Propagation News – 2 August 2015

| July 31, 2015

HF propagation conditions during last weekend’s IOTA contest were pretty dire. This was due to a perfect storm of typical summer conditions, a fairly low sunspot count and poor geomagnetic conditions, reflected in a Kp index of three. This was due to the arrival of material from a coronal mass ejection and the onset of a weak high speed solar wind stream from a coronal hole. One contestant said that he worked no stations outside of Europe at all in the IOTA contest, which just about sums it up!

Over the next week the solar flux index is predicted to be in the range 100-110 with the Ap index in the range five to sixteen. The third, fourth and fifth are predicted to be the most settled days geomagnetically, with Sunday, 2 August and next weekend predicted to be very unsettled with the chance of the Kp index hitting five. This means that you may be better off hunting DX during the week as next weekend may see a return of unsettled conditions with poor maximum usable frequencies in terms of F layer propagation and low DX potential.

As we are now in August, make sure you use the new smoothed sunspot number of 51 for your VOACAP-based prediction programs.

VHF and up propagation news

This will be another week of mixed, but not really strong indicators. Tropo-wise there are likely to be periods when there is a weak ridge of high pressure over southern parts of Britain and this could mean slightly enhanced prospects at times, both across to the Baltic, and south across Biscay towards Spain.

Unfortunately, for much of the week, there will be a large area of low pressure near north-western Britain and this will mean its only rain scatter on offer for many north-western areas of the UK.

For sporadic-E, the prospects are reasonable on two counts. Firstly there is a very non-summer jet stream, albeit weaker than last week, over the British Isles and into northern Europe. Jet streams are good places to generate the wave motion in the air that can propagate vertically to make sporadic-E.

Secondly, we are approaching the interesting part of the year for the Perseids meteor shower, which peaks around 12 August and meteors are generally regarded as the raw materials of sporadic-E. For a day-by-day update on the jet stream check out the sporadic-E blog on RSGB Forums.

It is also less than two weeks to the Perseids meteor shower, peaking around 12 August.

With EME, the moon declination is increasing and losses are lowest today and Monday

Category: GB2RS Propagation News