Propagation News – 19 December 2021
After a period with zero sunspots we’re pleased to announce that the drought is over. There are now at least five active groups on the solar surface and this could even increase over the coming days. The solar flux index had leapt up to 103 from 89 on Thursday and could go even higher. This puts us in the fun zone for 10 metres and it will be interesting to see what is workable over the next week.
There is an increased risk of solar flares during this time and we have already seen some C- and M-class events. Solar flares and their associated coronal mass ejections are generally detrimental to HF propagation, with flares causing short-lived blackouts and CMEs causing a lowering of MUFs a few days later.
On Thursday the solar wind speed had increased to more than 500 kilometres per second and with a negative interplanetary magnetic field, or Bz, the Kp index had climbed to three as a result. Let’s hope it doesn’t climb much higher.
The US Air Force predicts that the Solar Flux Index will remain above 100 until perhaps Wednesday the 22nd, when it may decline to the high 90s. But we really are in uncharted territory at the moment so keep an eye on SolarHam.com for regular updates.
And finally, this week is a good time to contact Santa Claus in Lapland. OF9X is on the air in the Arctic Circle over Christmas and has been spotted on 80, 40, 30, 20 and 10m so far. He will be operating CW, SSB and FT8. The DX cluster is probably the easiest way of knowing where the station is on the bands at any one time. Good luck with making contact!
VHF and up
The welcome return of high pressure and tropo conditions from the middle of the past week should last through to the middle of the coming week. This means there will be plenty more chances for further enhanced propagation on VHF/UHF bands and hopefully for the SHF UKAC on 23cm on Tuesday evening. The position of the high is such that even Scotland will enjoy some of the tropo and paths to the south across Biscay and into northern Spain are worth investigating.
From mid-week there are signs that the Atlantic weather systems will break through again, which will take away the Tropo options. One intriguing set of charts shows a front across the middle of the country with mild air to the south and cold air to its north on Christmas Day. Plenty of excitement potential there, but at such long lead times it’s no more than one of many possible outcomes at present.
For a little extra joy this Christmas, we are moving into a time of year that can offer surprise winter Sporadic-E, that’s mid-December to mid-January. Little predictability is available for these events, but do make use of the Propquest charts at propquest.co.uk to get a hint of your chances; focus upon the jet stream maps, the NVIS tab to see the foEs values and the EPI index for mapped distribution of any possible hot spots.
Last week’s Geminids meteor shower produced some excellent QSOs up to and including 70cm for the well-equipped stations. The tail end of the shower should continue to make meteor scatter interesting.
The Moon is at peak declination meaning plenty of time for EME contacts but with yesterday’s apogee path losses are at their highest. 144MHz sky noise will be low this week.
Category: GB2RS Propagation News
