Friday, 24 January 2014
I have now updated my HF propagation prediction charts for the first quarter of 2014 to take into account the latest predicted smoothed sunspot numbers. It is generally thought that we may now be at or past the second hump of this sunspot maximum, but the sun continues to throw some surprises.
For example, the observed sunspot numbers for the last six months of 2013 were 57.0, 66.0, 36.9, 85.6, 77.6 and 90.3, which shows the great variation.
The current predicted smoothed sunspot number (which is that recommended for VOACAP-based prediction programs) is about 61-62 for the next three months.
This equates to a 10.7cm solar flux index of about 110 (on 24th January it was 136 with an actual sunspot number of 121).
A flux over 100 suggests that 10m will continue to open on a fairly regular basis and the next few months should throw up some good opportunities for DX on the higher bands. However, the longer-term trend may be downwards.
On the downward side of the cycle we may also experience more unsettled conditions due to flares and coronal mass ejections. These may cause short-term D-layer absorption, poor or noisy conditions (especially on routes over the poles) or depletion of the F layer (with corresponding poor conditions on the upper HF bands). Looking on the bright side it may also give raise to aurorae.
The short-path HF predictions from the UK can be found via a link on the top right or by clicking here.
If you want to produce more detailed point-to-point calculations (and don't have your own program) I recommend VOACAP online at http://www.voacap.com/prediction.html
You can keep track of the current state of the sun at www.solarham.com
Chairman, RSGB Propagation Studies Committee