Propagation News – 22 October 2017
The latter half of last week saw more settled geomagnetic conditions with the Kp-index declining to one and even zero. This helped the HF bands enormously and there were openings up to and including 12 metres. The upper bands were full of signals, reflecting the better HF conditions associated with autumn. Higher critical frequencies also meant that 40m, or 7MHz, was often open around the UK during daytime.
The solar flux index was in the low 70s as the Sun’s disk was devoid of sunspots. A coronal mass ejection occurred on the far side of the sun, but it wasn’t directed towards Earth and so didn’t cause problems. This does suggest, though, that we could have sunspot, solar flare and coronal mass ejection activity in about week’s time. Next week it looks like we could suffer the effects of more coronal hole activity. The extreme ultraviolet image from the solar dynamics observatory or SDO spacecraft showed another equatorial coronal hole rotating into an Earth-facing position for the weekend.
The enhanced solar wind from this could hit the Earth sometime around Monday the 23rd or Tuesday the 24th, with its effects lasting until a couple of days thereafter.
As always, this could bring short-lived ionospheric enhancements, so keep an eye on the higher bands, but ultimately the Kp-index may rise and maximum usable frequencies could decline.
At the moment, the effects of coronal holes rather than sunspots are driving ionospheric conditions on the HF bands.
VHF and up
The week will start with a deep low moving across the UK, with strong winds and possibly some rain scatter options for the Gigahertz bands. Although the pattern remains unsettled in the north until later next week, there are signs that high pressure will begin to exert some influence in the second half of the week over southern areas. This means that from midweek, there is a possibility that southern UK, across to the continent and south past Biscay and Portugal towards the Azores, could experience some tropo conditions to round the week off.
Remember that there’s always aircraft scatter to make DX QSOs on the UHF and microwave bands. A group often congregates on 1296.165MHz and the ON4KST microwave chat on a Wednesday evening to experiment with digital mode QSOs. This so-called “digifest” is usually announced on social media and the UKmicrowaves reflector.
The Moon reaches apogee on Tuesday and maximum negative or southerly declination on Wednesday, so losses are at maximum and moon windows at their shortest. This makes it a good week to try your hand at using the man-made satellites that are available for VHF stations to use.
There is just one minor meteor shower of little note this week, so focus on the early mornings around dawn for the best chance of QSOs via random meteor scatter.
Category: GB2RS Propagation News
