Shelf Topography Research Articles

Peculiar Appearance of Nearly Symmetrical Tidal Flooding Time Along the Western Coast of Taiwan

ABSTRACTDuring the past several decades, nearly symmetrical tidal appearances, both the time of high water elevation and the tidal range, were noted along the western coast of Taiwan. Research corresponding to anomalous amplifications of tidal range have been well studied by Lin, et al. [1,2], but the particular symmetrical tidal appearance of high water time has not yet been clarified. In this paper, we firstly apply a harmonic analysis to tidal data compiling. Based on the results, the important symmetric appearances of high water time and tidal range can be located. Emphasis is given on the investigation of symmetrical distribution of high water time by superposing two progressive waves that interfere on a topographic shelf with specific width. A conceptual configuration of co-oscillating standing tides is proposed to demonstrate the symmetrical tidal range distributing in the space domain and oscillating in the time domain.

Large-eddy simulation of turbulent rotating convective flow development

Large-eddy simulations were carried out to simulate laboratory-scale isolated buoyant convection in unstratified water with shelf and slope topography in the presence of rotation and to compare and complement the experimental study of Jacobs & Ivey (1998) under the same conditions. The simulation code developed in this work was a three-dimensional incompressible Navier–Stokes solver and the simulation runs were performed on a distributed memory massively parallel computer, namely the IBM SP2, to study the effects of different applied heat fluxes and system rotation rates. We are able to show for the first time the detailed temporal evolution and spatial structure of the three-dimensional convective flow field. Rayleigh–Bénard instability in the form of circular concentric convective rings is recognized in the initiation process of the convection. The onset of Rayleigh–Bénard instability was investigated and the critical Rayleigh number was found to increase with Taylor number only when the Taylor number is greater than 5 × 103, where both non-dimensional parameters are based on the conductive layer thickness. The horizontally axisymmetric convective rings later break down and evolve into a quasi-two-dimensional vortex field. An azimuthal rim current develops around the periphery of the convective region. Our simulation results confirmed that the rim current velocity scales as Bt1/2/Hf3/2. Here B is the buoyancy flux applied over a bottom circular disk, f is the Coriolis parameter, t is the time and H is the distance between the tank bottom and the shelf. With increasing lateral temperature gradient the rim current undergoes a baroclinic instability. Our study of root-mean-square velocities in the convective region suggests that the transition from the buoyancy-flux-controlled to background-rotation-controlled flow occurred when the natural Rossby number Ro* became smaller than a critical value between 0.015 and 0.044. The simulation results of the convective overturning time, the wavelength of the baroclinic eddies and the density anomaly at steady state are all in reasonable agreement with the experimental data.

Late Quaternary changes of western equatorial Atlantic surface circulation and Amazon lowland climate recorded in Ceará Rise deep‐sea sediments

Today the western tropical Atlantic is the most important passage for cross‐equatorial transfer of heat in the form of warm surface water flowing from the South into the North Atlantic. Circulation changes north of South America may thus have influenced the global thermohaline circulation system and high northern latitude climate. Here we reconstruct late Quaternary variations of western equatorial Atlantic surface circulation and Amazon lowland climate obtained from a multiproxy sediment record from Ceará Rise. Variations in the illite/smectite ratio suggest drier climatic conditions in the Amazon Basin during glacials relative to interglacials. The 230Thex‐normalized fluxes and the 13C/12C record of organic carbon indicate that sea level fluctuations, shelf topography, and changes of the surface circulation pattern controlled variations and amplitude of terrigenous sediment supply to the Ceará Rise. We attribute variations in thermocline depth, reconstructed from vertical planktic foraminiferal oxygen isotope gradients and abundances of the phytoplankton species Florisphaera profunda, to changes in southeast trade wind intensity. Strong trade winds during ice volume maxima are associated with a deep western tropical Atlantic thermocline, strengthening of the North Brazil Current retroflection, and more vigorous eastward flow of surface waters.

Nutrient enrichment off Port Stephens: the role of the East Australian Current

In January 1997, a bloom of the dinoflagellate Noctiluca scintillans occurred off Port Stephens, on the New South Wales (NSW) central coast. The nutrient enrichment that presumably caused the bloom was apparently unrelated to local winds. The purpose of this study is to investigate the role of the East Australian Current (EAC) in promoting nutrient-rich slope water into the euphotic zone off Port Stephens. To this end, a regional model of the NSW coast is presented and a new mechanism for upwelling is proposed. The simulations indicate that uplifting of slope water results from the interaction of the EAC with the continental shelf topography near Laurieton, located to the north of Port Stephens. The uplifted water is consequently advected along the shelf to Port Stephens, where the EAC separates from the coast. As a result of this divergence, the uplifted slope water is upwelled to the surface, and outcrops over the shelf. In situ velocity and temperature measurements are presented as evidence for the upwelling mechanism and the proposed path of the upwelled slope water is inferred by modelling the dispersal of a passive concentration tracer injected to the north of the upwelling region. The proposed upwelling mechanism may provide insight into topographically induced upwelling in other western boundary current regions.

Modelling the impact of atmospheric and terrestrial inputs on the Black Sea coastal dynamics

Abstract. The dynamics on the North Western Shelf area of the Black Sea are examined, with an emphasis on the circulation induced by buoyancy due to the land drained fresh waters and by the interaction with the atmosphere, notably wind stress. A three-dimensional, multi-layer hydrodynamic model is employed with realistic topography and parameterisation of river plume physics. We focus on the seasonal patterns of transport of the river induced low-salinity waters within the Coastal Low Salinity Band and the conditions that influence their removal toward the shelf interior. The numerical simulations show that coastal circulation is greatly influenced by river runoff and especially in the case of the Danube, which is excessively high with monthly aver-aged values ranging from 5000 to 10000 m3 /s. A significant contribution of runoff comes from the neighbouring rivers. At the same time, the North Western Shelf is quite broad, so that the coastal dynamics are largely sheltered from the conditions in the deeper sea. Buoyancy due to river runoff thus dominates, creating a southward coastal current that is the predominant pathway for the land-drained inputs. As in all shelf areas, wind stress is a major circulation forcing mechanism and it modifies the buoyancy induced flow. It is shown that the seasonal variability in river runoff and wind stress, in combination with the shelf topography, determines the different pathways for the terrestrial inputs. Implications on the overall basin circulation are drawn, as the availability of low-salinity waters of river origin affects the upper Black Sea layer. Consequently, the formation of distinct water masses (such as the Cold Intermediate Layer) and the properties of the outflow toward the Mediterranean are also influenced.Key words. Oceanography: general (continental shelf processes; numerical modelling) – Oceanography: physical (air-sea interactions)

The adjustment of a shelfbreak jet to cross-shelf topography

A rigid-lid, finite-difference numerical model is used to study the adjustment of inviscid, along-shelf, barotropic shelfbreak jets to cross-shelf, channel topography. The channel is embedded in the shelf topography perpendicularly to the shelfbreak, the shelfbreak jet flows with the direction of propagation of long-wavelength, topographic Rossby waves, and the coast is sufficiently distant so as not to affect the flow. Three models are used that vary the strength of the channel topography S= f ΔhD/Uh , where f is the Coriolis parameter, Δ h is the difference between the shelf depth and the channel depth, D is the width of the slope into the channel, U is the maximum speed of the jet at the inflow, and h is the depth of the shelf. Estimation of the path of the jet from the inflow parameters and the geometry of the channel is possible in some cases. Generally, for large S the flow follows the topography of the channel and for small S the flow crosses the channel. The motivation for this study is the episodic flow of Scotian Shelf water from the Scotian Shelf across the Northeast Channel to Georges Bank. The steady, inviscid, non-linear, barotropic dynamics studied here do not allow such a flow for a channel of similar dimensions to the Northeast Channel and for flow speeds within the oceanographic range. Other factors such as stratification, wind stress and time variability need to be introduced to account for this phenomenon.

Sensitivity studies of circulation and ocean-shelf exchange off northen Norway

Abstract Knowledge about the general circulation on the shelf off northern Norway on a sufficiently SIJ.tall scale to include the influence of the shelf topography has been achieved before, through field investigations. However, little is known about what controls the flow in this area on the small scale. The objective of this study was to find what possibly controls the flow, with special emphasis on shelf circulation and ocean-shelf exchange. Dte to lack of sufficiently appropriate (small-scale, long-tenn) field data, an approach using a numerical model was adopted. Through model sensitivity experiments it was possible to study the effect of shelf topography and upwelling-favourable wind separately. Successful simulation of the general shelf circulation and vortex formations in agreement with field observations indicates that the model employed was performing realistically. There appears to be a strong correlation between the variation in the onshore flux in the Malangendypet trench and that in the alon...

Boundary currents over shelf and slope topography

Laboratory experiments are presented from a modelling investigation into the influence of shelf and slope topography on f-plane surface and intermediate flows along ocean boundaries. The surface flows are formed from an upstream source by the release of fresh water into a rotating tank containing salt water, while for the intermediate-water counterpart flows, neutrally-buoyant fluid was released from a submerged source into stably-stratified (two-layer) and quiescent receiving waters in solid body rotation. It is shown that the stability of these buoyancy-driven currents can be described satisfactorily by a combination of the dimensionless parameters Bu= N 2/ f 2, Ek=2 ν/ fD 0 2 and Ro= U 0/ fL 0, where N and f are the buoyancy and Coriolis frequencies respectively, D 0, L 0 and U 0 are the initial depth, width and velocity of the currents, respectively, and ν is the kinematic viscosity of the fluid. Furthermore, comparison with physical models of surface and intermediate flows along a vertical wall and over a flat bottom reveals that the stability regimes are not significantly altered by the presence of shelf topography. Variation of the depth of the surface flows with respect to the total fluid depth above the underlying shelf is shown to have a significant effect on the velocity and density structure of these flows. When the depth and width ratios are small, the surface flow is not affected by the varying topography. However, when the current occupies a considerable height above the shelf and is at least as wide as the shelf, upper layer fluid is transported offshore through the bottom Ekman layer, where it is arrested above the sloping bottom. At this location, a deepening of the upper layer develops due to potential vorticity conservation of the lower layer, accompanied by a local alongshore velocity maximum. This shelf break front prevents significant offshore transport of upper layer fluid far beyond the shelf break, even in cases where the flow is unstable. Comparison of the intermediate currents with dynamically-similar currents above a flat bottom does not reveal a stabilising effect of the slope. For unstable intermediate currents, offshore transport is not prohibited (as it is shown to be for surface currents over narrow shelves, due to the presence of the slope), and large scale instability patterns can extend over great distances from the slope. It is shown that the geostrophic nature of these currents is destroyed close to the sloping bottom. Here, the upper and lower density interfaces, denoting the vertical extents of the intermediate current, tilt sharply downwards.

Hybrid Coastal and Interior Modes for Two-Dimensional Homogeneous Flow in a Cylindrical Ocean*

Flows on coastal shelves and in the deep interior ocean are often considered separately, but transport of fluid between these two regions can have important biologial or environmental consequences. This paper considers a linear coupled coastal and deep interior-ocean model in the idealized context of a homogeneous two-dimensional cylindrical ocean with a rigid lid and axisymmetric step shelf topography. Both a semianalytical mode-matching approach and brute-force finite-element numerics have been used to analyze the linear dynamics. It is shown that hybrid planetary ?-plane Rossby and topographic shelf modes emerge. The structure of these inviscid modes is clarified by considering their frequency dependence on shelf break radius, by contrasting the evolution of hybrid modes to the evolution of pure shelf and pure ?-plane Rossby modes (considering streamfunction fields and particle paths), and by showing solutions of the initial value problem. Both �ocean� and �laboratory� parameter values are considered. Hybrid modes exchange information between the deep ocean and coastal shelves, especially at the intermediate frequencies where the separate planetary Rossby mode and topographic shelf mode dispersion curves overlap. The role of these modes is particularly clear in an initial value problem wherein a localized initial condition on the southern shelf later leads to large-scale interior ocean circulation. Forced�dissipative calculations reveal the sensitivity of resonantly generated hybrid Rossby�shelf modes to the strength of Ekman damping. For typical oceanic and laboratory parameter values hybrid modes are altered by increasing Ekman damping but do not disappear.

A Numerical Modeling of the Upper and the Intermediate Layer Circulation in the East Sea

Circulation in the upper and the intermediate layer of the East Sea is investigated by using a fine resolution, ocean general circulation model. Proper separation of the East Korean Warm Current from the coast is achieved by adopting the isopycnal mixing, and using the observed heat flux (Hirose et al., 1996) and the realistic wind stress (Na et al., 1992). The simulated surface circulation exhibits a remarkable seasonal variation in the flow patterns of the Nearshore Branch, the East Korean Warm Current and the Cold Currents. East of the Oki Bank, the Nearshore Branch follows the isobath of shelf topography from late winter to spring, while in summer and autumn it meanders offshore. The Nearshore Branch is accompanied by cyclonic and anticyclonic eddies in a fully developed meandering phase. The meandering and the eddy formation of the Nearshore Branch control the interior circulation in the Tsushima Current area. A recirculation gyre is developed in the region of the East Korean Warm Current in spring and grown up to an Ulleung Basin scale in summer. A subsurface water is mixed with the fresh surface water by winter convection in the northeastern coastal region of Korea. The well-mixed low salinity water is transported to the south by the Cold Currents, forming the salinity minimum layer (Intermediate Water) beneath the East Korean Warm Current water. The recirculation gyre redistributes the core water of the salinity minimum layer in the Ulleung Basin.

On the representation of the Southern Ocean water masses in an ocean climate model

In global ocean general circulation models used for climate studies, the simulated global deep ocean temperature and salinity generally appear to be lower than that observed. This may be due to an insufficient representation of the cryosphere in such models because the deep ocean thermohaline properties are strongly determined by high‐latitude surface conditions. In this study, it is our aim to arrive at an improved simulation of polar water mass characteristics and distribution in the framework of an ocean climate model. As a step toward identifying the critical factors influencing the high‐latitude water masses, in particular those of the Southern Ocean, we have proceeded a series of sensitivity experiments with a global sea ice‐ocean model. Forcing Southern Ocean sea ice with daily instead of monthly fluctuating wind enhances brine release due to new‐ice formation, which leads to a more pronounced core of Lower Circumpolar Deep Water (LCDW) in the Antarctic oceanic regime. Wider Antarctic shelf topography improves the distribution and thickness of sea ice, simultaneously providing a brine reservoir on the shelf, which is a crucial ingredient in the formation process of Antarctic Bottom Water (AABW). As a consequence, the salinity on the Antarctic shelf is increased with depth as observed. Intense southeasterly katabatic winds play a significant role in increasing the salinity, mainly off east Antarctica. It is suggested that modeled Southern Ocean water mass properties are highly sensitive to the large scale and regional forcing of Antarctic sea ice as well as the model representation of the shelf topography, the width of which is crucial to reproducing the first‐order features of near‐boundary convection.

Rectified Barotropic Flow over a Submarine Canyon

Abstract The effect of an isolated canyon interrupting a long continental shelf of constant cross section on the along-isobath, oscillatory motion of a homogeneous, incompressible fluid is considered by employing laboratory experiments (physical models) and a numerical model. The laboratory experiments are conducted in two separate cylindrical test cells of 13.0- and 1.8-m diameters, respectively. In both experiments the shelf topography is constructed around the periphery of the test cells, and the oscillatory motion is realized by modulating the rotation rate of the turntables. The numerical model employs a long shelf in a rectangular Cartesian geometry. It is found from the physical experiments that the oscillatory flow drives two characteristic flow patterns depending on the values of the temporal Rossby number, Rot, and the Rossby number, Ro. For sufficiently small Rot, and for the range of Ro investigated, cyclonic vortices are formed during the right to left portion of the oscillatory cycle, facing...

Sea-level changes and related depositional environments on the southern Marmara shelf

Petrographic data obtained from 182 surface sediment samples together with the available bathymetric data are used to investigate the effects of the last major sea-level changes on shelf evolution in the southern Sea of Marmara. Grain-size analysis reveals the presence of at least three belts or zones which are rich in coarse-grained (sand and gravel) sediments. These coarse-grained belts which are up to 45 km long, 15 km wide, show up to 20 m of relief and are presently found at 40–80 m (average 60 m) water depths. Based on microscopic examination and residual analysis, the sediments from these belts are interpreted as indicators of high-energy shallow waters where detrital siliciclastics, with some benthic contribution, accumulated. The presence of a 62–65 m deep sill in the Çanakkale Strait and the consideration of sea-level curves would suggest that the Marmara shelves must have been subaerially exposed down to −65 m water depths for about 10,000 yrs (22,000–12,000 yrs B.P.), sufficient time to modify former shelf topographies and form such bottom relief. While difficult to date, we believe that coarse-grained belts found on the southern Marmara shelf must be relict (i.e., former shorelines, beaches) and their formation is largely related to low stands of sea-level during the Late Pleistocene regression and early Holocene transgression. However, the available high-resolution seismic profiling data suggest that the neotectonism in this seismically active Sea of Marmara plays an important role to explain the raise of these older shorelines to their present levels on the sea-floor.

Downwelling Circulation on the Oregon Continental Shelf. Part I: Response to Idealized Forcing

Time-dependent downwelling on the Oregon continental shelf is studied with a two-dimensional approximation, that is, spatial variations across shelf and with depth, using the Blumberg-Mellor, finite-difference, stratified, hydrostatic, primitive equation model. The time-dependent response of a coastal ocean at rest to constant, downwelling-favorable wind stress is examined. Topography and stratification representative of the Oregon continental shelf are used for the basic case experiment. The wind stress forces onshore flow in a turbulent surface boundary layer. The compensating flow below the surface layer advects the density field downward and offshore and accelerates an alongshore current in the form of a vertically and horizontally sheared coastal jet. The dominant feature of the response flow field is a downwelling front that moves slowly offshore, leaving behind an inshore region where the density is well mixed. The downwelling front in the density field is concentrated near the bottom, while the front in alongshore velocity extends over the full depth and is nearly vertical, separating weak alongshore velocities inshore from the coastal jet offshore. The front contains strong vertical motion from the surface to the bottom and some recirculation. Much of the offshore flow from the base of the front is characterized by time- and space-dependent fluctuations involving spatially periodic separation and reattachment of the bottom boundary layer and accompanying recirculation cells. This flow has positive potential vorticity and appears to be finite-amplitude slantwise convection resulting from a hydrostatic symmetric instability. Additional experiments show the dependence of the response flow field an the magnitude of the wind stress, the initial stratification, and the shelf topography. Experiments with the vertical turbulent kinematic viscosity and diffusivity parameterized by a different turbulence closure scheme, as a function of a local Rich-ardson number, or as constants show dependence of the response flow field on the choice of turbulence submodel. The occurrence of a well-mixed region inshore and the existence of time- and space-dependent fluctuations associated with slantwise convection in the near-bottom offshore flow appear to be robust features of the two-dimensional downwelling response.

Bioclastic carbonate sediments on the southwestern Svalbard shelf

The poleward continuation of one of the largest known Arctic carbonate factories, the western Spitsbergenbank of the Barents Sea, has been surveyed along the narrow SW Svalbard shelf. On this shelf, formation of cold-water carbonate sediments occurs under glaciomarine environmental conditions. Mya truncata and Hiatella arctica colonized a soft glacio marine diamicton 3000–6000 years after the final retreat of the icedome from the SW Svalbard shelf. Since 2600 yr B.P., an increase of along-shelf bottom currents washed out the fine terrigenous deposits leaving behind a shelly lag-deposit and winnowed boulders on a morainic shelf topography. The most favourable depth interval promoting the establishment of an amalgamated bioclastic blanket is located in 50–80 m water depth. In this interval, strong bottom currents prevent sedimentation, thus, facilitating colonisation of filter-feeding benthic communities dominated by Balanus balanus and Chlamys islandica. Additional skeletal components are supplied by echinoderms, bryozoans, serpulids, brachiopods and gastropods. In shallower water depths, carbonate production is hampered by intense iceberg-scouring and release of ice-rafted debris from the still glaciated hinterland of Svalbard. In deeper water (>80 m), olive grey muds with dispersed pebbles rich in benthic foraminiferans, Clinocardium ciliatum and taxodont bivalves are present on all surveyed shelf banks. The deepest unit is a blue mud in water depths > 120 m with benthic foraminiferans, taxodont bivalves and sipunculids. Compared to Spitsbergenbank, carbonate production is much more restricted and impoverished on the SW Svalbard shelf, but is still an instructive modern example for the formation of skeletal carbonates resting on tillites in the geological record.

Current meter observations from the Labrador and Newfoundland shelves and comparisons with barotropic model predictions and IIP surface currents

Abstract Recent current measurements from the southern Labrador and northeastern Newfoundland shelves confirm the presence of inshore and offshore branches of the Labrador Current with high mean currents and low standard deviations. At mid‐shelf weaker and more variable currents occur over the banks, and cross‐shelf flows are found to be associated with the shelf topography. An annual cycle of the inshore branch, in phase with wind forcing, is significant on the NE Newfoundland Shelf but not detectable on Hamilton Bank. The phase of the annual cycle in the offshore branch is consistent with buoyancy, not wind forcing. The observations compare reasonably well with results from a barotropic model for the region and the International Ice Patrol (IIP) surface current map. Differences occur particularly in regions of high bathymetrie curvature or an ill‐defined shelf break. The model location of the Labrador Current lies inshore of that indicated by the data, suggesting the need for better definition of the no...

Topographic control on the dynamics of the Svalbard-Barents Sea ice sheet

The land surface of what is now the Barents Sea region may have been eroded to a sub-aerial platform prior to the Quaternary, due to both tectonic uplift-induced and sea-level lowering-induced erosion processes. The Barents Sea was then further eroded into its present form by the subsequent action of ice sheets. Two bedrock configurations, representing the pre-Quaternary sub-aerial Barents Shelf topography and the largely submarine morphology of the present day, were used as input to a glaciological ice sheet model so that the dynamic evolution of the maximum-sized ice sheets, caused solely by a change in bedrock elevation, could be identified. The ice-sheet model was run under constant glacial environmental conditions, until mass balance stability was reached, over both bedrock configurations. The simple parabolic ice sheet surface, which formed on a flat sub-aerial bedrock platform, was found to be significantly different in dynamic character compared with an ice sheet developed on the present submarine bedrock topography. In this latter situation, the central ice dome is drained by ice streams in Bjørnøyrenna, Storfjordrenna and smaller outlet glaciers in the north of the ice sheet.

A comparison of the spectral characteristics of observed and simulated tsunamis

The spectra of real tsunamis depend on the source characteristics, propagation effects on the deep ocean, shelf topography and harbour geometry. The separation between all these effects is possible if a large number of instrumental tsunami data is available and, in that case, the source parameters may be computed by cancellation of path and instrumental effects. This is not generally the case in the SW Iberian region, where, in spite of some very large historical events there is only a small number of instrumental tsunamis. A good case study for that methodology is given by the 28.02.1969 tsunami, which has been previously studied with rather encouraging results in terms of the comparison of arrival times and amplitudes between observed and simulated tsunamis. The aim of the present study is the comparison between the spectral characteristics of instrumental tide records and the synthetic wave forms computed with a shallow water model.

A Numerical Model of Internal Tides with Application to the Australian North West Shelf

A nonlinear, primitive equation, finite-difference numerical model is applied to the problem of the generation, propagation, and dissipation of internal tides over a cross section of the continental slope and shelf topography of a region on the Australian North West Shelf. The model is forced through the specification of the offshore tidal elevation and as such the full tidal field is modeled for the M2 constituent. An energetic internal tide is produced in the model with results showing sensitivity to changes in both stratification and bathymetry. The ratio of the slope of the internal wave characteristics to the bathymetry is generally less than or close to one, producing subcritical and approximately critical conditions. Model results are compared to previously reported observations and show reasonable agreement in terms of wave structure, propagation direction, and regions of generation and energy dissipation. The model shows a high degree of spatial variability in the amplitude and phase of internal wave currents and vertical displacements with motion tending to propagate along characteristic paths as beams of signal. However, dissipation prevents the beams from radiating large distances from the generation regions. The energy flux of the internal tide propagates both onshore and offshore and the magnitude of the flux is strongly dependent on the slope of the bathymetry with largest values occurring for steepest topography. The internal wave amplitude and hence energy flux is also found to be dependent on the magnitude of the vertical and horizontal mixing of momentum with maximum values achieved under conditions of no mixing.

Upwelling Circulation on the Oregon Continental Shelf. Part II: Simulations and Comparisons with Observations

Sixty-day simulations of flow on the Oregon continental shelf are performed using the Blumberg and Mellor sigma coordinate, primitive equation model. The model is two-dimensional (an across-shelf section) with high spatial resolution and realistic shelf topography. Forcing consists of surface heat flux, either hourly or low-pass filtered wind stress, and in one case, a constant alongshore pressure gradient. Model results are compared with current and hydrographic measurements from the CUE-2 program. The horizontal scale of the alongshore coastal jet is significantly influenced by the structure of the initial density and velocity fields. The model successfully reproduces the vertical shear in the alongshore velocity field v, but the model's mean v field is too strongly southward, and the variance in both the vvu and v fields is underpredicted. Inclusion of the alongshore pressure gradient, while improving prediction of the mean alongshore velocities, does not improve the model-data correlation. The time-mean model density agrees with observations at middepths over the shelf, but shows larger values than observed near the surface. The results demonstrate the importance of including a surface heat flux and of specifying realistic initial density and alongshore velocity fields.