Propagation News – 19 July 2015

| July 17, 2015

The sun continues to be unsettled as we slide down from the peak of solar cycle 24. This is to be expected as the downward portion of any cycle tends to throw up more solar flares and coronal mass ejections. The 12th and 13th were quite unsettled, with the Kp index reaching five on Monday due to an elevated solar wind stream and a prolonged period of the interplanetary magnetic field having a southward-facing component.

When the so-called Bz points south we are more likely to get coupling of solar plasma with the earth’s magnetic field and therefore unsettled conditions. The solar flux index declined this week with only two spots visible as group 2381 rotated out of view. Coming around the limb though is another spot, although early signs are that this is quite stable. Next week we can expect the solar flux index to continue around 100 with reasonably settled geomagnetic conditions and a Kp index of around two.

In addition to sporadic-E openings on the higher HF bands we may see possible short-path F2 layer openings up to 24MHz. Paths may exist to Western Australia on 18MHz or even 21MHz around 0700-0800, but these may have a maximum probability of only around 32 percent. Around noon, the probability of a contact rises to 50 percent on 15m.

VHF and up propagation

Sporadic-E was a little quiet last week, with mainly intra-European paths. From QSO reports, tropo was slightly enhanced but seems to have favoured stations further south than the UK, with openings via the Azores’ high. For both modes it’s been a case of being there at the right time. Don’t give up, it’s still the prime season for sporadic-E and summer Tropo.

Sporadic-E is going to behave slightly differently next week, since the main jet stream is migrating further north to be over northern Europe or Scandinavia by the second half of the week. This will probably favour sporadic-E openings into the Baltic and Scandinavia, rather than to the southeast into the Balkans and Italy.

In the coming week, there will be a large, but weak, area of high pressure over the near continent, but with the main Azores high dominating across Biscay and the nearby Atlantic west of Portugal.

This should offer some reasonable tropo sea paths to Spain, Portugal, Canaries and Azores. Later in the week there could be sea tropo to the east and land paths across to the continent should show some enhancement overnight and for a short period after dawn.

Slow-moving isolated thunderstorms, and perhaps heavier showers over northern Britain mean that there may be rain scatter opportunities on the higher bands on some days.

Category: GB2RS Propagation News