ARRL Propagation Bulletin №0015

SB PROP ARL ARLP015

ARLP015 Propagation de K7RA

Solar indicators, both sunspot numbers and solar flux, both dropped

this week, in fact on April 8 there were no sunspots. Average daily

sunspot numbers declined from 65.9 to 16.6, and average daily solar

flux went from 96.5 to 73.8, compared to the previous seven days, .

Average daily planetary A index went from 15.6 to 10.6, and average

daily mid-latitude A index declined from 13 to 9.3.

Predicted solar flux shows 75 on April 14–15, 85 on April 16–17, 80

on April 18, 95 on April 19–21, 92 on April 22–23, 90 on April

24–29, 80 on April 30, 78 on May 1–2, 72 on May 3–4, 75 on May 5–6,

72 on May 7–12, 75 and 85 on May 13–14, 88 on May 15–16, 95 on May

17–18, 92 on May 19–20, and 90 on May 21–26.

Predicted planetary A index is 8, 10 and 8 on April 14–16, 25 on

April 17–18, 12 and 8 on April 19–20, 5 on April 21–22, then 55, 28,

20 and 22 on April 23–26, then 28, 15, 8 and 5 on April 27–30, then

20, 10, 8 and 10 on May 1–4, 15 on May 5–6, 12 on May 7, 8 on May

8–10, 5 on May 11–13, then 20, 18 and 10 on May 14–16, 5 on May

17–19, then 55, 28, 20, 22, 28, 15 and 8 on May 20–26.

F.K. Janda, OK1HH sent us his geomagnetic activity forecast for the

period April 14 to May 9, 2017.

“Geomagnetic field will be:

Quiet on April 16, 20–22, 30, May 5, 9–10

Mostly quiet on April 14–15, 21, May 3–4, 6

Quiet to unsettled April 19, 29, May 1, 2, 7, 8

Quiet to active on April 23, 25–28

Active to disturbed on April 17–18, 24

“Amplifications of the solar wind from coronal holes are expected on

April (15,) 16–19, 24–27

“Remark: — Parenthesis means lower probability of activity

enhancement and/or lower reliability of prediction.”

Doctor Tamitha Skov’s latest video concerning space weather can be

found at:

http://bit.ly/2pwQIwu

Bil Paul (I think he must be KD6GUI) wrote on April 7:

“The high solar flux number for Wednesday, April 5 (around 95)

didn’t seem to translate into good propagation. I was out in my

kayak trying to qualify an island in Northern California for U.S.

Islands on the Air, running my usual 10w into an end-fed half-wave

wire vertical (won’t even get into how I can set that up while

operating from kayak!).

“As usual, started operating on 17m SSB. One contact told me I was

the only signal he was hearing on the entire band. Only obtained 3

contacts on 17 (SSB/CW), then went down and tried 20m. I could hear

Europe and South America coming in on SSB, but from my little pistol

setup, I only found 3 more contacts before I rolled up the rug and

went QRT.

“But it’s encouraging that the SF is often predicted to be running

considerably higher for the next 30 days or so.

“I don’t know if you read CQ magazine, but I have an article in the

April issue about a 91-year old ham/navy vet in PA who intercepted

Japanese code transmissions in Alaska during WWII.”

If you would like to make a comment or have a tip for our readers,

email the author at k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL

Technical Information Service web page at,

http://arrl.org/propagation-of-rf-signals. For an explanation of

numbers used in this bulletin, see

http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at

http://arrl.org/w1aw-bulletins-archive-propagation. More good

information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve

overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL

bulletins are at http://arrl.org/bulletins.

Sunspot numbers for April 6 through 12, 2017 were 38, 27, 0, 13, 13,

12, and 13, with a mean of 16.6. 10.7 cm flux was 75.7, 73.9, 73.1,

74.4, 73.6, 74.6, and 71.4, with a mean of 73.8. Estimated planetary

A indices were 7, 10, 16, 18, 5, 12, and 6, with a mean of 10.6.

Estimated mid-latitude A indices were 5, 9, 14, 16, 5, 10, and 6,

with a mean of 9.3.

NNNN

/EX

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