Propagation News – 15 May 2022

Well, it looks like the US Air Force was more accurate than NOAA with their solar flux index forecast last week. While the week started with an SFI at 117, by Thursday it had grown to 133. It has been mostly quiet from a geomagnetic point of view with a maximum Kp index of three, with mostly ones and twos.

The only downside has been a number of solar flares, which includes an X-class flare on Tuesday the 10th. The X1.5 event was observed from sunspot region 3006 at 1355UTC and resulted in a radio blackout over the Atlantic, Africa and South America. The critical frequency, as measured by the Chilton Ionosonde, dropped below 7MHz for a time, before recovering.

Despite this short-lived phenomenon, there has been plenty of DX to be worked on the higher bands. The 15m band has seen Asia and the Far East romping in on FT8 and there have been 10m band openings to Australia and the Middle East.

Next week NOAA predicts that the SFI will be in the range 118-122 with generally quiet geomagnetic conditions. But we give the same warning as we did last week. NASA gives a 45% chance of an M-class flare and a 15% chance of an X-class flare occurring at the moment. Any solar flare could trigger a coronal mass ejection and, if Earth-facing, we can expect a degradation in HF paths, perhaps 36 to 48 hours after the CME event as the solar plasma hits and the Kp index rises.

The better news is that the Sporadic-E season is now in full swing and plenty of low-power 10m beacons are becoming audible between 28.160 and 28.325MHz. These are often a good indicator of openings. A list of 10m beacons can be found on the RSGB website under On the Air. Just click on Beacons and Repeaters.

 VHF and up

There is a typical flavour to the current weather pattern with high pressure, initially to the south, being displaced east as an Atlantic low tries to push its associated weather fronts into western Britain. This will eventually lead to unstable, thundery bands of rain spreading into the country from the southwest. It makes detail complicated, but some rules still apply.

There will be some Tropo, especially at first and perhaps occasionally next week along the east coast and across the North Sea. However, the changing element is going to be how effectively the thundery rain areas move across the country, and they will reduce the Tropo chances and introduce some rain scatter.

There are some small meteor showers this week, the Eta Lyrids peaked on the 10 May but the o-Cetids, peaking on the 20 May, is the most significant. With this addition to the seasonal increase in random meteor flux, expect good conditions for meteor scatter DXing. Apart from the random meteor scatter options, the growing interest is in Sporadic-E and most days you can find something on the clusters to confirm that the new season is starting to simmer nicely.

The position of jet streams and the type of upper air weather pattern this week suggests that the main features will slow down and leave marked meanderings north and south. Preferred directions would be to Scandinavia and Baltic plus secondly looking south towards Spain and Portugal.

The Moon gets to minimum declination on Thursday, and today, Sunday, is perigee. The week’s trend will therefore be for shorter Moon windows until Thursday and rising path losses. 144MHz sky noise is high all week, reaching 2200K on Wednesday.

Category: GB2RS Propagation News