Propagation News – 9 July 2023
NOAA’s prediction that the Solar Flux Index, or SFI, would decline last week didn’t come to fruition. In fact, the SFI stayed in the 160s and 170s until Thursday, when it declined to 155.
The Sun produced more than 160 sunspots in June, the highest monthly number in more than two decades. This has led some newspapers to run more doom and gloom stories about solar Armageddon, while we amateurs look forward to some F2-layer DX!
Unfortunately, more sunspots do mean more chance of solar flares and coronal mass ejections, but we have to take the rough with the smooth.
As an example, we had an X1-class solar flare on the 2 June. This occurred at 2314UTC so didn’t affect the UK, but did cause an R3 radio blackout over the west coast of the USA and Pacific.
Otherwise, there is still DX to be bagged for well-equipped stations, such as Eric, FP/KV1J on the St Pierre and Miquelon islands on 12m FT8, and Marek, FH4VVK, on Mayotte island, on 10m FT8. Other DX worked this week by CDXC members includes the 4W6RU DXpedition on Timor Leste on various bands; Robert, 9N7AA in Nepal on 12m FT4; and V31XX in Belize on 20m CW.
Next week, the Space Weather Prediction Centre has the SFI at 155, rising to 175 by the end of the week. Unfortunately, the Kp index is forecast to rise to four over the weekend, possibility due to a large Earth-facing coronal hole, and again up to Kp five on the 12 and 13 July. If it happens, expect noisy bands and a decline in the maximum usable frequency.
As always, we encourage you to get on the HF bands, in the evening, night time and especially around dawn, which is when a lot of HF DX is being worked.
VHF and up
Low pressure dominates the whole weather pattern this coming week, driven by an active meandering jet stream across the Atlantic.
This provides several regions where the turbulence, generated on the edge of these strong winds up at 10km, can propagate upwards to trigger Sporadic-E propagation at about 110km height in the E region.
So, unsurprisingly, Sporadic-E will feature as a ‘go to mode’ for the coming week. Typically, single-hop paths within Europe will produce very strong signals, whereas multi-hop paths, for example across the Atlantic, will require several such refraction points from Sporadic-E patches, plus intervening reflections from the sea surface, and will have much higher losses.
These will usually be weak signals and probably very fleeting in view of the complex geometry of such paths.
Tropo need not concern us this week, but rain scatter is worth a look since the unsettled weather will provide several heavy rainfall events in some areas. Look for the brighter echoes on the rainfall radar displays, especially those associated with thunderstorms.
Random meteors could be useful in the early morning hours. We also have the start of two showers, Alpha Capricornids and Delta Aquarids, during next week, which don’t actually reach a peak until the end of July. So prospects for meteor scatter and Sporadic-E propagation are improving this month.
The aurora chances may be reasonable initially in view of the recent coronal hole transition, so keep an eye on the Kp index.
Moon declination goes positive on Sunday so there will be lengthening Moon windows. Path losses are currently low but will rise all week. 144MHz sky noise is low to moderate all week.
Category: GB2RS Propagation News
