Propagation News – 15 October 2017
Last week saw a mixed bag in terms of HF propagation. At the beginning, quiet geomagnetic conditions saw the HF bands alive with DX. With the K-index hovering between zero and one, the ionosphere was showing what it can do during a typical autumn day. There were openings up to and including 12 metres, with DX being worked as far afield as India, Cocos Keeling Island, the Falkland Islands, and Sao Tome and Principe off the west coast of Africa.
Unfortunately, and as we predicted, it didn’t last as a high-speed solar wind stream from a coronal hole, moving at more than 500 kilometres per second, impacted the Earth on Wednesday the 11th. This sent the K-index soaring to five and, after a brief ionospheric enhancement, maximum usable frequencies (MUF) started to plummet.
By Thursday the MUF over a 3,000km path was struggling to exceed 14MHz as the geomagnetic storm continued. However, another pre-auroral enhancement, probably due to a surge in the incoming solar wind stream, saw 10 metres open to DX briefly on Thursday afternoon, with Saudi Arabia booming in.
Next week, the solar flux index is predicted to remain in the range 74 to 80, reflecting where we are in the declining solar cycle. Ionospheric conditions may be unsettled this weekend following the final throes of the coronal hole solar wind stream, but should then improve.
Geomagnetic conditions are forecast to be quite settled after Tuesday the 17th, with a maximum K-index of two. If correct this means that reliable HF DX may return, giving good openings up to 21MHz, perhaps even 24MHz, for the rest of the week.
VHF and up
We are stuck in a very unsettled weather pattern and it seems like the north-west of the country is most likely to experience the more disturbed weather conditions with strong winds and a risk of gales. None of these things are good for tropo, but we may see some good options for rain scatter on the gigahertz bands.
We have nearby high pressure over the continent and this should be a player at first over this weekend. It will decline early next week and any temporary tropo is only likely to be available from southern Britain, favouring paths towards the Continent.
Meteor scatter conditions should be better this week, with the Epsilon-Geminids shower on Wednesday and the larger Orionids, peaking sometime in the early hours of Saturday. Interestingly, the Orionid meteor shower is one of the showers created by debris from Comet Halley.
You’d better get your QSOs in with the 3DA0MB eight-band EME DXpedition to Swaziland early next week. Moon declination goes negative again on Wednesday and the moon reaches apogee on Thursday, with highest losses. As the Sun and Moon are close on Thursday, noise will also be an issue on VHF. At least it’s a daytime moon and gigahertz band dish feed changes can be done without a torch!
More details of 3DA0MB are available on the HB9Q logger and Moon net.
Category: GB2RS Propagation News
