Propagation News – 2 March 2014

| February 28, 2014

Solar activity increased from low to moderate on the 23rd when one M class solar flare took place and again on the 24th when two took place. Activity increased further to high levels on the 25th when an X4 class flare occurred. The sunspot group responsible for the majority of these flares rotated into view on the 24th. Solar flux levels increased from 157 units on the 21st to 178 by the 26th, the average was 170 units. The 90 day solar flux average on the 27th was 158, that’s three units up on last week. X-ray flux levels increased slightly to peak at C1 units in the 25th. The average was B9.3 units. Geomagnetic activity started the period at slightly unsettled levels with an Ap index of 13 units on the 22nd and 17 the following day. Quiet conditions returned till the afternoon of the 27th when a coronal mass ejection arrived in association with the X4 class solar flare. The Ap index on the 27th was 24 units and the average for the period was Ap 11 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 570 kilometres per second on the 21st to 330 during the morning of the 27th. Speeds increased to 520 kilometres per second with the arrival of the coronal mass ejection. Particle densities were low except for an increase to 28 particles per cubic centimetre on the 23rd and to 82 during the afternoon of the 27th. Bz varied between minus and plus 3 nanoTeslas on the quiet days and between minus 18 and plus 14 nanoTeslas at the height of the disturbance during the afternoon of the 27th.

Finally, the solar forecast for the coming week. This week solar activity is expected to continue at moderate levels on some days but for activity to increase to high is unlikely. Solar flux levels are expected to be around the 170′s for most of the week. Geomagnetic activity is expected to be quiet every day. However, an Earth directed coronal mass ejection is possible, which would increase activity on its arrival. MUFs during daylight hours at equal latitudes are expected to be around 30MHz or slightly higher. Paths this week to the east coast of North America should have a maximum usable frequency with a 50 percent success rate of around 31MHz. The optimum working frequency with a 90 percent success rate of about 25MHz. The best time to try this path will be between 1400 and 1900 hours UTC.

Category: GB2RS Propagation News

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