Propagation News 3 November 2013

Solar activity continued at high levels, with four X class solar flares taking place, two on the 25th, one on the 28th and one on the 29th. Also seventeen M class flares occurred along with numerous C class solar flares, making this one of the most active weeks of this sunspot cycle. In total 23 X class solar flares have taken place so far for this cycle compared to 120 for the whole of the previous sunspot cycle. Solar flux levels peaked at 167 units on the 27th but then declined to 142 units by the 30th. The average was 156 units. The 90 day solar flux average on the 31st was 117, that’s four units up on last week. X-ray flux levels declined from C1.2 units to B5.9 by the 31st, the average was B9.7 units. Geomagnetic activity was very quiet every day except for the 30th when a weak disturbance arrived from a coronal mass ejection that departed the Sun on the 28th associated with the X1 class solar flare. The Ap on the 30th was 13 units. The average was Ap 4 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 260 kilometres per second to 480 by the 31st. Particle densities were low every day except for the 29th which increased in the evening to 26 particles per cubic centimetre. Bz varied between minus 2 and plus 6 nanoTeslas on the quiet days and between minus 10 and plus 12 nanoTeslas during the 29th. The continuing combination of high solar flux, low geomagnetic levels and seasonal factors made for excellent conditions on the higher HF bands. MUFs exceeded forecast values on most days and there were particularly good afternoon openings across to North America on 10 metres.

Finally, the solar forecast for the coming week. This week the quiet side of the Sun is expected to be looking our way. Saying that, activity will still have the potential to increase to moderate levels on some days. However, solar flux levels are expected to be lower that recent weeks and decline to around 120 units by next weekend. Geomagnetic activity should be mostly quiet provided that no coronal mass ejections heads are way. Next weekend though, a recurring coronal hole disturbance is expected to arrive. MUFs during daylight hours at equal latitudes should be around 35MHz for the south and 32MHz for the north. Darkness hour lows should be about 9MHz. Paths this week the east coast of North America should be about 32MHz. The optimum working frequency with a 90 per cent success rate will be around 27MHz. The best time to try this path will be between 1300 and 1700 hours UTC.

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

Category: GB2RS Propagation News