https://www.researchgate.net/publication/348419601
The occurrence of frequency downshifting and angular spreading under the influence of Benjamin-Feir instabilities and spilling breaking waves is confirmed. Knots and upwellings form on the free surface in the wake of spilling breaking waves. Upwellings are due to vortex rings. Knots are due to intense monopoles, dipoles, tripoles, and quadrupoles. Coherent structures in the ocean and atmosphere resonate with oblique wave modes. Whitecaps indicate that frequency downshifting and angular spreading are occurring-just as windrows and knots indicate the presence of an inverse energy cascade