Simultaneous measurements of the ocean wave—Radar modulation transfer function at L, C, and X bands from the research platformNordsee

摘要: Radar backscatter measurements were performed from the German Forschungsplattform Nordsee (FPN) in North Sea order to determine ocean wave-radar modulation transfer function (MTF), which relates backseat t ered radar power long surface waves. The operated quasi-simultaneously at 1.0 GHz (L band), 5.3 (C and 10.0 (X band) HH VV polarization by using a single antenna. MTFs obtained these frequencies polarizations are compared. Our of dependence MTF on wind speed wave frequency agreement with earlier measurements. It is shown that coherence between backscattered height strongly decreasing frequency. This implies real aperture operating low frequency, e.g., L band, best suited for imaging Residual MTFs, Mres, calculated subtracting theoretical tilt range measured total MTFs. According conventional theory, Mres should be identical hydrodynamic therefore independent polarization. However, experimental data show strong modulus phase We find larger values |Mres| than C X bands. In principle, difference can explained three-scale composite model takes into account also Bragg waves intermediate-scale (i.e., wavelengths waves). differences observed this experiment found much expected theory.