Propagation News – 20 December 2015

| December 18, 2015

The smoothed sunspot number for December is 46.1. This time last year it was 63.7, which shows how we are sliding down solar cycle 24.

Coronal mass ejections and coronal holes continue to cause problems at times, with the K-index hitting five on Tuesday the 15th. As the incoming plasma hits the earth you can sometimes get an initial positive phase on HF, with maximum useable frequencies increasing. This may be what happened on Saturday the 12th during the ARRL 28MHz contest. Ten metre DX conditions were good on Saturday, when the high latitude K-index recorded at College, Alaska, hit five. But by Sunday reports says DX conditions were not so good. This shows that it is a good idea to keep an eye on the upper HF bands, as openings can happen at any time.

This week, the solar flux index is predicted to be in the range 105-120, with geomagnetic conditions mostly settled with a predicted average Kp-index of two.

Using the Chilton ionosonde data, maximum usable frequencies are still hitting 25-28MHz at times, so watch for fleeting openings on 12 and 10 metres during daytime. For example, the 15 watt 5B4CY Cyprus beacon on 28.220MHz has been heard in the UK when the band is otherwise empty.

VHF and up propagation news

It looks like there is a low potential for tropospheric openings over Christmas week. This is due to very unsettled weather with mostly mild, and rather windy south-westerly patterns throughout the period. There will, however, be higher pressure over the continent, but much of the time this is some way to the south-east of us and not really a great option for tropo. There is just a chance the high will build a little closer to the UK just after Christmas, but this will probably only benefit the south-eastern parts of the country.

The small Ursids meteor shower, due yesterday or today, may already have peaked by the time you hear this bulletin, so it’s back to early morning random meteor scatter operation until the Quadrantids. This shower should happen before dawn on 4 January, and can produce more than 100 visible meteors per hour. It has a sharp, unpredictable peak lasting only a few hours so you have to be on the band at the right time to take advantage of it.

It’s a good week for EME, with low losses and lengthening moon windows due to the moon reaching maximum declination on Christmas day.

Finally, do remember that there’s always satellite QSOs to be had on the VHF bands irrespective of the weather. That’s all for this week, so season’s greetings from the propagation team.

Category: GB2RS Propagation News