Propagation News 20 October 2013

| October 18, 2013

The two large complex sunspot regions reported in last weeks report produced 5 M class solar flares this week along with 80 C class solar flares. Solar activity was moderate on the 11th, 13th, 15th and the 17th. These M class solar flares only had a limited effect on propagation. The remaining days activity was low. On the 17th 12 sunspot regions were visible. Solar flux levels increased from 128 units on the 12th to 136 by the 17th and averaged 129 units. The 90 day solar flux average on the 17th was 111 units, that’s one unit up on last week. X-ray flux levels increased from B4.1 units to B8.6 by the 17th. The average was B6.1. Geomagnetic activity was very quiet on the 13th with an Ap index of only one unit, however, during the 14th a small coronal hole disturbance took place and lasted into the 15th. The most disturbed day was the 15th with an Ap index of 17 units. The average was Ap 9 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 320 kilometres per second to 570 by the 15th. Particle densities were low throughout except for an increase to 23 particles per cubic centimetre on the 14th. Bz varied between minus 3 and plus 4 nanoTeslas on the quietest day and between minus 11 and plus 8 nanoTeslas during the small disturbance.

Finally, the solar forecast for the coming week. This week the quiet side of the Sun will be rotating into view. Solar activity is expected to be predominately at low levels but could increase occasionally to moderate levels particularly at the start of the week. Solar flux levels should decline and be around the 100 mark later in the week. Geomagnetic activity is expected to be mostly quiet providing no coronal mass ejections head our way, however, a weak disturbance is expected at the start of the period due to a small recurring coronal hole. MUFs during daylight hours at equal latitudes are expected to be around 27MHz for the south and 24MHz for the north. Darkness hour lows should be about 9MHz. Paths this week to South Africa should have a maximum usable frequency with a 50 per cent success rate of around 35MHz. The optimum working frequency with a 90 per cent success rate will be about 28MHz. The best time to try this path will be between 1100 and 1400 hours UTC.

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

Category: GB2RS Propagation News