AOGCM

An atmosphere–ocean general circulation model, or AOGCM, is a coupled computer model that simulates the large-scale behavior of the Earth's climate system by integrating an atmosphere general circulation model with an ocean general circulation model. Many AOGCMs also include simplified representations of land surface and sea ice, and may incorporate biogeochemical or carbon cycle modules. AOGCMs are used to study climate variability, the response to external forcings, and future climate change over decades to centuries.

Coupling is achieved by exchanging fluxes (heat, momentum, and freshwater) at the air–sea interface, enabling feedbacks between atmospheric weather patterns and ocean circulation. Operationally, AOGCMs require substantial computing resources and typically operate at coarse spatial resolution compared with regional climate models. They produce outputs such as global maps of temperature, precipitation, winds, ocean currents, and sea-ice extent, which are analyzed in historical simulations and scenario experiments.

Strengths include the ability to represent the dynamic coupling of atmosphere and ocean and to simulate long-term climatic trends. Limitations include biases in regional climates, particularly the tropical precipitation and high-latitude processes, uncertainties in cloud and convection parameterizations, and biases in ocean mixing. Projected changes also depend on emission scenarios and model structure, leading to spread across ensembles.

Historically, AOGCMs formed the core of major climate assessments and formed the basis for multi-model ensembles in CMIP activities. Over time, many AOGCMs evolved into more comprehensive Earth system models by adding interactive carbon and other biogeochemical cycles. Public data archives provide AOGCM outputs for research, evaluation, and policy analysis.