Friday, December 18, 2009

Smoothed sunspot number data updated

I have just updated the file of smoothed sunspot numbers (SSN) for VOAProp from this NOAA data file: ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/sunspot.predict.

I see that the maximum is being predicted to occur in March 2013 with a value of just 83.3 - about what we had half way through the decline of the previous cycle at the start of 2003, if you can remember what conditions then were like.

The smoothed figures put the minimum of the last cycle as last December, a year ago, with a value of 1.7. The predictions now run up to 2020 and the minimum of the next cycle is expected to be in January of that year with an SSN of 5.6.

This is the first time I have updated the SSN data file for about six months. I think that NOAA updates the data every month, but VOAProp requires the data in a different format. Updating it is something of a chore and I can't be bothered to do it very often as it doesn't change all that much from month to month.

I rarely use VOAProp myself and have come to the conclusion that propagation prediction software is almost worthless for amateur use, except to demonstrate to newcomers to HF radio the broad principles of how the time of day, the seasons and solar activity affect propagation to different parts of the globe.

The VOACAP engine used by VOAProp was developed by a short wave broadcaster and designed for broadcast use, and broadcasters are concerned about where and when propagation is reliable and strong. It is the fleeting moments of unpredictable propagation that are of most interest to we amateurs. I think the results of real-time prediction monitoring carried out by users of WSPR and Propagation Reporter are of far more use in showing what propagation is really like.
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