Propagation News 15 September 2013

| September 13, 2013

Once again this week solar activity was not what would be expected considering the present stage of the sunspot cycle. This week saw only a small number of sunspot groups on most days. On the 9th, only one very small sunspot group was visible. With all the groups small and stable solar activity was very low everyday except on the 6th when the only C class solar flare took place. Solar flux levels declined from 101 units on the 6th to 93 by the 11th and the 12th. The average was 96 units. The 90 day solar flux average on the 12th was 113 units, that’s one unit down on last week. X-ray flux levels declined from B3.1 units on the 6th to A7.9 units by the 12th, the average was B1.1 units. Geomagnetic activity was quiet everyday with an average of Ap 5 units. The most disturbed day was the 12th with an Ap of 7 units. Solar wind data from the ACE spacecraft saw solar wind speeds vary between 320 and 420 kilometres per second. Particle densities were low except for a brief increase to 22 particles per cubic centimetre during the afternoon of the 10th. Bz never vary more than minus 8 and plus 10 nanoTeslas during the period.

And finally the solar forecast for the coming week. Later in the week old regions are expected to return and rotate into view, until then solar activity is expected to be very low but could increase to low on some days. Solar flux levels are expected to be around the 100 mark or slightly below but could increase later in the week. Geomagnetic activity is expected is expected to increase tomorrow due to a small recurring coronal hole. Quiet conditions should return by midweek. MUFs during daylight hours at equal latitudes should be around 23MHz for the south and 20MHz for the north. Darkness hour lows should be about 11MHz. Paths this week to the Middle East should have a maximum usable frequency with a 50 per cent success rate of around 24MHz. The optimum working frequency with a 90 per cent success will be about 18MHz. The best time to try this path will be between 1000 and 1500 hours UTC.

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

Category: GB2RS Propagation News