Propagation News – 22 January 2023

| January 20, 2023

The solar flux index has continued to remain above 200, which is good news for the upper HF bands.

10m continues to surprise people with 10m FM around 29.600MHz bringing transatlantic contacts to many. AM around 29.000MHz is also bringing some exciting contacts.

The Sun is currently peppered with spots, with the recent solar flux index of 234 being the highest since 2014. But solar flares and coronal mass ejections remain a threat. We have had numerous M-class flares over the week, but nothing stronger.

The Kp index hit four on Wednesday 18 January due to a glancing blow from a coronal mass ejection and we can expect it to rise again on Friday or Saturday due to an Earth-facing coronal hole.

The Chilton and Fairford ionosondes remain offline so please select Dourbes if using The critical frequency, as measured at Dourbes, remains above 7MHz from around sunrise onwards, giving a MUF over 3,000km of more than 30MHz for much of the day. So do make the most of 10m, which is probably at its best right now. Make hay, or DX contacts, while the Sun shines, as they say!

The good news is that the Space Weather Prediction Centre expects the solar flux index to remain above 200 for the next week. It says the Kp index might rise again to perhaps five on the 26 and 27 January, but may otherwise be two to three in the early part of next week.

VHF and up

The overall weather pattern remains rather changeable at first, but with a tendency to form high pressure, initially in the south, more generally after mid-week.

In terms of propagation, a welcome return of Tropo conditions is likely, although it may take a while to develop more widespread lift conditions. Sometimes it takes a high-pressure region to become a ‘cloudy high’ to give the best chances of widespread Tropo. Ideally, the high needs to be located such that cloudy Atlantic air can move in across the country underneath the temperature inversion.

It’s still worth a check for aurora, as the Sun is very active at the moment but it’s probably a good time to put away Sporadic-E thoughts until the spring.

Random meteor scatter is always an option around dawn, but we are now into the meteor shower minimum period that lasts until the Lyrids in mid-to-late April.

Yesterday’s Moon perigee means that EME path losses are at their lowest but will slowly rise throughout the week. Declination is rising and goes positive on Thursday so Moon availability windows will lengthen. 144MHz sky noise is low all week, only going much above 300 Kelvin next Saturday.

Category: GB2RS Propagation News