Propagation – 28 April 2013

| April 26, 2013

And now the solar factual data for the period from Friday the 19th to Thursday the 25th of April compiled by Neil Clarke, G0CAS on Friday the 26th of April.

Sunspot regions were visible every day throughout the period, with one group which was much larger and magnetically complex than the others. This region produced numerous C class solar flares every day and on the 22nd an impulsive M1 class solar flare took place, which increased activity from low to moderate levels. Solar flux levels increased from 99 units on the 19th to 119 by the 25th. The average was 111 units. The 90 day solar flux average on the 25th was 112 units, that’s one unit up on last week. X-ray flux levels increased from B2.5 units on the 19th to B7.3 by the 25th, the average was B4.5 units. Geomagnetic activity was quiet every day till the 24th, when a predicted coronal hole disturbance arrived late on the 23rd. The Ap index for the 24th was 24 units. The average was Ap 7 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from a very slow 240 kilometres per second on the 21st to peak at 480 by the 24th. Particle densities were low initially but increased to 105 particles per cubic centimetre on the 23rd and 168 on the 24th. I feel sure that these are the highest densities record here on GB2RS. Bz varied between minus 5 and plus 6 nanoTeslas prior to the arrival of the coronal hole disturbance and between minus 12 and plus 11 nanoTeslas during the disturbance. A good sporadic-E opening took place during the afternoon of the 24th on 50MHz. Also, around the same time, an aurora reached the north of Scotland.

And finally the solar forecast for the coming week. This week the more active side of the Sun is expected to be looking our way. Several sunspot regions should be in view, with more rotating into view during the week. These regions have produced solar flares while on the far side of the Sun. Solar activity is expected to be low but could increase to moderate or high on the occasional day. Solar flux levels are expected to increase and be around 130 units for most of the week. Geomagnetic activity is expected to be at quiet levels but if a coronal mass ejection heads our way then activity would increase. MUFs during daylight hours at equal latitudes should be around 23MHz for the south and 20MHz for the north. Darkness hour lows should be about 12Mhz. Paths this week to Australia should have a maximum usable frequency with a 50 per cent success rate of around 24MHz. The optimum working frequency with a 90 per cent success rate will be about 18MHz. The best time to try this path will be between 0900 and 1100 hours UTC. Sporadic-E should take place on some days, especially on 28MHz and occasionally on 50MHz.

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

Category: GB2RS Propagation News

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