Propagation News – 1 May 2022

A week of high solar flux indices brought good openings on the higher bands. With the SFI consistently above 140 all week—at the time of writing—there have been reports of 10 metre openings well into the evening.

As Ian Goodier on the 10m UK Net Facebook group reported: “Tonight on 10m you could mistake the band for 20m—East Malaysia in one direction, Mexico in the other.”

There were also reports of Australian and New Zealand stations being worked on 10 metres, making this possibly one of the best weeks for 28MHz so far this solar cycle.

But there were some spanners in the works too. There were a lot of C-class solar flares and two M-class events this week. Geomagnetic conditions have also been disturbed at times, with Wednesday being the worst day with the Kp index hitting five twice on one day. Solarham.net said this was an unexpected geomagnetic storm as the Bz component of the interplanetary magnetic field (IMF) tipped south. Another solar storm is forecast for 29 April, thanks to a large coronal hole on the Sun’s equator.

NOAA predicts more of the same next week with the SFI probably above 130.

Geomagnetic conditions are predicted to be quiet next week, with an average Kp index of two. That is, at least until 7 May, when it could rise to four. However, this presupposes that we don’t have any coronal mass ejections to contend with. At this point in the solar cycle, solar flares and associated CMEs are commonplace and could push the Kp index higher, roughly 48 hours after any Earth-directed CME. As always, keep an eye on solarham.net for daily updates.

And finally, we can now expect a big upturn in sporadic E openings on the higher HF bands. Keep an eye on the European 10m beacons for openings and find out more in our VHF news.

VHF and up

As we move into May, the chances of sporadic E begin to increase and it’s worth keeping a close eye on the usual bands from 10m up to 6m and, later in the month, the 2m band might surprise us. The propquest.co.uk website contains a useful EPI map plot of regions where sporadic E may be more likely, based upon weather triggers of atmospheric gravity waves that are part of the formation process. It also contains a daily blog, with commentary to highlight significant jet streams and other regions of interest.

The main focus on the weather charts starts with high pressure bringing fairly good tropo conditions at the end of last week. Over this weekend, a small low will drift into western areas and generally disrupt the tropo propagation, producing a weaker pattern for next week, with a hint of isolated showers. Later in the week, some models bring another low south-east from Iceland to Denmark, introducing a cooler north-westerly flow with a few showers, until a new high builds next weekend. The result of this will be possible tropo windows later towards next weekend. There is a possibility of a little rain scatter in between, but generally limited.

The Eta Aquariid meteor shower will peak between midnight and dawn on Friday, 6 May. Its ZHR is a very respectable 50. The shower favours the Southern Hemisphere, and the radiant is low in the sky for the UK in the early pre-dawn hours.

The predictable cycle of moonbounce propagation continues this week with positive Moon declination peaking on Thursday, now almost coinciding with apogee, and therefore highest path losses. After mid-July the trend of rising declination and rising path loss reverses, until, in mid-2026, maximum declination coincides with perigee and minimum path loss again. 144MHz sky noise is generally low this week, reaching 500K on Wednesday.

Category: GB2RS Propagation News