Propagation News – 15 May 2016

The solar flux index hovered teasingly just below 90 this week, trying to make us believe that we are not heading towards the next sunspot minimum.

There were no significant solar flares, but we did have geomagnetic disturbances, particularly at the beginning of the week. This was due to an ongoing high-speed solar wind stream moving past our planet. The solar wind speed was elevated above 600 kilometres per second with a south-pointing Bz component—meaning it more easily coupled with the Earth’s magnetic field. The Kp index hit five on occasions, sparking visible aurora in northern latitudes.

These are not generally good conditions for long-distance HF contacts, although auroral contacts on the higher HF bands may be possible.

Next week, the solar flux index is predicted to be in the 90-95 region. Unsettled geomagnetic conditions may continue with this Sunday, the 15th, and next weekend looking the worst.

But enough of the doom and gloom, mid-May should be a good opportunity for sporadic-E on the upper HF bands, from 20m up.

VHF and up propagation news

There was some useful sporadic-E and auroral propagation around last week with some southern and western British Isles stations working Benin (TY2) via 50MHz multi-hop sporadic-E, and quite a few auroral contacts noted on bands up to 144MHz. Next week looks quieter at first with just weak jet streams, but perhaps a stronger and potentially more useful northwesterly jet stream propagating across Scotland into central Europe from midweek to lift hopes later.

With high pressure showing on the charts after the weekend, we could be distracted by tropo for a while. By the start of this weekend, high pressure will be building across western Britain from Iceland, but being a ‘cold’ high means that any tropo will be marginal since the low level air below the inversions will be dry and not provide much of a contrast to the dry air above.

The main change during the week is that a ‘warm’ high near the Azores will push a ridge towards southern Britain and this time may have moister air associated with it, so offers a chance of better tropo, especially to the south across Biscay to Spain.

For EME operators, the Moon’s declination is declining and losses are increasing, so early next week will be the last chance to work the D44TVD GHz Bands EME DXpedition.

Category: GB2RS Propagation News