Propagation News – 16 August 2020

By Sunday, sunspot region 2770 will have just about rotated out of view. After a promising start it quickly faded away, but there is more hope as active region AR2771, belonging to Cycle 25, is forming in the Sun’s south-east quadrant. A secondary bright plage region is also now turning into view off the south-east limb, although it appears to be spotless for now. This is very encouraging, as we think it shows that sunspot Cycle 25 is ready to get under way. On Thursday, the solar flux index was 74, with a sunspot number of 24.

Please note that on propquest.co.uk, the feed from the Chilton ionosonde has been down for a few days, but if you switch to FF051 Fairford you’ll find that feed is working.

Daytime critical frequencies have generally been in the range 4 to 5.3MHz, which means that 40m remains unsuitable for close-in NVIS contacts around the UK. You may find 60m or 5MHz more reliable for inter-UK working. But critical frequencies are generally staying higher just after sunset, which can be good news for stations chasing DX. The charts suggest that 14MHz is remaining open to contacts over 3,000km until nearly local midnight.

Next week NOAA predicts the solar flux index will remain at around 72, with the largest Kp index being two. This reflects the fact that there are no Earth-facing coronal holes at present, although this can change without much notice. Active region 2771 could develop further, as could the plage area in the south-east quadrant. But it really is guesswork at this point.

VHF and up

The weather pattern is changing into something much more unsettled generally, and not just in isolated instances of severe thunderstorms as we’ve seen recently. Tropo conditions were good in some parts as last week came to an end. It’s easy to get tropo over sea paths at this time of the year and, whilst there could still be some opportunities across the North Sea early next week, most areas will be in the realm of low pressure, so no more tropo.

The sporadic E season has had a little boost by the recent meteor input from the Perseids so it’s still worth looking at the usual times; mid-morning and late afternoon, to early evening. The season can last into early September, so there’s still time.

Rain scatter should be the mode of choice this coming week, with a slow-moving area of low pressure over the country bringing thundery showers and spells of heavy rain to many places. It’s a good time to use one of the many radar displays available online to track the heavy rain cells and try some GHz band rain scatter.

Mid-August is a good time for meteor scatter, so keep that on the list as the Perseids meteor shower declines. Opinion was that this year was not a vintage one, with many reporting poorer performance than last year. That said, meteorscan.com showed hourly rates at over 100 around 0600 on the 12th and 13th.

The Moon will be at peak declination this Saturday and path losses are falling as we approach perigee on Friday, so it’s a good week for EME. 144MHz sky temperatures are low.

Category: GB2RS Propagation News