Propagation News – 19 January 2017

| November 17, 2017

Last week saw the solar flux index stay steadfastly in the mid-70s thanks to a lack of visible sunspots on the solar surface. But by Thursday one had appeared over the limb and was designated sunspot 2687.

Geomagnetic conditions were mostly settled in the first half of the week, but a minor G1 geomagnetic storm commenced on Wednesday as an elevated solar wind stream moved past our planet. This continued into Thursday, with the Kp-index hitting four at times. This had a slightly detrimental effect on the ionosphere, with maximum usable frequencies over a 3,000km path struggling to exceed 21MHz at times.

Next week. NOAA forecasts the solar flux index will remain in the mid-70s. But we may have unsettled geomagnetic conditions on the 20th to the 22nd, due to yet another high-speed solar wind stream from a coronal hole. The hole is very much Earth-facing as it is right on the solar equator. It therefore has the potential to create unsettled and auroral conditions and a high K-index. The end of the week may therefore be better for HF DX, although, as always, be prepared for surprises.

To end on a positive note, this time of year is ideal for long-distance propagation on the lower bands and members of CDXC report lots of DX on 40m and 80m. For example, K6MYC in California has been worked by many hams in Europe from about 40 minutes before our local sunrise to about 30 minutes afterwards. Admittedly Mike does have 40 acres, seven 89-foot towers and a three-element beam for 80 metres, which helps!

VHF and up

We start with a weak area of high pressure and hence just a chance of some tropo, especially in the south of the UK and extending into the near continent and down across Biscay. Tropo can be amplified overnight and during the mornings, particularly in the misty mornings of autumn, but overall, this event looks marginal at best.

The second phase of weather propagation will come after mid-week when the pressure falls away as low pressure takes up position. There could be some coastal showers giving a chance of rain scatter on the microwave bands, principally on the western side of the country. In the east, there may still be some residual tropo since high pressure is likely to remain close by, although much weaker.

The new moon was on the 18th, so for the early part of next week the Moon will still be close enough to the Sun to make EME contacts a little more difficult. The Moon will also appear in the direction of the Milky Way so the sky noise temperatures will be particularly high. This coincides with low moon declination at this time of year. This is not so good for the microwave EME operators, who tend to prefer the Moon to be higher in the sky. But for those who do EME on the VHF bands, and without antenna elevation, the low moon may help.

The Leonids meteor shower peak has just passed, but there may be some useful tail-end meteors from the dust of associated comet Temple-Tuttle. The November Taurids is a minor meteor shower with a broad peak of around 10 days, but at a low rate. There may just be enough meteors around to make operating meteor scatter worthwhile, as long as you have patience.

Category: GB2RS Propagation News