As the wind speed increases beyond that necessary to fully develop the resonant waves, the first-order echoes are not predicted to increase in strength after saturation is reached at a given radio frequency. However, the second-order continuum contains contributions from the entire wave spectrum, including ocean waves of length greater than the resonant waves. Strong winds can excite and increase the spectral density of waves that are longer and faster than the resonant waves, which provide additional contributions to the second-order continuum. Typically, the power and Doppler frequency extent of the second-order clutter continuum will increase at a given radio frequency as the sea-state grows. For example, the troughs often appearing next to ...

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