ARRL

Secure Site Login

News

The K7RA Solar Update

02/22/2019

No sunspots are visible since January 30. The lack of sunspot activity has persisted for over 3 weeks, as of February 21. This past week (February 14-20) the average daily solar flux was only marginally higher, rising just barely from 70.4 to 70.6. Geomagnetic indicators were lower, with average daily planetary A index declining from 8.1 to 4.9, and average daily mid-latitude A index (measured at a single magnetometer in Virginia) dropping from 6.1 to 3.9.

One advantage at the bottom of the solar cycle is there is less geomagnetic activity, which is a benefit for propagation on 160, 80 and 60 meters. The recent issue of ARRL Contest Update mentioned this, when they talked about the CW weekend last week of the ARRL International DX Contest: “There are many reports that 160 and 80 meters experienced exceptional propagation. The phone version of this contest is coming up on March 2.” Also in the same Contest Update is a link to K0NR and his piece about how VHF has propagation opportunities beyond line-of-sight: http://www.k0nr.com/wordpress/2019/02/the-myth-of-vhf-line-of-sight/

 

In the 45-day outlook for solar flux, the current forecast shows predicted values below 70, for the first time in a few weeks, from March 1-10 and again on March 26 through April 6. We are approaching the end of the winter season, and the vernal equinox (first day of spring) happens on Wednesday, March 20. This suggests better HF conditions. Likewise, in the Southern Hemisphere is the autumnal equinox, a good period for HF propagation.

The 45-day solar flux prediction on February 21 was 71 on February 22 through March 1, 68 on March 2-10, 70 on March 11-25, and 68 on March 26 through April 7.

 

Predicted planetary A index is 10 and 8 on February 22-23, 5 on February 24-26, then 16, 20, 18, 12 and 8 on February 27 through March 3, then 5, 8, 5, 8, 10 and 8 on March 4-9, 5 on March 10-11, then 12 and 10 on March 12-13, 5 on March 14-17, then 12, 16, 12 and 8 on March 18-21, 5 on March 22-25, then 15, 18, 18, 12, 8 and 5 on March 26-31, then 8, 5, 8, 10, and 8 on April 1-5, and 5 on April 6-7.

 

Geomagnetic activity forecast for the period February 22 until March 20, 2019 from F.K. Janda, OK1HH:

Geomagnetic field will be

Quiet on February 24-26, March 10, 15-16

Quiet to unsettled on February 23, March 4-7, 9, 11, 18

Quiet to active on February 22, March 3, 8, 12-14, 17, 19-20

Unsettled to active on February 27, March 2

Active to disturbed on February 28, March 1

Solar wind will intensify on February 22, (28,) March (1-3, 6-9,) 13-15, 20

Parenthesis means lower probability of activity enhancement.

Again, there are changes in the configuration of active areas, so the predictability of the prognoses decreases and their computation is difficult.

 

Here is a Newsweek article on the solar corona and the next sunspot cycle: https://bit.ly/2BLeT2W

Regarding the recent unusual (and low) predictions for sunspot numbers and solar flux seen on the final few pages of NOAA’s weekly preliminary Report and Forecast, go to https://bit.ly/2TagxVI to see an update. We will probably need to wait for the next Space Weather Workshop in April. The Solar Cycle 25 Prediction Panel meets on Friday, April 5, 2019.

 

Wayne Greaves, W0ZW, of Farmington, New Mexico wrote in a recent email, “The level of activity during the ARRL International DX Contest (CW) last weekend certainly proved to me that you can work DX at the bottom of the solar cycle.  I even made a 10-meter contact with a station in Chile.”

 

Here is the latest video forecast from Dr. Skov: https://youtu.be/EHeO-5URiQU

 

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 February 14 through 20, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 71.4, 70.9, 70.7, 70.1, 69.9, 70.2, and 71, with a mean of 70.6. Estimated planetary A indices were 10, 4, 3, 4, 7, 3, and 3, with a mean of 4.9. Estimated mid-latitude A indices were 8, 4, 3, 3, 5, 2, and 2, with a mean of 3.9.

 

 



Back