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Proceedings Paper

Measurements of refractive variability in the marine boundary layer in comparison with mesoscale meteorological model predictions
Author(s): J. Förster; J. Riechen
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Paper Abstract

In the marine boundary layer, air-sea interaction processes have an impact on radar and infrared propagation. Range performance near the sea surface depends on the meteorological conditions and sea surface roughness. Strong gradients of humidity and temperature close to the air-water interface are most often the reason for abnormal propagation effects such as ducting or mirage. For ship borne radars the evaporation duct is the dominant propagation mechanism affecting the maximum detection range of horizon-search radars. Ducting can also increase sea clutter return within and beyond the geometric horizon. Surface-based ducts can enhance land clutter return from extended ranges. During a sea trial in the Baltic Sea in 2005, FWG characterized the environmental boundary layer. In-situ measurements included recordings of atmospheric and sea surface parameters. Simultaneous investigations were carried out at the land based test site and on board two ships. Based on FWG-buoy measurements and radiosoundings the sea surface and meteorological conditions were analyzed to study refractive variability within the maritime boundary layer. We compared measurement results with predictions of the mesoscale meteorological Local Model (LM), developed by German Weather Service. Radar propagation was measured in addition to atmospheric conditions. A research vessel was illuminated by radar operating at X-band on outbound and inbound runs. The radar system was located at the pier of the land based test site. Radar propagation characteristics were measured on board the ship with two omni directional antennas mounted in 5.5 m and 16.8 m height above mean sea level. Results of refractive variability are presented in conjunction with radar propagation data and model outputs.

Paper Details

Date Published: 28 September 2006
PDF: 15 pages
Proc. SPIE 6364, Optics in Atmospheric Propagation and Adaptive Systems IX, 636402 (28 September 2006); doi: 10.1117/12.690138
Show Author Affiliations
J. Förster, Federal Armed Forces Underwater Acoustics and Marine Geophysics Research Institute (Germany)
J. Riechen, Federal Office of Defence Technology and Procurement (Germany)

Published in SPIE Proceedings Vol. 6364:
Optics in Atmospheric Propagation and Adaptive Systems IX
Anton Kohnle; Karin Stein, Editor(s)

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