Heat balances and thermally driven lagoon-ocean exchangeson a tropical coral reef system (Moorea, French Polynesia)

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2015-02-25

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© 2015. American Geophysical Union. All Rights Reserved.The role of surface and advective heat fluxes on buoyancy-driven circulation was examined within a tropical coral reef system. Measurements of local meteorological conditions as well as water temperature and velocity were made at six lagoon locations for 2 months during the austral summer. We found that temperature rather than salinity dominated buoyancy in this system. The data were used to calculate diurnally phase-averaged thermal balances. A one-dimensional momentum balance developed for a portion of the lagoon indicates that the diurnal heating pattern and consistent spatial gradients in surface heat fluxes create a baroclinic pressure gradient that is dynamically important in driving the observed circulation. The baroclinic and barotropic pressure gradients make up 90% of the momentum budget in part of the system; thus, when the baroclinic pressure gradient decreases 20% during the day due to changes in temperature gradient, this substantially changes the circulation, with different flow patterns occurring during night and day. Thermal balances computed across the entire lagoon show that the spatial heating patterns and resulting buoyancy-driven circulation are important in maintaining a persistent advective export of heat from the lagoon and for enhancing ocean-lagoon exchange.

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10.1002/2014JC010145

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Herdman, LMM, JL Hench and SG Monismith (2015). Heat balances and thermally driven lagoon-ocean exchangeson a tropical coral reef system (Moorea, French Polynesia). Journal of Geophysical Research C: Oceans, 120(2). pp. 1233–1252. 10.1002/2014JC010145 Retrieved from https://hdl.handle.net/10161/10763.

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Scholars@Duke

Hench

James Hench

Associate Professor of Oceanography

Research in my lab focuses on fluid dynamics in the coastal ocean and its effects on transport processes. We use field measurements, computational models, and theoretical analyses to understand fundamental physical processes in these systems. We also work extensively on interdisciplinary problems that have a significant physical component to better understand the effects of water motion on the geochemistry, biology, and ecology of shallow marine systems. 

Much of our research is on coral reef hydrodynamics and our lab leads the Physical Oceanographic component of the Moorea Coral Reef LTER project 

Current projects include: 1) wave-driven circulation and exchange in coral reef, lagoon, and pass systems; 2) extreme events and their effects on coral reef systems; 3) understanding the effects of rough bottoms such as corals on circulation and scalar mixing; 4) the impact of stratification on vertical mixing in a highly stratified wind-driven estuary; 5) larval transport around a coral reef island; 6) sponge excurrents; and 7) the effects of wave forcing on corallivory. 


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