Propagation News 27 October 2013

| October 25, 2013

At the start of the period two small sunspot regions rotated into view but within days they had increased in size and magnetic complexity. By the 22nd solar activity had increased to moderate levels with small M class solar flares taking place. Activity increased to high levels on the 24th when four M class solar flares took place. The largest was a M9 peaking at just after midnight. In total 9 M class solar flares took place with four on the 24th. Solar flux levels responded well and increased from 133 units on the 19th to 161 by the 24th. The average was 143 units. The 90 day solar flux average on the 24th was 113, that’s two units up on last week. X-ray flux levels averaged B8.3 units. These weekly averages are the highest levels so far this year but not for the current sunspot maximum. Geomagnetic activity was very quiet every day, the most disturbed day was the 22nd with an Ap index of only 4 units. The average was Ap 2 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 420 kilometres per second on the 18th to 300 for the latter half of the period. Particle densities were low throughout. Bz varied between minus 5 and plus 7 nanoTeslas. With a higher solar flux and low magnetic activity the HF bands responded well with some of the best conditions for some time.

Finally, the solar forecast for the coming week. This week solar activity is expected to continue at moderate levels, at least on some days anyway. Solar flux levels should decline slightly and be around 130 units later in the week. Unless a coronal mass ejection heads our way, and there is a slight chance of that then geomagnetic activity is expected to be quiet every day. MUFs during daylight hours at equal latitudes should be around 30MHz for the south and 27MHz for the north. Darkness hour lows should be about 9MHz. Paths this week to Japan should have a maximum usable frequency with a 50 per cent success rate of around 25MHz. The optimum working frequency with a 90 per cent success rate of about 18MHz. The best time to try this path will be between 0800and 1100 hours UTC.

And that’s all for this week from the propagation team.

Category: GB2RS Propagation News