Spectral wave modelling of Typhoon Krosa

Abstract

This paper presents modelling the wave conditions in Typhoon Krosa prior to touching Taiwan in October 2007, with third-generation wave models of SWAN and WWM. The accuracy of the extreme wave measurement <i>H</i>_max = 32 m with significant wave height <i>H</i>_s &asymp; 24 m at the depth of <i>h</i> = 38 m is discussed first. It is concluded that the measurement does not appear faulty and is physically realistic. The numerical results are then analysed in order to examine the models' capability to reproduce the observed conditions. It is found that neither SWAN nor WWMII are able to hindcast the extreme measurement. Series of sensitivity tests are conducted for different numerical and diffraction schemes, and source functions. It is shown that, in the circumstances, the model performance only improves in response to the bottom-limited breaking formulation.