IR Propagation through the Marine Boundary Layer - Comparison of Model and Experimental Data

摘要

The propagation of IR radiation through the marine boundary layer is very much dependent on vertical temperature gradients. Due to the Air-Sea Temperature Difference (ASTD) the distance to the visible horizon for an imaging system can be shorter (ASTD < 0) or larger (ASTD > 0) than the distance to the geometric horizon. To analyse these phenomena FGAN-FOM took measurements in the mid and long wave IR. Location of the experiment was the Baltic Sea. A ship, equipped with IR point sources, was tracked while it was sailing in and out up to, and beyond, the horizon. Weather conditions during the measurement period showed interesting variations in ASTD and atmospheric turbulence (see paper 4884-11). Especially strong sub-refractive effects have been observed with ASTDs up to -5.0 ℃. This paper deals with the analysis of the detection range of point targets under different meteorological conditions. Experimental results are compared with the propagation model IRBLEM (IR Boundary Layer Effects Model) which was developed by DRDC-RDDC - Valcartier, Canada.