Infrared characterization and detection of ship wake based on ray tracing method

When the ship sails on the sea, a wake of several kilometers length and long continuous time will appear behind the ship. The bases for detecting ship through the infrared characterization of wake are provided by the apparent feathers of ship wake. Visible simulation of wake was achieved from the characterization of ship wake. An infrared imaging model of ship wake was established based on Cook-Torrance model. The infrared imaging characterization under different detecting conditions was obtained with ray tracing method, considering the environment influence of solar radiation, sky background radiation and atmospheric transmission comprehensively. Results indicate that, sea surface is integrally dark and ship wake is apparent at low elevation angle while the sea surface bright and ship wake weak at high elevation angle; the imaging characterization of Kelvin wake is weakly affected by air temperature, and turbulent wake is a dark band at low elevation angle and air temperature but a bright band at high air temperature; Kelvin wake will be eventually unrecognizable with increasing sea surface wind velocity, then the turbulent wake is the only ship wake characterization that can be recognized.