Propagation News – 19 January 2014

A large active sunspot region dominated the solar disc until it rotated out of view on the 14th and with it solar activity declined from moderate levels to very low. Only one M class solar flare took place but by the 15th solar activity was very low with no C class solar flares taking place. Solar flux levels declined rather dramatically from 175 units on the 10th to 121 by the 16th. The average was 146 units. The 90 day solar flux average on the 16th was 153, that’s one unit up on last week. X-ray flux levels declined from B7.2 units on the 11th to B4.5 by the 16th. The average was B6.4 units. Geomagnetic activity was quiet every day, saying that, a weak coronal disturbance took place on the 14th but the Ap index only reached 8 units. Paradoxically, the solar wind speed peaked at 920 kilometres per second, which is the highest speed in a long time. Anyway, the remaining days’ activity was quiet and the average for the period was Ap 4 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 370 kilometres per second on the 11th to 920 by the 13th. Speeds then declined back to 370 by the 16th. Particle densities were low every day except for the 10th, which increased to 35 particles per cubic centimetre. Bz never varied more that minus 7 and plus 8 nanoTeslas during the period.

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 low most days but could increase to moderate levels on some days. Solar flux levels should be at their lowest for this solar rotation and be around the 110’s but should start to increase again later in the week. Geomagnetic activity is expected to start the period at quiet levels but then increase after midweek due to a recurring coronal hole. MUFs during daylight hours at equal latitudes should be around 30MHz. Darkness hour lows should be about 8MHz. Paths this week to Australia should have a maximum usable frequency with a 50 per cent success rate of around 29MHz. The optimum working frequency with a 90 per cent success rate will be about 24MHz. The best time to try this path will be between 0900 and 1200 hours.

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

Category: GB2RS Propagation News