Propagation News – 18 September 2022

We had an expected boost to the solar flux index last week, thanks to a returning sunspot group. This, when added to sunspot region 3098, pushed the SFI to 152 on the 11th. The returning group, which has now been updated to active region 3102, isn’t quite the threat it was on its last visit, but may still be capable of M-class solar flares.

The good news is that an SFI of up to 150+, coupled with better autumnal propagation, has seen the HF bands come alive at times.

Jeff, ZL7/K5WE on Chatham Island has been workable on 40m CW and FT8. He is due to be on air until 21 September. Brian, 9J2BO in Zambia, a regular in the Commonwealth Contest, has also been worked on 10 metres CW. It is worth noting that this is a good month for north-south paths, such as the UK to South Africa, and UK to South America.

The beginning of last week was better than the second half, which suffered from an elevated Kp index due to an enhanced solar wind. Also, a high-speed stream from a high-latitude coronal hole on the Sun was forecast to batter the Earth from the 16th onwards.

The critical frequency over the UK has fluctuated from less than 5MHz at sunrise to more than 7MHz around lunchtime and later. If you are looking for good inter-G conditions you are better off waiting until the afternoon.

Next week, NOAA predicts that the SFI will decline into the 120s. This weekend may also be unsettled on the geomagnetic front as well. Expect the Kp index to rise to four or five, with a characteristic drop in the MUF. Hopefully, conditions will improve after the weekend with the Kp index forecast to drop to around two.

As always, things can change very quickly, thanks to solar flares and CMEs, so keep an eye on solarham.com and propquest.co.uk.

VHF and up

There should be some useful tropo about in the coming week, initially over western Britain at first, but gradually extending across most areas as high pressure moves in across the British Isles.

The eastern side of the country will start this weekend in a more showery northerly flow down the east coast, so tropo is unlikely here until we are into next week. Once established it should bring enhanced conditions to most areas and into the near continent, but limited options across the North Sea where the cool showery weather retains control and limits potential for QSOs to the east.

The other modes to have in mind are meteor scatter, particularly in the early mornings. The Sextantids meteor shower is under way, but doesn’t reach its peak until the 27th.

In the disturbed sequence of solar conditions, aurora is always a possibility so keep an eye on the Kp index; anything above five should be worth checking out.

The Moon is at maximum positive declination at the moment, so is visible for long periods. Apogee is the point at which the Moon is furthest from Earth. It takes place on Monday when path losses are at their highest for the month. 144MHz sky noise starts the week at a moderate 500 Kelvin but quickly falls low for the rest of the week.

Category: GB2RS Propagation News