Real merits of the wind wave model with an optimized source function

Abstract

On the basis of the author's earlier results, a new source function for a numerical wind-wave model optimized by the criterion of accuracy and speed of calculation is substantiated. The proposed source function includes (a) an optimized version of the discrete interaction approximation for parametrization of the nonlinear evolution mechanism, (b) a generalized empirical form of the input term modified by adding a special block of the dynamic boundary layer of the atmosphere, and (c) a dissipation term quadratic in the wave spectrum. Particular attention is given to a theoretical substantiation of the least investigated dissipation term. The advantages of the proposed source function are discussed by its comparison to the analogues used in the widespread models of the third generation WAM and WAVEWATCH. At the initial stage of assessing the merits of the proposed model, the results of its testing by the system of academic tests are presented. In the course of testing, some principals of this procedure are formulated. The possibility of using the testing results to study the physics of evolution processes in wind waves is shown. It is noted that the specially added block of the dynamic boundary layer of the atmosphere makes it possible to give an exhaustive description of the air-sea-interface's characteristics, which may be used to improve wave forecasting. This new modeling quality allows us to make a statement about the construction of a model of the next (fourth) generation.

Spectra of long‐term series for wind speed and wave height in the Indian Ocean area

“…The wind wave model WAM-4 [The WAMDI Group, 1988] was used. Physical parameterization of the model has been modified earlier to improve its accuracy [Polnikov, 2005;Samiksha et al, 2015].…”

The role of wind waves in dynamics of the air-sea interface

“…Final result is achieved by restriction of such a series with its several first terms. The short description of this theory is given in paper [10], the final formulas are written there, as well, which are used in our further calculations related to an estimation of the dissipation processes impact on the dynamics of WUL. 2 Here we omit the sing in font of T, defining the direction of the momentum flux downward in vertical coordinate z, measured upward from the mean sea level.…”

“…To find certain estimations of integral fluxes I E and D E , it needs to carry out calculations for wind wave evolution in accordance with solutions of equation (1) for certain terms of the source function. To this end, we use the formulas for the source function terms given in paper [10] and the wave spectrum calculation technique described there in detail.…”

“…Spectrum on the central line of OY was calculated by the model (1), whilst values of the spectrum on the lateral lines at each time step were corrected in accordance with the values of S(σ, θ, x, t) obtained on the central line. Such an approach models the wave evolution on a site with a straight and infinite shore line along OY (see [10]). The discretization values, X and Y, applied to a space grid of a rectangular kind (∆X = ∆Y), were strongly varied with the aim to secure a wide range of nondimensional fetches given by the ratio (13) where W corresponds to the wind speed at the horizon 10 m. Values of W were varied in the limits 10-30 m/s.…”

Wave Hindcast Experiments Using Wam Cycle 4.5.3 - Validation with In situ Measurements in the North Indian Ocean

“…It is stated that, even though, the third-generation wave models are capable of simulating waves accurately, they can in any case be enhanced with a suitable demonstration of greatly complex physical processes of wind induced waves [4][5][6]. There has been considerable advancement in the field of wave modelling and prediction all over the world [7][8][9][10][11][12].…”