For transmission 7 February 2010
Sorry: the usual update could not be posted here at the usual time because of a changeover in computer systems. G3USF
Now the solar report and forecast, prepared by Neil, G0CAS, and Martin, G3USF.
The active sunspot group referred to in last week’s report eventually disappeared on the 31st. Solar activity remained very low until yesterday, when a couple of smallish C-class flares were reported. The average solar flux for the week was 4 points down at 75. The 90-day average was unchanged at 77. The X-ray flux declined from an average A7.0 to a shade under A3.0. However, solar wind speeds were somewhat higher, increasing from 325km/sec on the 30th to 597km/sec on the 3rd, when Earth was battered by a high-speed coronal stream, which brought unsettled geomagnetic levels. It has since fallen back again to 316km/sec The Ap index went up to 9 on the 2nd and 3rd. Even so, the average daily Ap figure for the week was only a modest 5. Particle densities were little affected and mostly stayed in single figures. The interplanetary magnetic field, Bz, varied between plus and minus 6 nanoTeslas.
Looking ahead now, we currently have three cycle 24 groups in view. They produced two C-class flares up to the time this report was prepared yesterday and appear very likely to give rise to more. The solar flux has already picked up and seems likely to return to at least the 80s. More important in terms of propagation, the geomagnetic field is expected to stay predominantly quiet, though coronal hole activity may lead to unsettled or even active levels midweek. Expect MUFs at equal latitudes to be about 23MHz in southern Britain and 20MHz in the north. Darkness hour lows should be in the vicinity of 8MHz. Paths to the Far East are expected to have a maximum usable frequency, that’s a 50 per cent probability of success, around 19MHz. The Optimum Working Frequency, which should be workable almost every day, will be about 15MHz. The best time to work out there will be between 0800 and 1100UTC. So look for good morning openings on 14MHz, followed by propagation to western North America around 1600.
And that’s all for another week from the propagation team.
___________________________________________________________________________