Models of HF spectral occupancy over a sunspot cycle.

A long-term joint UK–Swedish–German project has been undertaken on the measurement and analysis of HF spectral occupancy over northern Europe. This has resulted in an extensive database of spectral occupancy measurements made at four sites over a complete sunspot cycle, and mathematical models for spectral occupancy have been developed. The procedures for measuring and modelling spectral occupancy are briefly presented, with final stable-day and stable-night models for northern Europe, when using calibrated monopole antennas. Accuracy of fit and examples of extrapolation in time and in space are presented. [ABSTRACT FROM AUTHOR]