Ripples on sea surface take the direct responsibility on back-scattering of radar waves at air-sea interface. They are modulated and respond differently under various atmospheric conditions. In present study, various atmospheric stability conditions are simulated in a large wind-wave flume. A two-dimensional scanning laser slope gauge is developed to map surface slope of ripple. From the direct measurements on ripples, the stability effects on normalized cross-section of radar backscattering, σ_0, are derived according to the principle of Bragg-resonant backscattering of radar waves. Present result indicates thatσ_0 is enhanced under unstable conditions and vice versa for stable situations. Different from traditional concept that wind-friction velocity can imply the atmospheric stability effects and fully define ripple structures andσ_0, present study indicates an opposite result. In order to setup accurate radar remote sensing model, a stability parameter besides the wind-friction velocity is necessary.
展开▼
