SOURCE TERMS IN A 3RD-GENERATION WIND-WAVE MODEL

A new third-generation ocean wind wave model is presented. This model is based on previously developed input and nonlinear interaction sourc e terms and a new dissipation source term. It is argued that the dissi pation source term has to be modeled using two explicit constituents. A low-frequency dissipation term analogous to wave energy loss due to oceanic turbulence is therefore augmented with a diagnostic high-frequ ency dissipation term. The dissipation is tuned for the model to repre sent idealized fetch-limited growth behavior. The new model results in excellent growth behavior from extremely short fetches up to full dev elopment. For intermediate to long fetches results are similar to thos e of WAM, but for extremely short fetches the present model presents a significant improvement (although the poor behavior of WAM appears to be related to correctable numerical constraints). The new model furth ermore gives smoother results and appears less sensitive to numerical errors. Finally, limitations of the present source terms and possible improvements are discussed.