Propagation News – 20 April 2014

| April 17, 2014

The number of sunspot regions increased during the period. 11 were visible on the 16th. Several developed in size and magnetic complexity, though solar activity remained at low levels when only large C class solar flares took place. However, late on the 16th, a M1 class solar flare occurred. Solar flux levels increased from 136 units on the 12th to 184 by the 16th. The average was 151 units. The 90 day solar flux average on the 16th was 155 units, that’s one unit up on last week. X-ray flux levels increased from B4.4 units to B8.7 by the 16th. The average was B6.1 units. Geomagnetic activity increased on the 12th and the 13th when the Ap index increased to 22 and 14 units respectively. Activity then declined to quiet levels for the remained of the period. The average was 10 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 430 kilometres per second to 290 by the 15th. Particle densities were moderate most days at around 20 particles per cubic centimetre but on the 13th increased briefly to 64 particles per cubic centimetre. Bz varied between minus 9 and plus 5 nanoTeslas on the most unsettled day and between minus and plus 4 nanoTeslas on the quietest days.
Finally, the solar forecast for the coming week. This week will see most of the present active sunspot regions rotate out of view and solar activity is expected to remain at low levels but with a chance of increasing to moderate levels on some days. Solar flux levels are also expected to decline and be in the 140′s later in the week. Geomagnetic activity should be quiet every day. No coronal hole disturbances are expected but if a coronal mass ejection heads are way then activity would increase. MUFs during daylight hours at equal latitudes should be around 27MHz. Darkness hour lows should be about 14MHz. Paths this week to the east coast of North America should have a maximum usable frequency of about 24MHz. The optimum working frequency with a 90 per cent success rate will be around 19MHz.
And that’s all for another week from the propagation team.

Category: GB2RS Propagation News