Circulation models refer to mathematical representations or simulations that are used to predict and understand the behavior of ocean currents, atmospheric circulation patterns, and other fluid systems. These models help scientists study how different factors such as temperature, salinity, winds, and water density can affect the movement of fluids in various environments. By using these models, researchers are able to make predictions about future changes in ocean currents or weather patterns based on current data and observations. Overall, circulation models play a crucial role in understanding complex fluid dynamics systems and predicting their behavior over time.