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The K7RA Solar Update

03/06/2020

Last week we pointed out in ARLP009 that the NASA STEREO images (at https://stereo.gsfc.nasa.gov/ ) showed two bright spots, magnetically complex, about to rotate over the sun’s eastern horizon and onto the visible solar disc. I was hoping these might develop into sunspots, but they both quickly faded away, so currently we have seen no sunspots in 33 days. Clearly, we are still at solar minimum.

These STEREO images are always in real time, constantly updated, so they always show a live update of images.

Over the past week average daily solar flux shifted from 70.5 to 70, average daily planetary A index stayed the same at 6.7, while average daily mid-latitude A index shifted slightly from 5 to 4.6.

This period of low solar flux and very stable geomagnetic indicators is great for 160-meter propagation, especially now during the winter season, when we enjoy very low atmospheric noise.

On Thursday, Spaceweather.com reported a faint coronal mass ejection detected by STEREO spacecraft on March 2. This is slow moving and expected to hit Earth on March 7 and is probably why planetary A index is predicted at 8 on March 7-8.

Predicted solar flux over the next 45 days is 70 on March 6-13 and 71 on March 14 through April 19.

Predicted planetary A index is 6 on March 6, 8 on March 7-8, 5 on March 9-14, then 10, 8, 10 and 8 on March 15-18, then 5, 10, 8 and 5 on March 19-22, then 8, 12, and 10 on March 23-25, 5 on March 26-30, then 20, 15 and 8 on March 31 to April 2, and 5 on April 3-19.

David Moore reports, “space weather model gives earlier warning of satellite-killing radiation storms. Two-day notice lets satellite operators take protective measures against energetic electrons: https://www.sciencedaily.com/releases/2020/03/200302153600.htm

A new machine-learning computer model accurately predicts damaging radiation storms caused by the Van Allen belts two days prior to the storm, the most advanced notice to date, according to the new article.”

This reports a new type of solar event, and how it might be used to predict the onset of a new solar cycle: https://link.springer.com/article/10.1007/s11207-020-1595-3

N0JK comments: "The VP8PJ DXpedition just went off the air at about 0102z on March 6. The group did an outstanding job being ‘available’ for contacts despite adverse conditions. They stayed an additional day - March 5. This was fortuitous as VP8PJ enjoyed a great 15-meter opening to North America all afternoon.  This with an SFI of just 70 and the Kp index of 1.

“As for propagation - from Kansas -  VP8PJ was heard most frequently on 40, 30, and 20 meters. They had a consistent signal on 30 meters. I am sure even low power stations with simple antennas on 30 meters were successful working VP8PJ. I logged them here logged with about 50 W and a ‘rain gutter’ antenna. They had a good signal on 40 meters, but they were more difficult to work. Twenty meters was the best band to work them on SSB.

“Seventeen meters and up were more challenging. On my fixed mobile, the 17-meter signal was very weak until March 1. I heard nothing on 15 meters until March 5. Nothing on the higher bands on any day. I noted spots by North American stations for VP8PJ on 10 meters March 1 and 3. VOACAP did not predict any 10-meter propagation to North America for VP8PJ to the Midwest, even for an 'expert DXer'."

Here is the latest video from Tamitha Skov, WX6SWW: https://youtu.be/mJBpFqP5b8k

This weekend is the phone portion of the ARRL International DX Contest. Check http://www.arrl.org/arrl-dx for details.

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 http://www.arrl.org/propagation and 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 27 through March 4, 2020 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 70.9, 70.6, 70.1, 69.3, 69.3, 70, and 69.8, with a mean of 70. Estimated planetary A indices were 4, 6, 11, 8, 5, 6, and 7, with a mean of 6.7. Middle latitude A index was 2, 4, 8, 6, 4, 4, and 4, with a mean of 4.6.

 



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