Propagation News – 4 May 2014

Twenty seven minutes after the start of the period an X1 class solar flare took place, however, since then only a sprinkling of C class solar flares took place and then not on every day. Solar activity was high on the 25th due to the X1 flare but then declined to very low on the 27th, 29th and the 1st. Solar flux levels declined slightly to 118 units by the 27th but then increased to 126 units by the 1st. The average was 122. The 90 day solar flux average on the 1st was 154 units, that’s two units down on last week. X-ray flux levels declined from B6.1 units on the 25th to B2.5 by the 28th. The average was B3.4 units. Geomagnetic activity start at quiet to unsettled levels but on the 30th activity increased due to a slow moving coronal mass ejection associated with the X1 class flare. The Ap index for the 30th was 20 units and the average for the period was Ap 10 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 550 kilometres per second on the 25th to a slow 260 kilometres per second by the 28th and the 29th. Particle densities were low except for the 30th, which increased to 34 particles per cubic centimetre and 55 on the 1st. Bz varied between minus 3 and plus 4 nanoTeslas on the quietest day. Bz remained around minus 10 nanoTeslas for around 16 hours on the 30th, which produced a small disturbance during the afternoon which resulted in 50 and 144MHz auroral contacts across most of northern Europe but only a handful were reported from the UK. The first, scattered, sporadic E contacts of the season took place and you can expect more in the coming weeks, possibly extending to 70MHz.

Finally, the solar forecast for the coming week. This week the more active side of the Sun will rotate into view. At least two active regions are expected to be seen, one at the start of the week and the other next weekend. Solar flux levels should increase and be around 150 units by the end of the week. Geomagnetic activity is expected to be quiet every day. No coronal hole and coronal mass ejections are expected. MUFs during daylight hours at equal latitudes should be around 27MHz. Darkness hour lows are expected to be about 14MHz. Paths this week to Australia should have a maximum usable frequency with a 50 percent success rate of around 25MHz. The optimum working frequency with a 90 percent success rate will be about 20MHz. The best time to try this path will be between 0800 and 1100 hours UTC.

Category: GB2RS Propagation News