Onshore Currents Research Articles

Influence of Suspended Aquaculture on Hydrodynamics and Nutrient Supply in the Coastal Yellow Sea

AbstractEffects of aquaculture on hydrodynamics and associated nutrient supply in a typical aquaculture area of the coastal Yellow Sea are investigated with high‐resolution model experiments and in situ data. The results show a significant reduction in nutrient supply, which is associated with alternations of three hydrodynamic conditions: the onshore current across the outer‐boundary of aquaculture area, upwelling within the offshore (depth >10 m) aquaculture area, and water exchange in the near‐coastal (depth <10 m) aquaculture area. First, the onshore current in the bottom layer of the aquaculture boundary, which transports high‐concentration nutrients from the major nutrient source of offshore bottom water, is significantly weakened by suspended aquaculture. As a result, nutrient supply from offshore sources is reduced by 50%−60%. Second, the upwelling velocities in the offshore aquaculture area are reduced by 2–6 × 10−3 cm/s, which leads to an approximately 25% reduction in nutrient supply to the euphotic layer. Third, the water exchange in the near‐coastal aquaculture area remains approximately unchanged because the weakened onshore currents within the aquaculture layers (0–4 m) are compensated by the enhanced onshore currents in the lower layers. As a result, the nutrient supply in the near‐coastal aquaculture area does not significantly change, whereas the nutrient supply in the offshore aquaculture area has been reduced by approximately 60%.

Wintertime Submesoscale Offshore Events Overcoming Wind‐Driven Onshore Currents in the East China Sea

AbstractCoastal offshore currents transport terrestrial materials from coastal areas to continental shelf areas in the upper layer; these currents are regarded as unimportant in winter when wind‐driven onshore currents are dominant. In this paper, both long‐term observations and high‐resolution simulations in the East China Sea reveal unique wintertime offshore currents in the upper layer that are widespread in the 30–70‐m isobath area and even overcome the wind‐driven onshore currents at the 50–70‐m isobaths. The mixed layer instabilities, frontogenesis and turbulent thermal wind, which constitute a mechanism in the generation of submesoscale offshore currents, have a growth rate that is fast enough to compete with the wind‐driven dynamics when the winter monsoon is relatively weak (<10 m/s). The alternation of the weak‐wind and strong‐wind modes during the winter monsoons provides a general condition for the repeated occurrence of remarkable submesoscale cross‐shore transport and carbon sequestration in coastal seas.

Deep current structure in the Toyama Deep-Sea Channel in the Japan Sea

The flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore and onshore currents over the east- and west-side slopes in the channel, respectively, is suggested. A bottom intensified flow characteristic was observed at the offshore stations in the Yamato Basin. The asymmetric current system in the channel is also suggested by the asymmetric distribution of water characteristics across the TDSC in Toyama Bay; a cold dense water mass with higher dissolved oxygen (DO) and higher transmittance (Tr) was found over the west-side slope of the channel, whereas a water mass with lower DO and lower Tr was distributed over the east-side slope, suggesting a turbidity current from the head of Toyama Bay. The currents facing the shallower depth on their right-hand-side, along with the density distribution in the TDSC, suggest a density current system under the influence of the earth’s rotation. The dissolved oxygen concentration in the TDSC was significantly lower than that in the offshore region of the same temperature range. This suggests that the water mass over the west-side slope in the TDSC is a modified offshore water mass which experienced significant mixing with the low DO water mass over the east-side slope in the TDSC, probably due to strong shear between the offshore and onshore currents in the narrow channel.

Wintertime submesoscale offshore events overcoming the wind-driven onshore currents in the East China Sea

Wintertime submesoscale offshore events overcoming the wind-driven onshore currents in the East China Sea

Wintertime submesoscale offshore events overcoming the wind-driven onshore currents in the East China Sea

Wintertime submesoscale offshore events overcoming the wind-driven onshore currents in the East China Sea

Analysis of Measured Surface Nearshore Currents Using Multiple Drifters on Anmok Beach, South Korea

Lim, H.S.; Kim, M.J.; Kim, D.H., and Lee, H.J., 2019. Analysis of measured surface nearshore currents using multiple drifters on Anmok beach, South Korea. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 46-50. Coconut Creek (Florida), ISSN 0749-0208.To understand the mechanism of sediment transport and beach erosion processes in the surf zone near the coast of the Korean Peninsula, the development of coastal erosion control technology, an R&D project supported by the Korean government, has been conducted since 2013. Anmok Beach, located on the eastern coast of the Korean Peninsula, has been studied by measuring currents and sediment transport using bottom-mounted acoustic sensors and offshore long-term wave observation since February 2015. Moreover, for measurement of surface currents, multiple Lagrangian drifters were developed and successfully deployed nine times near the surf zone and submerged breakwaters close to Kangneung northern breakwaters. The variation of the measured bottom currents was induced directly by seasonal wave height and direction, depending on the incoming waves from the NNE in winter, ENE in summer, and NE, normal to the shoreline, in the case of high waves. However, the measured surface currents were affected not only by the incoming waves in the presence of high-energy waves, but also by wind speed and direction in the presence of low-energy waves. In this study, the observed surface nearshore currents measured by small Lagrangian GPS drifters near the surf zone and submerged breakwaters at Anmok were analyzed to investigate the variability of the wave-induced currents and nearshore surface currents generated by different wave and wind environments. The drifter experiments showed that offshore surface currents in the surf zone were predominantly developed, especially by strong seaward winds that opposed the direction of the weak waves. However, onshore surface currents were developed by wave-induced currents generated by the interaction of waves from offshore accompanied by sea winds. This measurement is now used to calibrate and validate the coastal sediment modeling system for the eastern coast of the Korean Peninsula.

Ocean variability and air-sea fluxes produced by atmospheric rivers

Atmospheric rivers (ARs) cause heavy precipitation and flooding in the coastal areas of many mid-latitude continents, and thus the atmospheric processes associated with the AR have been intensively studied in recent years. However, AR-associated ocean variability and air-sea fluxes have received little attention because of the lack of high-resolution ocean data until recently. Here we demonstrate that typical ARs can generate strong upper ocean response and substantial air-sea fluxes using a high-resolution (1/12°) ocean reanalysis. AR events observed during the CalWater 2015 field campaign generate large-scale on-shore currents that hit the coast, generating strong narrow northward jets along the west coast of North America, in association with a substantial rise of sea level at the coast. In the open ocean, the AR generates prominent changes of mixed layer depth, especially south of 30°N due to the strong surface winds and air-sea heat fluxes. The prominent cooling of SST is observed only in the vicinity of AR upstream areas primarily due to the large latent heat flux. Using a long-term AR dataset, composite structure and variations of upper ocean and air-sea fluxes are presented, which are consistent with those found in the events during CalWater 2015.

Fine scale depth regulation of invertebrate larvae around coastal fronts

AbstractVertical migrations of zooplankters have been widely described, but their active movements through shallow, highly dynamic water columns within the inner shelf may be more complex and difficult to characterize. In this study, invertebrate larvae, currents, and hydrographic variables were sampled at different depths during and after the presence of fronts on three different cruises off the southern coast of South Africa. Internal wave dynamics were observed in the hydrographic data set but also through satellite imagery, although strong surface convergent currents were absent and thermal stratification was weak. During the first two cruises, fronts were more conspicuous and they preceded strong onshore currents at depth which developed with the rising tide. Vertical distributions of larvae changed accordingly, with higher abundances at these deep layers once the front disappeared. The third cruise was carried out during slack tides, the front was not conspicuous, deep strong onshore currents did not occur afterward and larval distributions did not change consistently through time. Overall, the vertical distributions of many larval taxa matched the vertical profiles of shoreward currents and multivariate analyses revealed that these flows structured the larval community, which was neither influenced by temperature nor chlorophyll. Thus, the ability to regulate active vertical positioning may enhance shoreward advection and determine nearshore larval distributions.

Optimizing an oceanographic-larval model for assessment of the puerulus settlement of the western rock lobster, Panulirus cygnus, in Western Australia

Western rock lobster larvae have a 9–11 mo pelagic larval phase that makes them susceptible to the oceanographic environment, such as the poleward-flowing Leeuwin Current, surface winds, and wave-induced Stokes drift. An innovative oceanographic-larval modelling approach, which incorporated these physical drivers and complex larval behavior, was used to investigate the cause of the major reduction in postlarval (puerulus) settlement in the late 2000s. Individual-based biophysical larval models, taking into account the sensitivity to different wind effects on the surface water movement and different levels of puerulus swimming, were developed utilizing 19 yrs of meteorological and oceanographic data (1994–2012). Model optimization was achieved by assessing modelled and observed puerulus settlements along the Western Australian coast for 24 model simulations with different combinations of model parameters. A postmodel analysis then assessed the effect of the timing of larval release, abundance and spatial distribution of larval release, and duration of larval development. Model results revealed that a mismatch between the seasonal timing of spawning, larval development, and onshore current systems needed to return the larvae to the coast appears to be the primary cause of the low settlement in the late 2000s. Since the mid-2000s, there has been an earlier start of the spawning season due to warmer winter temperatures, which may have caused the ocean currents and eddies to diffuse the larvae in the open ocean before they can be transported back to the coast by onshore currents and weakened winter storms.

Pelagic key species and mechanisms driving energy flows in the northern Benguela upwelling ecosystem and their feedback into biogeochemical cycles

Abstract The northern Benguela Upwelling System (nBUS) has been facing increasing temperatures and decreasing dissolved oxygen (DO) levels over the last decades. This has implications for key processes and trophic interactions within the ecosystem including shifts in community composition, distribution ranges, and trophic levels, changes in energy flows and migration patterns with feedbacks to biogeochemical processes. Here we summarise the results gained from the GENUS project (Geochemistry and Ecology of the Namibian Upwelling System) focussing on the geochemical and ecological structures and processes dominating the pelagic component of the nBUS. Spatial and temporal distribution patterns of key species of zooplankton and fish larvae yielded biomass estimates (5 to 81 g Wet Mass m−2 (10 to 90% quantile) with a median of 19.5 g Wet Mass m−2 for the upper 200 m) and potential impacts on the vertical carbon flux. Vertical distribution ranges of key taxa were determined reflecting their specific abilities to tolerate hypoxia and, hence, their different adaptive mechanisms to cope with the Oxygen Minimum Zone (OMZ). The shoaling of the 2.5 mL O2 L−1-oxycline (0.24 m y−1) constrains sensitive species and hampers daily and seasonal vertical migrations. It may also affect the ability of organisms to maintain themselves within nearshore habitats by hindering vertical migration into deeper onshore currents. Respiration rates of key species were determined with one standard method (optode respirometry), showing an average respiration rate of 54.6 mL O2 d−1 (g Dry Mass)−1 for the bulk fraction of mesozooplankton, allowing also the estimate of DO consumption by mesozooplankton at different depth layers. Stable isotopic ratios (N, C) revealed trophic interactions and positions of zooplankton and fish. Our results reveal many players within a small range of trophic levels and a dominance of zooplankton taxa (copepods, euphausiids) in terms of biomass over small pelagic fish (sardine, anchovy), essential to consider for future higher-resolution ecosystem modelling.

Water Exchange across Isobaths over the Continental Shelf of the East China Sea

AbstractOnshore and offshore currents and the associated volume transport across three isobaths (50, 100, and 200 m) over the continental shelf of the East China Sea were examined using daily reanalysis data in 1993–2012. After being averaged along the isobaths, the velocities across 100 and 50 m are onshore in the bottom layer but offshore in the surface layer. In contrast, those across the 200-m isobath are onshore in the surface and bottom layers but without a clear direction in the midlayer, suggesting a three-layer structure. The surface offshore current across the 100-m isobath mainly arises from the Taiwan Strait Current, while the surface onshore current across the 200-m isobath mainly arises from the Kuroshio, both of which converge in the area between the 100- and 200-m isobaths and flow toward the Tsushima Strait. The control of bottom Ekman dynamics on the onshore bottom currents is important at the 100-m isobath, partly important at the 200-m isobath, and slightly important at the 50-m isobath. The seasonal variations of onshore and offshore currents in the surface layers across the three isobaths are likely caused by local winds, the Taiwan Strait Current, and the Changjiang discharge, while those in midlayer across the 200-m isobath demonstrate a strong geostrophic control and can be interpreted from a traditional viewpoint on the Kuroshio intrusion over the entire water column across the shelf slope. The close connection of bottom onshore currents across the three isobaths suggests that the bottom layer is an important pathway for water exchange of shelf water and the open sea.

Simulation of the effect of an oil refining project on the water environment using the MIKE 21 model

A case study of the Caofeidian oil refining project is conducted. A two-dimensional convective dispersion mathematical model is established to simulate the increase in the concentration of pollutants resulting from the wastewater discharge from the Caofeidian oil refining project and to analyze the characteristics of the dispersion of pollutants after wastewater is discharged and the effect of the wastewater discharge on the surrounding sea areas. The results demonstrate the following: (1) The Caofeidian sea area has strong tidal currents, which are significantly affected by the terrain. There are significant differences in the tidal current velocity and the direction between the deep-water areas and the shoals. The direction of the tidal currents in the deep-water areas is essentially parallel to the contour lines of the sea areas. Onshore currents and rip currents submerging the shoals are the dominant currents in the shoals. (2) The pollutant concentration field in the offshore areas changes periodically with the movement of the tidal current. The dilution and dispersion of pollutants are affected by the ocean currents in different tidal periods. The turbulent dispersion of pollutants is the most intense when a neap tide ebbs, followed by when a neap tide rises, when a spring tide ebbs and when a spring tide rises. (3) There are relatively good hydrodynamic conditions near the project's wastewater discharge outlet. Wastewater is well diluted after being discharged. Areas with high concentrations of pollutants are concentrated near the wastewater discharge outlet and the offshore areas. These pollutants migrate southwestward with the flood tidal current and northeastward with the ebb tidal current and have no significant impact on the protection targets in the open sea areas and nearby sea areas.

Analysis of Observed Streaming in Field Measurements

AbstractAnalysis of velocity and suspended sediment concentration data from field measurements at Pearl Beach in New South Wales, Australia, reveals the existence of onshore currents in the close vicinity of the rippled bed, whereas the velocity is offshore directed farther up in the water column. This might be caused by wave-induced streaming beneath irregular waves over ripples. To test this hypothesis, a simple one-dimensional vertical bottom boundary layer model capable of capturing streaming was applied, yielding a qualitatively fair agreement between the predicted and measured mean velocity and suspended sediment concentration profiles, although the predicted suspended sediment concentration was 1 order of magnitude smaller. Overall, these model results support the hypothesis of the mean near-bed onshore velocity caused by wave-induced streaming over ripples.

Vertical structure and variation of currents observed in autumn in the Korea Strait

To observe vertical structure and temporal variations of currents in the Tsushima Warm Current region of the Korea Strait, a moored buoy system was deployed in autumn 2009. The moored buoy system measured vertical profiles of current, temperature, and salinity for 24 days and a background hydrographic survey was performed. Along-strait northeastward currents were dominant in the upper layer (8–35 m). The mean current veers counterclockwise from 48 m to 74 m as much as 50°, and its speed is reduced with depth. There were distinct northward onshore currents near the bottom (65–80 m). It was demonstrated that thermal wind relation holds in the inclined pycnocline layer, which generates the counterclockwise veering current structure. Density gradient along the strait is a main factor producing the cross-strait onshore current component below the upper-layer and the cross-strait density gradient reduces the along-strait current component with depth. Previous studies have never focused on the effect of the along-strait density structure on current structure. The first Empirical Orthogonal Function mode (CM1) of current variability explains 70% of local current variations and its vertical structure is close to the mean current structure. The correlation analysis among variations of CM1 current, slope of sea level anomaly (SSLA) and local wind anomaly revealed that the variation of CM1 current is mainly related to the variation of SSLA across the strait (c-SSLA), which is known to be controlled by remote and local wind forcing. Similarity between vertical structures of mean and CM1 current suggests that thermal wind relation is the main dynamics maintaining the counterclockwise turning of CM1 current below the upper layer although the upperlayer CM1 current is controlled by c-SSLA through barotropic geostrophic relation. Time series of temperature and salinity indicate that the thermohaline front between Korean Coastal Water and Tsushima Warm Current Water meanders in time and migrates over the mooring station back and forth. The front meandering and migration also affect the local SSLA and CM1 current variations in autumn in the Korea Strait.

Numerical simulations of larval transport into a rip‐channeled surf zone

Competent larvae of intertidal invertebrates have to migrate toward shore for settlement; however, their migration through the surf zone is not understood. We investigated larval transport mechanisms at a rip‐channeled beach. Because tracking larvae in the surf zone is infeasible, we used a three‐dimensional biophysical model to simulate the processes. The coupled model consists of a physical module for currents and waves, and a biological module for adding larval traits and behaviors as well as Stokes drift to Lagrangian particles. Model calculations were performed with and without onshore wind forcing. Without wind, wave‐driven onshore streaming occurs in the bottom boundary layer outside the surf zone. With onshore wind, onshore currents occur near the surface. In the surf zone, offshore‐directed rip currents and compensating onshore‐directed currents over shoals are formed in both no‐wind and wind cases. In the biological module, neutral, negative, and positive buoyant particles were released offshore. Additionally, particles either sank in the presence of turbulence or not. Two scenarios achieved successful onshore migration: Negatively buoyant larvae without wind forcing sink in the turbulent bottom boundary layer and are carried onshore by streaming; positively buoyant larvae drift toward shore in wind‐driven surface currents to the surf zone, then sink in the turbulent surf zone and remain near the bottom while transported shoreward. In both cases, the larval concentration is highest in the rip channel, consistent with field data. This successful result is only obtained if turbulence‐dependent sinking behavior and Stokes drift are included in the transport of larvae.

The vertical structure of the circulation and dynamics in Hudson Shelf Valley

AbstractHudson Shelf Valley is a 20–30 m deep, 5–10 km wide v‐shaped submarine valley that extends across the Middle Atlantic Bight continental shelf. The valley provides a conduit for cross‐shelf exchange via along‐valley currents of 0.5 m s−1 or more. Current profile, pressure, and density observations collected during the winter of 1999–2000 are used to examine the vertical structure and dynamics of the flow. Near‐bottom along‐valley currents having times scales of a few days are driven by cross‐shelf pressure gradients setup by wind stresses, with eastward (westward) winds driving onshore (offshore) flow within the valley. The along‐valley momentum balance in the bottom boundary layer is predominantly between the pressure gradient and bottom stress because the valley bathymetry limits current veering. Above the bottom boundary layer, the flow veers toward an along‐shelf (cross‐valley) orientation and a geostrophic balance with some contribution from the wind stress (surface Ekman layer). The vertical structure and strength of the along‐valley current depends on the magnitude and direction of the wind stress. During offshore flows driven by westward winds, the near‐bottom stratification within the valley increases resulting in a thinner bottom boundary layer and weaker offshore currents. Conversely, during onshore flows driven by eastward winds the near‐bottom stratification decreases resulting in a thicker bottom boundary layer and stronger onshore currents. Consequently, for wind stress magnitudes exceeding 0.1 N m−2, onshore along‐valley transport associated with eastward wind stress exceeds the offshore transport associated with westward wind stress of the same magnitude.

Application of seismic sedimentology to prediction of beach and bar sandbodies in gentle slope of lacustrine basin: A case study of the Lower Cretaceous in Chepaizi area, Junggar Basin, NW China

Abstract The exploration of beach and bar sandstone reservoirs is a tricky issue. In this study, under the guidance of seismic sedimentary theory, the 90° phase shift technique, stratal slicing, and quantitative seismic sedimentology were used to identify and characterize the distribution of beach and bar sandbodies and reflect the evolutionary history in the Chepaizi area, Junggar Basin. Four third-order sequences in the Lower-Cretaceous and relevant systems tracts in the study area were studied using seismic sedimentology, and with the assistance of the comprehensive analysis of core, lithology and well-logging data, stratal slices were interpreted and calibrated, and the distribution and evolution of beach bar sandbodies were predicted. Based on the detailed and extensive analyses on sedimentary characteristics and seismic sedimentary quantitative results, this study established two typical beach and bar sedimentary models in the Chepaizi area, namely normal bedrock-beach bar and fan delta-beach bar. In early sedimentary period of SQ I, beach and bar sandbodies were reformed by coastal, wave and onshore currents, and developed around the lateral margin of the fan delta front. During sedimentary periods of SQ II to SQ IV, the northern provenance stopped supplying sediments, and the wave and coastal currents eroded the bedrock of the western Chepaizi uplift and transported sediments to the study area, forming beach and bar sandbodies parallel to or obliquely intersecting with coastal line.

Resonant Diurnal Oscillations and Mean Alongshore Flows Driven by Sea/Land Breeze Forcing in the Coastal Southern California Bight

Abstract This study presents observations of the cross-sectional structure of resonant response to sea/land breezes (SLBs) off Huntington Beach (HB) in the Southern California Bight (SCB). A resonant response to local diurnal wind stress fluctuations associated with SLB forcing occurs intermittently and produces strong diurnal oscillations of flow and temperature resulting from enhanced work of the diurnal local wind on the sea surface. At nighttime (daytime), a coherent cross-sectional circulation with offshore (onshore) currents in the surface layer (upper 15 m) and onshore (offshore) currents in the intermediate layer around 20 m are generated, with a three-layered vertical structure on the outer shelf. The authors find a net cross-shore eddy heat flux (net cooling of nearshore water) during the period of strong response to SLB, that is, a rectified mean heat flux and steeper isotherms resulting from the diurnal SLB fluctuations. The steepened mean isotherms are also found to be in thermal–wind balance with intensified mean equatorward flow, which thus can also be generated by the resonant SLB dynamics. Similar rectified onshore transport of other quantities is expected, relevant for biogeochemical processes. The distribution of maximum diurnal kinetic energy in time and across the shelf supports the concept that subinertial shears create the sufficient condition for resonant response to SLB forcing.

An approach to modeling wind currents in Kerch Strait

The Kerch Strait plays an important role in the for� mation of the oceanographic regime of the Black Sea and the Sea of Azov, which are connected by this strait. In the conditions of the modern climate changes and anthropogenic influence on the marine ecosystems, the strait is a natural transport link for these interac� tions. In addition, the characteristics of the ecosystem in Kerch Strait are subjected to significant variations, which influence the character of its economical use. Systematic investigation of currents in the Kerch Strait connecting the Sea of Azov and the Black Sea is principally important for understanding the physical nature of circulation variability and its influence on the regional climate. The water level regime in Kerch Strait is formed under the influence of two main causes: fluctuations of the sea level in the Black Sea and the Sea of Azov and direct wind forcing with account for the coastline form and bottom topography. Wind forcing has a double effect: on the one hand, it causes sea level variations at the ends of the strait and in the strait that results in the gradient currents and, on the other hand, it influences the water surface directly and causes the velocity vari� ations and sometimes variations in the direction of the currents due to the tangential wind stress. Wind plays the main role in the formation of currents in Kerch Strait. The wind flows over the entire basin and over the strait. The current field is also influenced by the difference in the sea level at the ends of the strait caused by the onshore and offshore wind currents and differences in the freshwater balance in the basins of the Black Sea and the Sea of Azov. DESCRIPTION OF THE MATHEMATICAL MODEL The coastline of Kerch Strait is very complex. It is indented by bays and spits, and the existence of Tuzla Island makes the calculation domain multiply con� nected. It is also important that the bottom topogra� phy of the strait is very uneven. The depths of the nav� igation part of the strait are 8–10 m and increase in its southern part to 19 m. At the same time, the depth of the coastal region in Tamanskii and Dinskii bays ranges between 0.5 and 4 m. Such a distribution of depths allows us to state that the bottom topography is

The island‐scale internal wave climate of Moorea, French Polynesia

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 ≥30 m around the entire island. Temperature changes of 1.5°C to 3°C are accompanied by surges of upward and onshore flow and vertical shear in onshore currents. Superimposed on annual temperature changes of approximately 3°C, 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 500 m depth, and a subsurface fluorescence maximum above the strong nutricline at approximately 200 m. Minimum buoyancy periods range from 4.8 to 6 min, with the maximum density gradient occurring at 50 to 60 m depth in summer and deepening to approximately 150 to 200 m 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.