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Residual exchange flows in estuaries can be either laterally sheared, vertically sheared, or a mix of both, depending on the competition between baroclinic and barotropic forcings. Observations of the residual flow structure at subtropical, semi-arid and temperate estuaries indicate that the dominant forcing (horizontal density gradient or tidal stress) may vary at a fortnightly to seasonal timescale. This work aims at characterizing the variability of residual flow drivers in estuaries based on process-oriented numerical simulations with simplified geometry. The hydrodynamic model (Delft3D) is constituted by a straight estuarine channel of 80 km in length and a Gaussian-shape cross-section of 1 km in width, forced by a semi-diurnal (M2) tide. The computational grid includes 240 and 15 nodes along and across the channel, respectively (about 333 m x 67 m resolution) and 20 uniform vertical layers. A total of 20 runs of 6 months were performed to explore the effects of various channel depths, river discharges and tidal amplitudes on the spatial structure of residual flows. The results show distinct cross-channel structures for each experiment and suggest a switch of the dominant driver (between tidally-driven and density-driven) along the channel in some cases. The spatial variability of residual flows is first examined against both the horizontal density gradient and the tidal velocity amplitude to characterize the competition between barotropic and baroclinic forcings. The dynamics of residual flow is then approximated by the tidally averaged momentum equation, applied at every grid point of the model domain, to derive dimensionless parameters (such as the densimetric tidal Froude number) for prediction of the dominant residual flow drivers both temporally and spatially (i.e., along the channel).

A framework is presented for the study of hydrodynamics in semienclosed basins. The framework is anchored on a generalized momentum balance in which the drivers of momentum are tides, density gradients and winds. The drivers are balanced by friction and Earth’s rotation. The relative influence of either drivers or balancing agents may be cast in terms of their ratio, represented by nondimensional numbers. Thus, the relative influence between three different pairs of forcings is expressed as follows. Comparisons between tidal forcing and density gradients are cast in terms of a densimetric tidal Froude number. Similarly, the effect of wind forcing versus density gradients is contained in a Wedderburn number, and the impact of wind forcing compared to tidal forcing is described by a ‘Stress number’. Comparisons of balancing agents are contained in the Ekman number, representing the dynamic depth of a semienclosed basin – high Ekman numbers indicate dynamically shallow basins. The hydrodynamic interplay among drivers and balancing agents can thus be drawn on a triangular prism. Each face of the prism represents a parametric space that characterizes the relative dominance of any pair of forcing agents. The height of the prism denotes the dynamic depth. Every semienclosed basin, except any dominated by wind-wave forcing, can be represented on a face of this triangular prism or inside the prism, depending on the dominant hydrodynamics. Thus, any semienclosed basin can be described by a cloud of points inside and on the prism faces, representing the basin’s temporal and spatial variability in its hydrodynamics.

A 10-year time series of surface salinity values along an estuary-river transition documents their spatial structure and their temporal variability. Decomposition of detided time series into empirical modes indicates that the first mode, explaining almost 95% of the overall variance, has the typical sigmoid spatial structure found in estuaries. The temporal variability of mode 1, referred to as salinity index, displays annual and semiannual signals that are modulated from year to year. A fit of the salinity index to harmonics associated with luni-solar orbital motions and solar activity explain more than 70% of the index variance. This suggests that a) gravitational forcing from moon and sun, and b) the thermodynamic influence of solar activity, both impact salinity intrusions into rivers. The mechanistic linkage is unknown, but it is likely that it develops through atmospheric pressure, winds, air temperature, and water level. These variables are influenced by gravitational forcing and solar activity as observed elsewhere. The main finding is that the salinity variability at an estuary-river transition is influenced by gravitational forces and solar activity, i.e., saltwater intrusion could be determined by the modulation of astronomic influences. Similar variability may be found for mixing processes in coastal regions.

Estuarine and coastal geomorphology, biogeochemistry, water quality, and coastal food webs in river-dominated shelves of the Gulf of Mexico (GoM) are modulated by transport processes associated with river inputs, winds, waves, tides, and deep-ocean/continental shelf interactions. For instance, transport processes control the fate of river-borne sediments, which in turn affect coastal land loss. Similarly, transport of freshwater, nutrients, and carbon control the dynamics of eutrophication, hypoxia, harmful algal blooms, and coastal acidification. Further, freshwater inflow transports pesticides, herbicides, heavy metals, and oil into receiving estuaries and coastal systems. Lastly, transport processes along the continuum from the rivers and estuaries to coastal and shelf areas and adjacent open ocean (abbreviated herein as “river-estuary-shelf-ocean”) regulate the movements of organisms, including the spatial distributions of individuals and the exchange of genetic information between distinct subpopulations. The Gulf of Mexico Research Initiative (GoMRI) provided unprecedented opportunities to study transport processes along the river-estuary-shelf-ocean continuum in the GoM. The understanding of transport at multiple spatial and temporal scales in this topographically and dynamically complex marginal sea was improved, allowing for more accurate forecasting of the fate of oil and other constituents. For this review, we focus on five specific transport themes: (i) wetland, estuary, and shelf exchanges; (ii) river-estuary coupling; (iii) nearshore and inlet processes; (iv) open ocean transport processes; and (v) river-induced fronts and cross-basin transport. We then discuss the relevancy of GoMRI findings on the transport processes for ecological connectivity and oil transport and fate. We also examine the implications of new findings for informing the response to future oil spills, and the management of coastal resources and ecosystems. Lastly, we summarize the research gaps identified in the many studies and offer recommendations for continuing the momentum of the research provided by the GoMRI effort. A number of uncertainties were identified that occurred in multiple settings. These include the quantification of sediment, carbon, dissolved gasses and nutrient fluxes during storms, consistent specification of the various external forcings used in analyses, methods for smooth integration of multiscale advection mechanisms across different flow regimes, dynamic coupling of the atmosphere with sub-mesoscale and mesoscale phenomena, and methods for simulating finer-scale dynamics over long time periods. Addressing these uncertainties would allow the scientific community to be better prepared to predict the fate of hydrocarbons and their impacts to the coastal ocean, rivers, and marshes in the event of another spill in the GoM.

Water level measurements at four sub-basins of a highly dissipative coastal lagoon were used to study variability at tidal and subtidal scales and to determine whether atmospheric forcing influenced variations in water level at tidal scales. The amplitude of the main astronomic constituents, which were diurnal, attenuated quickly to

The hydrodynamic characteristics (wave transmission, reflection, and dissipation) of nine different scrap-tire floating breakwater configurations are studied in a wave flume for a wide range of inp...

This textbook provides an in-depth overview of the hydrodynamics of estuaries and semi-enclosed bodies of water. It begins by describing the typical classification of estuaries, followed by a presentation of the quantitative tools needed to study these basins: conservation of mass, salt, heat, momentum, and the thermodynamic equation of seawater. Further topics explore tides in homogeneous basins, including shallow water tides and tidal residual flows, wind-driven flows in homogeneous basins, density-driven flows, as well as interactions among tides, winds and density gradients. The book proposes a classification of semi-enclosed basins that is based on dominant dynamics, comparing forcing agents and restorative or balancing forces. Introduction to Estuarine Hydrodynamics provides an introduction for advanced students and researchers across a range of disciplines - Earth science, environmental science, biology, chemistry, geology, hydrology, physics - related to the study of estuarine systems.

In siliciclastic systems, submarine groundwater discharge (SGD) provides a fraction of freshwater and nutrients delivered to coastal waters, but in many carbonate karst terrains SGD represents the predominant source of terrestrial water and solutes. Water compositions may be modified by reactions in subterranean estuaries, altering chemical fluxes via SGD. In carbonate settings, feedbacks between organic carbon remineralization and calcium carbonate mineral (CaCO3) dissolution and precipitation may alter carbon dioxide (CO2) and phosphorus (P) concentrations and fluxes associated with SGD. To assess these effects, we sampled water from multiple submarine springs along the east coast of the Yucatan peninsula, as well as inland cenotes, and a coastal groundwater well. We measured ammonium (NH4), phosphate (PO4), major element, dissolved inorganic and organic carbon concentrations (DIC and DOC), fluorescent characteristics of colored dissolved organic matter (CDOM) and modeled calcite saturation indices (SIcal) and the partial pressure of dissolved CO2 (PCO2). These data indicate that reactions along a hypothetical flow path to the coast control the composition of terrestrial fresh water entering the subterranean estuary. Non-conservative mixing between brackish groundwater and lagoon water reflect changes to groundwater compositions within the subterranean estuary from CO2 produced during organic matter remineralization and CaCO3 dissolution. Although both organic matter remineralization and carbonate dissolution should liberate P, molar N:P ratios in spring discharge are higher than the Redfield Ratio of 16:1, suggesting sequestration of remineralized P through sorption to carbonate minerals within the STE. This result indicates that SGD, the primary source of water and nutrient to this coastal zone, results in P limitation in coastal water and is a source of CO2 despite buffering by CaCO3 dissolution. This result also emphasizes the importance of biogeochemical reactions within subterranean estuaries for estimates of SGD solute delivery to the oceans and impacts to the coastal carbon cycle.

Time series of current velocity profiles were obtained at the mouth and head of a Brazilian subtropical estuary, the Ararangua, to study its dry-period response to fortnightly tidal forcing, river pulses and wind forcing. The Ararangua exemplifies a series of river-dominated estuaries along southern Brazil with widths 30 m3/s but 200 m3/s appeared in two other occasions late in the observation period and caused seaward flushing of the entire system. Overall, the estuarine circulation resembled that of a fjord when river discharge was moderate and weaker: an active upper layer driven by river discharge moving over a semi-stagnant lower layer. Strongest subtidal exchange developed ∼2–3 days after neap tides, in contrast to other studies where fortnightly modulation is determined by vertical mixing from tides. In the lower estuary, subtidal flows seemed to result from a combination of vertical mixing, from tides and wind, and from tidal advection. Moreover, the lower estuary was much more sensitive to wind forcing than the upper estuary. The upper estuary responded preferentially to river discharge and tidal forcing.

Flow interactions between two inlets of Mobile Bay, Alabama, and the Gulf of Mexico are described with ship-mounted ADCP surveys obtained on consecutive days. These two inlets, Main Pass (MP) and Pass aux Herons (PaH), remain interdependent throughout the diurnal tidal cycle. A phase lag of 31.6° (~2.1 h) affects the diurnal tidal currents between the two openings in the lower Mobile Bay. Tidal discharge through each inlet exhibits a time lag, that results in a phase-dependent discharge ratio between the two inlets. Consequently, the magnitude and direction of exchange flows between the two inlets are time-dependent. Early in the rising tide, Mobile Bay receives seawater only through MP while simultaneously discharging estuarine water through PaH. During the beginning of falling tide, Mobile Bay receives seawater through PaH while simultaneously discharging estuarine water through MP. Net transports through MP and PaH during the study period are positive and negative, respectively. Thus, Mobile Bay receives seawater from the Gulf of Mexico through MP and discharges a portion of this seawater, along with estuarine water, to eastern Mississippi Sound through PaH. The characterization of magnitudes and spatial structures of exchange flows in the lower bay determine how buoyant suspended matter connects between the Gulf, Bay, and Sound.

ADCP data on both sides of the island in ASCII format All files are from the East Side of the Island (July 25-27, 2018), except for "West_Side_0_000_ASC.TXT" (Jul 28-29, 2018). The files are readily readable and their format follows the default from the WinRiver software of Teledyne Instruments &nbsp

Intertidal creeks (

Kelp forests affect coastal circulation but their influence on upwelling around headlands is poorly understood. Tidal-cycle surveys off two headlands with contrasting kelp coverage illustrated the influence of kelp forests on headland upwelling. Underway acoustic Doppler current and backscatter profiles were collected simultaneously to surface water temperature. Surveys occurred along three off-headland transects in July 25-29, 2018, off Isla Natividad, located midway on the western coast of the Baja California peninsula. Flows and water temperature distributions off the headland with no kelp coverage were consistent with headland upwelling. In contrast, the kelp around the headland with dense coverage: 1) attenuated the ambient flow; 2) favored an increase in effective radius of flow curvature; 3) promoted flow ducting, which consists of enhancing flow through channels unobstructed by kelp; and 4) suppressed headland upwelling. Kelp suppressed upwelling by channeling the flow away from the headland, keeping nearshore waters warmer than offshore. PLAIN LANGUAGE ABSTRACT: This study documents a way in which biology can affect physics in coastal ocean environments. In particular, the study describes how a kelp forest suppresses the upward pumping of cool subsurface waters that is typically found around headlands. Such suppression of subsurface waters injection occurs via a process that we refer to as 'flow ducting.' In flow ducting, coastal flows are channelized through kelp gaps, concentrated in bands30 m wide, and kept away from the morphological influences of a headland. This ducting is analogous to the tortuous flow through porous media.

Saltwater intrusion (SWI) in deltas, estuaries, and other coastal areas represents a pressing problem affecting the sustainability of freshwater resources. Observations and numerical experiments are used to investigate SWI in the surface waters of the Italian's largest river delta (the Po Delta) under low discharge conditions. The model successfully reproduced the observed salinity variations along main river branches and in the delta lagoons and investigated fresh and saltwater dynamics during the entire summer 2017. The numerical model is used to explore the hydrological response of the delta system to climate change. The relative effect of controlling factors on saltwater penetration, such as sea-level rise (SLR), air-sea fluxes, and reduction of river discharge, was evaluated. Results suggest that changes driven by climate and SLR will exacerbate SWI in the surface waters of the Po Delta system. Extent of SWI in the major river branch is projected to increase up to 80% further into the river. Persistence of SWI at the same site is expected to increase 100% longer. Moreover, additional synthetic simulations were used to investigate the sensitivity of SWI to several river discharges and relative SLR values, highlighting the effects of the two factors in the delta. Such results show different combinations of river discharge and relative SLR values that represent possible scenarios, and are important for managing SWI in river-sea systems affected by both climatic and anthropogenic factors such as discharge changes from dam construction, land use, and irrigation.

Information on the transport and distribution of microplastics in coastal lagoons is scarce. This study provides the first evaluation of microplastic distribution in a hypersaline coastal lagoon and explores natural and anthropogenic factors that drive their location and transport. The study combines different field strategies: spatial distribution of microplastics in sediments, for September 2017 (wet season and peak use of the lagoon) and February 2018 (winter season, characterized by intense Northerly winds and least use of the lagoon); spatial distribution of microplastics in the water column in the winter season; ocean-lagoon exchanges of water and microplastics at the lagoon entrance during tidal cycles. Also, one-year records of water level variations along the lagoon provide connections between local pressure gradients and water fluxes. Statistical analyses indicate relationships between temporal variations of microplastic concentrations and human activities. Results show marked seasonality in sources and transport agents. During the summer, microplastics concentration was related to human activities. After this season, the accumulated precipitation in the continental karst region leads to an increase in the water level at the head of the lagoon. The resulting pressure gradient promotes seaward flushing of hypersaline water and of microplastics. At tidal (diurnal) time scales, measurements at the mouth of the lagoon revealed that more particles were collected in ebb than in flood. This variability underscores the need to resolve tidal variability for microplastic sampling in coastal lagoons and estuaries.

Data sets used and codes for figures

Hurricane Harvey reached Category 4 when it made landfall on the coast of Texas in late August 2017. Harvey not only affected the coastal region with wind speeds that peaked near 50 m/s, it also dumped ~7.6 × 1010 m3 of rain over 3 days. This rainfall was equivalent to the discharge of the Amazon River over the same period and made Harvey the wettest tropical cyclone to affect the United States. Winds and rainfall interacted to produce atypical storm surges along the coast and estuaries of Texas and compound flooding in the Houston region. Data from the NOAA's Center for Operational Oceanographic Products and Services provided information on water levels in this region. The highest water levels, 3 m above predicted, occurred from August 27th to 29th at Buffalo Bayou in the uppermost reaches of the Galveston-Trinity-Tabbs-Burnet Bay system. The peak surge occurred on Aug 29th because of the triple punch of a) the ocean wind stress and corresponding surge, plus the rainfall-related land-derived discharge from b) Buffalo Bayou and then from c) the San Jacinto River. Winds from the ocean persisted during that 3-day period and drove onshore water transport. This transport, together with anomalously high mean sea levels and the coastline modifications in the upper bay system, delayed the seaward motion of the land-derived discharge. Numerical model simulations that turned forcings on and off, highlighted the importance of the two river pulses in causing the widespread flooding. Simulations also underscored the influence of the interaction between land-derived discharge and ocean-derived surge along different parts of the Houston-Galveston Bay system.

Quarter-diurnal tidal constituents are linked to tidal asymmetries and play a role in the morphodynamic evolution of inlets, estuaries and lagoons. A two-year non-continuous dataset of current velocities and waves was used to improve understanding on the generation of quarter-diurnal harmonics. Data analysis provides evidence for the generation of quarter-diurnal harmonics by wind-induced waves. Data were collected at the entrance to the Arcachon Lagoon, a mixed-energy tidal inlet in Southwest France. Temporal variability of the quarter-diurnal tidal current was identified through wavelet analysis of the main velocity component (alongshore velocity). Quarter-diurnal velocity amplitudes, bottom and wave stresses, and significant wave height suggested a linkage between quarter-diurnal amplification and wave action. Both significant wave height and wave stress were coherent with quarter-diurnal current amplitudes at synoptic frequencies, most markedly in winter months of both years observed. These coherences corroborated the hypothesis that wind-induced waves enhance bottom stresses that can generate and augment quarter-diurnal currents in this region.

Hydraulic jumps, transitions from supercritical to subcritical flows, tend to maintain suspended particles in the water column and enhance biological productivity near the surface. Transitions occur from flow adjustments as the flow moves through a cross-section reduction, such as a reef crest. Hydraulic jumps can also inhibit the settlement of coral larvae and bivalve mollusks, but could favor connectivity among reefs by dispersing planktonic organisms to surrounding areas. The Veracruz Reef System (VRS) was chosen as a case study of hydraulic jumps produced over reef crests. This system is located in the southwestern part of the Gulf of Mexico (GoM) and features 50 coral reef structures. The area is influenced by vertical stratification that modifies its dynamics. Hydrographic and yearlong current data collections in the area during 2009 identified fronts and a cyclonic recirculation. On the other hand, the presence of a hydraulic jump weakened the cyclonic recirculation on the leeward side of the reefs. The vertical gradient of the horizontal velocity suggested the influence of vertical eddies at least 35% of the time throughout the entire year. Moreover, the current velocity profiles showed a bidirectional behavior in spring and summer conditions of stratified waters. These bidirectional flows contrasted the unidirectional structure caused by frictional dynamics during northerly winds.

Inner-shelf and shoreline morphology exert control on the variability of gravity waves. Although gravity waves can influence nearshore morphodynamics, their behavior is not well understood at inner-shelves close to cuspate forelands with complex bathymetry. In order to study the effects of cape shoals on gravity wave variability, water level and velocity data were collected during Fall 2013, Spring 2014, and Fall 2014 within the swales on either side of Shoal E, near Cape Canaveral, Florida. Short wave energy fluxes (periods from 3 to 20 s, or frequencies from 50 to ~ 300 mHz) were calculated from time series of spectral densities, whereas cross-shoal infragravity energy fluxes (periods from 20 to 500 s, or frequencies from 2 to 50 mHz) were calculated from cross-spectra of pressure and cross-shoal velocities. Ratios of short-gravity-wave energy fluxes between inner and outer swales of Shoal E ranged from 0.5 to 3. Values 1 were typically associated to large (wave heights > 1 m) and short waves (periods 5 s) likely related to dissipation. Ratios > 1 were exhibited by large and long (periods > 10 s) waves because of refraction. Values close to 1 were related to small waves regardless of the wavelength. In addition, infragravity reflection coefficients were quantified as the ratio of seaward to landward infragravity energy fluxes. Reflection coefficients and spatial variations in infragravity fluxes indicate that instruments were located in the shoaling zone during Fall 2013 and Fall 2014. Infragravity energy flux differences between inner and outer swales further suggest Shoal E may have acted as a source of infragravity energy. Differences in reflection between swales on either side of Shoal E could be attributed to asymmetric short-wave shoaling and breaking, partial infragravity reflection, and infragravity energy trapping near the shoal. However, instrument configuration did not allow for along-shoal calculations, which hindered resolution of edge waves that might develop over the shoal. Our results provide evidence, albeit incomplete, of surface-gravity-wave energy scattering and dissipation over cape-related shoals. Such wave transformations, including infragravity energy forcing, may provide a positive feedback for the long-term stability of cuspate forelands by preventing the full complement of deep water wave energy from reaching the shoreline.

River discharge, precipitation, wind, water level and salinity measurements were used to investigate saltwater intrusion in a subtropical estuary. The upstream limit of saltwater intrusion was defined by the position of the 2 g/kg isohaline ( X 2 ) as it changed each tidal cycle. Observations were obtained from November 2014 to November 2015 along the Suwannee River, at Florida's Big Bend. Observations provided information to construct a first-order autoregressive Markov-chain model and predict X 2 . The model predicts X 2 from its position in the previous tidal cycle, from river discharge, from water level, from precipitation and from wind velocity. In order to capture the seasonality of the Suwannee River discharge, the analysis was done separately for high and low river discharge regimes. The high discharge regime for the particular year of observations coincided with the cold season and had a mean value of 360 m3/s. The low discharge regime overlapped with the warm season and had a mean of 198 m3/s. As expected, saltwater intrusion was inversely related to river discharge. Values of X 2 were 0.4 km for a discharge of 377 m3/s, and 6 km for a discharge of 195 m3/s. The autoregressive model was able to reproduce the observed seasonality of saltwater intrusion in the Suwannee River. The model was then used to project values of X 2 for different scenarios of climate change as represented by possible combinations of river discharge and water levels.

Wind-stress is one of the main drivers of estuarine circulation. The lateral structure of wind-induced flows in estuaries has been described mainly with analytical and numerical models. The aim of this study is to investigate, with observations, the lateral structure of wind-induced flow in a coastal plain estuary, the James River, Virginia. Such structure was explored with the first Empirical Orthogonal Function (EOF1) mode derived from month-long moored ADCPs deployed at two cross-sections in the estuary. Mode 1 explained 53% of the variance and was attributed to wind forcing. Its lateral structure (eigenvectors) consisted of upwind flow centered in the channel at middle depth, downwind flow over the shoals, and a vertically sheared bidirectional flow over the channel slope. Wavelet coherence analysis showed that along-estuary wind was highly coherent with mode 1 (coherence squared > 0.9), especially at the period band between 4 and 6 days. The along-estuary wind stress and the temporal variation of mode 1 showed an anti-phase coherence, with the wind stress leading mode 1 persistently. In addition, an analytical solution showed a lateral structure similar to the eigenvectors obtained with EOF1. The conclusion is that the lateral structure described by EOF1 was induced by wind-stress and was consistent with analytical and numerical model results. These results are among the handful available that confirm the theoretical structure of wind-driven flows over laterally varying bathymetry.

Ocean-estuary exchange variability was studied from 2008 to 2014 at a low latitude coastal plain estuary, Todos os Santos Bay, Brazil, near 13°S. Wind data from Climate Forecast System Reanalysis (CFSR) were used to complement the results of a high-resolution regional ocean model, ROMS. Volume exchange occurred under two distinct circulation patterns, namely Circ + and Circ − , that matched the down-estuary (spring/summer) and up-estuary (autumn/winter) wind regimes respectively. Circ + promoted water-column stratification, while Circ − lasted longer, induced more volume exchange, and reversed the estuarine circulation. In addition, a clockwise lateral circulation (looking into the estuary) occurred during Circ + , whereas a counterclockwise lateral circulation was observed during Circ − . Connectivity was observed between Jaguaripe River and Todos os Santos Bay entrance. Increases in Jaguaripe River discharge, in conjunction with up-estuary winds, promoted a northward advection of the river plume toward the main entrance of the estuary, creating a lateral density gradient over Todos os Santos Bay' western shoal. Our results demonstrate that findings about estuarine circulation at higher latitudes are applicable to low latitude estuaries when dynamical depth and/or basin's width indicate that Earth's rotation is relevant.

Upwelling and uplift events from 2008 to 2012 were analyzed at the South Equatorial Current bifurcation region and in the Salvador Canyon near 13°S. Wind data from Climate Forecast System Reanalysis (CFSR) were used to complement the results of a high-resolution regional ocean model. Upwelling and uplift events occurred predominantly during spring and summer. Previous studies have suggested upwelling implications for fisheries and fish diversity in the region. Uplift events were, on average, longer than upwelling events. Spatially, the strongest events were found over the adjacent shelf of Todos os Santos Bay and Salvador Canyon. This was also the region with the most frequent events. Analysis of forcing mechanisms revealed that wind-driven upwelling, mainly due to upward Ekman pumping, is dominant, with current-driven upwelling providing an additional contribution. Connectivity between Salvador Canyon and Todos os Santos Bay upwelling processes was observed in 20 events, preferentially during the austral summer. This connectivity was linked to a northward coastal undercurrent, which, in turn, advected upwelled/uplifted water from the canyon to the bay-adjacent shelf area. Connectivity occurred under two conditions: i) intense canyon upwelling and ii) low influence of the Brazil Current flow on the shelf. The results of this study demonstrate that wind-driven upwelling contributes directly to the connectivity phenomenon, whereas Brazil Current encroachment inhibits this process. Hence, the results shown herein are widely applicable to upwelling regions under the influence of Western Boundary Currents and/or submarine canyons where upwelling may occur.

Model output.&nbsp