The Effect of Wave Processes on the Coupled Global Climate Simulations: an Overall Assessment

Coupled models are essential for climate studies but exhibit systematic biases due to missing key processes. In particular, the physical processes associated with waves are neglected. In this study, the wave model WAVEWATCH III (WW3) is coupled to the Chinese Academy of Sciences Earth System Model (CAS-ESM2.0) to investigate the interactions between waves and other climate components. Three wave-related processes—wave-induced mixing, Stokes drift, and sea spray—are incorporated to assess their impacts on climate simulations. The results show that these processes impact the ocean thermal-salinity structure, mixed layer depth (MLD), ENSO, atmospheric circulations, and sea ice distribution in different degrees. Wave-induced mixing enhances vertical heat exchange, deepening the global MLD and alleviating sea surface temperature (SST) and salinity biases, particularly in the eastern tropical Pacific, the ACC, and the North Atlantic. Stokes drift transports heat to higher latitudes. In contrast, sea spray induces surface cooling and enhances convective instability under strong wind conditions through a positive feedback between the ocean and atmosphere. Although the inclusion of wave-related processes improves the spatial distribution of SSTA variability and shifts its variability center closer to observations, the spectral power remains severely overamplified. The atmospheric circulations respond accordingly to SST cooling, thereby alleviating excessive precipitation over the eastern equatorial Pacific and weakening the strong subtropical high. The cooling of ocean and atmosphere induced by wave processes improves the simulation of sea ice in the Antarctic by sea-ice and air-ice interactions.