Propagation News – 28 August 2022

There was a welcome upturn in ionospheric propagation this week, with much DX being worked. While the solar flux index remained mainly in the low 100s, quieter geomagnetic conditions, with the Kp index at one or two, helped a lot. We are also heading towards September and better propagation conditions as the ionosphere cools down, resulting in more monatomic elements and fewer diatomic ones. The monoatomic elements in the ionosphere are easier to ionise so MUFs go up accordingly.

Along with daytime critical frequencies above 6MHz we have seen 40m opening up to shorter distances too, sometimes down to 100km, but mainly in the range 100-500km.

Over longer distances, there have been reports of some choice DX being workable, including KH6KB in Hawaii on 17m CW, 9V1YC in Singapore on 12m FT8 and A35JP in Tonga on 15m FT8.

As long as the Kp index stays low we can expect a lot more like this over the coming months.

Next week, NOAA predicts that the solar flux index may climb a little, perhaps ending the week in the range 110-116. Geomagnetic conditions are unlikely to be as good next week, with 27 August being the most disturbed with a predicted Kp index of four.

A large coronal hole is moving to be Earth-centric on Friday, although it is largely at one of the Sun’s poles. This means that any fast solar wind might be directed away from Earth, but we could get a glancing blow late on Sunday or early Monday.

Watch for a rise in the Kp index and a general lowering of the MUF if it does.

VHF and up

The end of last week finally brought some heavy rain and thunderstorms to some eastern areas and weakening weather fronts to the northwest. This may have given some rain scatter opportunities, but only temporarily.

As we head through this weekend high pressure starts to rebuild over the UK and will dominate the weather over the British Isles over the coming week. This will make Tropo a principal player for the next week. In early September it’s still plenty warm enough that inland areas could see the temperature inversions breaking down during the daytime heating, so for best results make the most of the night time and early morning lifts.

We may have a few days left when Sporadic-E could occur before the transition away from high summer weather patterns, but it is getting much harder to find now. Focus on 10m or perhaps 6m digital modes for best results and, of course, check the usual DX clusters.

Don’t forget aurora and meteor scatter modes, however this week, these modes will be overshadowed by the Tropo characteristics as the high builds.

Moon declination goes negative again late Monday, so shortening Moon windows this week. Path losses continue to fall throughout the week and 144MHz sky noise is low until next weekend.

Category: GB2RS Propagation News