Propagation News

| February 22, 2013

And now the solar factual data for the period from Friday the 8th to Thursday the 14th of February, compiled by Neil Clarke, G0CAS on Friday the 15th of February.

Only two new sunspot regions appeared during the period, with a maximum of four regions visible on some days. On the whole solar activity was at very low levels, with one small C class solar flare taking place on the 9th, 12th and 14th. Solar flux levels declined from 108 units on the 9th to 100 by the 13th and 14th. The average was 104. The 90 day solar flux average on the 14th was 117 units, that’s three units down on last week. X-ray flux levels varied little day to day and averaged B1.7 units. This is definitely not what we would expect so close to sunspot maximum. Geomagnetic activity was quiet until the 13th, when a weak disturbance commenced and lasted into the 14th. The cause of the disturbance is not known but is probably due to a glancing blow from a coronal mass ejection from an eruptive filament. Several of these took place during the period. The most disturbed day was the 14th, with an Ap index of 12 units. The average was Ap 6 units. Solar wind data from the ACE spacecraft saw solar wind speeds decrease from 480 kilometres per second on the 8th to 340 by the 13th. Particle densities where low except for a brief increase to 15 particles per cubic centimetre on the 13th and the 14th. Bz varied between minus 3 and plus 4 nanoTeslas on the quiet days and between minus and plus 9 nanoTeslas on the 13th and the 14th.

And finally the solar forecast for the coming week. This week solar activity is expected to be predominately at low levels, with only C class solar flares taking place. There is though a chance that the occasional stronger solar flare could take place and increase activity. Solar flux levels are expected to be around the 110 mark, or slightly less for most of the week. Geomagnetic activity is expected to be at quiet levels until later in the week, when activity could increase slightly due to a small recurring coronal hole. MUFs during daylight hours at equal latitudes should be about 24MHz for the south and 21MHz for the north. Darkness hour lows should be around 8MHz. Paths this week to Australia should have a maximum usable frequency with a 50 per cent success rate of around 26MHz. The optimum working frequency with a 90 per cent success rate will be about 21MHz. The best time to try this path will be between 0900 and 1300 hours.

Category: GB2RS Propagation News

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