Propagation News

And now the solar factual data for the period from Friday the 14th to Thursday the 20th of September, compiled by Neil Clarke on Friday the 21st of September.

As forecast, the quiet side of the Sun was looking our way and with it solar activity was at very low levels, at least till the 17th when activity increased to low levels. Occasional C class solar flares started to take place every day from the 17th until the end of the period. This rise in activity was due to a couple of sunspot groups approaching the solar limb prior to rotating into view on the 18th and the 19th. Solar flux levels increased from 97 units on the 16th to 117 by the 20th. The average was 104 units. The 90 day solar flux average on the 20th was 122 units, that’s one unit down on last week. X-ray flux levels increased slightly from B1.5 units on the 14th to B2.7 by the 20th. The average was B2 units. Geomagnetic activity started at quiet levels but by mid afternoon on the 19th a weak coronal hole disturbance commenced and lasted just about to the end of the period. The most disturbed day was the 19th, with an Ap index of 14 units. The average was Ap 8 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 350 kilometres per second on the 16th to 620 kilometres per second on the 20th. Particle densities were low but increased to 14 particles per cubic centimetre on the 20th. Bz varied between minus 3 and plus 4 nanoTeslas on the quietest day and between minus 11 and plus 13 nanoTeslas on the most disturbed day.

And finally the solar forecast from Sunday the 23rd of September. This week solar activity is expected to be at low levels, however, there is a chance that activity could increase to moderate levels on some days particularly later in the week. Solar flux levels should increase every day and by next weekend be around the 130’s, or maybe slightly higher. Geomagnetic activity is expected to be quiet but could increase late in the week due to a small recurring coronal hole. MUFs during daylight hours at equal latitudes should be around 25MHz for the south and 22MHz for the north. Darkness hour lows should be about 10MHz. Paths this week to Japan 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 19MHz. The best time to try this path will be between 0900 and 1200 hours UTC.

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

Category: GB2RS Propagation News