domenica 20 settembre 2015

Propagation News – 20 September 2015

September 18, 2015   

Despite ongoing solar coronal holes, and their contribution to the high-speed solar wind, HF conditions have fared a little better than in previous weeks. This is due to the traditionally better autumnal HF conditions, which should improve further as the month goes on. Despite the geomagnetic K-index never really dropping below three, and often hitting five, maximum usable frequencies have exceeded 18MHz at times, sometimes making 21MHz. Radio hams waiting for decent 10m openings may still have to wait another month though—and then they may be sparse, given the poor solar flux index. NOAA predicts that the solar flux index this week will be around 105, dropping to 90. The K-index may suffer yet again from the effects of the high-speed solar wind.

Thursday and Friday are predicted to be the most unsettled, geomagnetically speaking.

The Six Gs DXpedition to Niue Island in the Pacific should be under way by now. The best predicted paths to E6GG look to be on 20m and 17m, with an optimum short-path opening on 17m between 1000 and 1400UTC, and again at 1800. There may also be a long-path opening on 17m around 1900UTC.

As a reminder, September is a good month for north-south paths on HF, such as UK to South Africa and South America. In between geomagnetic storm events we should also see the lower bands becoming more usable too.

VHF and up propagation:

Today looks promising for tropo conditions to the continent and the south-east, but this is only likely to last for a day or so. By Wednesday there may be some tropo from the west of the UK which could couple into the Atlantic tropo systems off Iberia and west Africa.

The remnants of tropical storm Henri brought some nice rain scatter propagation to 5.7 and 10GHz last week, but sadly few UK stations were active to take advantage of it. Next week is looking drier, but still be aware of the possibility of rain scatter on the GHz bands in any showers that might crop up. Watch out for auroras as there are a number of sunspots with the potential for M-Class solar flares.

The sporadic E season is over so it’s unlikely that there will be much in the way of propagation by that mode on the VHF bands.

There are no major meteor showers this week so keep looking in the early mornings for the best random meteor scatter opportunities.

For EME operators, the moon is at its lowest declination today, so we will see short Moon windows, but losses will be at their lowest at perigee on Monday.