Solar activity was low every day except for the 24th when the only M class solar flare took place, increasing activity to moderate levels. Only 24 C class solar flares occurred during the period. Solar flux levels declined from 118 units on the 24th to 99 by the 28th, which is the lowest level since last September. By the next day levels had increased to 101 units. The average was 109 units. The 90 day solar flux average on the 29th was 142 units, that’s five units down on last week. X-ray flux levels declined from B4.9 units on the 24th to B2.5 by the 28th and the average was B3.5 units. Geomagnetic activity started at unsettled levels on the 23rd with an Ap index of 19 units. This was due to a small coronal hole. Activity then declined to quiet levels for the remainder of the period and the average was Ap 7 units. Solar wind data from the ACE spacecraft saw solar wind speeds decline from 570 kilometres per second on the 23rd to 280 by the 27th. Particle densities were low except for a brief increase to 22 particles per cubic centimetre on the 27th, and 16 on the 28th and the 29th. Bz varied between minus 12 and plus 15 nanoTeslas on the 23rd, which was the most disturbed, and between minus 3 and plus 1 on the quietest day. Although Sporadic-E occurred it was rather poor for late May.
Finally, the solar forecast for the coming week. The slightly more active side of the Sun is expected to be rotating into view. Solar activity is expected to mostly low with C class solar flares taking place on most days. Solar flux levels should increase as the week progresses and be around the 120’s next weekend. Geomagnetic activity is expected to be quiet at first but from midweek activity is expected to increase in response to a recurring coronal hole. MUFs during daylight hours are expected to be around 22MHz. Darkness hour lows should be about 14MHz. Paths this week to Japan should have a maximum usable frequency with a 50 per cent success of around 20MHz. The optimum working frequency with a 90 percent success rate will be about 15MHz. The best time to try this path will be between 1000 and 1300 hours. Sporadic-E is expected to take place most days, with opening up to 70MHz. There is a slight chance of openings up to 144MHz.
Category: GB2RS Propagation News