Propagation News – 16 February 2014

Solar activity was moderate to high, with multiple M-class flares an almost daily occurrence, in addition to numerous C-class flares. However, although a number of coronal mass ejections were reported none of them proved to have a substantial Earth-directed component. As predicted, the solar flux declined, from 178 on the 7th to 167 on the 13th. The average for the week was 169 – a drop of 16 units. However, the 90-day average was an unchanged 155. The X-ray flux stayed high, averaging a healthy C1.3. Geomagnetic levels were a bit higher than in the last week or so, with the Ap index reaching 23 on the 8th, 18 on the 9th and a slightly unsettled 12 on the 10th. This was enough to depress MUFs on the HF bands and allow Scandinavian operators to report aurora at VHF – but insufficient for UK operators to make auroral contacts. The Ap index was at quiet or slightly unsettled level during the remainder of the period. Wind speeds reported by the ACE spacecraft ranged between 283km/sec on the 7th and 565km/sec on the 11th.

Finally, the forecast for the coming week. The active region that played a major role during the past week will be moving away from a geoeffective position and succeeding regions have yet to show signs of bringing increased activity. C-class and M-class flares may occur but there is only an outside chance of a major X-class flare. Solar activity may be low on some days. Solar flux looks likely to continue the decline of recent days, possibly to as low as 140. The geomagnetic field may be unsettled over the next couple of days as a result of coronal hole activity, but should be quiet or slightly unsettled for the rest of the period. Aided by seasonal factors, MUFs at equal latitudes should reach 32MHz on the better days, while darkness lows are expected to be about 9MHz. Paths to eastern North America should have an MUF – that’s a 50 percent chance of a contact – of 32MHz. The optimum working frequency, at which there should be a 90 percent chance of success, will be 25MHz. The path should be best between 1400 and 1700UTC. West Coast contacts will be more difficult but may be possible on good days around 1600UTC.

Category: GB2RS Propagation News