Propagation News – 14 September 2014

| September 12, 2014

On the 4th two large sunspot regions rotated into view and between them they produced numerous C class solar flares everyday and one M class solar flares on the 6th and the 9th and two on the 11th. On the 10th activity increased to high when a X1 class flare occurred, the first since the 11th of June. Solar flux levels increased from 144 units on the 5th to 164 by the 8th, the average was 155 units. The 90 day solar flux average on the 11th was 129 units, that’s one unit down on last week. X-ray flux levels varied little day to day and averaged B9.5 units. Geomagnetic activity was quiet everyday except for the 11th, which increased possibly due to the arrival of a coronal mass ejection that departed the Sun on the 9th. The Ap index on the 11th was 13 units. The quietest day was the 8th with an Ap of 5 units. The average was Ap 8 units. Solar wind data from the ACE spacecraft saw solar wind speeds 330 and 490 kilometres per second. Particle densities increased to around 40 particles per cubic centimetre on the 6th, 10th and the 11th, the remaining days densities were low. Bz varied between minus 12 and plus 15 nanoTeslas on the most disturbed day.

Now the solar forecast for the coming week. At least for the first half of the week the two active sunspot regions will still be visible before rotating out of view. Solar activity is expected to be at low levels but there is a good chance that activity could increase at least till midweek. Solar flux levels should be around the 150’s for most of the week but could start to decline by next weekend. Geomagnetic activity is expected to be low, however, if an Earth directed coronal mass ejection takes place this would increase activity. MUFs during daylight hours at equal latitudes should be around 25MHz. Darkness hour lows are expected to be about 12MHz. Paths this week to Japan should have a maximum usable frequency with a 50 percent success rate of around 27MHz. The optimum working frequency with a 90 percent success rate will be about 21MHz. The best time to try this path will be between 0900 and 1200 hours UTC.


Category: GB2RS Propagation News