Propagation News – 19 October 2014

Sunspot groups decayed and disappeared or rotated out of view and by the 12th only two groups remained visible. Since then new groups appeared but there are two sunspot groups about to rotate into view that are already producing M class solar flares. Solar activity was at very low levels on the 11th and the 13th but increased to moderate levels during the evening of the 14th when an impulsive M1 class solar flare took place but within three hours a long duration M2 class flare occurred. A further impulsive M4 class flare took place on the 16th. Solar flux levels declined from 121 units on the 10th to 111 by the 12th but then increased to 139 units by the 16th. The average was 120 units. The 90 day solar flux average on the 16th was 131 units, that’s one unit up on last week. X-ray flux levels increased from B2.9 units on the 12th to C1.3 by the 15th. The average was B5.5 units. Geomagnetic activity was quiet everyday except for the 14th which increased in response to a weak coronal hole disturbance to 17 units. The average was Ap 8 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 300 kilometres per second on the 10th to 590 early on the 15th. Particle densities were moderate on some days but on the 12th increased to 80 particles per cubic centimetre. Bz varied between minus 9 and plus 12 nanoTeslas on the most disturbed day and between minus 3 and plus 4 nanoTeslas on the quietest day.

Now the solar forecast for the coming week. This week the more active side of the Sun is expected to be looking our way. Solar activity could be moderate or even higher on some days. Solar flux levels are expected to increase into the 160s. Geomagnetic activity is expected to start at quiet levels but is expected to increase from midweek onwards. MUFs during daylight hours at equal latitudes should be about 34MHz. Darkness hour lows should be around 10MHz. Paths this week to Australia should have a maximum usable frequency with a 50 percent success rate of around 31MHz. The optimum working frequency with a 90 percent success rate will be about 25MHz. The best time to try this path will be between 08.00 and 12.00 hours UTC.

Category: GB2RS Propagation News