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Behavior of a wave-driven buoyant surface jet on a coral reef

September 12, 2017

A wave-driven surface buoyant jet exiting a coral reef was studied in order to quantify the amount of water re-entrained over the reef crest. Both moored observations and Lagrangian drifters were used to study the fate of the buoyant jet. To investigate in detail the effects of buoyancy and along-shore flow variations, we developed an idealized numerical model of the system. Consistent with previous work, the ratio of along-shore velocity to jet-velocity and the jet internal Froude number were found to be important determinants of the fate of the jet. In the absence of buoyancy, the entrainment of fluid at the reef crest, creates a significant amount of retention, keeping 60% of water in the reef system. However, when the jet is lighter than the ambient ocean-water, the net effect of buoyancy is to enhance the separation of the jet from shore, leading to a greater export of reef water. Matching observations, our modeling predicts that buoyancy limits retention to 30% of the jet flow for conditions existing on the Moorea reef. Overall, the combination of observations and modeling we present here shows that reef-ocean temperature gradients can play an important role in reef-ocean exchanges.

Citation Information

Publication Year 2017
Title Behavior of a wave-driven buoyant surface jet on a coral reef
DOI 10.1002/2016JC011729
Authors Liv M. Herdman, James L. Hench, Oliver Fringer, Stephen G. Monismith
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research C: Oceans
Index ID 70190634
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center