Propagation – 24th March 2013

| March 24, 2013

And now the solar report for the period from Friday 15 March to Thursday the 21st, compiled by Martin Harrison, G3USF, on Friday the 22nd.

Solar activity remained mostly low, though C-class flares were reported almost every day, and a smallish M-class flare occurred on the 21st. The solar flux slowly declined, from 123 on the 15th to 106 on the 21st. The average was 116, a drop of four points on the previous week’s level. However, the 90-day average was unchanged, also at 116. The X-ray flux showed little daily variation and averaged B3.0. At the start of the period geomagnetic activity was low, with an Ap of 6 units. It rose to an unsettled Ap of 10 on the 16th as a result of a coronal mass ejection on the 12th. This was followed by a jump to minor storm level early on the 17th, caused by another coronal mass ejection on the 15th. Solar wind speeds increased to 790km/sec on the 17th. MUFs were depressed by several MHz throughout the day, with east-west and high-latitude paths the most severely affected. VHF aurora was reported during most of the day, peaking around 1600 to1700 and reaching all areas of the UK, with contacts into Scandinavia and Germany on both 50 and 144MHz. This was the best auroral event so far this year. Geomagnetic activity then fell back to quiet levels for the next few days, but was back to an unsettled Ap of 10 on the 21st, again as a result of coronal hole effects.

Now the forecast for the week from today. Solar activity will mostly continue to be mostly low, with mostly C-class flares, though there is potential for an occasional M-class flare. And there is always a chance of an Earth-directed coronal mass ejection. In the light of the events of the past week it is perhaps worth a reminder that chances of auroral events tend to be greater around the equinoxes. This week, MUFs at equal latitudes should be around 24MHz in southern Britain and 21MHz in the north. Paths to India and South-East Asia should have a maximum usable frequency of 32MHz, where there should be a 50 per cent chance of a QSO. The optimum working frequency, where there should be a 90 per cent chance of success, will be around 26MHz. The best times for this path will be between 0800 and 1400.UTC

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

Category: GB2RS Propagation News