Propagation News – 10 January 2016

As we’ve entered 2016 it would be nice to have some better HF propagation conditions. Unfortunately, life is never that simple or accommodating! This week we have suffered from the effects of a high speed solar wind stream that flowed from a geo-effective coronal hole on the sun. The effect was a K-index of five in the early hours of Wednesday morning, with continued problems into Thursday. The sun has been otherwise quite quiet with only two visible sunspot groups, one of which is really tiny, and a solar flux index of 95.

This week one model has a high-speed solar wind stream predicted to hit the Earth on the 11th or 12th. But both the NOAA and USAF predictions have conditions more settled with a K-index of two. The solar flux index should remain around 100-110. This should mean maximum useable frequencies of up to around 21MHz on DX paths during daylight, with occasional openings on the higher HF bands.

The critical frequency has been approaching 7MHz around noon, which means 40m may be open to NVIS signals around the UK. If not, then drop down to 5MHz for better reliability. At night, even 80m may struggle to remain open for inter-G contacts, but should be optimum for DX.

VHF and up propagation news

A winter 50 and 70MHz sporadic E opening occurred for UK stations last Sunday, and there have been more QSOs spotted throughout the week. Keep a watch for others this week as they are not uncommon around the New Year.

A large area of low pressure will move across the country and into Europe during this weekend leaving us under a northerly weather pattern for much of the week. This is a generally less favourable pattern for tropospheric enhancements, but it could produce large—possibly wintry—showers around our coasts, which may be a useful boost for gigahertz bands rain scatter propagation.

Some weather models predict the arrival of a substantial high next weekend, but it may stay to the west of Ireland and maintain the cold northerly instead, so tropo is not guaranteed. If this potential high forms in cold, dry northerly air with no obvious moisture layer near the surface, there are only weak tropo prospects.

Moon declination is at a minimum today so we have short moon windows, increasing as the week goes on, with losses falling as it comes in towards perigee, its closest point to Earth.

Category: GB2RS Propagation News