Propagation News – 30 June 2013

| June 28, 2013

And now the solar factual data for the period from Friday the 21st to Thursday the 27th of June compiled by Neil Clarke, G0CAS on Friday the 28th of June.

Up to eight sunspot groups were visible on some days. Most were small and quiet but a couple of groups produced an M class solar flare on the 21st and again on the 23rd. Otherwise, solar activity was at low levels. Solar flux levels declined from 133 units on the 21st to 100 by the 27th. The average was 118 units. The 90 day solar flux average on the 27th was 123 units, that’s two units up on last week. X-ray flux levels declined from B5.5 units on the 21st to B2.6 by the 27th. The average was B4.3 units. Due to a large recurring coronal hole, geomagnetic activity started the period at unsettled levels. The most disturbed day was the 24th, with an Ap index of 20 units. The 26th was quiet, with an Ap index of only 3 units, before a weak coronal mass ejection disturbance arrived the next day with an Ap of 8 units. The average was Ap 13 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase to 770 kilometres per second on the 23rd and then decline to 360 by the morning of the 27th. Particle densities were low except from a brief increase to 16 particles per cubic centimetre on the 21st and 25 on the 27th. Bz varied between minus 8 and plus 10 nanoTeslas during the disturbance and between minus 3 and plus 2 nanoTeslas on the quietest day.

And finally the solar forecast for the coming week. This week solar activity is expected to start at low levels but from midweek activity could increase on some days. An active sunspot region is expected to rotate into view by Monday or Tuesday. Solar flux levels could be around 100 units at first but should then increase to around 120 units. Geomagnetic activity is expected to be at quiet levels till the end of the week when a small recurring coronal hole is expected to increase activity slightly. MUFs during daylight hours at equal latitudes should be around 22MHz for the south and 19MHz for the north. Darkness hour lows should be around 14MHz. Paths this week to India should have maximum usable frequency with a 50 per cent success rate of about 22MHz. The optimum working frequency with a 90 per cent success rate will be around 17MHz. The best time to try this path will be between 1000 and 1700 hours UTC. Sporadic-E should take place most days with openings up to 144MHz still possible especially during the more intense openings.

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

Category: GB2RS Propagation News