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The K7RA Solar Update


Tad Cook, K7RA, Seattle, reports: Sunspots disappeared on 4 days over the past week, but then returned. The average daily sunspot number declined from 14.3 to 5.4, while average daily solar flux went from 73.8 to 71. Geomagnetic indicators remain quiet. The average daily planetary A index increased from 3.7 to 4.4.

Predicted solar flux is 70 on August 21 – 22; 69 on August 23 – 28; 72 on August 29; 73 on August 30 – September 5; 72 on September 6 – 9; 71 on September 10 – 11; 70 on September 12 – 19; 71 on September 20 – 23; 72 on September 24 – 25; 73 on September 26 – October 2, and 72 on October 3-4.

Predicted planetary A index is 5 on August 21 – 22; 6 on August 23 – 25; 5 on August 26 – 28, 8, 16, and 8 on August 29 – 31; 5 on September 1 – 14, 10 on September 15 – 16, 5 on September 17 – 24, then 8, 16, and 8 on September 25 – 27, and 5 on September 28 – October 4.

According to the geomagnetic activity forecast for the period August 21 – September 16 from F.K. Janda, OK1HH, the geomagnetic field will be:

  • quiet on September 5-7

  • quiet to unsettled on August 22, (23,) 24-25, (26-28,) September 2-4, 8-9

  • quiet to active on (August 21, 29-31, September 1, 16)

  • unsettled to active — not expected

  • active to disturbed — not expected

  • Solar wind will intensify on: August (21-23,) 24-25, 29, September 1-2, (4-6,) 8, 15-16

Notes: Parentheses mean lower probability of activity enhancement.

Thanks to Max White for this link to a article about a dent in Earth’s magnetic field and the South Atlantic Anomaly.

Here’s the latest report from Space Weather Woman Tamitha Skov, WX6SWW. The CME she speaks of turned out not to be geo-effective, so we missed a disturbance.

Reader David Moore alerted us to a ScienceDaily article on the NASA THEMIS Mission. “A special type of aurora, draped east-west across the night sky like a glowing pearl necklace, is helping scientists better understand the science of auroras and their powerful drivers out in space.”

George Hall, N2CG, writes:

“Reading The K7RA Solar Update of August 14 regarding your personal experience of Solar Cycle 19 when you were a young boy listening to the low-band VHF FM 2-way radio in your dad's company car in California and suddenly hearing stations in Texas and other midwestern states brought back fond memories of a similar nature I experienced in Solar Cycle 20.

“I was a Radioman on active duty in the US Coast Guard stationed at NIK/NJN on the US Naval Air Station, Argentia, Newfoundland. The Crash Crew — a fire department specifically devoted to incidents on the airport with specially equipped fire trucks that could literally drive right up on top of a fire on the ground and expel fire extinguishing foam from the underside of the crash crew trucks to put out the fire — at Argentia was a 24/7/365 operation that monitored the airport control tower's VHF Low Band (30 – 49 MHz).

“Over the radio one bright sunny early afternoon in June 1968 came the call ‘ROLL THE GEAR ROLL THE GEAR,’ which is the highest response precedence for the Crash Crew to man the crash crew trucks and head for the airport crash site. The Argentia Newfoundland Crash Crew immediately headed for the airport, but saw no evidence of a crash — no smoke or fire. The senior on-scene crash crew member called the tower to ask if this was a drill. The tower replied they also heard the ‘ROLL THE GEAR’ call, but it was not [from] them, and for the crash crew to return to station.

“Later that day it was determined that the ‘ROLL THE GEAR’ call actually came from the US Naval Air Station in Rota, Spain, over 2,500 miles away. Both Argentia and Rota used the same VHF Low Band frequency.

“Thanks for bringing back the fond memories of over 52 years ago.” [Edited for length. — Ed]

Sunspot numbers for August 13 – 19 were 11, 0, 0, 0, 0, 12, and 15, with a mean of 5.4. The 10.7-centimeter flux was 72.3, 70.8, 70.6, 70.9, 70.8, 71.3, and 70.5, with a mean of 71. Estimated planetary A indices were 4, 4, 3, 4, 3, 7, and 6, with a mean of 4.4. Middle latitude A index was 5, 3, 3, 5, 3, 7, and 9, with a mean of 5.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out K9LA’s Propagation Page.

A propagation bulletin archive is available. Monthly charts are no longer be updated on this page. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

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