A regional climate model coupled to ocean waves: Synoptic to multimonthly simulations

The NCAR regional climate model RegCM is coupled to the WAM ocean model, us ing the sea-state-dependent roughness parameterization derived in the HEXOS experiment. Coupled model simulations are shown to give reduced wind speed s U-10 compared to uncoupled simulations. This is in accord with other rece nt studies. However, the wave-atmosphere coupling is effected through the f riction velocity field u(*), rather than through the wind field U10. Thus b ecause the coupling gives enhanced resistive friction, U10 is weakened, whe reas u(*) is enhanced. Wave heights, driven by u(*), are also increased in our coupled model simulations compared to uncoupled model simulations. Coup led 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.