Propagation News 1 September 2013

The number of sunspot groups gradually declined and by the end of the period only three regions were visible. Most groups were small and stable, however, on the 23rd four small C class solar flares took place and there was one on the 29th. Solar flux levels declined from 124 units on the 23rd to 108 by the 28th. The average was 113 units. The 90 day solar flux average on the 29th was 114, that’s one unit up on last week. X-ray flux levels declined from B5 units on the 23rd to B2.4 by the 28th and the 29th. The average was B3.3 units. Geomagnetic activity started at unsettled levels with an Ap index of 16 units due to a coronal hole disturbance. Quiet conditions took place till the 27th when a coronal mass ejection disturbance arrived. The Ap index for the 27th was 19 units. The average was 10 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 530 kilometres per second to 320 by the 27th. Speeds increased again to 510 kilometres per second on the 28th. Particle densities were low except for an increase to 36 particles per cubic centimetre on the 27th. Bz varied between minus 13 and plus 11 nanoTeslas on the 27th and between minus 4 and plus 3 nanoTeslas during the quietest day.

And finally the solar forecast for the coming week. This week the more active side of the Sun is expected to rotate into view. However, it will be later in the week before solar activity could increase and solar flux levels show an increase. Geomagnetic activity is expected to be mostly quiet but around midweek a small recurring coronal hole disturbance is expected. 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 11MHz. Paths this week to Japan should have a maximum usable frequency with a 50 per cent success rate of around 21MHz. The optimum working frequency with a 90 per cent success rate of about 16MHz. The best time to try this path will be between 1000 and 1300 hours UTC.

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

Category: GB2RS Propagation News