Propagation News – 8 November 2020

Sunspots are a bit like buses. You wait forever and three come along at once! Last week we had active regions 2778 and 2779, which pushed the solar flux index up to 88. This week we have sunspot region 2781, which is a monster. At the time of writing, this region had pushed the SFI to 88 again, but it has been active in terms of solar flares. These have been minor C-class events, so not too much to worry about. The good news is that geomagnetic conditions have been very settled over the past week, with the Kp index running between zero and two. This no doubt helped ionospheric propagation.

There was some good DX reported over the past seven days. TX0T, the DXpedition to Tatakoto Atoll, OC-298, in French Polynesia, has been worked by several stations in the UK. The Far East has also been workable, especially on FT8, where Indonesia, China and Japan have all been spotted.

Next week, NOAA predicts the SFI will be in the range 72-76. The good news is that geomagnetic conditions are predicted to be quiet with a maximum Kp index of two.

We may get some radio blackouts or sudden ionospheric disturbances as a result of M or C-class solar flares from active region 2781, but these are difficult to predict. Radio blackouts occur when the strong, sudden burst of X-rays from a solar flare hits the Earth’s atmosphere, blocking high-frequency radio signals in the D-region of the ionosphere. NOAA puts the probability of an R1/R2 radio blackout at 15 percent, and an R3 radio blackout at just five percent. Overall then, it looks like a good week for HF propagation.

VHF and up

There was a brief return of tropo at the end of the last week. The first of this autumn’s opportunities was complete with fog below the inversion layer. Unfortunately, the related high and its tropo is not due to last and indeed will have probably moved away during the weekend. It does, though, show the capability of a good temperature inversion, with foggy air trapped below it, to produce good tropo.

The last vestiges of it are now clearing away across the northern North Sea, but may still be just worth exploring for the 48th Marconi Memorial VHF CW Contest on Sunday. During the weekend, the weather pattern changes to a more unsettled type, which remains dominant through the coming week. This will bring GHz band rain scatter, but also some strong winds at times.

As we approach the Leonids meteor shower on the 17th we also have a smaller shower, the Northern Taurids, peaking this Thursday, so meteor scatter conditions should be above average. It is also worth the occasional check for sporadic E on FT8 on 10m and 6m.

The Moon’s declination is high but starting to fall, going negative on Thursday, so Moon visibility windows will shorten. The Moon is at perigee next Saturday so path losses are low. 144MHz sky noise is low for most of the week.

Category: GB2RS Propagation News