Atmosphere Ocean Science Colloquium
Analytic Theory of Wind-Driven Sea
Speaker: Vladimir Zakharov, University of Arizona and the Lebedev Physical Institute
Location: Warren Weaver Hall 1302
Date: Monday, October 3, 2016, 3:30 p.m.
The weak-turbulent theory of wind-driven sea is developed using regular methods of theoretical physics. The key point that makes it possible is existence of the natural dimensionless small parameter: the ratio of air and water density. As far as this parameter is really small, about 1/1000, the main physical process on the sea surface is the nonlinear interaction of weakly nonlinear waves. This process allows the self-consistent statistical description which can be performed in terms of kinetic equation for wave spectra, similar to kinetic equation used in the solid state physics. The kinetic equation derived "from first principle" has a rich family of exact solutions both stationary and self-similar. Free parameters in these solutions can be chosen by taking into account the interaction with turbulent atmospheric boundary layer. Interaction with wind can be described by few empirical parameters found by comparison of numerical solution of kinetic equation with experimental data on wave spectra in open sea and in laboratory. The developed theory of wind-driven sea describes perfectly the shape of spectra and their dependence on space and time. This theory can be used as a base for well-justified models for wave forecasting.