17 June 1996 Atmospheric mirage and distortion modeling for IR target injection simulations
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Abstract
Atmospheric effects at low elevation angles can complicate shipboard infrared search and tracking (SIRST) of distant low altitude targets, such as sea skimming cruise missiles. Here we focus upon the effects of ray refraction and atmospheric distortion. For constant-flux surface layer conditions we discuss target magnification and demagnification and atmospheric distortions. For sufficiently negative air-sea temperature differences (ASTD), the maximum intervision range (MIVR) of low altitude targets is reduced, but the target is significantly magnified compared to no-refraction predictions. Negative ASTD can give rise to an inferior mirage which we discuss with a model-data comparison. Positive ASTD extends a target MIVR, but the target image is severely demagnified, closer to the horizon, and more degraded by atmospheric turbulence. We discuss environments that are likely to violate constant-flux conditions and include an example of a superior mirage. Although horizontal inhomogeneity may well influence superior mirage formation, we show that inhomogeneity is not necessary to explain features such as numerous mirages or multiple (three) horizons.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Steven R. Church, "Atmospheric mirage and distortion modeling for IR target injection simulations", Proc. SPIE 2742, Targets and Backgrounds: Characterization and Representation II, (17 June 1996); doi: 10.1117/12.242989; https://doi.org/10.1117/12.242989
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KEYWORDS
Refraction

Sensors

Distortion

Water

Atmospheric modeling

Infrared radiation

Infrared imaging

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