Propagation News 22 December 2013

| December 20, 2013

During the period several new sunspot regions appeared but none were capable of producing anything stronger than small C class solar flares, which had no effect on propagation. However, with less than an hour to go before the end of the period an impulsive M3 class solar flare took place from a region that is just starting to rotate into view. Solar flux levels declined slightly from 163 units on the 13th to 153 by the 19th. The average was 158 units. The 90 day solar flux average on the 19th was 140 units, which is five units up on the previous week. X-ray flux levels varied little day to day and averaged B7.1 units. Geomagnetic activity was quiet every day except for the 14th, which increased slightly due to a small recurring coronal hole. The Ap index was 12 units and the average was Ap 4 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from a slow 270 kilometres per second on the 13th to 610 by the next day. Speeds then gradually declined to 340 by the 18th. Particle densities were low most days but increased to 108 particles per cubic centimetre on the 13th. On the quiet days the Bz varied between minus 4 and plus 3 nanoTeslas and between minus 12 and plus 14 nanoTeslas on the 14th which was the most disturbed day.

Finally, the solar forecast. For the next two weeks solar activity is expected to be mostly at low levels but there is a chance that activity could increase, mostly to moderate levels on some days. Solar flux levels are expected to be around the 160s for most of the period but could increase slightly during the second week. Geomagnetic activity is expected to be mostly quiet, however, two coronal hole disturbances are expected to increase activity, the first on the 26th and the 27th of December and again on the 3rd and the 4th of January. MUFs during daylight hours at equal latitudes should be around 30MHz or slightly higher. Darkness hour lows should be about 7MHz. Paths for the next two weeks to the east coast of North America should have a maximum usable frequency with a 50 per cent success rate of around 34MHz. The optimum working frequency with a 90 per cent success rate will be about 28MHz. The best time to try this path will be between 1200 and 1700 UTC. A short but reliable sporadic E season takes place during the Christmas and New Year period, with openings up to 50MHz.

Good DX for 2014 to everybody.

Category: GB2RS Propagation News