2023 Volume 79 Issue 17 Article ID: 23-17007
This study estimates the spatio-temporal changes in the whitecap coverage process from the development of whitecaps associated with wave breaking to the residual foam, and discusses the statistical characteristics of the whitecap coverage process by using sea surface image observations for storm surge events associated with the passage of a bomb cyclone and a typhoon. We propose a new method to estimate the crest lengths of whitecaps by using optical flow to estimate the local velocity of the whitecap image. This method can represent the characteristics of wave crest lengths that grow with the development of breaking waves and remain behind the wave breaking. The exponential scaling of the time-averaged wave crest length shows a -6 power law in the high wave speed region, consistent with previous reports for both bomb cyclones and typhoon events. Spatio-temporal spectrum of whitecap image enables us to separate active whitecaps from residual bubbles, which develop with the development of wave breaking.
