Propagation News – 18 July 2021

| July 16, 2021

The solar flux index remained in the 70s last week, reflecting the lack of decent sunspots. What spots we did have were both minuscule and un-noteworthy. The high-speed wind stream from a large solar coronal hole impacted the Earth a little later than predicted. In the end, it hit us during the late afternoon and early evening of Wednesday the 14th, pushing the Kp index to four. Its effects were felt during the evening’s RSGB’s 80 metre club championship contest with a noisy band, fading and compromised signals.

The good news is that the major outage of the server at the University of Massachusetts Lowell has now been fixed. This means that the ionosonde data on the website for the foF2 graphs is back and all services have resumed. To recap, Propquest gives us near real-time displays of the critical frequency over the UK and from this, it also extrapolates likely maximum useable frequencies over different path lengths.

Sporadic-E remains the most interesting mode for HF propagation, with extensive openings on the higher bands.

Next week NOAA predicts that the SFI will be in the high 70s and might even reach 81 during the middle of the week. At the moment, it does look like the Sun may be free of coronal holes, which bodes well for a settled ionosphere. The risk of solar flares also appears to be low.

Don’t forget that it is the RSGB’s Islands on the Air contest next weekend, which may throw up some interesting DX on HF.

VHF and up

At the moment, you will find some lovely tropospheric ducting across the Mediterranean from east to west, typical for high-summer. Sadly, few UK visitors will be able to take advantage of it. Pascal, F5LEN produces a day-by-day Tropo ducting forecast. Just Google F5LEN Tropo to find it, and you will see that Tropo ducting is quite commonplace at this time of the year.

In view of a return to high-pressure weather at home, keep a lookout for good sea paths across the Irish Sea, North Sea and English Channel. Tropo paths overland tend to fade quickly as the sun heats things up in the early morning, but often the sea paths remain active through the day.

The Sporadic-E season is still under way with occasional openings up to 2m and not just on FT8; CW and SSB are getting involved too. The jet streams are looking weaker in the coming week for European paths, but still worth checking out paths across the Atlantic later in the day or farther afield to the Far East in the early morning.

As ever, check the clusters and set aside a little time late afternoon for the best chance of getting into any Sporadic-E that might present itself.

May 2022 sees the point in the Lunar cycle where the closest approach of the Moon, perigee, coincides with minimum declination. It’s not until September 2026 that the highest declination coincides with perigee again. This all means that for the next few years, lowest EME path losses occur with the Moon at low declination and Moon visibility windows are short. This week, declination is negative and still falling, so Moon visibility windows will shorten. Path losses will continue to fall throughout the week until perigee on Wednesday.

There are no significant meteor showers until the Southern delta Aquarids at the end of this month. This shower has a broad ZHR peak of 25 running from the 26th of July through to the 31st of July. Until then, continue to look around dawn for the best random meteor scatter opportunities.

Category: GB2RS Propagation News