GB2RS News

And now the solar factual data for the period from Friday the 20th to Thursday the 26th of January, compiled by Neil Clarke, G0CAS on the 27th of January.

The two large sunspot regions mentioned in last week’s report continued to dominate the solar disc and solar activity. Numerous C class solar flares took place on a daily basis but the largest event was a long duration M8 proton solar flare during the morning of the 23rd. Associated with this event were multi-frequency radio emissions spanning from 25MHz through to 15.4GHz, a fast moving large coronal mass ejection and a sudden ionospheric disturbance. Solar flux levels declined from 142 units on the 21st to 126 by the 25th. The average was 137 units. The 90 day solar flux average on the 26th was 143, that’s one unit down on last week. X-ray flux levels varied little day to day and averaged B5.8 units. Geomagnetic activity started at quiet levels but during the early hours of the 22nd a coronal mass ejection arrived from the solar flare of the 19th. The Ap index for the 22nd was 24 units. This was the first disturbed day since the 1st of November last year. Then around 1500 hours on the 24th a second, faster coronal mass ejection arrived associated with the M8 flare from the 23rd. This disturbance did not last as long but the Ap index for the 24th was also 24 units. Activity then declined back to quiet levels by the 26th. The average was Ap 13 units. Solar wind data from the ACE spacecraft saw solar wind speeds increase from 290 kilometres per second on the 21st to 650 by the 25th. Particle densities increased to 63 particles per cubic centimetre during the 22nd. Bz varied between minus 4 and plus 6 nanoTeslas on the quietest day and between minus 29 and plus 28 nanoTeslas on the 22nd and between minus 18 and plus 29 nanoTeslas during the 24th.
Radio aurora took place on four consecutive days from the 22nd. By far the strongest was the evening of the 22nd, which lasted into the 23rd, when stations on the south coast could participate. Northern England and Scotland also had the pleasure of an exceptional visual aurora, where skies were clear of clouds. Further down the radio spectrum, the HF bands were badly degraded especially the high latitude paths. However, they recovered quite rapidly with MUFs back up to 27MHz or higher with paths to Africa and South America on 28MHz better than expected considering magnetic levels.
And finally the solar forecast. This week the slightly quieter side of the Sun is expected to be facing our way. Solar activity should be low on most days with only a slight chance that activity will increase to moderate levels. Solar flux levels should be in the 120s for most of the week. Geomagnetic activity is expected to be quiet everyday. This week there is only a small chance that any coronal mass ejections will head our way. MUFs during daylight hours at equal latitudes should be around 29MHz. Darkness hour lows are expected to be about 8MHz. Paths this week to the east coast of North America should have a maximum usable frequency with a 50 per cent success rate of around 28MHz. The optimum working frequency with a 50 per cent success rate will be about 21MHz. The best time to try this path will be between 1300 and 1800 hours UTC.
And that’s all for this week from the propagation team.

The RSGB propagation news is also available in a Saturday update, posted every Saturday evening and for more on propagation generally, see http://www.rsgb.org/committees/psc.php

Also see the UK HF Propagation Prediction pages by Gwyn Williams, G4FKH