venerdì 29 ottobre 2021

Propagation News – 31 October 2021

Well, we had another topsy-turvy week, with the sunspot number going from a lowly 10 to a much more impressive 91. We started last week with a virtually spotless solar surface, but this week the Sun is peppered with spots, with five active regions in place on Thursday. The net result is the maximum usable frequencies have been climbing, with 3,000km-plus paths being reached at times on 24 and even 28MHz, according to the Propquest website.

There has been plenty of DX to be worked as well, with HD8R in the Galapagos Islands, VK9DX on Norfolk Island, both on CW, and 7P8RU in Lesotho making it into many amateur’s logs. The first two were on 30 metres, which is well worth a look. Special event station HS400OZ in Thailand has also been putting in an appearance on 30m FT8 and has been workable from the UK. With Solar Cycle 25 now well under way, it is always worth checking the higher bands too, such as 12 and 10 metres.

Next week NOAA predicts the solar flux index will be in the range 85-96, starting the week at the higher end and then declining. Geomagnetic conditions are predicted to be quiet, with a maximum Kp index of two. However, this could change if a coronal mass ejection occurs. For example, Region 2887, which was Earth-centric on Thursday, has unleashed one M-class and several C-class flares. A large flare, accompanied by a CME, could easily disrupt the HF bands for days.

VHF and up:

The current spell of unsettled weather will become more widespread and affect much of the country during the first half of the coming week. There had been a hint of Tropo in the southeast last week, but we’ll have to wait for the second half of the week before there is a return of weak Tropo in the south as a transient ridge crosses the country. This will be replaced by further unsettled weather by the weekend. In propagation terms this means that rain scatter on the GHz bands may be on offer again through much of the coming week. Otherwise it is the chance of aurora or meteor scatter that could entice us on to the VHF bands.

The Orionids meteor shower is coming to an end and the Taurids are in progress, but with a ZHR of not more than five, there’s little to get excited about. We have to wait until mid-November for the Leonids, so stick to the time around dawn to maximise your chances with random meteors until then.

For EME enthusiasts, Moon declination is high early this week, going negative on Tuesday. Path losses are at their lowest with perigee on Friday but this coincides with low negative declination, meaning the Moon will be low in the sky at zenith. This trend of lowest declination getting closer to perigee reverses in June next year, but not until June 2026 will we see maximum declination coincide with perigee. (