Low-altitude infrared propagation in a coastal zone: refraction and scattering

Abstract

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.

Development of the Mediterranean extinction code (MEDEX)

“…2 The results show that refractive effects are the primary parameter influencing near-surface propagation, while aerosols can also have a very large effect in this coastal region. 3 The electro-optical propagation codes IRBLEM 4 and EOSTAR 5 aim at a description of these effects by including both refraction and extinction due to gases and aerosols for the marine environment. The previously mentioned MODTRAN code describes the attenuation of electro-optical radiation by gases and aerosols.…”

Simulating an extreme over-the-horizon optical propagation event over Lake Michigan using a coupled mesoscale modeling and ray tracing framework

“…Under similar data-sparse situations, the atmospheric optics community commonly invokes the assumption of horizontal homogeneity. [8][9][10][11][12] The shortcomings of such an unphysical assumption were clearly illustrated by van Eijk and Kunz. 13 In this study, we make use of satellite-based data in tandem with in-situ measurements to avoid the assumption of homogeneity.…”

Finding the range to a distant object near the sea surface

“…An application of the transfer map calculation is the determination of a "geometric" gain, which is a change in signal intensity due entirely to the nature of the refractive field between target and sensor [3]. The propagation factor F is defined as the ratio between the actual field amplitude at a selected field point and the corresponding field amplitude at that point in free-space propagation conditions.…”