Oceanographic Experiments with Polarimetric Radiometer

Airborne measurements of the sea surface have been carried out with the imaging, polarimetric, radiometer system, aiming at determining the wind direction. Initial measurements in 1996 over Danish waters and over the Atlantic Ocean off the coast of Brittany confirmed the directional signatures of the sea brightness temperature as reported by other researchers, and have led to an ongoing development of algorithms and of improved instrumentation, see the project: "Polarimetric Radiometer". During the fall of 98 airborne experiments were carried out near the Danish oil fields in the North Sea with the intention of determining the wind vector pixel by pixel in the radiometer imagery. Polarimetric radiometers at 16 and 34 GHz were connected to an imaging antenna featuring a 1 m aperture offset parabolic reflector. Aircraft attitude was measured to better than 0.1° using an INU (Inertial Navigation Unit) mounted directly on the antenna structure. In spite of moderately favorable weather conditions, wind directions were successfully determined with errors of typically 10°. (Related projects - see: www.dcrs.dtu.dk).