This paper discusses the mean ocean circulation and tropical variability simulated by the Max Planck Institute for Meteorology (MPI-M) coupled atmosphere-ocean general circulation model (AOGCM). The model, which served as a prototype for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) simulations, does not require flux adjustment to maintain a stable climate. The study focuses on key oceanic features such as sea surface temperatures (SSTs), large-scale circulation, meridional heat and freshwater transports, and sea ice, comparing the model's results with observations. A parameterization that accounts for the effect of ocean currents on surface wind stress is implemented in the model. This parameterization significantly improves the mean state in the tropical Pacific, reducing the strength of trade winds and equatorial upwelling, and decreasing the equatorial cold SST bias by more than 1 K. Equatorial SST variability also becomes more realistic, with a reduction of about 30% in the eastern equatorial Pacific and a reduction in the extension of SST variability into the warm pool. The dominant El Niño-Southern Oscillation (ENSO) period shifts from 3 to 4 years without this parameterization. The paper is structured into sections covering the ocean and sea ice model, the mean state, and the simulation of tropical variability. The mean state analysis highlights improvements in SST biases and sea ice concentrations, while the tropical variability section discusses the reduced westward propagation of SST anomalies and the shift in ENSO period. The impact of the new wind stress parameterization on the mean state and interannual variability is also detailed, showing significant changes in wind stress curl, SST, and precipitation patterns.This paper discusses the mean ocean circulation and tropical variability simulated by the Max Planck Institute for Meteorology (MPI-M) coupled atmosphere-ocean general circulation model (AOGCM). The model, which served as a prototype for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) simulations, does not require flux adjustment to maintain a stable climate. The study focuses on key oceanic features such as sea surface temperatures (SSTs), large-scale circulation, meridional heat and freshwater transports, and sea ice, comparing the model's results with observations. A parameterization that accounts for the effect of ocean currents on surface wind stress is implemented in the model. This parameterization significantly improves the mean state in the tropical Pacific, reducing the strength of trade winds and equatorial upwelling, and decreasing the equatorial cold SST bias by more than 1 K. Equatorial SST variability also becomes more realistic, with a reduction of about 30% in the eastern equatorial Pacific and a reduction in the extension of SST variability into the warm pool. The dominant El Niño-Southern Oscillation (ENSO) period shifts from 3 to 4 years without this parameterization. The paper is structured into sections covering the ocean and sea ice model, the mean state, and the simulation of tropical variability. The mean state analysis highlights improvements in SST biases and sea ice concentrations, while the tropical variability section discusses the reduced westward propagation of SST anomalies and the shift in ENSO period. The impact of the new wind stress parameterization on the mean state and interannual variability is also detailed, showing significant changes in wind stress curl, SST, and precipitation patterns.