Propagation News

| February 22, 2013

And now the solar factual data for the period from Friday the 15th to Thursday the 21st of February, compiled by Neil Clarke, G0CAS on Friday the 22nd of February.

The number of sunspot groups increased as the week progressed to seven visible groups by the 21st. One of these regions produced an unexpected impulsive M1 class solar flare on the 17th that increased activity to moderate levels. On the 15th and 16th solar activity was very low. The remaining activity was at low levels, with C class solar flares taking place. Solar flux levels increased from100 units on the 15th to 114 by the 20th. The average was 104 units. The 90 day solar flux average on the 21st was 115 units, that’s two units down on last week. X-ray flux levels increased slightly to peak at B3.6 units on the 19th, the average was B2.5 units. Geomagnetic activity was quiet on the 15th with an Ap index of only three units, however, activity increased to just unsettled levels on the 16th and the 17th. The most disturbed day was the 16th, with an Ap of 11 units. The average was Ap 6 units. Solar wind data from the ACE spacecraft saw solar wind speeds vary between 300 and 440 kilometres per second. Particle densities were low on the 15th and 21st and moderate on the other days, with densities peaking close to 20 particles per cubic centimetre. Bz varied between minus and plus 11 nanoTeslas on the 16th, which was the most disturbed day, and between minus and plus 3 nanoTeslas on the quietest day.
And finally the solar forecast for the coming week. This week the quiet side of the Sun is expected to be looking our way. Solar activity is expected to be at low levels or even very low on the occasional day. Solar flux levels are expected to be below the 100 mark but may increase slightly later in the week. Geomagnetic activity is expected to be mostly quiet, but could increase towards next weekend 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 South America should have a maximum usable frequency with a 50 per cent success rate of around 30MHz. The optimum working frequency for a 90 per cent success rate is about 23MHz. The best time to try this path will be between 1100 and 1800 hours UTC.

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

Category: GB2RS Propagation News