Four Dimensional System Engineering Demands on Radar Operating in a Coastal Sub-refractive Environment

Surface sub-refraction in the littorals reduces radio frequency (RF) horizon and introduces an expensive ameliorating system margin requirement. Along coastal Virginia, sub-refractive events are driven by synoptic scale meteorological features with three day time scales. Air/land/sea interactions introduce diurnal and mesoscale variations. This paper describes these inhomogeneities in terms of range dependent propagation factor loss relative to a standard atmosphere. Four dimensional thermodynamic profiles supporting the refractivity field calculation are provided by the Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS). The Advanced Refractivity Effects Prediction System (AREPS) is employed to predict the performance of notional S and X band radars operating 24 nm offshore.