Propagation News – 17 January 2016

| January 15, 2016

We’ve had another week of disturbed geomagnetic conditions, with the K index hitting four at times. This was due to an ongoing high-speed solar wind stream from a coronal hole on the sun. As we predicted, the solar flux index remained in the range 100-110, bringing lacklustre HF performance at times.

Next week looks like more of the same, with the USAF predicting a solar flux index in the range 95-105. There are currently two sunspot groups visible on the sun, but as they rotate out of view the rest of the sun is looking fairly spotless at the moment.

NOAA is predicting unsettled geomagnetic conditions on Thursday and Friday next week, with the K index possibly hitting four again. Another model has a high-speed solar wind stream hitting the Earth on Monday or Tuesday.

With such conflicting information is it hard to predict HF conditions, but if the quieter geomagnetic state can last just a little longer, and one model is wrong, we may get better ionospheric conditions for the upper HF bands, perhaps on 18 and 21MHz, at the beginning of the week. There have even been some fleeting openings up to 28MHz. The lower HF bands are still in the doldrums during daytime, with 40m closing early to near vertical incidence radiation contacts around the UK. Luckily, 80m can then take over.

VHF and up propagation news

After putting up with low pressure and flat conditions for some time, we now have real signs of high pressure returning to the charts. Weather models are showing high pressure building in cold air so we could be in for a prolonged period of quiet, settled weather with sharp frosts and some freezing fog. This means that there may be good low level temperature inversions near the surface as well as elevated inversions aloft due to the high pressure. This could produce good tropospheric openings, although stronger winds over western Britain suggests that the better conditions will be in the east and over the North Sea into the near continent and southern Scandinavia.

More 50MHz Sporadic-E openings occurred last week so it’s still worth keeping a lookout mid morning and at teatime for DX opportunities on an otherwise empty band. That said, once the high pressure moves in to cover a large part of Europe, it will remove the persistent strong jet stream, which has probably underpinned these recent winter Es events

Moon declination reaches maximum on Friday so we have long moon windows this week but with losses increasing as the week goes on.

Category: GB2RS Propagation News