Friday, June 02, 2017

Propagation Report from BDXC

Last week the solar flux index declined from the low 80s to 74. The sun was spotless, but propagation was dominated by strong geomagnetic storming on Sunday the 28th of May. Sky watchers across many northern locations reported visible aurora. This was due to the south-pointing Bz component of the interplanetary magnetic field, which coupled more strongly with the Earth’s, allowing solar particles to flow into the poles.

The K index soared to a high of seven on the 28th, bringing a brief HF enhancement before auroral conditions with suppressed maximum useable frequencies ensued. HF conditions were described as “abysmal” by one GB2RS reader – we thought you should know why!

Next week the solar flux index is predicted to remain around 70, although a new sunspot is heading around the eastern limb of the sun and has already been producing C-class solar flares.

A small solar coronal hole was also facing Earth on Wednesday. This may cause unsettled geomagnetic conditions around Friday the 2nd of June, and through this weekend. With National Field Day this weekend, this could potentially result in an elevated K index, noisy bands and subdued maximum usable frequencies. Otherwise, for field day we expect 20 metres to be the main daytime band, with occasional short-skip Sporadic-E openings on 7MHz to 28MHz. Forty metres may be good in the morning and evening, with 80 metres, and perhaps even 160m, coming alive at night.

We don’t expect much daytime F2 layer DX on 21MHz and higher, but do take a look.

The next week or so is dominated by a tendency for low pressure on the charts, mainly just to the northwest of Britain. This is expected to produce a showery south-westerly weather pattern, so good for rain scatter on the GHz bands, but it gives limited options for tropospheric openings. That leaves us to hope for some Sporadic-E propagation, especially for the 6m and HF CW NFD contests this weekend.

The good news is that we are firmly in the Sporadic-E season. Since one of the key weather contributors to Sporadic-E, jet streams, are likely to be present for much of the week, if we have low K index figures there should be some Sporadic-E to work on VHF bands from 10m through 6m and 4m, and perhaps even 2m. The jet streams are likely to be over the near continent during this contest weekend, albeit as a weak feature, but may offer a good direction for paths into Europe. There is also a slight bias towards Scandinavia and the Baltic. Later in the weekend a new Atlantic jet stream will reach Spain and may promote some Sporadic-E activity to Spain early next week, moving east to support paths to Italy and Balkans midweek onwards.

This is a poor week for moonbounce, with low moon declination in the northern hemisphere and high degradation, peaking Thursday and Friday. This may be a good time to check out your antenna and receiver systems on sun noise.

This week sees one of the summer low points in terms of meteor showers. There are no substantial showers forecast, with just the low count Northern June Aquilids due around the 10th June. But there are always random meteors to enhance those quiet days.

And that’s all from the propagation team this week.

(Mike Terry/BDXC)