Propagation News – 18 October 2015

| October 16, 2015

We’ve had another week of unsettled HF conditions. Geomagnetic storming was observed on Monday at high latitudes as a high-speed solar wind stream, flowing from a geo-effective coronal hole, caused problems. By Wednesday the Kp index peaked at five and the bands were left noisy with only fairly local European stations audible on 40-20m.

The solar flux index was 96, but conditions were dominated by the negative effects of the solar wind.

The Chilton ionosonde showed the critical frequency to be just 5.4MHz at noon on Wednesday, giving a predicted maximum usable frequency of only around 15.4MHz over a 3,000km path. Thursday was a lot better, with 21MHz opening up, showing what a difference a day can make.

The poor conditions due to coronal holes are likely to continue on and off over the coming week. Sky watchers, especially around the Arctic Circle, should be alert for visual aurora once it is dark.

It is not all bad news though – there is DX to be heard if you look for it. Mike, 5H3EE in Tanzania was 599+ on a 20m dipole on Wednesday evening when little else could be heard on the band.

It looks like another week of mainly high pressure on the charts over the UK, although there will be some lows passing by to the North.
Most areas should have a chance of slight lift conditions on occasions during the week. The high is likely to move from North to South and then later divide, leaving one centre to the East and another to the South-West.

The way tropo works means that the ducting is better at higher frequencies and then slowly improves at lower frequencies as the temperature inversion develops. Even if you don’t operate on the GHz bands, you can always check for activity on the cluster to watch for increased activity on 23 and 70cm, before 2m shows.

Check the SSB and CW segments as well as FM, and of course look for beacons – the new RSGB Yearbook has all the latest lists and frequencies.
The Orionids meteor shower, one of two created by debris from Comet Halley, peaks in the early hours of Tuesday morning, so look for enhanced meteor scatter on 2, 4 and 6 metres.

The moon is at maximum negative declination tomorrow, so short EME windows will start to lengthen and losses decrease as we go towards perigee on the 26th.

And that’s all from the propagation team for this week.

Category: GB2RS Propagation News