GB2RS News

Now the solar factual data for the period from the 25th to the 31st of January, compiled by Neil Clarke, G0CAS on the 1st of February.

The active group that was mentioned in last weeks report that produced the M class solar flares remained visible even though it decreased in size every day until it disappeared on the 31st. The group never produced any more flares and solar activity was very low every day. Meanwhile, elsewhere on the solar disc a group emerged on the 30th and grew in size rapidly. Growth slowed on the 31st. Likewise, this group as so far remained quiet. Solar flux levels declined from 81 units on the 25th to 73 by the 29th. The average was 77. The 90 day solar flux average on the 31st was also 77 units. That’s the same level as last week. Geomagnetic activity was quiet everyday. The most disturbed day was the 30th with an Ap index of only 4 units. The average was Ap 3 units. Solar wind data from the ACE spacecraft saw solar wind speeds vary between 320 and 450 kilometres per second. Particle densities were low except for the 28th and the 30th which increased to 15 and 19 particles per cubic centimetre respectively. Bz fluctuated no more than minus and plus 7 nanoTeslas for the period.
And finally the solar forecast. A lot will depend this week on if any sunspot groups appear. Solar activity is expected to be very low. There will be a slight chance of activity increasing to low. Solar flux levels are expected to be into the 80s if spots do appear or the 70s if the solar disc is spotless. Geomagnetic activity is expected to be at quiet levels everyday. MUFs during daylight hours at equal latitudes are expected to be about 23MHz for the south and 20MHz for the north. Darkness hour lows should be around 8MHz. Paths this week to Japan should have a maximum usable frequency with a 50 per cent success rate of around 19MHz. The optimum working frequency with a 90 per cent success rate will be about 15MHz. The best time to try this path will be between 0800 and 1100 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