Propagation News – 12 May 2019

| May 10, 2019

Sunspot group 2740 has now returned and is emitting a lot of radio noise. reports large bursts have been recorded on 20 and 25MHz. The bursts sound like waves breaking on the shore and are caused by beams of electrons accelerated by explosions in the sunspot’s magnetic canopy. As the electrons slice through the Sun’s atmosphere, they generate a ripple of plasma waves and radio emissions detectable on Earth.

The last week saw slightly better HF conditions. Andy, M0NKR reports working Nobby, FW5JG on 20 metres on Wallis and Futuna Islands. Jim, G3YLA also reported working James, K6AR just north of San Diego in California at 1400Z, also on 20 metres.

Sporadic E has also been growing this week. Beacon signals were logged on 10 metres from Poland on Wednesday, and Spain and Italy on Thursday. The 10m beacons, from 28.160 to 28.325MHz are a good guide to propagation, especially as many of them run less than five watts.

Next week, NOAA predicts the solar flux index will be 76, thanks to the two sunspots groups now visible on the solar disk. A weak, slow-moving coronal mass ejection observed on Tuesday, 7 May is predicted to deliver a glancing blow to our geomagnetic field this weekend. Otherwise, geomagnetic conditions will be settled with a maximum K-index of two next week, although more coronal mass ejections from sunspot groups 2740 and 2741 are a strong possibility. This could lead to an elevated K-index and poorer HF conditions in the short term.

Daytime critical frequencies remain in the 4 to 5MHz range, with the maximum usable frequency over 3,000km occasionally exceeding 18MHz. The night-time critical frequency is mostly now staying above 3.5MHz, which means 80m should remain open to NVIS signals around the UK throughout the night.

VHF and up

It’s an unsettled end to the week with further showers for many areas, so there is still some scope for rain scatter on the microwave bands. Some of the showers could be heavy with a chance of hail and thunder, so watch out for rain static.

The big change will come after the weekend when the pressure builds quickly to produce a large area of high pressure over the country and improved weather all round. It also means a good chance of tropo and maybe checking out those solar panels for your off-the-grid portable set up.

Sporadic E has been showing its hand during the last week and there should a reasonable chance of jet streams in good locations for further sporadic E in the coming week.

Use the website to see the daily updates. Starting this weekend, there will be a jet stream over the Pyrenees that translates east to the Alps. This means we could start off with paths to EA/CT and gradually move to Italy and IS0 in the central Mediterranean.

The Eta Aquarids meteor shower has now peaked, although there are still meteors associated with this shower up to about 24 May, so expect to hear some pings throughout this week. We now enter a bit of a lull in shower activity until the July Delta Aquarids.

Full Moon occurs next Sunday, 19 May. This is a low declination full Moon, meaning that the Moon reaches full illumination at its lowest point in the sky of this lunar cycle. This period should be more favourable for stations without antenna elevation, although the low declination often means more terrestrial obstructions for the antenna view of the Moon. Path loss will increase through the week, as will libration—the Moon’s apparent ‘wobble’—that lets us see up to 59 percent of its surface.

Category: GB2RS Propagation News