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Proceedings Paper

Measurements of IR and visual propagation in the marine boundary layer
Author(s): Lars Trygve Heen; Eirik Blix Madsen; Oddvar Selnes
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Paper Abstract

Two field trials have been performed on the west coast of Norway to study propagation effects (in particular refraction and turbulence effects) close to the sea surface. A complete meteorological station and a temperature profile buoy were used to characterize the propagation environment, while sensor height was logged continuously. Land and ship mounted sources were studied using infrared (midwave IR and longwave IR FPAs) and visual cameras at about 4 m above mean sea level (MSL). The land-based sources were mounted about 2-13 m above MSL, while the ship mounted sources were 10 m above sea level. Both sub- and superrefractive conditions were studied during the trials. The sensors were mounted on a programmable motion controller, which allowed extraction of absolute apparent pitch angles of the imaged sources. Apparent horizon distances have been determined for the ship sources, while mirror plane positions and apparent elevation (pitch) angles have been determined for the land sources. In addition, normalized variance of intensity (scintillation index) has been calculated for a number of cases. The scintillation index can easily be converted to refractive index structure parameters (Cn2), one of the key parameters characterizing optical turbulence. Measurement results are compared to results from the IR Boundary Layer Effects Model (IRBLEM *). *) IRBLEM is proprietory to the Department for National Defence of Canada as represented by DRDC-Valcartier

Paper Details

Date Published: 11 November 2004
PDF: 9 pages
Proc. SPIE 5572, Optics in Atmospheric Propagation and Adaptive Systems VII, (11 November 2004);
Show Author Affiliations
Lars Trygve Heen, Norwegian Defence Research Establishment (Norway)
Eirik Blix Madsen, Norwegian Defence Research Establishment (Norway)
Oddvar Selnes, Norwegian Defence Research Establishment (Norway)

Published in SPIE Proceedings Vol. 5572:
Optics in Atmospheric Propagation and Adaptive Systems VII
John D. Gonglewski; Karin Stein, Editor(s)

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