venerdì 16 settembre 2016

Propagation News – 18 September 2016

The solar flux index followed the NOAA prediction this week, declining to 85 by Thursday. Geomagnetic conditions were regrettably not as settled as we would have liked, with the K-index hitting three at times thanks to a continued high speed solar wind stream from a coronal hole. Luckily, no Earth-directed coronal mass ejections were observed and there were no major solar flares.

This weekend, and early next week, NOAA predicts geomagnetic conditions will continue to be unsettled, with a maximum planetary K-index of four at times. Next weekend, the 24th and 25th, may however be a little more settled.
The Sun is looking fairly spotless at the moment and the solar flux index is predicted to be a lacklustre 75 to 80.
Band conditions continue to improve, although maximum usable frequencies are being suppressed by the lack of sunspots.

The good news is we have the autumnal equinox this week, and so are at an optimum time for north-south paths on HF, such as UK to South Africa and South America.

September can also offer some good opportunities for grey-line propagation on the lower bands around sunrise.
Andy, M0NKR reports 40m has been good to the Pacific this week. He also worked Ken, T32AZ on East Kiribati on 20 metres, so it is all about being on the right band at the right time.

VHF and up propagation:

Late summer is the classic high pressure season of the year. Together with early morning mist and fog, there are plenty of reasons why VHF and UHF tropo should be on your operating schedule.

At the end of the hot weather last week, conditions fell off a little, but there were some huge thunderstorms, which produced rain scatter right down to 1.3 GHz.

This week there will be high pressure just to the south of Britain and partially over southern areas at times. This should offer good tropo across the southern half of the country down to the south over France and Germany overnight as the surface cools.

Daytime heating usually destroys any surface night-time temperature inversions, which are needed for tropo. The downside is that there may be a series of lows tracking over the north, which means winds and rain and no tropo.
It’s the late show for EME operators in the early part of this week with moonrise in the early evening, getting later as the week progresses.

Lengthening Moon windows push moonset out to early afternoon at the end of the week. Lowest losses will occur early in the week.

The Orionids meteor shower continues, with no large peak, into November, so continue to look out for enhanced meteor scatter conditions this coming week.