Propagation Forecast Bulletin 6 ARLP006
From Tad Cook, K7RA
Seattle, WA February 9, 2018
To all radio amateurs
Compared to the previous seven days, solar activity increased in the first week of February. There were two days with no sunspots, February 1 and 3. On February 2 a new sunspot region emerged, but by the next day it had disappeared. Another sunspot region appeared on February 4, and the area it covered on February 4-7 was 80, 130, 160 and 200 millionths of the solar hemisphere.
We haven’t seen as much coverage since October 7, 2017 when the total sunspot area was 220 millionths of the solar hemisphere and the sunspot number was 11, the minimum non-zero sunspot number.
A dozen days prior on September 25 the sunspot number was 36 and the total sunspot area (as always, expressed in millionths of a solar hemisphere) was 560.
You can see that already the sunspot numbers and solar flux have dropped since last year: ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2017_DSD.txt
As a reference, you can compare these numbers with the peak of the current cycle in 2014: ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2014_DSD.txt
Note the year contained in the above two URLs. You can edit that to look at any year, back to 1994.
You can look here to see graphs of sunspot and solar flux activity, and see what the daily numbers were for the previous peak and minima: http://www.wm7d.net/hamradio/solar/
So last week the average daily sunspot number increased from 3.7 (at the end of January) to 10.3 and average solar flux from 69.1 to 72.5. Average planetary A index decreased modestly from 6.3 to 4.4, while average mid-latitude A index (measured at one location, in Virginia) decreased from 4.9 to 3.6.
The heightened activity should continue over the next week. Predicted solar flux is 78 on February 9-10, 76 on February 11-12, 74 on February 13-14, 72 on February 15-16, 70 on February 17-22, 69 on February 23-28, 70 and 71 on March 1-2, 72 on March 3-14, 71 on March 15, 70 on March 16-21, and 69 on March 22-25.
Predicted planetary A index is 8 on February 9, 5 on February 10-16, then 8, 10, 5, 8, 10, and 8 on February 17-22, 5 on February 23 through March 13, then 8, 12, 8, 10, 5, 8, 10 and 8 on March 14-21 and 5 on March 22-25.
F.K. Janda, OK1HH sent this geomagnetic activity forecast for the period February 9-March 8, 2018.
“Geomagnetic field will be:
- Quiet on February 12-14, 20
- Mostly quiet on February 17, 23, 25-27, March 1-3, 5-8
- Quiet to unsettled on February 11, 15, 18-19, 21-22, 24, 28
- Quiet to active on February 9-10, 16, March 4
- Active to disturbed-not anticipated
“Amplifications of the solar wind from coronal holes are expected on February 5-6, 9-12, 18-19, 27-28.”
Al Kaiser, N1API of Meriden, Connecticut sent a report on Sunday, February 4:
“During the 10-10 QSO Party on Sunday February 4 we had what was probably a nice sporadic-E opening that started with NC about 1507 UTC, then nothing until TN on 1704 which quickly changed to solid signals from OH, IL, IN, AND MI. By about 1822 it was all over. 10 meters always has some surprises in store.”
Jeff, N8II reported from West Virginia on February 8:
“This week, there is very little good news of improved openings on 17 (a bit better than a week ago) and 15 meters so far despite the considerably higher SFI.
“But, all of the low bands including 160 seem better thanks to more ionosphere. Tonight, February 9 UTC, I worked A45XR (Oman) first call on 80M CW at 0053Z who was S8 and around the same time logged Denmark and Slovenia with good signals. I also logged Z61DX Kosovo, on 17M CW at 1540Z today February 8th for a new band country and Z60A was S9 on 40 CW tonight, but too many calling to get through. There were many S9+ Europeans on 20M this morning, much better signals than a month ago.”
A new space weather video from Dr. Tamitha Skov can be seen at: http://bit.ly/2EtXBtz
If you would like to make a comment or have a tip for our readers, email the author at, firstname.lastname@example.org .
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 February 1-7, 2018 were 0, 11, 0, 11, 13, 17, and 20, with a mean of 10.3. 10.7 cm flux was 69, 68.8, 69.2, 73, 74, 76.9, and 76.6, with a mean of 72.5. Estimated planetary A indices were 4, 4, 3, 3, 8, 5, and 4, with a mean of 4.4. Estimated mid-latitude A indices were 2, 3, 2, 3, 8, 4, and 3, with a mean of 3.6.