Propagation News – 3 October 2021
Life is starting to get a bit more interesting in terms of the Sun and HF propagation. This week we have seen more sunspots, a coronal mass ejection and some minor solar flares, so the Sun is definitely waking up. The solar flux index passed 100 on Thursday, reaching 102. This is high enough to allow 10 metres to open up, which will no doubt be helped by the move into Autumn HF conditions as well. There have been widespread reports that 10m is becoming more active, especially on FT8, so don’t miss out on any choice DX that is around.
Argentina and Brazil have both appeared on FT8 in the afternoons. Robert, 3B9FR on Rodriguez Island has been worked on 10m CW. SSB is seeing some activity as well, with Gary, G0FWX reporting on the 10 Metre UK Net Facebook group that he worked ZT1T and ZS1F in South Africa.
As we’ve said before, now is a good time for North-South paths to open up on HF so make the most of them. Propquest shows that 15 metres, and 12 metres, are now often opening reliably during daylight hours, so make the most of all the higher HF bands, that is 15, 12 and 10 metres.
Predicting what will happen next week is tricky. NOAA places the SFI in the high 70s, but this could easily be exceeded if this current crop of sunspots continues. NOAA also predicts unsettled geomagnetic conditions on the fifth, when the Kp index could rise to four. Unsettled geomagnetic conditions are also forecast for this weekend.
As always, solar flares could temporarily shut down the HF bands at any time during daylight hours and are hard to predict. And any associated CME could cause problems on HF, perhaps two to three days later.
VHF and up
Unsettled weather at this time of the year is typical and quite often due to the migration south of the jet stream across the Atlantic and into western Europe. This brings deep lows and active weather fronts and heavy showers, all good for rain scatter operation, as highlighted by the excellent rain scatter conditions during last week’s SHF UKAC contest. Incidentally, the jet stream can still be useful for ‘out of season’ Sporadic-E, particularly for digital modes up to 6m or to 10m for CW/SSB.
This unsettled weather lasts through to the middle of next week, then there are some diverging opinions from the models. One evolution brings high pressure in from the Azores after Wednesday, so there is a chance of Tropo to end the week. Another model output suggests that the low pressure remains until the delayed high arrives next weekend.
There are, of course, auroral and meteor scatter possibilities to check out and the autumn is a favoured season for auroral activity.
The 8th of October, at around 1830UTC, brings the peak of the Draconids meteor shower, with a respectable ZHR of 10 expected. Every now and again the Draconids produce spectacular storms and huge outbursts as in 2011 where the ZHR was 300. This is unlikely this year as the shower’s parent comet, 21P Giacobini-Zinner, made its closest approach to the sun in September 2018.
Moon declination is positive until Wednesday and EME path losses are at their lowest with perigee on Friday. There is DX interest with the SV5/HB9COG DXpedition to Rhodes still active until Tuesday.
Category: GB2RS Propagation News
