Propagation News – 15 June 2014

Several large sunspot regions appeared and some were complex enough to produce large solar flares. Solar activity started the period at moderate levels on the 6th when a M1 class solar flare occurred. Later, on the 10th and the 11th activity increased to high when a single X class solar flare took place on both days. Also, on the 11th 3 M class flares took place and six on the 12th. In total 60 C class solar flares took place and 10 M class flares during the period. Solar flux levels increased from 133 units on the 6th to 175 by the 12th. The average was 156. The 90 day solar flux average on the 12th was 139, that’s one unit up on last week. X-ray flux levels increased from B3.7 units on the 6th to peak at C1.1 units by the 12th. The average was B7.3 units. Geomagnetic activity started at quiet levels but started to increase late on the 7th to peak the next day with an Ap index of 37 units. This was due to a coronal mass ejection that departed the Sun several days earlier. The rest of the period was quiet and the average was Ap 12 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 320 kilometres per second on the 7th to 650 by the 8th and again on the 11th. Particle densities increased to 31 particles per cubic centimetre on the 7 and 94 on the 8th. Bz varied between minus 4 and plus 6 nanoTeslas on the 11th and between minus 17 and plus 21 nanoTeslas on the most disturbed day which was the 8th.

Finally, the solar forecast for the coming week. This week the more active side of the Sun is expected to rotate out of view. Until then solar activity is expected to be low to moderate. Solar flux levels are expected to decline and by next weekend to be around the 130’s. Geomagnetic activity is expected to be mostly quiet provided that no Earth directed coronal mass ejections heads our way. MUFs during daylight hours at equal latitudes should be around 22MHz. Darkness hour lows should be around 14MHz. Paths this week to the Middle East 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 will be about 16MHz. Sporadic-E is expected most days with double hop Sporadic-E openings on 50MHz possible also on this path.

Category: GB2RS Propagation News