ARRL

Secure Site Login

News

The K7RA Solar Update

02/15/2019

Another week passed with no sunspots, and as of February 14 it has been over two weeks since any sunspots were observed, the last on January 30. February 7 through 13 saw average daily solar flux decline from 71.1 to 70.4, compared to the previous seven days. Geomagnetic indices were lower, with average daily planetary A index declining from 11.6 to 8.1, and average mid-latitude A index going from 8 to 6.1. Lower geomagnetic activity is generally good for HF propagation.

Predicted solar flux over the next 45 days is 70 on February 15-21, 72 on February 22-25, 71 on February 26 through March 9, 70 and 71 on March 10-11, 72 on March 12-24, and 71 on March 25-31.

Predicted planetary A index is 12 and 8 on February 14-15, 5 on February 16-18, then 12, 20, 12 and 8 on February 19-22, 5 on February 23-26, then 12, 15, 15 and 10 on February 27 through March 2, 5 on March 3-4, then 8, 5, 8, 10, 8 and 5 on March 5-10, 8 on March 11-12, 5 on March 13-17, then 12, 20, 12 and 8 on March 18-21, 5 on March 22-25, 12 on March 26, 15 on March 27-28, 10 and 5 on March 29-30.

The prediction of solar flux always at 70 or above over the next 45 days is a positive sign for HF propagation, and the spring equinox returns on March 20, indicating gradually improving HF propagation.

Geomagnetic activity forecast for the period February 15 until March 13, 2019 from F.K. Janda, OK1HH.

Geomagnetic field will be:
Quiet on February 16-17, 24-26
Quiet to unsettled on February 18, 27, March 3-4, 6-7, 10-11
Quiet to active on February 15, 23, March 5, 8-9, 13
Unsettled to active on February 19, 22, March 1-2, 12
Active to disturbed on February 20 (- 21), 28

Solar wind will intensify on February (19,) 20-21, (22, 28) March (1-3, 6-9, 13). Parenthesis means lower probability of activity enhancement.

Jon Jones, N0JK, writes to us from Lawrence, Kansas, where he operates on 6 meters with a very modest antenna and low power: "A set of rare off season 6 meter Sporadic-E openings appeared on the evening of February 7, and again the morning of February 8.

“February 7 sporadic-E appeared suddenly on 6 meters starting around 2300z from W2, W3 to W4, and W4 to WØ.

“The next morning February 8, there was strong sporadic-E on 50 MHz across the eastern United States and Canada. NØLL (EM09) worked short Es (high MUF) to W4HLR (EM56) at 1450z. The opening finished around 1845z with K9MU (EN44) working VE1JF (FN74).

“The only months with less Sporadic-E than February in North America are:  March, September and October."

The latest video from Dr. Tamitha Skov, WX6SWW: https://youtu.be/H2jDNtUvZkI

Reader Ken Miller, K6CTW, has an interesting and informative article in the current February 2019 issue of Electric Radio magazine titled "DXing During Periods of Low Sunspot Activity." Ken and the publisher of Electric Radio have generously offered to share this article with our readers. For a PDF copy of the article, email a request to k7ra@arrl.net and title the message “K6CTW article.” If you would like to make a comment, email the author at k6ctw@earthlink.net.

For more information concerning radio propagation, see the ARRL Technical Information Service 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 February 7 through 13, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 70.2, 71.8, 70.3, 70, 69.9, 70.2, and 70.4, with a mean of 70.4. Estimated planetary A indices were 4, 9, 10, 6, 9, 6, and 13, with a mean of 8.1. Estimated mid-latitude A indices were 3, 7, 6, 4, 7, 5, and 11, with a mean of 6.1.

 



Back