RESUMEN
During a number of transmission experiments over littoral waters, quantitative measurements of atmospheric refraction phenomena were carried out to determine the range performance of optical-IR sensors. Examples of distortion and intensity gain generated by spatial variations of the atmospheric refractive index are shown. A high-precision ray-tracing model has been developed for better understanding of the phenomena and to satisfy the requirements for accuracy of the meteorological data used in refraction models. The output of the model includes the propagation function, the intensity gain, and details of the ray curvature and of the optical phase behavior along the path between the target and the observer. Examples of measured transmission data and their interpretation are presented.
RESUMEN
Midwave and long-wave infrared propagation were measured in the marine atmosphere close to the surface of the ocean. Data were collected near San Diego Bay for two weeks in November 1996 over a 15-km horizontal path. The data are interpreted in terms of effects expected from molecules, aerosol particles, and refraction. Aerosol particles are a dominant influence in this coastal zone. They induce a diurnal variation in transmission as their character changes with regular changes in wind direction. A refractive propagation factor calculation is introduced, and it is systematically applied to the model and to the data analysis. It is shown that this refractive propagation factor is a necessary component of a complete near-sea-surface infrared transmission model.