Propagation News 24 November 2013

Several large and active sunspot regions were visible but through the week one by one they rotated off the solar disc and out of view. Only two new sunspot regions were numbered during the period. Solar activity reached high levels on the 19th due to the only X class solar flare to take place. M class solar flares occurred on four days when activity was moderate. They were all rated at the M1 level. The remaining days solar activity was low with a total of 75 C class solar flares taking place. Solar flux levels declined from 178 units on the 15th to 141 by the 21st. The average was 162 units. The 90 day solar flux average on the 21st was 126 units, that’s two units up on last week. X-ray flux levels declined from C1 units on the 16th and the 17th to B6 by the 21st. The average was B8.4 units. Geomagnetic activity was quiet every day, however, on the 16th the daily Ap figure did reach 10 units, possible due to a very small coronal hole. The average was Ap 5 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 580 kilometres per second on the 16th to 340 by the 21st. Particle densities started the period at 23 particles per cubic centimetre but then declined to below 10 particles per cubic centimetre for the remainder of the period. Bz varied between minus 10 and plus 12 nanoTeslas on the 16th and on the quiet days between minus 2 and plus 3 nanoTeslas.

Finally, the solar forecast for the coming week. This week the more quiet side of the Sun is expected to be looking our way. Solar activity is expected to be at low levels but a stronger solar flare could take place on some days. Solar flux levels should decline to the 120’s around midweek but then start to rise again. Geomagnetic activity is expected to be quiet every day provided that no coronal mass ejections head our way. MUFs during daylight hours at equal latitudes should be around 30MHz or slightly higher. Darkness hour lows should be about 8MHz. Paths this week to South America should have a maximum usable frequency with a 50 per cent success rate of around 36MHz. The optimum working frequency with a 90 per cent success rate of about 30MHz. The best time to try this path will be between 1100 and 1600 hours UTC.

Category: GB2RS Propagation News