Propagation News – 4 October 2015
Better autumnal HF conditions continued this week with more settled geomagnetic conditions and a healthy solar flux index that reached 131 on Thursday. However, the solar proton flux increased slightly that day, which may have caused some problems.
During such an event, the Earth can be showered with highly-energetic solar particles. When these protons arrive at Earth and enter the atmosphere over the polar regions enhanced ionisation can be produced at altitudes below 100km.
Ionisation at these low altitudes can be particularly effective at absorbing HF radio signals and can render HF communications impossible throughout the polar regions. This type of event is also known as a Polar Cap Absorption Event or PCA, and paths through the North Pole may be affected. Otherwise, autumn continues to be a good time to try the upper HF bands.
Data from the Chilton Ionosonde show that the maximum usable frequency on Thursday rose to nearly 26MHz on 3,000km paths. So our advice is to try listening or calling on 15, 12 and even 10m this week to see if the bands are open.
As always, solar flares, coronal mass ejections and high-speed solar wind streams may cause disrupted conditions at times.
VHF and up propagation news
After a good week of enhanced VHF/UHF tropo conditions, especially in the north of the country, the area of high pressure responsible for the ducting is showing signs of collapsing in the coming week, as low pressure moves past north-west Britain. Models suggest that there may be a chance of the high reasserting itself over south-eastern Britain later in the week but, at the time of writing, it seems the best conditions will be behind us by this weekend.
The Draconids meteor shower peaks on Thursday so keep a lookout for a short-term improvement in meteor scatter opportunities either side of the peak.
With positive Moon declination all next week we will have long Moon windows for EME, extending from late night through to late afternoon the following day. Losses will increase over the week as the Moon approaches apogee.
Category: GB2RS Propagation News
