The K7RA Solar Update

SEATTLE, WA, Sep 2, 2005--Geomagnetic activity was down quite a bit from last week, but solar wind and a south-pointing Interplanetary Magnetic Field late Wednesday left Earth vulnerable. Mid-latitude K-index reached 4, and the planetary K index rose to 6. The IMF is from our sun, and the point where it contacts Earth's magnetic field is called the magnetopause. Earth's magnetic field protects us from solar wind, and the Earth's magnetic field at the magnetosphere usually points north. When the IMF points south, however, it is opposite Earth's magnetic field, and the two link up. This carries energy from the sun directly into the earth, and this can cause aurora and geomagnetic instability. This is generally bad for high-frequency radio propagation.

The IMF was continuing to point south as of the evening of September 1, and this could leave Earth vulnerable to a coronal mass ejection (CME) erupting on the sun on Wednesday, August 31 at 2230 UTC. The wind from this event is traveling at about 3.36 million miles per hour, or 1500 km per second. The predicted planetary A index for Friday through Monday, September 2-5 is 30, 25, 10 and 10. Sunspot numbers and solar flux should rise slowly over the next week.

As September begins, we look forward to the fall equinox in the Northern Hemisphere--always a better time for HF propagation. It is also time to look at the average solar flux and sunspot numbers from August, comparing them to previous months.

Average daily sunspot number in August was 65.6, down slightly from 68.7 in July. July average daily solar flux was 96.5, declining to 92.4 in August.

The average daily sunspot numbers for the months October 2004 through August 2005 were 77.9, 70.5, 34.7, 52, 45.4, 41, 41.5, 65.4, 59.8, 68.7 and 65.6. Average daily solar flux for the same months was 106, 113.7, 95, 102.3, 97.2, 89.9, 85.9, 99.5, 93.7, 96.5 and 92.4.

Peter Baskind, N4LI. of Germantown, Tennessee (EM55) reported that on August 27 there was a great 6 meter opening in which he worked stations around the eastern US and Caribbean. Most surprising was a 30 minute opening to Argentina with LU6DRV (GF05) peaking sometimes over S9--uncommon he says for that far north.

I remembered this week that a ham I used to chat with on AMTOR in the 1980s, W5KSI, Angelo Glorioso Jr. lived in New Orleans. I e-mailed him and his son to inquire about their welfare, hoping they'd evacuated early from the city before the storm. His son (Angelo III, N5UXT) answered right back, saying he was in Baton Rouge and his dad had evacuated to Houston, Texas, on Sunday morning. I rang up Angelo, asked how he was doing, and he said "Everything is gone," including the house he's lived in for 50 years and his mother's home. Angelo lived about 500 feet east of Bayou Saint John, on Filmore Avenue, a mile south of Lake Pontchartrain. The last they saw their home was around 10 AM Sunday morning when Angelo and his wife began the 360-mile drive to the Bunker Hill Village area of Houston via Interstate 10.

Even though all of I-10 was switched for the evacuation to westbound traffic only, the traffic crawled the whole way. Angelo and his wife drove nearly non-stop until 4:30 PM Monday, an average speed of less than 12 MPH. Angelo told me he wakes up in the morning expecting the nightmare to be over, and then it sinks in, that it really did happen. But he is grateful he made it out of New Orleans safely with his family.

Western Washington Section Manager Ed Bruette, N7NVP, sent along some non-ham frequencies to monitor for possible hurricane traffic. Of course, these are outside the ham bands, and all we should do is listen. All are in upper sideband. USN/USCG hurricane nets are on 7507 and 9380 kHz. American Red Cross also uses upper sideband for disaster communication on 2802.4, 3171.4, 5136.4, 5141.4, 6859.5, 7550.5 and 7698.5 kHz, but 7550.5 is the primary frequency. Hugh Stegman, NV6H, has compiled a list of hurricane recovery frequencies.

I've been asked recently about any new sunspots from the next solar cycle. The conventional wisdom is that sunspots with a new magnetic polarity are actually from the next solar cycle. I talked to Bill Murtagh of the NOAA Space Environment Center, and he said a recent one was what he called a rogue sunspot group or a "gnarly group." In fact, spots with a magnetic polarity opposite to the prevalent one appear from time to time throughout the solar cycle, and are a good indicator for enhanced geomagnetic activity to come.

I asked Bill about the sunspot cycle prediction tables in the back of the Preliminary Report and Forecast (mentioned in the "Solar Update" of August 5). I was curious how these are updated and when, and I also noted that the prediction for solar cycle minimum around the end of 2006 had not changed in several years. Bill said this estimate is still valid, but they should have an update in April 2006 to be announced during Space Weather Week. A panel of experts will meet to come up with an updated model for the end of the current cycle.

Bill said that so far the prediction for the smoothed sunspot number for the peak of the next cycle ranges from a pessimistic 50 maximum to 150 maximum. By contrast, the famous Cycle 19 from the late 1950s had a smoothed peak of 201.3, and cycles 21 and 22 (the last two) peaked at 164 and 158. Current Cycle 23 peaked at 120.8.

Bill said the smoothed solar flux and sunspot numbers are averaged over 13 months, so the most recent number that is not a prediction would be six months ago. The number shown for the current month would be the six predicted months in the future combined with the previous six observed months.

For more information concerning radio propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page. An archive of past bulletins is on the ARRL Web site.

Sunspot numbers for August 25 through 31 were 76, 57, 91, 99, 88, 68 and 48, with a mean of 75.3. The 10.7 cm flux was 92.4, 93.2, 92.1, 89.8, 89.2, 86, and 84, with a mean of 89.5. Estimated planetary A indices were 24, 11, 7, 7, 9, 4 and 36, with a mean of 14. Estimated mid-latitude A indices were 18, 5, 4, 5, 5, 3 and 17, with a mean of 8.1.

Amateur solar observer Tad Cook, K7RA, 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 in The ARRL Letter. Readers may contact the author via e-mail.

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