The island-scale internal wave climate of Moorea, French Polynesia
Abstract
Analysis of five-year records of temperatures and currents collected at Moorea reveal
strong internal wave activity at predominantly semi-diurnal frequencies impacting
reef slopes at depths 30m around the entire island. Temperature changes of 1.5C to
3C are accompanied by surges of upward and onshore flow and vertical shear in onshore
currents. Superimposed on annual temperature changes of approximately 3C, internal
wave activity is high from Oct-May and markedly lower from Jun-Sep. The offshore pycnocline
is broadly distributed with continuous stratification to at least 500m depth, and
a subsurface fluorescence maximum above the strong nutricline at approximately 200m.
Minimum buoyancy periods range from 4.8 to 6min, with the maximum density gradient
occurring at 50 to 60m depth in summer and deepening to approximately 150 to 200m
in winter. The bottom slope angle around all of Moorea is super-critical relative
to the vertical stratification angle suggesting that energy propagating into shallow
water is only a portion of total incident internal wave energy. Vertical gradient
Richardson numbers indicate dominance by density stability relative to current shear
with relatively limited diapycnal mixing. Coherence and lagged cross-correlation of
semi-diurnal temperature variation indicate complex patterns of inter-site arrival
of internal waves and no clear coherence or lagged correlation relationships among
island sides. Semi-diurnal and high frequency internal wave packets likely arrive
on Moorea from a combination of local and distant sources and may have important impacts
for nutrient and particle fluxes in deep reef environments. © 2012 American Geophysical
Union. All Rights Reserved.
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https://hdl.handle.net/10161/10769Published Version (Please cite this version)
10.1029/2012JC007949Publication Info
Leichter, JJ; Stokes, MD; Hench, JL; Witting, J; & Washburn, L (2012). The island-scale internal wave climate of Moorea, French Polynesia. Journal of Geophysical Research: Oceans, 117(6). 10.1029/2012JC007949. Retrieved from https://hdl.handle.net/10161/10769.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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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

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