Lagoon circulation

Abstract

Coral reef lagoons span a wide spectrum from small nearly closed to large and open lagoons in atolls. Water circulation in these lagoons results from the strength and duration of driving forces (e.g., wind speed and direction, wave-swell height and direction, tides, major currents, and salinity and water temperature variations) and their interaction with the morphology and geometry of the lagoon. In small nearly closed lagoons, currents are directed nearly parallel to the coastline because of the morphological and geometric constraints under the action of waves, tides, and winds. As the size and openness of the lagoon increases, winds and tides become the dominant forces of water circulation. In large lagoons of atolls, winds and tides are the primary forces of circulation assisted by the wave driven across the reef flux. However, because these lagoons are much deeper, water stratification becomes relevant and twolayer flows are common.