Propagation News 17 November 2013

The number of sunspot groups increased from 4 to 9 visible groups by the end of the period. Several were produced large solar flares. Solar activity continued to reach high levels again this week. Two X class solar flares took place, one on the 8th and the other on the 10th. The number of M class flares was down on the previous week, along with the number of C class solar flares. Solar flux levels increased from 146 units on the 8th to 176 by the 14th. The average was 161 units. The 90 day solar flux average on the 14th was 124 units, that’s four units up on last week. X-ray flux levels increased from B6 units to C1 by the 14th and the average was B8.8 units. A coronal hole disturbance arrived on the 9th and lasted into the 11th with an Ap index of 22 units on the 9th and 18 on the 11th. The remaining days were quiet and the average was Ap 9 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 370 kilometres per second on the 8th to 660 on the 9th. Speeds then gradually declined to 340 kilometres per second by the end of the period. Particle densities were low every day. Bz varied between minus 12 and plus 9 nanoTeslas during the disturbance and between minus and plus 3 on the quietest day. The HF bands remained in good shape though the effects of decreasing day length in the northern hemisphere are becoming more evident.

Finally, the solar forecast for the coming week. This week solar activity is expected to continue at moderate levels on most days. There is also a small chance that activity could increase occasionally to high. Solar flux levels though are expected to decline slightly and be around the 130 units by next weekend. Geomagnetic activity could be unsettled today but the remainder of the week should be quiet provided no coronal mass ejections head our way. MUFs during daylight hours at equal latitudes should be above 30MHz with the darkness hour lows are expected to be around 9MHz. Paths this week to Australia should have a maximum usable frequency with a 50 per cent success of about 33MHz. The optimum working frequency with a 90 per cent success rate will be about 27MHz. The best time to try this path will be between 0700 and 1200 with a peak around 0900 hours UTC.

Category: GB2RS Propagation News