Influence of evaporation ducts on radar sea return

Modelling of radar sea return is discussed with consideration of propagation conditions. Both the intensity and propagation direction of energy incident at the sea surface can be significantly affected by the refractive condition of the atmosphere. The paper describes and evaluates a model that incorporates both of these effects for the situation where the propagation conditions are characterised as evaporation ducts. Such ducts are the most persistent marine propagation environment on a worldwide basis for low- altitude propagation. It is shown that commonly encountered evaporation ducts can profoundly affect sea returns.