On the knowledge of radar coverage at sea using real time refractivity from clutter

The principle of `refractivity from clutter` (RFC) is to invert the radar sea clutter data to retrieve the refractive index conditions in the low troposphere. This method enables to foresee radar coverage especially in the presence of abnormal refractive conditions. First, this study introduces a new formulation of the radar equation and clarifies the physical hypotheses applied in RFC. This formulation takes into account the sea clutter variations because of the grazing angle variations at very low angle and the refraction effects in one single term. This work also focuses on the analysis of results obtained using the real time `improved best fit` (IBF) inversion method for RFC. The latter is summarised and discussed with main attention on the reliability of the inverted data and on their relevancy with respect to the prediction of radar coverage.