Circulation is a research area that focuses on the movement of fluids, such as air or water, in natural systems. This can include studying the circulation patterns of ocean currents, atmospheric circulation patterns, and the circulation of nutrients and pollutants in ecosystems. Understanding circulation is important for predicting weather patterns, studying climate change, and managing natural resources. Researchers in this field often use mathematical models, remote sensing techniques, and field observations to study fluid dynamics and the impact of circulation on various natural systems.