Propagation News – 23 February 2014

| February 21, 2014

Solar activity increased to moderate levels on the 14th when four M class solar flares took place and again on the 16th and the 20th when a single M class flare took place. Solar activity on the remaining days was low when numerous C class flares occurred. Solar flux levels declined from 167 units on the 14th to 151 by the 18th. The average was 157 units. The 90 day solar flux average on the 20th was 155 units. X-ray flux levels declined slightly and ended the period at B7.5 units. The average was B8.5 units. Geomagnetic activity started at quiet levels with an Ap index of only 2 units on the 14th before increasing on the 16th to an Ap of 18 units, due to a coronal hole. The second disturbance on the 19th and the 20th was much stronger when the Ap increased to 42 and 40 units respectively, this was due to a coronal mass ejection that departed the sun on the 16th. The average was Ap 17 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 300 to 540 kilometres per second. Particle densities were high most days with 62 particles per cubic centimetre recorded on the 15th. Bz varied between minus and plus 3 nanoTeslas on the quietest day and between minus 18 and plus 15 nanoTeslas on the 19th and the 20th.

And finally, the solar forecast. Two returning active sunspot regions should have just rotated into view. Therefore, solar activity is expected to increase to moderate levels on some days. There is a small chance that activity could increase to high on the occasional day. Certainly, solar flux levels are expected to increase to around the 170s, or maybe slightly higher. Geomagnetic activity is expected to be mostly quiet but a recurring coronal hole disturbance is expected on the 25th. MUFs during daylight hours at equal latitudes should be around 30MHz. Darkness hour lows should be about 9MHz. Paths this week to Japan should have a maximum usable frequency with a 50 per cent success rate of around 26MHz. The optimum working frequency with a 90 per success rate will be about 20MHz. The best time to try this path will be around 0800 hours.

Category: GB2RS Propagation News