Modification of the Physics and Numerics in a Third-Generation Ocean Wave Model

Abstract

Abstract The ocean wave model WAM was recently upgraded to improve the coupling between the sea state and the air flow and, in particular, enhance the growth of young wind sea over that of old wind sea. Prior to this change, numerous validations of the original wind input physics by the wave modeling community had shown a consistent underprediction of wave heights in the Southern Hemisphere. Preliminary tests of the upgraded version indicated that the change in physics improved wave height predictions but did not completely eliminate the bias. To specifically test the upgraded version, a one-month hindcast study for the Australian region was conducted using both the improved and the original physics. The hindcast significant wave heights were compared against observations from three locations wound the Australian coast and were found to he overpredicted by the upgraded physics and underpredicted by the original physics. A series of experiments were then made that indicated the upgraded physics were sensit...