And now the solar factual data for the period from Friday the 11th to Thursday the 17th of May, compiled by Neil Clarke, G0CAS on Friday 18th of May.
The large solar flare producing the sunspot region mentioned in last week’s report remained visible till the 17th, when it rotated out if view. The group showed gradual decay from the 11th and produced several C class solar flares every day until early on the 17th, when it produced a M5 proton solar flare. A large coronal mass ejection also took place. Solar flux levels declined from 136 units on the 11th to 129 by the 15th. The average was 132 units. The 90 day solar flux average on the 17th was 115 units, that’s two units up on last week. X-ray flux levels declined slightly from B6.1 units on the 11th to B4.3 by the 14th. The average was B5.1 units. Geomagnetic activity started at unsettled levels due to a coronal hole disturbance. The 13th was the most disturbed, with an Ap index of 14 units. From the 14th onwards, activity had declined to quiet levels. The average was Ap 9 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 650 kilometres per second on the 11th to 340 by the end of the period. Particle densities were low every day. Bz varied between minus 7 and plus 10 nanoTeslas on the 17th and between minus 2 and plus 3 nanoTeslas on the quietest day, the 14th. Sporadic-E took place most days on bands between 28 and 70MHz with reflections up to 100MHz on occasional days, but there are no reports yet of anything on 144MHz.
And finally the solar forecast. This week, the quieter side of the Sun is expected to be rotating into view. Solar activity is expected to be at low levels but, on occasions, there may be a small chance that activity could increase to moderate levels. Solar flux levels should decline and be around 110 units later in the week. Geomagnetic activity is expected to start at quiet levels but around midweek a recurring coronal hole disturbance is expected. This disturbance should be over by next weekend. MUFs during daylight hours at equal latitudes should be around 24MHz for the south and 21MHz for the north. Darkness hour lows should be about 13MHz. Paths this week to Australia should have a maximum usable frequency with a 50 per cent success rate of around 22MHz. The optimum working frequency with a 90 per cent success rate will be about 17MHz. The best time to try this path will be between 0900 and 1200 hours. Interestingly, the long path will be at its best around 2200 hours and the MUF could be up to 24MHz. Sporadic-E is expected on most days, with openings up to 70MHz on some days. If any intense openings take place then 144MHz could be reached.
And that’s all for this week from the propagation team.