Solar Flux Index Today
The solar flux index (SFI) is the intensity of solar radio emissions at 10.7 cm (2,800 MHz).
The SFI represents the level of solar activity. Higher solar flux increases ionization in the ionosphere, enhancing HF radio propagation and enabling long-distance communication for ham radio operators. However, it can also lead to increased radio noise and potential disruptions. Monitoring solar flux as well as other propagation indicators is essential for optimizing communication strategies and maintaining reliable connections.
Currently, SFI is Loading solar flux data... (solar flux units, where 1 sfu=10⁻²² watts per meter²/Hz).
The NOAA Space Weather Prediction Center provided this data.
Solar Flux and HF Radio Propagation
Higher SFI values correlate with improved HF propagation conditions:
| SFI (sfu) | 67 | 83 | 102 | 124 | 148 | 172 | 196 | 219 | 240 | 273 |
| SSN | 0 | 25 | 50 | 75 | 100 | 125 | 150 | 175 | 200 | 250 |
| MUF (MHz) | <12 | <15 | > 21 | > 24 | > 28 | > 50 | ||||
| HF Conditions | BAD | Low | Average | Good | Better | Best | ||||
|---|---|---|---|---|---|---|---|---|---|---|
The project Understanding HF Propagation provides a detailed overview and tutorials covering this subject.
In particular, read there about the solar indices.
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