venerdì 21 ottobre 2016

Propagation News – 23 October 2016

Last week the solar flux index fell back to the high 70s. Geomagnetic conditions were unsettled over the weekend, but improved as the week went on. We are well and truly into the autumn HF season now, which is reflected in higher daytime maximum usable frequencies and lower night-time ones. However, we continue to be dogged by unsettled geomagnetic conditions at times, which have impacted MUFs and generally created poor HF opportunities. But when conditions have became more settled there have been band openings up to 12 metres.

As this is being written sunspot 2602 is heading towards the solar rim and there is nothing to replace it. As a result NOAA predicts the solar flux index will remain in the range 70-75 next week, and HF conditions are likely to hampered by high K-indices from the 22nd onwards. We may even see the K-index hit six early in the week, due to recurrent coronal hole activity, and it could remain high until at least Wednesday.

Apart from possible auroral openings, there might be a pre-ionospheric storm event enhancement this weekend, although these are very hard to predict.

The last storm resulted in a good 10m opening to the Middle East and South America, so keep an eye on the higher HF bands this weekend.

VHF and up propagation:

It’s a mixed week with unstable air still producing showers near the east coast at first with some scope for rain scatter on the GHz bands. Around midweek, a more changeable westerly flow will bring windier weather across the north of Britain, so we need to be looking to the south for a high to develop over Brittany and bring a chance of some tropo later in the week, which may then extend into parts of northern Britain later. Now this high is placed such that it may not be a great provider, but the peak times should be overnight and early morning, especially in regions where fog and mist has formed.

The Orionids meteor shower is over now, so it’s back to early morning random meteor QSOs on the lower VHF bands. There are still quite long daytime moon windows for EME operation, but Moon declination goes negative on Thursday and losses are approaching their highest at the end of the week.