Determination of Ocean Wave Spectra from Doppler Radio Return from the Sea Surface

RADIO backscatter from the sea surface has attracted considerable attention because of its potentiality for remote measurement of sea state. Ward1, for example, has shown that with ionospheric propagation and time-gating techniques relatively small patches of the ocean (∼100 km2) can be sampled successively at ranges extending up to several thousand kilometres. The ocean wave origin of the sea echo has been established clearly1–6, but the success of the method rests ultimately on the ability to recover the ocean wave spectrum—or at least significant parameters of the spectrum—from the properties of the returned radio signal.