Propagation News – 26 January 2014

| January 24, 2014

For the fifth successive week solar activity was low or very low. Each day brought a scattering of C-class flares, but there were none of greater magnitude. These had little effect on propagation. However, solar flux levels recovered some of the ground lost in the previous week, starting the period at 125 units and reaching 136 units on the 23rd. The average over the week was 134. The 90 day flux average dropped to B3.6 on th 23rd. The average was B3.9. Geomagnetic activity was mostly low or very low, with the Ap index in single figures every day. The highest reading was a slightly unsettled 9 units on the 22nd. Solar wind speeds ranged between a low of 270km/sec on the 19th and 584km/sec on the 22nd, when Earth was buffeted by a high speed coronal stream. Particle densities were low every day except for the 21st, when they increased to 29 particles per cubic centimetre. Bz varied, at most, between minus 8 and plus 9 nanoTeslas, during the period. The combination of substantial solar flux levels and low geomagnetic activity made for good HF conditions, with all continents workable up to 28MHz on a daily basis.

Finally, the solar forecast for the coming week. This week the more active side of the Sun is expected to be looking our way. Solar activity is expected to be initially low, but there is a fair chance it will increase to moderate at times. Solar flux levels should improve, possibly reaching 160 in the second half of the week. Geomagnetic activity is expected to start at quiet levels but then increase somewhat around midweek due to a recurring coronal hole. And, as is so often the case, there is an outside chance of an upset arising from an Earth-directed coronal mass ejection. MUFs during daylight hours at equal latitudes should be around 30MHz. Darkness hour lows should be about 8MHz. Paths this week to South America should have a maximum useable frequency with a 50 percent success rate of around 235MHz. The optimum working frequency with a 90 percent success rate will be around 28MHz. The best time to try this path will be between 1100 and 1700UTC.

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

Category: GB2RS Propagation News

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