Abstract. The NCAR regional climate model RegCM is coupled to the WAM ocean model, using the sea-state-dependent roughness parameterization derived in the HEXOS experiment. Coupled model simulations are shown to give reduced wind speeds U•0 compared to uncoupled simulations. This is in accord with other recent studies. However, the wave-atmosphere coupling is effected through the friction velocity field u,, rather than through the wind field U•0. Thus because the coupling gives enhanced resistive friction, U•0 is weakened, whereas u, is enhanced. Wave heights, driven by u,, are also increased in our coupled model simulations compared to uncoupled model simulations. Coupled model outputs are shown to compare favorably with air-sea observations collected during the recent Labrador Sea Deep Convection Experiment in 1997, both for synoptic storm timescales and for seasonal timescales.
IntroductionExchanges of momentum, heat, and water vapor at the airsea interface have long been recognized as important physical processes for the study of climate dynamics and climate change, occurring on different timescales. Better representations of these fluxes are essential for climate modeling on all timescales. This is particularly true with regard to coupled atmosphere-ocean climate models, whether implemented regionally or globally. In the case of coupled atmosphere-ocean general circulation models (GCMs) it is often necessary to [1998] used coarser grids of 60 and 120 km, which resulted in reduced sensitivity to cyclone intensity and surface fluxes. Moreover, while they found that atmosphere-wave coupling gives small effects on storm development and atmospheric circulation, the impact on surface variables was notable. Relative to uncoupled simulations, they found a slight weakening of the central pressure depression, as well as reduced wave heights and surface wind speeds, with increased momentum flux.