QST de W1AW
Propagation Forecast Bulletin 4 ARLP004
From Tad Cook, K7RA
Seattle, WA January 23, 2004
To all radio amateurs
SB PROP ARL ARLP004
ARLP004 Propagation de K7RA
Average daily sunspot numbers and solar flux rose modestly this week. Sunspot numbers were up by nearly four, and solar flux rose by nine points.
In last week's bulletin, we reported that we were entering a solar wind. The effects can be seen in the planetary A index for last Friday. Geomagnetic indices were down by Saturday. On Monday, January 19, energy from a coronal mass ejection hit Earth, but it only caused high geomagnetic activity at high latitudes. For the January 19 and 20 the planetary A index was only an unsettled 17 and 16, but the college A index in Fairbanks, Alaska was 37 on both days.
A strong solar wind from another coronal mass ejection hit earth at 0130 UTC on January 22 causing a strong geomagnetic storm. Mid-latitude Fredericksburg A index as reported by NOAA was 35, and mid-latitude A index as reported by WWV was 46. The college A index on January 22 was 80, and planetary A index was 62.
Another coronal mass ejection should hit earth on January 23 or 24, although latest projections on Thursday show predicted planetary A index for January 23-26, Friday through Monday at 25, 15, 15 and 10. The Prague Geophysical Institute predicts a minor geomagnetic storm for January 23, unsettled to active conditions for January 24, unsettled conditions on January 25, quiet to unsettled conditions for January 26, and active geomagnetic conditions on January 27 and 28.
Users of the WA4TTK Solar Data Plotter, a free program, can see the prominent rise in sunspot numbers and solar flux at the end of October 2003. The lower frame, showing a detailed plot of activity over the past eight months shows the October peak followed by the declining activity from the same sunspot group over the following solar rotations. With several sunspot groups rotating off the visible disk, solar flux over the next few days should decline from 120 down to 110. It should rise again after January 26-27 for another short-term peak around the end of the first week of February.
Spaceweather.com displayed a fantastic photo of a giant filament of hot gas rising above the sun taken by Gary Palmer of Los Angeles on January 21. It's available at the Science @ NASA site.
Vern Rabin of Colorado took another photo of the same filament.
We haven't mentioned the beacon network operated by the IARU and the Northern California DX Foundation in a while. The 18 beacon stations operate all over the world on 20, 17, 15, 12 and 10 meters and are a good tool for gauging propagation. The NCDXF Web site lists many software tools for use with the beacon network. There are programs that work on many platforms in addition to current and recent versions of Windows, including DOS, Linux, OS/2, Windows 3.1 and Palm Pilot.
This weekend is the CQ Worldwide 160-meter CW Contest. Conditions for the contest might be good if geomagnetic conditions don't cause havoc. The ARRL January VHF Sweepstakes also is this weekend, and VHF conditions might not be disturbed if a geomagnetic storm occurs. In addition, the British Amateur Radio Teledata Group is sponsoring its 2004 RTTY Sprint Contest this weekend.
For more information about propagation and an explanation of the numbers used in this bulletin see the Propagation page on the ARRL Web site.
Sunspot numbers for January 15 through 21 were 57, 68, 56, 72, 87, 94 and 104, with a mean of 76.9. The 10.7 cm flux was 119.1, 120.3, 122.6, 119.5, 134.6, 128.9 and 130.1, with a mean of 125. Estimated planetary A indices were 16, 26, 14, 18, 17, 16 and 12, with a mean of 17.