Propagation de K7RA
9 February, 2019Solar wind pushed geomagnetic indicators higher last week (on February 1-2), and average planetary A index rose from 7 (for the seven days ending January 30) to 11.6 on January 31 through February 6.
When geomagnetic conditions are active, we usually see higher indices at high latitudes. Alaska's College A index (measured at a magnetometer near Fairbanks) was 40 on February 1, indicating disturbed conditions for the higher latitudes, with a great deal of absorption rather than reflection of HF radio waves.
There were no sunspots recorded over this period, so average daily sunspot numbers plunged from 19.6 to 0. Average daily solar flux declined from 74.5 to 71.1.
Predicted solar flux for the next 45 days is 70 on February 8-15, 72 on February 16-25, 71 on February 26 through March 11, and 72 on March 12-24. These are actually pretty good numbers for the bottom of the solar cycle. Notice there are no predicted flux values below 70.
Predicted planetary A index is 15, 12 and 8 on February 8-10, 5 on February 11-18, then 12, 20, 12 and 8 on February 19-22, 5 on February 23-26, then 12 on February 27, 15 on February 28 and March 1, then 10, 8, 12 and 8 on March 2-5, 5 on March 6-17, then 12, 20, 12 and 8 on March 18-21, and 5 on March 22-24.
Geomagnetic activity forecast for the period February 8 through March 5, 2019 from F.K. Janda. OK1HH.
"Geomagnetic field will be:
Quiet on February 24-26
Quiet to unsettled on February 9, 11, 14, 18, 27, March 4
Quiet to active on February 12-13, 15-17, 23, March 5 Unsettled to active on February 8, 10, 20, 22, March 1-3
Active to disturbed on February 19, 21, 28
"Solar wind will intensify on February (19,) 20-21, (22, 28), March 1-4, 6.
"Parenthesis means lower probability of activity enhancement."
If you are using any propagation prediction program such as W6ELprop, you will want to use the predicted smoothed sunspot number (which as of February 4) is 8 for February and March 2019, 7 for April and May, and 6 for June through August.
These predicted smoothed sunspot numbers are updated on the first Monday of each month as part of the weekly reports at, ftp://ftp.swpc.noaa.gov/pub/warehouse/2018/WeeklyPDF/ . You can find the predicted smoothed sunspot and solar flux numbers toward the end of each report, on pages 10 and 11 of the current issue.
Note the problematic predicted numbers which first appeared a month ago have still not been corrected. This is probably affected by the recent federal government shutdown.
This February 1 report is from Ken Brown, N4SO of Grand Bay, Alabama using FT8:
"40 meters has been very good with this sampling of DX call signs:
"A45XR Oman, 9K2HQ Kuwait, A65BR United Arab Emirates, YT1TX Serbia, FK8CB New Caledonia, YD7JLI Indonesia, TF5B Iceland, R9YM Asiatic Russia, UA9UR Russia, TA1OSN Turkey, and E74BYZ Bosnia and Herzegovina.
"A full list would be very long."
Report from Mike Schaffer, KA3JAW in Easton, Pennsylvania:
"While monitoring the 11-meter citizen band on Tuesday, January 15, 2019 from 10:55 pm EST (0355 UTC Jan. 16th) I started to hear long distance mobile stations travelling along west bound on Interstate 10 highway from Tallahassee to Pensacola, Florida via sporadic-E.
"Kind of odd for the Es to be extended up until this hour. Most of the time it will drop out around 9:30 pm local time. Solar Flux Index was reported at 70. The geomagnetic field was quiet.
"On Thursday, January 17 (0350 UTC January 18th) was hearing stations from Tallahassee to Sarasota, Florida. Solar Flux Index was reported at 69. The geomagnetic field was quiet.
"The next night there was no 11M Es heard from any direction as a Northeast Winter polar vortex storm was moving eastward from the Midwest that was being strengthened by the Arctic air blast from Canada.
"On Saturday January 26 late evening I noted the Australian Jindalee Operational Radar Network (JORN), Over-the-Horizon Backscatter Radar
(Longreach) transmitter emitting 560kW ERP in Queensland, Australia.
Could be testing their upgraded electronics, signal processing to boost radar coverage and detection capabilities using slower scan rates to detect smaller aircraft, ships, missile launches, low-earth satellites passing over the Coral Sea towards the North Pacific Ocean using digital FM-CW modulation.
"Operations were between 11 am to 12 pm Australian Eastern Standard Time. Signal strength ranged from faint to fair. Distance was 9,872 miles. The mid-point propagation distance was 4,936 miles, which put the ionospheric refracted footprint touching 300 plus miles northwest from Honolulu, Hawaii along the Gray-Line path while the solar flux rose to 77."
The latest from Dr. Tamitha Skov, WX6SWW:
"This year is already off to an amazing start. We have an ongoing solar storm that is bringing long-awaited aurora to many places in the world. I have seen aurora field reports as far south as Germany in Europe and Montana in the United States. In the south, aurora has graced the skies over Tasmania and New Zealand. Although these solar minimum storms pale by comparison to those just a few years ago, one thing is certain. This Space Weather community is growing."
"This storm has been reasonably weak, yet I have seen a flood of aurora photos, along with numerous amateur radio reports, and even several GPS questions from many new names and faces. I must say, this is a welcome surprise-- and I have YOU to thank for it. The word is definitely getting out!
"As for the forecast this week, we still have a sleepy Sun for the most part. The current solar storm will slowly wane over the next few days, which could bring us some pulsating aurora and sub-auroral arcs (aka STEVE) before it's gone. But soon thereafter the weather will turn quiet again. I will take this quiet time to ponder a next-generation forecast and lean optimistically into the promise tomorrow brings."
Here is Dr. Skov's latest video: https://youtu.be/bDPdyxfNWdA
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 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 January 31 through February 6, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 72.1, 72.1, 70.9, 71.1, 70.7, 70.6, and 70, with a mean of 71.1. Estimated planetary A indices were 14, 17, 17, 11, 7, 5, and 10, with a mean of 11.6. Estimated mid-latitude A indices were 12, 10, 11, 8, 5, 3, and 7, with a mean of 8.
• All propagation reports can be found at:
http://www.southgatearc.org/propagation
TNX Southgate
