Propagation News – 28 May 2017
Last week’s forecast of unsettled geomagnetic conditions at the beginning of the week and more settled conditions later was fairly accurate. The K index at high latitudes rose to five on Monday, but settled down to two and three by Thursday. At middle latitudes it was very settled after Wednesday. The solar flux index was in the range 74 to 78, with just one single sunspot group visible on the solar surface.
As a result, HF conditions were not outstanding, although there were F2-layer openings up to 17 metres and even occasionally 15 metres at times. As we move towards having summer HF conditions, the maximum usable frequency over a 3,000km path is often staying above 7MHz through the night, with occasional night-time F-layer openings up to 14MHz.
Sporadic-E is also proving worthwhile, with good short skip openings on HF, predominantly around late morning and late afternoon, although these can also occur at other times.
Next week we may see similar conditions, with the solar flux index in the low to mid seventies. Uncharacteristically, we expect to see more settled geomagnetic conditions next week, which should bode well for HF. As a result there may be some good daytime F2-layer DX to be had,
There is some uncertainty in the weather models for the week ahead and no real agreement between them. They predict alternating periods of high and low pressure. The high pressure period predicted for the beginning of the week has some agreement, so should provide some Tropo opportunities.
In the summer these favourable conditions are quite often to be found throughout the day and night across the seas around Britain, but only briefly around dawn over the land. Mist and fog are good indicators that there may be some lift conditions.
There have been some very good Sporadic-E openings recently, including some transatlantic JT65A QSOs. These openings are associated with activity produced near jet streams in the upper atmosphere at 10km, which can couple with the E region 100km higher to produce the right conditions for Sporadic-E. Check the RSGB Forum, Propagation Q&A, for a daily blog on the prospects for these favoured conditions. The low-pressure periods may produce some heavy showers, and associated rain scatter on the GHz bands.
The Omicron – Cetids daytime meteor shower continues until the 2nd of June, but is past its peak so stick to early mornings for random meteor scatter QSOs.
The Moon reached perigee last Friday and is at maximum declination today, so the early part of the week is best for EME. Losses will increase and windows shorten as the week progresses.
And that’s all from the propagation team this week.
Category: GB2RS Propagation News
