Propagation News – 19 March 2017

Despite zero sunspots and a solar flux index of only 70, there was good DX to be had last week. This was helped by more settled geomagnetic conditions over a period of days, thanks to a lack of coronal hole activity. The RSGB Commonwealth Contest saw UK amateurs making contacts into all parts of the world, although these were primarily on 7, 14 and 21MHz. This pattern will no doubt predominate over the next few years until we get past solar minimum.

A group of UK amateurs have been operating from Ghana as 9G5X and have shown how this part of the year can give good north-south propagation. They have been audible on 20 and 15 metres, and there are even reports of very weak openings to the UK on 10m.

A look at the Solar Dynamic Observatory’s extreme-ultraviolet image of the Sun on Thursday showed a coronal hole on the sun’s equator, which is rotating to be geo-effective in a few days.

NOAA predicts solar material from the hole may hit us midweek, so look out for an elevated K-index. This can be a double-edged sword, resulting in enhanced conditions during the initial phase, before maximum usable frequencies decline with noisy conditions follow.

The solar flux index is predicted to remain in the low to mid-70s.

VHF and up

There were some good tropo openings last week, but this is unlikely to last. By this weekend the high will have declined as lows move in from the Atlantic and they will dominate the weather for much of the coming week. Interestingly, there are signs of high pressure returning at the end of the week, but this is handled very differently in different weather models. One only brings the high as far in as Ireland, while another model develops a fully-fledged high over Scotland by next weekend. This is clearly an uncertain signal, but at the moment the week looks much less productive for tropo than last week.

As we come very close to April, the seasonal April showers this week should offer some good chances for rain scatter on the gigahertz bands. There is the possibility of VHF auroral activity mid-week if the K-index rises as predicted.

With negative Moon declination all this week, windows are short and the Moon is at low elevation. Today is apogee so losses are at their highest, but decreasing as the week goes on.

Category: GB2RS Propagation News