Propagation News – 2 June 2013

| May 31, 2013

And now the solar factual data for the period from Friday the 24th to Thursday the 30th of May, compiled by Neil Clarke, G0CAS on Friday the 31st of May.

The large sunspot groups from the previous week decayed and simplified this week, as a result solar activity declined to low levels on most days with only small strength C class solar flares taking place. On the 27th, 28th and the 30th solar activity decreased further to very low levels when no C class solar flares took place. Solar flux levels declined from 127 units on the 24th to 104 by the 30th. The average was 113 units. The 90 day solar flux average on the 30th was 123 units, that’s one unit up on last week. Geomagnetic activity started the period at minor storm levels with an Ap index of 23 and 40 units on the 24th and the 25th respectively. Activity then declined to quiet levels till the end of the period. The average was Ap 15 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase to 850 kilometres per second on the 25th and again on the 28th. Speeds then declined to 350 kilometres per second on the 30th. Particle densities started the period at 18 particles per cubic centimetre but declined to 1 particle per cubic centimetre for the last three days of the period. Bz varied between minus 14 and plus 11 nanoTeslas during the disturbance and between minus 1 and plus 2 nanoTeslas on the quietest day. A weak radio aurora took place during the disturbance, however, few contacts were made from the UK.

And finally the solar forecast for the coming week. This week the more active side of the Sun is expected to rotate into view. It will though be later in the week before solar activity could increase to moderate levels. Solar flux levels will gradually increase and could be up to the 130’s by next weekend or even slightly higher. Geomagnetic activity could be unsettled today and tomorrow due to a recurring coronal hole. However, activity should decline for the remainder of the week. MUFs during daylight hours at equal latitudes should be around 23MHz for the south and 20MHz for the north. Darkness hour lows should be around 13MHz. Path this week to the east coast of North America 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 1600 and 2200 hours. Levels will be somewhat lower if geomagnetic activity increases. Sporadic-E is expected most days with opens up to 144MHz possible during any larger more intense openings.

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

Category: GB2RS Propagation News