Propagation News

| September 16, 2012

And now the solar factual data for the period from Friday the 7th to Thursday the 13th of September, compiled by Neil Clarke on Friday the 14th of September

Six sunspot groups were visible on the 7th but this was down to three by the 13th. Solar activity increased to moderate levels on the 8th and 9th when a single M1 class solar flare took place on both days. Solar activity was low on the remaining days with occasional small C class solar flares taking place. Solar flux levels declined from 133 units on the 7th to 99 by the 13th. The average was 115 units. The 90 day solar flux average on the 13th was 123, that’s one unit down on last week. X-ray flux levels declined from B7.1 units on the 8th to B3.1 by the 13th. The average was B4.9 units. Geomagnetic activity was quiet every day. The most disturbed day was the 8th, with an Ap index of 10 units. The average was Ap 6 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 440 kilometres per second on the 8th to a slow 260 kilometres per second on the 11th and the 12th. Speeds then increased on the 13th to 450 kilometres per second, which are the first signs of an expected coronal hole disturbance arriving. Particle densities were low except for a rise to 25 particles per cubic centimetre on the 12th. Bz varied between minus 7 and plus 11 nanoTeslas on the 12th and between minus 3 and plus 2 nanoTeslas on the quietest days. Though well past the summer seasonal peak, occasional Es events took place on both 50 and 70MHz.

And finally the solar forecast from Sunday the 16th of September. This week the quiet side of the Sun is expected to be looking our way. Solar activity is expected to be low, with only C class solar flares taking place and only a small chance of any larger flares. Solar flux levels should be just below the 100 mark today but from midweek levels should start to increase. Geomagnetic activity could be unsettled at first due to the after effects from a coronal hole disturbance that is just coming to an end and then be mostly quiet for the remainder of the week. MUFs during daylight hours at equal latitudes should be about 24MHz for the south and 21MHz for the north. Darkness hour lows should be around 10MHz. Paths this week to South Africa should have a maximum usable frequency with a 50 per cent success rate of around 30MHz. The optimum working frequency with a 90 per cent success rate will be about 24MHz. The best time to try this path will be between 1100 and 1600 hours UTC.

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

Category: GB2RS Propagation News

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