Propagation News – 16 June 2013

| June 14, 2013

And now the solar factual data for the period from Friday the 7th to Thursday the 13th of June compiled by Neil Clarke, G0CAS on Friday the 14th of June.

At first four sunspot groups were visible but this declined to only one on the 10th and the 11th. Solar activity started at high levels on the 7th when an M5 solar flare took place from a sunspot group that was in the process of rotating out of view. Activity then declined to low levels till the 10th and then from the 11th to very low levels when no solar flares took place. Solar flux levels declined from 110 units on the 7th to 90 by the 12th, however, levels increased to 99 units by the end of the period. The average was 98 units. The 90 day solar flux average on the 13th was 121. That’s one unit down on last week. X-ray flux levels declined from B2.5 units on the 7th to B1.3 by the 11th. The average was B1.8 units. Geomagnetic activity started at storm levels, probably due to a glancing blow from a coronal mass ejection that departed the Sun a couple of days earlier. The Ap index for the 7th was 42 units. Activity then declined to quiet levels for the rest of the period. The average was Ap 12 units. Solar wind data from the ACE spacecraft saw solar wind speeds vary between 340 and 490 kilometres per second. Particle densities were high at the start of the period with a peak of 44 particles per cubic centimetre on the 10th. Densities declined by the end of the period. Bz varied 12 and plus 10 nanoTeslas on the 7th when there was a 15 hour period when the Bz was negative. Bz varied between minus and plus 4 nanoTeslas on the quieter days. During the afternoon of the 12th a Sporadic-E opening took place from the UK to central and southern Europe on 144MHz.

And finally the solar forecast for the coming week. This week solar activity is expected to be low but activity could increase to moderate levels especially later in the week. Solar flux levels should increase and be approaching or into the 120s. Geomagnetic activity is expected to start the forecast period at quiet levels but later in the week and next weekend activity is expected to increase due to a recurring coronal hole. MUFs during daylight hours are expected to be around 23MHz for the south and 20MHz for the north. Darkness hour lows should be about 13MHz. Levels could be lower later in the week due to the anticipated increase in geomagnetic activity. Paths this week via the short path to Australia should have a maximum usable frequency with a 50 per cent success rate of around 21MHz. The optimum working frequency with a 90 per cent success rate will be about 16MHz. The best time to try this path will be between 0700 and 1100 hours. MUFs via the long path will be slightly higher and the best time for this path will be during the evening. Sporadic-E is expected to take place most days this week. The coming week and the week after normally, but not always sees the best openings up to 144MHz.

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

Category: GB2RS Propagation News

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