Features of the atmospheric boundary layer block for three versions of the WAM wind wave model

Abstract

The estimated characteristics of the atmospheric boundary layer, obtained by the simulation of wind wave fields using three versions of the WAM numerical model are compared with the well-known empirical dependences of drag coefficient C_d on wind speed U₁₀ and wave age A, as well as with the dependence of dimensionless roughness height z_n on inverse wave age u*/ср. Calculations carried out for several years in the areas of the Pacific and Indian oceans, based on the ERA-interim and CFSR wind reanalyses have shown good agreement between the model and empirical dependences C_d(U₁₀) and C_d(A). The range of estimated variability for z_n(u*/с_р) has been found to be significantly less than empirical. It has been also found that estimated values of wind speed U_10W(t) are overestimated from 5 to 10% in all versions of WAM models compared with the input wind reanalysis U_10R(t) at the moments of appearance maximum values of wind U_10R(t). The reasons for the established features of the WAM model and their dependence on the model version are discussed.