Influence of Tidal Forcing on North Atlantic Simulation in a Coupled Climate Model

The eight main tide constituents have been implemented into a coupled climate model to investigate the influence of tidal forcing on North Atlantic simulation. When implementing the tidal forcing, the bias in SST simulation in the middle latitudes significantly reduces, and the simulated SST in high latitudes becomes cooler. The above changes in SST simulation lead to decrease by about 30% in the bias of simulated net sea surface heat flux with tidal forcing. However, the sea ice increases obviously. The pathway of North Atlantic circulations, especially the western boundary current has been simulated fairly better due to the tidal forcing. This is the major reason for the improvements of SST and net sea surface heat flux simulation. Transports of the upper North Atlantic and deep boundary current both decrease with tidal forcing. Compared with observation data, the transport of Atlantic meridional overturning circulation (AMOC) in the tide experiment is captured well in the upper 2000 m at 26.5°N. The lower transport of AMOC leads to less poleward heat transport with tidal forcing. This is the reason why temperature becomes warmer in the lower and middle latitudes and cooler in the high latitudes in the tide experiment. The sea ice also increases by 40% in the Northern Hemisphere.