Propagation News

| September 9, 2012

And now the solar factual data for the period from Friday the 31st of August to Thursday the 6th of September, compiled by Neil Clarke on Friday the 7th of September.

Considering there were two large and magnetically complex groups visible, they both remained relatively quiet and only produced numerous C class solar flares except for a single M1 solar flare on the 6th. Solar flux levels increased to 146 units on the 1st but then gradually declined to 128 by the 6th. The average was 137 units. The 90 day solar flux average on the 6th remained unchanged from the previous week at 124 units. X-ray flux levels declined from B9.8 units on the 1st to B4.4 by the 6th and the average was B6.9 units. Geomagnetic activity started at quiet levels on the 31st with an Ap index of only 3 units but by the 3rd activity increased to peak at 40 units. This was in response to a coronal mass ejection that departed the Sun on the 31st. Just as that storm was declining a coronal hole disturbance arrived which allowed geomagnetic activity to continue to the end of the period. The average was Ap 20 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 290 kilometres per second to peak at 590 by the 5th. Particle densities increased to 54 particles per cubic centimetre on the 3rd and remained elevated at around 20 particles per cubic centimetre till the 6th. Bz varied between minus 3 and plus 2 nanoTeslas on the quietest day and between minus 23 and plus 15 nanoTeslas on the 3rd. A good week for many VHF/UHF operators, with a stable high pressure system producing extended tropo propagation on 144MHz and above, particularly towards France, Germany and Spain. Also, disturbed geomagnetic levels on the 3rd resulted in auroral propagation on 6 and 2 metres lasting some twelve hours and, at its peak, extending down to central England.

And finally the solar forecast from Sunday the 9th of September. This week the quiet side of the Sun is expected to rotate into view, therefore, solar activity should be low with only C class solar flares taking place. Solar flux levels are expected to decline and be in the 90’s later in the week. Geomagnetic activity should be quiet until later in the week, when a small recurring coronal hole is expected to arrive and last into the weekend. MUFs during daylight hours at equal latitudes should be around 24MHz for the south and 21MHz for the north. Darkness hour lows should be about 11MHz. Paths this week to India should have a maximum usable frequency with a 50 per cent success rate will be around 23MHz. The optimum working frequency with a 90 per cent success rate is expected to be 18MHz. The best time to try this path will be between 1100 and 1600 hours.

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

Category: GB2RS Propagation News

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