Measurement of wave groups using radar-image sequences


A method is presented to localise wave groups in space and time utilising radar-image sequences of the ocean surface. The distribution and the properties of individual wave groups in spatial-temporal dimensions are investigated for typical sea states. The wave groups are selected from radar-image sequences, which were acquired by the wave monitoring system WaMoS II, by considering the spatial-temporal wave envelope. The amplitude of the wave envelope is determined by calibrating the image spectrum to an in situ sensor spectrum. It is demonstrated that the method can be employed for the determination of both location and size of wave groups from radar images. The spatial and temporal development of wave groups, their extension and velocities are studied. It is shown that the group velocity of waves measured in shallow and deep water agree on average with the group velocities resulting from linear wave theory, but we will show wave groups on the ocean that move with different velocities.
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