Propagation News – 2 October 2022

The HF bands have been really humming this week, making up for the summer doldrums. A lot of this is due to the seasonal change in the ionosphere that results in more monatomic species and fewer diatomic ones.

These are easier to ionise, which is good news for radio amateurs everywhere as the MUF rises.

A quick check shows that all the HF bands up to 10m have been serving up DX, so make the most of it. There have been 10m openings to as far as Wyoming and California. The solar flux index has been static at 135, and that may not change too much as we enter next week with the return of old sunspot region 3098, which still appears to be active.

The Kp index reached six on Tuesday due to the impact of a coronal mass ejection on the Sun. This resulted in widespread visible aurora.

Unfortunately, a large coronal hole will become Earth-centric on Friday the 30th, which may result in a high-speed solar wind stream that is expected to reach Earth beginning late on the 30 September and into the 1 October.

If the stream’s Bz is pointing south it could result in minor (G1) to moderate (G2) geomagnetic storming. Visible and radio aurora at higher latitudes may be possible heading into the new month as well.

NOAA predicts that the solar flux will remain around the 130 mark, but that the Kp index may elevate to five or even six over the first half of the week.

So we may have seen the best of the DX for the time being, at least until the Kp index recovers.

VHF and up

The current period of weather is fairly typical of autumn with a mix of fine, settled ridges of high pressure interrupted by some passages of low pressure with their attendant fronts and bands of showers.

These can be very vigorous systems with scope to bring gales to some areas making this a good time of the year to make those final checks of antenna guys and fixings before winter comes.

In terms of propagation, there will be some active rain bands crossing the country, plus a chance of a few showers. This raises the possibility of some rain scatter on the GHz bands, although less intense than summer events.

The shower part of the story tends to favour the seas around our coasts, but in stronger autumn winds you will need to keep on top of the tracking rate which can be quite brisk.

The occasional periods of high pressure bring a good chance of Tropo at times, especially towards the continent from Biscay and France across to Germany and Poland. There will be some overnight mist and fog, which usually gives a boost to Tropo for part of the day at least.

Other exotic modes, like aurora, are certainly worth consideration after recent examples, plus of course, the chance of some random meteor scatter.

The daytime Sextantid meteor shower is still active through to 9 October although we are past the peak.

The Moon is at minimum declination today (Sunday) and at perigee on Tuesday. Path losses will be low and Moon windows will lengthen as the week progresses. 144MHz sky noise is high today, but low from Tuesday.

Category: GB2RS Propagation News