Propagation News 18 August 2013

Several sunspot regions were visible everyday, two groups appeared on the 10th and then increased in size and magnetic complexity. Solar activity was low everyday except for the 12th which increased to moderate levels when the only M class solar flare took place. Solar flux levels increased from 103 units on the 10th to 125 by the 14th. The average was 119 units. The 90 day solar flux average on the 15th was 114 units, that’s two units down on last week. X-ray flux levels increased from B2.1 units on the 9th to B4.8 by the 13th. The average was B3.4 units. Geomagnetic activity started at quiet levels but during the 13th a small and weak coronal hole disturbance arrived, this continued till the end of the period. The Ap index was 10, 11 and 16 units for the 13th 14th and the 15th respectively. The average was Ap 9 units. Solar wind data from the ACE spacecraft saw solar wind speeds decrease from 550 kilometres per second on the 10th to 320 by the morning of the 13th. Later that day speeds started to increase to peak at 650 kilometres per second on the 15th. Particle densities were low every day except for an increase to 17 particles per cubic centimetre on 13th. Bz varied between minus and plus 3 nanoTeslas on the quietest day and between minus 9 and plus 10 nanoTeslas during the disturbance.

And finally the solar forecast for the coming week. This week the quieter side of the Sun will be rotating into view. Solar activity is expected to be at low levels but there is a slight chance that activity could be at moderate levels particularly during the first half of the week. Solar flux levels should decline and be around the 110 mark later in the week. Geomagnetic activity is expected to be quiet at first but it will not be long before activity increases due to a recurring coronal hole. Activity should only increase to unsettled levels for a couple of days and then decline to quiet levels for the remainder of the week. MUFs during daylight hours at equal latitudes should be about 23MHz for the south and 20MHz for the north. Darkness hour lows should be around 12MHz. Paths this week to India should have a maximum usable frequency with a 50 per cent success rate of around 22MHz. The optimum working frequency with a 90 per cent success rate will be about 17MHz. The best time to try this path will be between 1100 and 1500 hours UTC. Sporadic-E is expected to take place on some days, which will be less frequent now as the end of the summer season approaches.

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

Category: GB2RS Propagation News