VE2XIP had a problem I’ve encountered but he did something about it. Understanding HF propagation reports provides a good summary about solar indices that mean something for the hf radio amateur.
The Solar Flux and Sunspot numbers measure solar activity and higher values indicate better hf conditions.
“High SFI values has almost no influence on 30m,40m,80m and 160m bands. SFI value over 150 indicates ideal HF propagation conditions … if you see SN numbers over 100, you can expect good propagation conditions, if and when these spots are facing us.”
The other factors are about geomagnetic activity and, for these, lower is usually better. The A index can go up to 400 but values below 5 are best for the upper hf bands. The K index goes between 0 and 9 and values lower than 4 are best for the upper hf bands.
Of course, this is just a recipe. The real fun gets into understanding the interaction between the atmosphere and radio waves, the sun and the atmosphere, and the earth’s magnetic field and the sun and the atmosphere. There is a lot to learn about here.
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