Propagation News – 28 February 2016

| February 26, 2016

This week didn’t bring the better HF conditions that we talked about in the last GB2RS. This was due to a declining solar flux index and generally active geomagnetic conditions. The SFI declined to 88 by Thursday due to a lack of sunspots, although NOAA had predicted around 100 to 110. The K-index also fluctuated between one and three due to ongoing solar coronal holes, although there were no major geomagnetic events. Together this brought reasonable propagation during the ARRL DX CW contest, with many of the eastern and mid-western states being workable up to 21MHz, but 10 metre openings were a little lacklustre.

We now have one solitary sunspot group on the solar surface—and it’s a small one at that. So next week the SFI should start with a lowly 85, but is predicted to finish the week at a more promising 115, according to the US Air Force. The geomagnetic K-index may continue to remain reasonably unsettled due to coronal holes. The first, third and sixth of March may potentially be worse with a predicted K-index of four.

We are now entering a period where north-south paths are potentially much better on HF, but east-west paths may suffer, especially on the higher bands.

VHF and up propagation news

It’s thin pickings again for VHF/UHF tropo this week. There will be some weak ridging at first and again from midweek, but these cold air winter highs or ridges are not necessarily great at producing good lift conditions. Ideally, we need a good flow of cloudy moist air from the Azores or Biscay, but alas not this week.

Other potential sources of higher frequency action may come from isolated wintry showers around the coasts, which can make good sources of scatter mode propagation on the GHz bands. This week will favour the North Sea for scatter points.

Last Wednesday’s cluster reports saw a short 50MHz sporadic-E opening from the South-West down to Spain and Portugal, so remember to check the lower bands around lunchtime for these rare surprises.

The seasonally-low random meteor rates continue and, with no major showers, early morning continues to be best time day for random meteor scatter operation.

The Moon heads towards its lowest declination on Friday and the short, low elevation windows added to high losses mean not much time for QSOs. But it is a good week to check out your EME systems. At this this time of year the sun is reaching up to 30 degrees elevation at noon so you can again use the sun for cold sky noise measurements to check your system sensitivities on the higher bands.

Category: GB2RS Propagation News