Propagation News – 28 September 2014

| September 26, 2014

Numerous sunspot regions were visible everyday, some were large and complex, but for what ever reason failed to produce any significant solar flares. Saying that, a M2 class solar flare took place on the 23rd, otherwise solar activity was at low levels with only a small number of C class solar flares taking place everyday. Solar flux levels increased from 119 units on the 20th to 158 by the 25th, the average was 134 units. The 90 day solar flux average on the 25th was 134 units, that’s three units up on last week. X-ray flux levels averaged B5.3 units and increased during the period to C1 by the 25th. Geomagnetic activity started at active levels due to a coronal mass ejection that departed the Sun several days earlier, the Ap index on the 19th was 22 units. Activity declined to quiet levels till the 24th when a coronal hole disturbance arrived and the Ap on the 24th was 25 units. The average was Ap 12 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 660 kilometres per second on the 21st to 380 by the 23rd and the 24th. Particle densities were low except for the 19th that increased to 40 particles per cubic centimetre. Bz varied between minus 4 and plus 5 nanoTeslas on the quietest day and between minus 13 and plus 16 nanoTeslas on the 19th.

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 is expected to be low but could increase to moderate levels on any day. Solar flux levels are expected to increase to around the 160’s. At the start of the forecast period geomagnetic activity is expected to be at ‘active’ levels due to a series of positive polarity, equatorial recurring coronal holes, by midweek activity should have declined to quiet levels. MUFs during daylight hours at equal latitudes should be around 32MHz. Darkness hour lows are expected to be about 11MHz. Paths this week to Japan should have a maximum usable frequency with a 50 percent success rate of around 28MHz. The optimum working frequency with a 90 percent success rate will be about 24MHz. The best time to try this path will be between 0800 and 1100 hours UTC.

Category: GB2RS Propagation News