  We propose an original technique for the HF radar estimation of the main sea
state parameters by exploiting the amplitude modulation of the radar signal
time series. While the classical method for ocean wave measurement is based on
the second-order ocean Doppler spectrum, this alternative approach makes use of
the dominant first-order Bragg echo in the radar signal, which has a larger
signal-to-noise ratio and allows for a farther spatial coverage. We apply this
method to a yearly set of HF radar data in the vicinity of Toulon
(Mediterranean coast of France) and compare it with the classical second-order
method, where we use a nearby buoy record as ground truth. The Doppler
spectrum-based method is slightly more accurate in estimating the significant
wave height and the mean period at a short distance but the temporal approach
allows for a significant increase in range and better captures the variability
of wave parameters over time.
