Propagation News – 16 March 2014

Two large active sunspot regions between them produced in total 12 M class solar flares and numerous C class solar flares. The largest solar flare of the period was a M9 which occurred late on the 12th. However, solar activity was low on the 7th when only C class solar flares took place. Solar flux levels finished the period where they started at 148 units and showed little variation day to day except for the 11th which increased to 165 units. The average was 150 units. The 90 day solar flux average on the 13th was 158, that’s two units down on last week. X-ray flux levels increased from B5.4 units on the 7th to C1.4 by the 10th and the 11th before declining back to B7.3 units by the 13th. The average was B8.4 units. Geomagnetic activity was quiet everyday except for a small disturbance that took place on the 13th. The most disturbed day was the 13th with an Ap index of 11 units. The average was Ap 4 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 420 on the 7th to a very slow 250 kilometres per second by the 12th. Speeds then increased and ended the period at 520 kilometres per second. Particle densities were low except for a brief increase to 14 particles per cubic centimetre late on the 12th and 20 the next day. Bz varied between minus 2 and plus 3 nanoTeslas on the quietest day and between minus 8 and plus 9 nanoTeslas on the 13th.

Finally, the solar forecast for the coming week. This week solar activity is expected to be at moderate levels on most days with the return of a couple of active regions. Solar flux levels could decline to the 140 later in the week. Geomagnetic activity is expected to be mostly quiet everyday, however, if an Earth directed coronal mass ejection heads our way then activity would increase. MUFs during daylight hours at equal latitudes should be slightly above 30MHz. Darkness hour lows should be about 11MHz. Paths this week to Australia should have a maximum usable frequency with a 50 per cent success rate of around 30MHz. The optimum working frequency with a 90 per cent success rate will be about 24MHz. The best time to try this path will be between 0800 and 1200 hours UTC.

Category: GB2RS Propagation News