Propagation News – 13 October 2019

| October 11, 2019

We had a mixed bag of HF propagation over the last seven days, although Monday saw maximum usable frequencies over a 3,000km path climb above 21MHz. Conditions were less good on Thursday morning, mainly due to an elevated Kp index, which reached four thanks to an enhanced solar wind with a south-facing Bz component.

There was DX to be had though, including A82X in Liberia, TO80SP in St Pierre and Miquelon and the ZK3A DXpedition to the Tokelau Islands. They unfortunately had to end their operations early due to the illness of an island resident, but well-equipped stations were able to work them earlier.

There were no sunspots recorded during the last seven days. We apologise for saying the same last week when in fact a small spot appeared and then vanished the next day!

Next week NOAA has the solar flux index pegged at 68. The good news is that it doesn’t think we will have any geomagnetic disturbances. A shot of the Sun taken by the Solar Dynamics Observatory on Thursday, the 10th, showed no coronal hole activity at all. As we know all too well this could change as the week goes on, but for now we predict settled geomagnetic conditions with maximum usable frequencies near their seasonal norms.

We are now seeing the better autumnal propagation as the ionosphere cools, although you may be forgiven for thinking we are not. The low solar flux is not making the bands come alive to SSB and to a lesser extent CW, although modes like FT8 with its lower required signal to noise ratio is letting DX be worked on a regular basis.

VHF and up

It’s hard to get too much enthusiasm for next week’s VHF propagation prospects as autumn is the season of changeable weather patterns. The coming week is no exception. There will be low pressure nearby for much of the week with the main centres tracking close to Scotland, but also affecting the south at times. These will also bring windy weather at times to test the summer antenna work! The upside of course is that this unsettled weather pattern will bring some good prospects for rain scatter on the GHz bands again.

As for tropo, it’s not looking good for UK stations with high pressure displaced to the south over France, Biscay and the Azores and thus well out of range for any extended tropo paths.

This Sunday sees Moon declination go positive so we’ll see a continuing increase in Moon window lengths and peak Moon elevation. We are past apogee for this lunar month now, so losses will be falling as well. Sky noise on VHF is low but increasing, reaching 500 kelvin at 144MHz next Saturday.

There is one small meteor shower this coming week, the Epsilon-Geminids on the 18th. We are a week and a day from the much more intense Orionids shower so we should see some improvement then in meteor scatter conditions.

Category: GB2RS Propagation News