Coastal upwelling systems are regions of the ocean where surface waters are replaced by cold, nutrient-rich waters from deeper depths. These systems are important for marine ecosystems, as they provide the nutrients that support phytoplankton growth, which in turn forms the base of the food chain.

Waves and mixing play a key role in driving coastal upwelling systems. Waves generate currents that transport water offshore, which in turn causes water from deeper depths to rise to the surface to replace the lost water. The mixing of surface waters with deeper waters also helps to bring nutrients to the surface.

The strength of coastal upwelling systems depends on a number of factors, including the strength of the wind, the shape of the coastline, and the presence of offshore currents. Strong winds can generate large waves and currents, which lead to more intense upwelling. Upwelling is also more likely to occur along straight coastlines than along irregular coastlines, as the straight coastline allows the wind to generate stronger currents. Offshore currents can also affect upwelling, as they can transport cold, nutrient-rich waters away from the coast.

Coastal upwelling systems are found in many parts of the world, including the California Current, the Humboldt Current, and the Benguela Current. These systems are important for supporting a variety of marine life, including fish, seabirds, and marine mammals.

In addition to their role in driving coastal upwelling systems, waves and mixing also play a role in other important coastal processes, such as erosion, sediment transport, and the formation of sandbars.