Propagation News

| October 7, 2012

And now the solar factual data for the period from Friday the 28th of September to Thursday the 4th of October, compiled by Neil Clarke G0CAS on Friday the 5th of October.

Solar activity started at low levels but, on the 30th, as several sunspot groups were rotating out of view, one produced the only M class solar flare of the period. This was an impulsive type solar flare and no earthward coronal mass ejection was associated with the event. Activity declined to very low levels on the 3rd and the 4th. Solar flux levels declined from 138 units on the 28th to 110 by the 4th. The average was 126 units. The 90 day solar flux average on the 4th was 123 units, that’s one unit down on last week. X-ray flux levels initially increased to peak at B7.6 units on the 1st but as the active regions departed the solar disc levels declined sharply to B1.8 by the end of the period. The average was B4.5 units. Geomagnetic activity started at quiet levels but around noon on the 30th a coronal mass ejection arrived that departed the Sun late on the 27th. The disturbance lasted for about 24 hours and the Ap index on the 1st was 36 units. Aurora was report on 50 and 144MHz during the evening of the 30th. The quietest days were the 28th and the 4th with an Ap of 3 units. The average was Ap 10 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from a slow 260 kilometres per second during the morning of the 30th to 460 by early the next day. Particle densities were low except for a few hours around midnight on the 30th and into the 1st when they increased to 20 particles per cubic centimetre. Bz varied between minus 1 and plus 3 nanoTeslas on the quietest day and between minus 20 and plus 10 nanoTeslas during the disturbance.

And finally the solar forecast for the coming week. This Week the quieter side of the Sun should be rotating into view. Solar activity is expected to be at low levels on most days. Solar flux levels should start around 100 units with levels increasing slightly towards next weekend. Geomagnetic activity should be mostly quiet but a weak disturbance could take place around midweek. MUFs during daylight hours at equal latitudes should around 27MHz for the south and 24MHz for the north. Darkness hour lows should be about 10MHz. Paths this week to the Middle East should have a maximum usable frequency with a 50 per cent success rate of around 25MHz. The optimum working frequency with a 90 per cent success rate will be about 20MHz. the best time to try this path will be between 1500 and 1900 hours UTC.

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

Category: GB2RS Propagation News