?
From last week to this week, the average daily sunspot number more than doubled, rising over 75 points to 140.7. The sunspot number was highest on Sunday, October 24 when it was 178. The daily sunspot number hasn't been this high since late 2003, when it was also 178 on November 30.
I know that last week we were looking forward to the decline toward solar minimum in a couple of years. But the minimum and maximum are never determined until long after, when we get a chance to look at charts of long running moving averages. In between is a great deal of variation, such as what we are seeing now.
For this weekend, expect great conditions for the DX contest, and you can expect the higher HF bands to yield plenty. Average solar flux for this week was about 131, and you can expect continuing solar flux between 130-135 through the weekend. Saturday, October 30 may have some mildly unsettled geomagnetic conditions, with a planetary A index of 12. Currently as this bulletin is being composed late Thursday night U.S. West Coast time, WWV is reporting a mid-latitude K index of 0.
Several readers sent in articles concerning a new report claiming there has been more solar activity over the past seven decades than any time in the previous 8,000 years. You can read about it on the web at, http://www.spaceref.com/news/viewpr.html?pid=15385 and http://www.space.com/scienceastronomy/sunspot_record_041027.html.
Carl Zelich, AA4MI wrote to tell us about http://www.dx-central.com/. On the home page they post the latest geophysical alerts and solar flux from WWV, and they have many other resources. I noticed a link to http://www.dxtuners.com, where you can remotely tune and listen to radios all over the world via the internet.
If you would like to comment or have a tip, email the author at, k7ra@arrl.net.
For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service propagation page at, http://www.arrl.org/tis/info/propagation.html.
A word about the solar flux numbers for this week. On Monday, October 25 the observatory in Penticton, British Columbia did not report a 10.7 cm noon solar flux. Although the local noon (2000z) measurement is the official daily solar flux, there are also daily measurements at 1700 and 2300z. We report 141.4 for that day by averaging the 1700 and 2300z numbers of 139.6 and 143.2.
Sunspot numbers for October 21 through 27 were 112, 134, 141, 178, 146, 124 and 150 with a mean of 140.7. 10.7 cm flux was 112.1, 122.5, 131.6, 140.2, 141.4, 136.7 and 129.5, with a mean of 130.6. Estimated planetary A indices were 8, 6, 4, 9, 13, 3 and 3, with a mean of 6.6. Estimated mid-latitude A indices were 5, 5, 1, 6, 9, 0 and 2, with a mean of 4.