Examination of the Impact of a Coupled Atmospheric and Ocean Wave System. Part I: Atmospheric Aspects

Abstract

Abstract To take into account the change of surface roughness length induced by ocean waves, a coupled atmospheric and ocean wave model system is developed. A two-way coupling is done between a mesoscale atmospheric model, MC2, and an oceanic wave model, a regional version of WAM Cycle-4. Two different approaches, based on the wave age of Smith et al. and the wave-induced stress of Janssen, are used to compute a coupling parameter, called the Charnock parameter, expressed as the nondimensional surface roughness length. The coupling between the two models is accomplished by the use of this parameter, which is a function of sea state, instead of the constant value obtained from empirical studies using the well-known Charnock relation. The coupled atmospheric and ocean wave system was applied to four intense storms in the western Atlantic, to examine the impact of the two-way interaction using real midlatitude storm cases. In Part I, the atmospheric forecasts resulting from this two-way coupling are discusse...