modeling study of turbulent mixing over the continental shelf comparison of turbulent closure schemes limitation is imposed during upwelling favorable winds the majority of turbulent mixing occurs in the top and the bottom boundary layers and in the vicinity of the vertically and horizontally sheared coastal jet turbulent mixing in the coastal jet is primarily driven by shear production the near surface flow on the inner shelf becomes convectively unstable as wind stress forces the upwelled water to flow offshore in the surface layer during downwelling favorable winds the strongest mixing occurs in the vicinity of the downwelling front the largest turbulent kinetic energy and dissipation are found near the bottom of the front turbulence in the bottom boundary layer offshore of the front is concentrated between recirculation cells which are generated as a result of symmetric instabilities in the boundary layer flow index terms 4219 oceanography general continental shelf processes 4568 oceanography physical turbulence diffusion and mixing processes 4255 oceanography general numerical modeling 4279 oceanography general upwelling and convergences

assimilation of moored velocity data in a model of coastal wind driven circulation off oregon multivariate capabilities 1 horizontal current measurements from an array of moored acoustic doppler profilers are assimilated sequentially into a model of coastal wind driven circulation off oregon during the upwelling season of may august 2001 model results are compared against independent moored and ship survey data to document a positive effect of velocity data assimilation da on other oceanic variables of interest such as the sea surface height ssh temperature potential density surface salinity and near bottom turbulence parameters significant improvement is achieved for the nearshore ssh even when data are assimilated from only two moorings at an alongshore distance of 50 km from the ssh verification site at 45 n in an area of simple shelf bathymetry with relatively small alongshore variations the model even without da provides a good description of the isopycnal structure on a cross shore section at 44 2 n over complicated bathymetry velocity da may improve the slope of isopycnals but at the same time not necessarily the density values themselves data assimilation based on a time invariant representation of the forecast error covariance may inhibit spatial variability on horizontal scales smaller than the assumed forecast error decorrelation scale an experiment involving assimilation of both velocity and moored salinity measurements demonstrates that moored velocity da improves transport of buoyant surface water the level of improvement in the near bottom turbulent dissipation and bottom stress found with the da model indicates that it is suitable for future studies of spatial and temporal variability in the bottom boundary layer off oregon

time dependent wind driven flow over a shallow midshelf submarine bank 1 during summer 2001 high resolution hydrographic velocity and bio optical surveys were conducted over heceta bank off central oregon north of the bank upwelling over simple bottom topography exhibited a classic response with a midshelf baroclinic coastal jet and upwelled isopycnals the coastal upwelling jet follows the bank topography as it widens offshore before reaching the southern end of the bank where the shelf break turns almost 90 back toward the coast the ensuing adjustment involves the offshelf transport of coastal water and the material it contains the jet meanders anticyclonically in the lee of the bank before resuming its equatorward path seaward of the shelf break a pool of high chlorophyll 15 mg m 3 near surface water is found in the low velocity lee region created by the bank a low temperature high salinity bottom water pool supplied primarily from the south lies over the inshore region of the bank this bottom pool is up to 40 m thick and contains elevated levels of suspended material by creating an east west perturbation in the coastal upwelling front the flow topography interaction introduces an alongshore pressure gradient when southward upwelling favorable winds relax this alongshore pressure gradient can drive flow back to the north this leads to northward flow on the inshore side of the bank ultimately setting up the potential for recirculation around the entire bank complex on a timescale of about 10 days strong northward winds during summer lead to downwelling within 15 km of the coast accompanied by significant 0 2 m s 1 wind driven northward currents

altimeter derived variability of surface velocities in the california current system 2 seasonal circulation and eddy statistics abstract satellite surface height and temperature fields are used to examine the seasonal surface circulation in the california current system in spring and summer an equatorward jet develops next to the coast with an initial latitudinal structure that responds to the latitudinal distribution of equatorward alongshore winds this jet moves offshore from spring to fall and develops meanders and closed eddies that contribute eddy kinetic energy and water mass properties to the nearby deep ocean higher eke appears first in spring near the coast and moves offshore with the seasonal jet along altimeter tracks parallel to the coastline 200 and 400 km offshore the greatest eke is found in summer and fall respectively with wavelengths of approximately 300 km these are the wavelengths of the largest meanders and the distance between the largest eddies visible in altimeter snapshots of the jet at 600 800 km offshore the wavelengths are generally smaller 100 150 km similar to eddy sizes reported by others for the quiescent northeast pacific some energy with longer wavelengths arrives at the track 600 km offshore in winter and 800 km offshore in spring which we interpret as the most offshore extension of the eke generated by the jet and eddy system closer to the coast in the previous spring and summer a sequence of snapshots from october 1992 to october 1993 shows details of the evolution of the jet and eddy system over one complete annual cycle

chemical mass transport between fluid fine tailings and the overlying water cover of an oil sands end pit lake fluid fine tailings fft are a principal by product of the bitumen extraction process at oil sands mines base mine lake bml the first full scale demonstration oil sands end pit lake epl contains approximately 1 9 x108 m3 of fft stored under a water cover within a decommissioned mine pit chemical mass transfer from the fft to the water cover can occur via two key processes 1 advection dispersion driven by tailings settlement and 2 fft disturbance due to fluid movement in the water cover dissolved chloride cl was used to evaluate the water cover mass balance and to track mass transport within the underlying fft based on field sampling and numerical modeling results indicated that fft was the dominant cl source to the water cover and that the fft is exhibiting a transient advection dispersion mass transport regime with intermittent disturbance near the fft water interface the advective pore water flux was estimated by the mass balance to be 0 002 m3 m 2 d 1 which represents 0 73 m of fft settlement per year however the fft pore water cl concentrations and corresponding mass transport simulations indicated that advection rates and disturbance depths vary between sample locations the disturbance depth was estimated to vary with location between 0 75 and 0 95 m this investigation provides valuable insight for assessing the geochemical evolution of the water cover and performance of epls as an oil sands reclamation strategy

anomalous southward advection during 2002 in the northern california current evidence from lagrangian surface drifters 1 equatorward velocities in the upwelling jet of the northern california current were 0 05 0 06 m s 1 faster in spring and summer 2002 than on average over 1998 2002 this result is based on a five year data set of surface drifters released across the continental margin off central oregon 44 65 n during april and july of each year at this speed anomalous water displacements of over a degree of latitude can occur in 20 25 days given a source of cold subarctic water to the north this anomalous southward displacement is a plausible explanation for the cold nutrient rich halocline water observed off oregon during the summer of 2002 this interannual variability in the northern california current and its implications for the ecosystem response i e increased primary productivity may be contrasted with interannual variability of the opposite sign increased poleward velocity warmer temperatures and decreased productivity observed in this same region during el nino years

wind forced modeling studies of currents meanders and eddies in the california current system this process oriented study of the california current system ccs uses a high resolution multilevel primitive equation ocean model on a plane to isolate the response of that eastern boundary oceanic regime to temporal and spatially varying wind forcing to study the generation evolution and maintenance of many of the observed features such as currents meanders and eddies in the ccs the model is forced from rest with seasonal climatological winds in response to the prevailing wind direction surface equatorward currents develop along with upwelling of cooler water along the coast and a poleward undercurrent baroclinic barotropic instabilities in the equatorward surface current and poleward undercurrent result in the generation of meanders near the coast as the meanders intensify cold upwelling filaments develop along the coast and subsequently extend farther offshore in time the meanders form both cyclonic and anticyclonic eddies which subsequently propagate farther offshore longer simulation times 3 4 years in which a quasi equilibrium state for the ccs is reached show a seasonal cycle in response to the wind forcing for the coastal currents upwelling and filaments the meanders and eddies however can be quasi permanent as well as seasonal features the quasi permanent features play a significant role in modifying coastal currents upwelling and filaments which leads to large temporal and spatial variability in the ccs in a sensitivity study the results from several numerical experiments are used to examine the dependence of the generation of the currents meanders and eddies on the type of coriolis parameterization wind forcing and coastline geometry both the meridional variability of plane and the alongshore component of the wind stress are shown to be key ingredients for generating realistic vertical and horizontal structures for the cores of the surface equatorward and the subsurface poleward currents with such structures the currents are baroclinically and barotropically unstable resulting in the generation of meanders filaments and eddies irregularities in the coastline geometry are shown to be important for anchoring upwelling and filaments as well as for enhancing the growth of meanders and eddies cyclonic eddies tend to form in the vicinity of capes while anticyclonic eddies tend to form in the coastal indentations between capes the region off cape blanco is identified as the location where the coastal equatorward flow off oregon leaves the coast to develop a meandering jet off california the results from these experiments support the hypothesis that wind forcing and coastline irregularities on a beta plane are important mechanisms for the generation of many of the observed features of the ccs

the diffusive tortuosity of fine grained unlithified sediments abstract use of fick s first law to estimate solute fluxes is arguably the most common and important calculation related to the geochemistry and environmental chemistry of fine grained unlithified sediments in such porous media the diffusion coefficient in this law must be reduced by the square of the tortuosity to account for the longer diffusive paths experimental methods to estimate tortuosity are specialized or time consuming and not routinely done an analysis of available data shows that tortuosity is accurately correlated to readily measured porosity values through the simple relation 2 1 l n 2

a nested grid model of the oregon coastal transition zone simulations and comparisons with observations during the 2001 upwelling season 1 the oregon coastal transition zone octz extends several hundred kilometers offshore where shelf flows interact with the northern california current a primitive equation numerical ocean model is used to study the upwelling circulation in this region from 1 may to 1 november 2001 this octz model obtains initial and boundary conditions from a larger scale model of the california current system and forcing from a regional atmospheric model product the model results are compared with extensive in situ and remotely sensed data and the model is found to provide a realistic representation of flows both over the shelf and in the broader octz simulation of coastal sea level and shelf currents over the complex topography of the central oregon coast is improved quantitatively relative to previous regional models a particularly significant qualitative improvement is realistic representation of coastal jet separation and eddy formation offshore of cape blanco three dimensional lagrangian analysis of water parcel displacement shows that the surface waters inshore of the separated jet are upwelled from near the bottom along the shelf as far north as 45 5 n a large eddy which incorporates some of this upwelled water and carries it farther westward forms offshore in the late summer ensemble simulations show a distinction between the strongly deterministic response to wind forcing over the shelf and the more unstable less predictable jet separation and offshore eddy formation processes in the region near cape blanco

the hydraulics of an evolving upwelling jet flowing around a cape upwelling jets flow alongshore in approximate geostrophic balance with the onshore pressure gradient induced by coastal upwelling observations of such jets have shown that they often move offshore downstream of capes leaving a pool of upwelled water inshore comparisons are made between this behavior and the hydraulic transition of a potential vorticity conserving coastal current as it passes a topographic anomaly at which it is exactly critical to long coastal trapped waves an analytic 1 5 layer model of coastal hydraulics with constant potential vorticity in each layer predicts flow fields i e jet separation in critical situations that resemble observations when scales approximate cape blanco on the oregon coast separation occurs at a jet transport of around 0 76 3 106 m3 s21 similar to observed transports time dependent semigeostrophic calculations suggest that during an upwelling season the jet would evolve from a weak flow which was subcritical everywhere and symmetric about the cape to an exactly critical state that made a transition from subcritical to supercritical structure at the head of the cape the predicted flow field at critical transition consists of a narrow upwelling jet upstream of the cape that moves offshore and broadens at the cape this critical state would be accompanied by a downstream jump back to subcritical conditions further upwelling favorable winds would lead to transient waves that propagated upstream and downstream modifying the upstream and downstream conditions and restoring criticality thus the head of the cape exerts hydraulic control on the flow and prevents the jet transport from increasing above its critical level inherent in the hydraulic approach is the assumption that alongshore scales are large for realistic alongshore scales solutions modified by coastline curvature suggest that the convexity of the head of a cape slightly inhibits the transition to a strongly upwelled downstream state by increasing the required critical transport in the presence of topographic features with finite alongshore scale the hydraulic approach can be used to construct a flow field although this flow field has an inherent error arising from the implicit assumptions regarding scales estimation of this error for topography representing cape blanco suggests that in places the cape is rather abrupt for hydraulic theory to be valid

upwelling induced by the frictional stress curl and vertical squeezing of the vortex tube over a submerged valley in the east china sea we conducted a process oriented modeling study to investigate the characteristics and dynamics of the prominent upwelling over a vast submerged valley in the east china sea ecs the valley is inversely funnel shaped with the west bank and the east bank oriented in the north south direction a cross bank upward transport occurred along the west bank it intensified northward and peaked around the head of the valley an along bank southward pressure gradient force pgf formed the cross bank geostrophic transport for the upwelling over the valley the pgf reached its maxima at the head of the valley our momentum and vorticity dynamic analyses revealed that a bottom stress curl mainly contributed the pgf along the west bank at the same time both the bottom stress curl and the nonlinear vorticity advection contributed to the pgf around the head the bottom stress curl was due to the bottom shear vorticity of the coastal current and the curvature vorticity around the head the nonlinear vorticity advection formed because of the vertical squeezing of vortex tube as the current flowed over the valley the nonlinearity mainly affected the pgf around the head whereas the bottom stress curl contributed to the pgf over the entire valley the ratio of the nonlinear to frictional contributions to the pgf increased as the coastal current intensified our study demonstrates that the pgf that drives the upwelling over the valley is the combined result of the nonlinearity due to vertical squeezing of vortex tube and bottom frictional effects

ensemble based estimates of the predictability of wind driven coastal ocean flow over topography abstract the predictability of coastal ocean circulation over the central oregon shelf a region of strong wind driven currents and variable topography is studied using ensembles of 50 day primitive equation ocean model simulations with realistic topography simplified lateral boundary conditions and forcing from both idealized and observed wind time series representative of the summer upwelling season the main focus is on the balance relevant to practical predictability between deterministic response to known or well predicted forcing uncertainty in initial conditions and sensitivity to instabilities and topographic interactions large ensemble and single simulation variances are found downstream of topographic features associated with transitions between along isobath and cross isobath flow which are in turn related both to the time integrated amplitude of upwelling favorable wind forcing and to the formation of small scale eddies simulated predictability experiments are conducted and model fo

numerical model simulations of continental shelf flows off northern california abstract the three dimensional circulation on the continental shelf off northern california in the wind events and shelf transport west experiment region during summer 2001 is studied using the primitive equation regional ocean modeling system roms the simulations are performed with realistic topography and initial stratification in a limited area domain with a high resolution grid forcing consists of measured wind stress and heat flux values obtained from a west surface buoy the general response shows a southward coastal upwelling jet of up to 1 m s 1 and a weakening or reversal of currents inshore of the jet when upwelling winds relax model results are compared to west moored velocity and temperature measurements at five locations to codar surface current observations between pt reyes and bodega bay and to hydrographic measurements along shipboard survey lines the model performs reasonably well with the highest depth averaged velocity correlation 0 81 at the inshore mooring 40 m water depth and lowest correlation 0 68 at the mid depth mooring 90 m depth the model shows generally stronger velocities than those observed especially at the inshore moorings and a lack in complete reversal of southward velocities observed when upwelling winds relax the comparison of surface velocities with codar measurements shows good agreement of the mean and the dominant mode of variability the hydrography compares closely at the southern and northern edges of the survey region correlation coefficients between 0 90 and 0 97 with weaker correlations at the three interior survey lines correlation coefficients between 0 44 and 0 76 mean model fields over the summer upwelling period show slight coastal jet separation off pt arena and significant separation off pt reyes the cape regions also experience relatively strong bottom velocities and nonlinearity in the surface flow across shelf velocity sections examined along the shelf reveal a double jet structure that appears just north of bodega bay and shows the offshore jet strengthening to the south we examine the dynamics during an upwelling and subsequent relaxation event in may 2001 in which the west measurements show evidence of a strong flow response the alongshelf variability in the upwelling and relaxation response introduced by pt reyes is evident analysis of term balances from the depth averaged momentum equations helps to clarify the event dynamics in different regions over the shelf a clear pattern in the nonlinear advection term is due to the spatial acceleration of the southward jet around the capes of pt arena and pt reyes during upwelling results from a three dimensional lagrangian analysis of water parcel displacement show significant southward displacement in the coastal jet region including a strong signal from the double jet alongshelf variability in parcel displacements and upwelling source waters due to the presence of pt arena and pt reyes is also apparent from the lagrangian fields a cyclonic eddy like recirculation feature offshore of pt arena prior to the upwelling event causes large patches of onshore displaced parcels additionally across shelf variability in the response of water parcels along the d line includes decreased vertical displacement and increased alongshelf displacement in the offshore direction

determining the mean depth of overland flow in field studies of flow hydraulics in field studies of interrill overland flow conducted on runoff plots the mean depth of flow is usually obtained by averaging measurements of flow depth at regularly spaced points across the plot including points where there is no flow although this procedure may be appropriate in studies aimed at runoff prediction it is not in studies concerned with flow hydraulics in the latter studies more realistic results can be obtained by excluding those points where the depth is zero and reducing the width of flow in proportion to the number of points excluded failure to do this results in the underestimation of the actual mean flow depth reynolds number and friction factor where discharges are small or microtopography is large this underestimation is likely to be significant

on the spatial structure of coastal circulation off newport oregon during spring and summer 2001 in a region of varying shelf width 1 a time series of hourly surface current maps in the shelf waters off newport oregon was made during april september 2001 using five seasonde hf current mappers during coastal advances in shelf transport coast the surface currents responded rapidly to the changing winds in repeated patterns that were strongly affected by bottom topography an equatorward current jet repeatedly formed in response to upwelling winds its strength but not its trajectory covarying with the meridional wind stress near cape foulweather 44 8 n where the shelf begins to widen the jet rotates weakens and trends offshore to the south first along then across the isobaths below cape foulweather inshore of the jet a lee region of generally weak currents was commonly observed the equatorward jet core was most commonly observed near the 80 m isobath between 45 0 n and 44 4 n but transited offshore between spring and summer over heceta bank at newport 44 6 n it was rarely observed less than 8 km from the coast a second inshore equatorward jet previously unknown was observed repeatedly south of waldport 44 4 n sustained downwelling wind episodes produced poleward currents though less responsively north of cape foulweather strongest poleward flow was generally trapped near the coast surface currents were correlated with the northward wind except regionally far from shore over heceta bank responding within half a day response to the wind varies spatially being intensified in the narrow shelf northern region the equatorward jet persists through periods of zero wind forcing coastal sea level covaries with the meridional wind and the primary mode of ocean current response

numerical simulation of flow around a tall isolated seamount part i problem formulation and model accuracy abstract a sigma coordinate ocean circulation model is employed to study flow trapped to a tall seamount in a periodic f plane channel in part i errors arising from the pressure gradient formulation in the steep topography strong stratification limit are examined to illustrate the error properties a linearized adiabatic version of the model is considered both with and without forcing and starting from a resting state with level isopycnals the systematic discretization errors from the horizontal pressure gradient terms are shown analytically to increase with steeper topography relative to a fixed horizontal grid and for stronger stratification as measured by the burger number for an initially quiescent unforced ocean the pressure gradient errors produce a spurious oscillating current that at the end of 10 days is approximately 1 cm s 1 in amplitude the period of the spurious oscillation about 0 5 days is shown to be a consequence of the particular form of the pressure gradient terms in th

modeling bottom mixed layer variability on the mid oregon shelf during summer upwelling abstract results from a model of wind driven circulation are analyzed to study spatial and temporal variability in the bottom mixed layer bml on the mid oregon shelf in summer 2001 the model assimilates acoustic doppler profiler velocities from two cross shore lines of moorings 90 km apart to provide improved accuracy of near bottom velocities and turbulence variables in the area between the mooring lines model results suggest that the response of the bml thickness to upwelling and downwelling favorable winds differs qualitatively between an area of simple bathymetric slope at 45 n and a wider shelf area east of stonewall bank 44 5 n at 45 n the bml grows in response to downwelling favorable conditions in agreement with known theories east of stonewall bank the bml thickness is increased following upwelling events in this area the southward upwelling jet detaches from the coast and flows over a wider part of the oregon shelf creating conditions for ekman pumping near the bottom based on

the relative importance of wind strength and along shelf bathymetric variations on the separation of a coastal upwelling jet abstract a high resolution numerical model with idealized topography is used to investigate the degree to which a coastal upwelling jet separates from the shelf as it flows around a submarine bank depending on the wind strength and the horizontal scale of the bank experiments were run using several wind forcing magnitudes and submarine banks with different geometries so as to explore a wide range of the flow strength as measured by the rossby number ro and the ratio of the squares of the internal rossby radius of deformation and curvature of the topography as denoted by the burger number bu the intensity of the jet separation is strongly dependent on both parameters with maximum separation with increasing ro and bu close to 1 when large amounts of upwelled water are exported toward deeper waters for small bu separation is minimal and independent of ro for high ro the degree of separation decreases at large bu since the bank acts only as a small perturbation to the flow term balances in the a

combined effects of wind driven upwelling and internal tide on the continental shelf abstract internal tides on the continental shelf can be intermittent as a result of changing hydrographic conditions associated with wind driven upwelling in turn the internal tide can affect transports associated with upwelling to study these processes simulations in an idealized alongshore uniform setup are performed utilizing the hydrostatic regional ocean modeling system roms with conditions corresponding as closely as possible to the central oregon shelf wind only wo tide only to and tide and wind tw solutions are compared utilizing cases with constant upwelling favorable wind stress as well as with time variable observed stress the tide is forced by applying cross shore barotropic flow at the offshore boundary with intensity sufficient to generate an internal tide with horizontal velocity amplitudes near 0 15 m s 1 corresponding to observed levels the internal tide affects the subinertial circulation mostly through the changes in the bottom boundary layer variability re

field measurement of the velocity of overland flow using dye tracing a new method of computing the mean velocity of overland flow using dye tracing is proposed in which a specified cross section is divided into zones of relatively uniform flow characteristics termed partial sections the mean surface velocity for each partial section is determined by timing the passage of injected dye and this figure is multiplied by 0 67 0 70 or 0 80 depending on whether the flow is laminar transitional or turbulent to give mean velocity the mean velocity for the entire cross section is calculated by multiplying the mean velocity of each partial section by its cross sectional area summing the products for all the partial sections and dividing by the total area of the cross section a field test shows that mean velocity derived in this manner differs from mean velocity derived by the discharge method i e by dividing discharge measured volumetrically by cross sectional area by an average of only 7 07 per cent thus the partial section technique appears to provide a reliable method of estimating mean velocity of overland flow

continuity of the poleward undercurrent along the eastern boundary of the mid latitude north pacific abstract several recent data sets improve our view of the poleward undercurrent of the california current system as part of a triennial national marine fisheries service nmfs survey of pacific whiting a series of 105 shipboard acoustic doppler current profiler adcp velocity sections across the shelf break from 33 to 51 n at about 18 km meridional spacing were collected from july to august 1995 significant 0 05 m s 1 subsurface poleward flow occurred in 91 of the sections a mean cross shelf section using the entire data set has statistical significance revealing an undercurrent core 0 1 m s 1 from 200 275 m depth 20 25 km off the shelf break the mean poleward volume transport in a 125 325 m layer is 0 8 0 2 10 6 m 3 s 1 we focus particular attention on the cape blanco to cape mendocino region and the nmfs results are compared with shipboard adcp three weeks later from a study of coastal upwelling processes near cape blanco adcp streamfunction maps are derived and strongly suggest that one portion of flow is continuous over the 440 km meridional extent of the analysis region other portions of the flow show evidence of offshore turning separation and the formation of anti cyclonic eddies we also note that isopycnic potential vorticity from alongslope ctd stations during the nmfs survey appears to be a tracer for the poleward flow

modeling upwelling circulation off the oregon coast 1 time dependent three dimensional upwelling circulation on the continental shelf off the oregon coast is studied using a primitive equation numerical model a limited area domain with a high resolution curvilinear grid is utilized the response of the coastal ocean to forcing by observed wind stress and heat flux during the summer 2001 time period of the coastal ocean advances in shelf transport coast field experiment is investigated model results are compared to coast current and hydrographic measurements the shelf velocity and density fields are generally characterized by the presence of a southward alongshore coastal jet with an upwelling density front on the shoreward side of the jet the large variability in shelf topography associated with heceta bank exerts a major influence on the shelf velocity and density fields over the bank the alongshore coastal jet is displaced offshore and colder upwelled water extends farther from the coast northward mean flow and upward motion are found inshore of the jet three dimensional flow structures in response to variable shelf bottom topography are presented and an analysis of time and space dependent alongshore momentum balances is applied to clarify the associated dynamics in general northward pressure gradients set up over the bank during southward upwelling winds accelerate currents on the inshore side of the jet northward when the winds relax analysis of term balances in the depth averaged equation for potential temperature shows that during upwelling across shore advection makes the major contribution to cooling over most of the region except inshore over heceta bank where alongshore advection also plays a significant role

near surface dynamics of a separated jet in the coastal transition zone off oregon 1 three dimensional circulation in the coastal transition zone ctz off oregon is studied using a 3 km resolution model based on the regional ocean modeling system the study period is spring and summer 2002 when extensive observations were available from the northeastern pacific component of the global ocean ecosystems dynamics project our main focus is on near surface transports particularly in an area off cape blanco where an energetic coastal current is separated in the ctz comparisons with available observations velocities from midshelf moorings surface velocities from high frequency radars satellite sea surface temperature maps along track sea surface height altimetry and seasoar hydrography show that the model reproduces qualitatively correctly the flow structure and variability in the study area the near surface flow behavior during 26 july to 21 august a late summer time period of strong time variable southward winds is examined during that period the coastal jet separates from the continental shelf around cape blanco 43 n the energetic separated jet continues to flow southward in a near coastal region between 42 2 n and 43 n it subsequently turns around 42 n to flow westward offshore past 127 w relatively vigorous up and downwelling is found concentrated in the region of the separated jet frontogenesis secondary circulation nonlinear effects of the relative vorticity on the ageostrophic ekman transport and submesoscale instabilities contribute to the vertical circulation within the jet vertical velocities are found to reach 50 m d 1 in the offshore part of the jet and 100 m d 1 in the near coastal part where the jet is aligned with the wind direction

eddy covariance measurements of evaporation from great slave lake northwest territories canada the first direct measurements of evaporation from a large high latitude lake great slave lake northwest territories canada were made using eddy covariance between july 24 and september 10 1997 and june 22 and september 26 1998 the main body of the lake was ice free between june 20 and december 13 1997 and june 1 1998 and january 8 1999 with the extended ice free season in 1997 1998 coinciding with 48c above normal air temperatures and an abnormally strong el nino measurements extending roughly 5 0 to 8 5 km across the lake were made from a small rock outcrop located near the main body of the lake the lake was thermally stratified between mid july and september with the thermocline extending down to approximately 15 m high winds were effective in mixing warm surface waters downward and when accompanied by cold fronts resulted in large episodic evaporation events typically lasting 45 hours the daily total evaporation was best described as a function of the product of the horizontal wind speed and vapor pressure difference between the water surface and atmosphere seasonally the latent heat flux was initially negative directed toward the surface followed by a steady increase to positive values directed away from the surface shortly after ice breakup the latent heat flux then remained positive for the remainder of the ice free period decreasing midsummer and then steadily increasing until freeze up the sensible heat flux was small and often negative most of the spring and summer yet switched to positive and began to increase in the early fall extrapolation of evaporation measurements for the entire ice free periods gave totals of 386 and 485 mm in 1997 and 1998 1999 respectively

wind relaxation and a coastal buoyant plume north of pt conception ca observations simulations and scalings in upwelling regions wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems the coastal ocean response to wind relaxation around pt conception ca is simulated with a regional ocean model roms forced by realistic surface and lateral boundary conditions including tidal processes the model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner shelf mooring locations throughout the study a poleward propagating plume of southern california bight water that increases shelf water temperatures by 5 c is also reproduced modeled plume propagation speed spatial scales and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface trapped and slope controlled dynamics plume momentum balances are distinct between the offshore 30 m depth region where the plume is surface trapped and onshore of the 30 m isobath within 5 km from shore where the plume water mass extends to the bottom and is slope controlled in the onshore region bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core numerical experiments without tidal forcing show that modeled surface temperatures are biased 0 5 c high potentially affecting plume propagation distance and persistence

coastal upwelling in the california current system abstract coastal upwelling in the california current system has been the subject of large scale studies off california and baja california and of small scale studies off oregon recent studies of the winds along the entire coast from 25 n to 50 n indicate that there are significant along shore variations in the strength of coastal upwelling which are reflected in the observed temperature distribution active upwelling appears to be restricted to a narrow coastal band about 10 25 km wide along the entire coast but the region influenced by coastal upwelling may be much wider intensive observations of the upwelling zone during summer off oregon show the presence of a southward coastal jet at the surface a mean vertical shear a poleward undercurrent along the bottom and persistently sloping isopycnals over the continental shelf most of the upwelling there occurs during relatively short periods several days long of upwelling favorable winds during the upwelling season off oregon the offshore ekman transport is carried by the surface ekman layer and the onshore return flow occurs through a quasi geostrophic interior it is not known whether the structure and dynamics observed off oregon are typical of the upwelling zone along the entire coast though some of the same features have been observed off baja california current and future research will eventually show whether the oregon results are also applicable in the region of persistently strong upwelling favorable winds off northern california and in the region of complex bathymetry off central and southern california

equilibrium structure and dynamics of the california current system this paper addresses the structure and dynamical mechanisms of regional and mesoscale physical variability in the subtropical northeast pacific ocean using the regional oceanic modeling system roms the model is configured with a u s west coast domain that spans the california current system ccs with a mesoscale horizontal resolution up to as fine as 3 5 km its mean seasonal forcing is by momentum heat and water fluxes at the surface and adaptive nudging to gyre scale fields at the open water boundaries its equilibrium solutions show realistic mean and seasonal states and vigorous mesoscale eddies fronts and filaments the level of eddy kinetic energy eke in the model is comparable to drifter and altimeter estimates in the solutions with sufficiently fine resolution because the model lacks nonseasonal transient forcing the authors conclude that the dominant mesoscale variability in the ccs is intrinsic rather than transiently forced the primary eddy generation mechanism is the baroclinic instability of upwelling alongshore currents there is progressive movement of meanseasonal currents and eddy energy offshore and downward into the oceanic interior in an annually recurrent cycle the associated offshore eddy heat fluxes provide the principal balance against nearshore cooling by mean ekman transport and upwelling the currents are highly nonuniform along the coast with important influences by capes and ridges in both maintaining mean standing eddies and launching transient filaments and fronts

wind driven coastal trapped waves off southern tamaulipas and northern veracruz western gulf of mexico during winter 2012 2013 four months of observations from a near coastal mooring deployed off southern tamaulipas northern veracruz coast western gulf of mexico during winter 2012 2013 provide velocity and pressure series in a coastal region where apparently no in situ measurements have been formally reported the observations show numerous events of intense alongshore velocities with magnitudes typically exceeding 30 cm s 1 related to intensified winds associated with cold fronts invading the western gulf during fall winter via coastal trapped motions coming from northern locations these motions can be explained by a time dependent coastal trapped wave ctw mode using a phase speed 4 m s 1 which is consistent with analyses of correlation lag of historical sea level data ctw dynamic modes and sensitivity to such a phase speed the ctw time dependent mode reproduces most of the variability of the sea level and hence the alongshore barotropic velocity observed at the mooring and it can also be used to estimate the contribution of remote regions to the variance observed at the central portion of the western gulf the mooring s location more than half of that variance is generated in the southernmost coast of texas and northernmost coast of tamaulipas and 40 is generated in the central and southern portions of tamaulipas coast thus the method described in this paper is useful not only to explain the near coastal flow variability but it also presents the potential predictability of intensified flow events in the western gulf of mexico

hydraulics of interrill overland flow on a semi arid hillslope southern arizona parsons a j abrahams a d and luk s h 1990 hydraulics of interrill overland flow on a semi arid hillslope southern arizona j hydrol 117 255 273 simulated rainfall experiments were conducted on an 18 m wide by 35 m long runoff plot located in southern arizona by using a wide plot that extended from the divide to beyond the rill heads it was possible to examine the full range of lateral variability and downslope changes in interrill overland flow on a shrub covered semi arid piedmont hillslope the mean depth d mean velocity v and reynolds number re of overland flow were computed for two measured sections situated 12 5 and 21 m from the top of the plot at a section d vs re and v vs re relations show that increases in re are accomodated largely by increases in d these hydraulic relations are principally the result of resistance to flow increasing with re as overland flow spreads into new areas inasmuch as the maximum equilibrium discharge simulated in these experiments has a return period of about 7 yr increasing resistance to flow as re increases may be considered typical of most overland flow events on shrub covered piedmont hillslopes in southern arizona downslope hydraulic relations differ strikingly from at a section relations under equilibrium runoff conditions resistance to flow decreases rapidly as re increases permitting increases in re to be accomodated entirely by increases in v the decrease in resistance to flow is due to progressive downslope concentration of flow into fewer deeper threads under non equilibrium conditions downslope hydraulic relations may be quite different from those obtaining at equilibrium but resistance to flow always decreases downslope this is the result of low flows following pathways formed by higher flows that concentrate downslope analyses of overland flow hydraulics at the scale of interrill areas produce results that are quite different from those obtained from small plots a knowledge of the hydraulics at this scale is essential if models of interrill overland flow are to become more realistic and hence better predictors of runoff hydrographs and sediment yield

resistance to overland flow on desert hillslopes abstract this study examines the relation between the darcy weisbach friction factor f and the reynolds number re for overland flow on six runoff plots in semiarid southern arizona the surfaces of these plots are irregular and covered with stones as overland flow increases the stones and microtopographic protuberances which constitute the major roughness elements are progressively inundated thereby altering the flow resistance analyses of 14 cross sections reveal that the resulting f re relations have two basic shapes convex upward and negatively sloping these shapes bear little resemblance to the conventional f re relation for shallow flow over a plane bed whose shape is a function of the state of flow rather they are explained in terms of the simultaneous operation of two processes the first is the progressive inundation of roughness elements and increase in their wetted upstream projected area as discharge increases this process causes f to increase the second is the progressive increase in the depth of flow over already inundated parts of the bed as discharge increases this process causes f to decline whether the f re relation has a positive or a negative slope depends on whether the first or second process dominates and this depends on the configuration of the bed and level of discharge these findings have profound implications for the mathematical modeling of overland flow on desert hillslopes whether a model is based on the saint venant equations or makes use of the kinematic wave approximation it requires the specification of a relation between f and re or surrogates thereof and the computed hydrograph is very sensitive to the form of this relation hitherto the most widely used relation has been the conventional one for shallow flow over a plane bed however the present study suggests that this relation does not apply to desert hillslopes additional field and laboratory studies are needed to learn more of the behavior and controls of f re relations on such hillslopes so that models of overland flow can employ more realistic relations and better simulate runoff hydrographs

the role of wind stress curl in jet separation at a cape abstract a high resolution numerical model is used to study the importance of spatial variability in the wind forcing to the separation of a coastal upwelling jet at a cape an idealized topography and wind field based on observations from the cape blanco oregon region are used several simulations are investigated with both the intensity and the spatial structure of the wind forcing varied to isolate the importance of the observed intensification in the wind stress and wind stress curl magnitudes to the separation process a simulation using a straight coast confirms that the presence of the cape is crucial for separation wind stress intensification by itself with zero curl does not aid separation the wind stress curl intensification south of the cape on the other hand is important for controlling details of the process because the positive wind stress curl drives upwelling isotherms in the offshore region tilt upward creating a pressure gradient that sustains an intensification of the southw

connectivity and larval dispersal along the oregon coast estimated by numerical simulations 1 connectivity and larval dispersal is explored off the oregon coast during the summer upwelling season of 2001 using numerical ocean circulation simulations the study region with strong wind driven currents and variable topography is modeled using the regional ocean modeling system roms forced by the coupled ocean atmosphere mesoscale prediction system a large number of passive particles as models of planktonic larvae are released daily for 120 days from 1 may to 28 august at depths of 1 7 15 20 50 and 75 m at every grid point shoreward of the 200 m isobath on average 32 km offshore the particles are transported by the three dimensional currents of the model simulation the competency time window for larval settlement is assumed to be in between days 15 and 35 after larvae are released larval settlement occurs at the shallowest location during the competency time window connectivity matrices reveal that some of the places of highest retention are similar to the proposed oregon marine reserve sites especially cape perpetua the heceta bank region has high probabilities as both a source and a destination for settled larvae larvae released in the heceta bank region often settle at higher latitudes than their release location there are strong correlations between the number of settled larvae shallower than the 50 m isobath and a 6 to 8 day running mean of the alongshore wind stress larvae are retained near the shore when the winds averaged over the previous 6 to 8 days are relaxed or downwelling favorable

results from a three dimensional nested biological physical model of the california current system and comparisons with statistics from satellite imagery 1 a three dimensional model of the california current system ccs from 35 n to 48 n extending offshore to 134 w is coupled with a four component trophic model the model reproduces many conspicuous characteristics in the ccs including complex filamentary mesoscale surface features seen in the pigment and temperature from satellite imagery wind driven coastal upwelling at appropriate spatial and temporal scales and the close correlation between prominent features seen in pigment and those in temperature observed by satellites abbott and zion 1985 statistical estimates of the characteristic spatial scales of variability as calculated from the coupled nested model agree with those previously estimated from satellite images for both surface temperature and pigment denman and abbott 1988 1994 model estimates of the characteristic temporal scales of variability from decorrelation times agree with those previously estimated from satellite images typical model decorrelation times lie between 2 and 4 days in agreement with calculations from earlier sequences of coastal zone color scanner czcs and advanced very high resolution radiometer avhrr satellite images denman and abbott 1988 1994

time dependent linear theory for the generation of poleward undercurrents on eastern boundaries abstracta time dependent inviscid linear theory for the generation of poleward undercurrent flow under upwelling conditions along midlatitude ocean eastern boundaries is proposed the theory relies on a conceptual separation of time scales between the rapid coastal trapped wave response to upwelling winds and the subsequent slow interior quasigeostrophic evolution solutions are obtained under idealized conditions in which the coastal boundary and the continental slope topography are uniform alongshore and the time dependent wind stress forcing is applied over a limited meridional range uniform cross shore and directed alongshore a time dependent coastal boundary condition on the slow time scale interior flow consisting of the low frequency geostrophically balanced sea surface height disturbance over the outer shelf is obtained from consideration of the fast time scale coastal trapped response a quasigeostrophic potential vorticity equation is then solved to determine the interior response t

variational assimilation of satellite observations in a coastal ocean model off oregon 1 satellite along track sea surface height ssh and multisatellite sea surface temperature sst maps are assimilated in a coastal ocean circulation model off oregon the study period is june october 2005 featuring intensive separation of the coastal upwelling jets in the eddy dominated coastal transition zone ctz the data assimilation da system combines the nonlinear regional ocean modeling system roms and the advanced variational regional ocean representer analyzer avrora tangent linear and adjoint codes developed by our group the variational representer da method is implemented in a series of 6 day time windows with initial conditions corrected at the beginning of each window to avoid the problem of matching the model and observed ssh mean levels the observed ssh slope has been assimilated location timing and intensity of jets and eddies in the ctz are constrained to improve accuracy of nonlinear model analyses and forecasts in the case assimilating ssh alone the geometry of the sst front is improved ssh assimilation results in the cross shore transport more uniformly distributed along the coast than in the free run model an outer front is identified in the da analyses at a distance of 200 km from the coast a strong subsurface horizontal temperature gradient across this front influences the depth of the thermocline in an area between the front and the continental slope the da correction term is comparable in magnitude to dominant terms in the volume integrated heat equation the time averaged da correction term in the volume integrated heat balance is closer to 0 in the combined ssh sst assimilation case than in the case assimilating ssh alone

numerical treatment of cross shelf open boundaries in a barotropic coastal ocean model abstract using a barotropic coastal ocean model with a straight coastline and uniform cross shelf bottom slope seven different cross shelf open boundary conditions four of which are applied in either implicit or explicit form are compared in three numerical experiments 1 a mound of water is allowed to collapse and radiate waves toward the open boundaries 2 a uniform alongshelf wind stress is applied at zero time over the entire shelf and held constant for the duration of the experiment 3 a uniform cross shelf wind stress is applied at zero time over the entire shelf and held constant for the duration of the experiment the boundary condition which is most transparent to waves consists of a sponge at the outer edge of the model domain with an orlanski radiation condition at the outer edge of the sponge several open boundary conditions perform adequately in the wind stress experiments but the orlanski radiation condition alone without a sponge appears to give the best total performance of thes

finite amplitude evolution of instabilities associated with the coastal upwelling front abstract a primitive equation model is used to study the finite amplitude evolution of instabilities associated with the coastal upwelling front simulations of increasing complexity are examined that represent idealizations of summer conditions off the oregon coast including cases with steady and with time variable wind in a domain with alongshore uniform bathymetry and with time variable wind in a domain with realistic oregon coast bathymetry the numerical results indicate that the fastest growing mode in this system has approximately an 8 10 km alongshore wavelength but that once the disturbances grow to finite amplitude the predominant alongfront scale increases rapidly because of nonlinear effects separation of the total kinetic energy into contributions from the alongshore average flow and perturbation about that average shows that the initial growth of the perturbation kinetic energy is due to potential energy conversion but transfer of energy from the kinetic energy of the alongshore average

application of remote wind forced coastal trapped wave theory to the oregon and washington coasts abstract the theory of coastal trapped waves generated by remote wind forcing clarke is used to calculate coastal subsurface pressure ssp and longshore velocity along the oregon and washington coasts for three two month periods summer of 1972 summer of 1978 and winter of 1977 the response in ssp and longshore velocity is assumed to be dominated by the mode one wave in every case coherence squared between observed and modeled ssp is significant at the 95 level over the entire low frequency band 0 2 cpd with an average phase difference less than 30 greater than 80 of the variance in coastal ssp is accounted for by the mode one coastal trapped wave ctw the ssp response off washington and oregon during summer is primarily 35 of the variance a result of wind forcing between san francisco and cape mendocino california wind stress in this region during summer is significantly larger than that off oregon and washington at low frequencies so that the ctw generated off california propagate

coastal ocean response to summer upwelling favorable winds in a region of alongshore bottom topography variations off oregon 1 repeated mesoscale surveys of waters over the shelf and slope off oregon were conducted during spring and summer of 2001 to study the spatial structure of the velocity and hydrographic fields the ocean response to wind forcing is compared between a region of relatively simple topography with alongshore uniformity and a region of complex topography including a shallow submarine bank heceta bank in the simple topography region the upper water column is influenced by upwelling and fresh water from the columbia river during spring with the low salinity water located farther offshore during summer variability in the fields is mostly confined within 30 km from the coast over heceta bank the region of higher variability is broader spanning most of the shelf the coastal upwelling jet is located inshore of the pinnacle of the bank during spring moving offshore during summer the region inshore of the bank is characterized by low velocities and flow recirculation near surface fields show that the circulation evolves considerably between seasons in both regions the area influenced by upwelled water is much broader during summer dense waters found over midshelf off newport are upwelled to the north and advected south dense waters inshore of heceta bank are substantially influenced by water from the north during spring but their source is mostly from the south during summer south of the bank the separation of the jet significantly increases the cross isobath transport constituting an efficient mechanism for transport of material from the shelf into deeper waters

a modeling study of eulerian and lagrangian aspects of shelf circulation off duck north carolina the effects of wind forced upwelling and downwelling on the continental shelf off duck north carolina are studied through experiments with a two dimensional numerical primitive equation model moored and shipboard measurements obtained during august november 1994 as part of the coastal ocean processes coop inner shelf study iss are used for model data comparisons the model is initialized with realistic stratification and forced with observed wind and heat flux data both strongly stratified and weakly stratified conditions found during august and october respectively are studied august is characterized by fluctuating alongshelf wind direction and october is dominated by downwelling favorable winds the across shelf momentum balance is primarily geostrophic on the continental shelf the alongshelf momentum balance is mainly between the coriolis force and vertical diffusion with additional contributions from the local acceleration and nonlinear advection terms the model solutions are utilized to acquire detailed information on the time and space dependent variability of the across shelf circulation and transport and to investigate the dependence of this circulation on the seasonal change in stratification when the stratification breaks down as in october the across shelf transport is reduced significantly in comparison with the theoretical ekman transport for large wind stress values the paths of individual model water parcels are traced using two methods calculation of lagrangian trajectories and time evolution of three lagrangian label fields the august period produces complex lagrangian dynamics because of the switching between upwelling and downwelling winds the october period illustrates a mean downwelling response that advects parcels across and along the shelf and vertically

spatial and temporal variability of the m2 internal tide generation and propagation on the oregon shelf abstracta 1 km horizontal resolution model based on the regional ocean modeling system is implemented along the oregon coast to study average characteristics and intermittency of the m2 internal tide during summer upwelling wind driven and tidally driven flows are simulated in combination using realistic bathymetry atmospheric forcing and boundary conditions the study period is april through august 2002 when mooring velocities are available for comparison modeled subtidal and tidal variability on the shelf are in good quantitative agreement with moored velocity time series observations depth integrated baroclinic tidal energy flux ef its divergence and topographic energy conversion tec from the barotropic to baroclinic tide are computed from high pass filtered harmonically analyzed model results in a series of 16 day time windows model results reveal several hot spots of intensive tec on the slope at these locations tec is well balanced by ef divergence changes in background stratific

large scale sea level response to atmospheric forcing along the west coast of north america summer 1973 abstract along the west coast of north america the response of sea level to fluctuations in alongshore wind stress at large alongshore scales 1000 km accounted for a substantial faction of the total sea level variance during summer 1973 space time contour plots of sea level and alongshore stress show that the response of sea level to poleward propagating wind stress events was generally stronger than the response to equatorward propagating events atmospheric forcing was most effective in two regions along the coast with relatively strong forcing and response along northern california and oregon and somewhat weaker forcing and response along northern baja california the forced fluctuations in sea level propagated poleward away from these forcing regions causing local sea level to be most correlated with alongshore wind stress earlier in time and at a distant equatorward 1ocation along the southern and central california coast fluctuation in sea level were partly forced along northern baja cali

distant effect of assimilation of moored currents into a model of coastal wind driven circulation off oregon 1 an optimal interpolation oi sequential algorithm is implemented for a threedimensional primitive equation model to assimilate current measurements from acoustic doppler profilers moored on the oregon shelf as a part of the coastal ocean advances in shelf transport coast upwelling experiment may august 2001 a stationary estimate of the forecast error covariance required by the oi is computed based on the error covariance in the model solution not constrained by data assimilation lagged model error covariances are used to account for the effect of previously assimilated data the forecast error covariance has a shorter alongshore spatial scale than the model error covariance unconstrained by the data as an effect of propagating dynamical modes assimilation of currents from one or two of the moorings located on the path of the upwelling jet helps to improve the model data rms error and correlation at the mooring sites located at an alongshore distance of 90 km south or north from the assimilation sites the coastal jet is deflected offshore over heceta bank and assimilation of data from an inner shelf mooring in the jet separation zone does not help to improve prediction in the far field larger improvements are obtained for the first part of the study period yeardays 146 190 in the second part days 191 237 the geometry of our limited area model possibly limits prediction accuracy in numerical experiments involving assimilation of data from only one mooring the actual and expected rms error improvements are compared providing a consistency test for the forecast error covariance

a numerical modeling study of the upwelling source waters along the oregon coast during 2005 abstract regional ocean circulation along the oregon coast is studied numerically for forcing fields derived from year 2005 and climatological mean conditions the primary object is to study directly the lagrangian pathways by which fluid arrives in the oregon upwelling zone roughly half of the upwelling fluid is found to arrive in the regional domain from alongshelf source points primarily north but also south of the oregon upwelling zone while the other half ultimately arrives from points offshore and west of the zone for both the year 2005 and the climatological simulations different regimes of dominant alongshelf source waters are found with cape blanco being a dividing point for northern versus southern sources and with the water parcels coming primarily from depths below 100 m for the offshore sources most upwelling fluid originates from depths between 150 and 250 m during 2005 but from within the upper 150 m for the climatological simulations in both cases there are specific regions alon

a separating coastal upwelling jet at cape blanco oregon and its connection to the california current system the coastal upwelling region near cape blanco oregon 433n o the west coast of the united states was studied using a towed ctd on seasoar a shipboard acoustic doppler current pro ler adcp satellite sea surface temperature maps and surface drifters during august 1995 the equatorward upwelling jet was inshore of the shelfbreak north of cape blanco meandered gently o shore around the cape and then veered sharply o shore just to the south of the cape analysis of vertical sections of density velocity and spicinessa con rmed the separation of an upwelling jet and front the jet was followed from over the shelfbreak north of the cape to 100 km o shore downstream of the cape the separating jet originates from the coastal upwelling jet leaving the shelf but is augmented by an o shore branching of the poleward undercurrent by combining information from adcp streamfunction maps with analysis of hydrographic data including distributions of the tracer like quantity spicinessa a conceptual model of the three dimensional circulation near the cape emerges a mid shelf upwelling jet encounters a coastal promontory then turns o shore stretching and deepening as it crosses the continental margin the jet then turns back shoreward cyclonically where the deepened equatorward ow encounters the top of the poleward undercurrent owing along the continental slope this causes a portion of the undercurrent to turn o shore to join and strengthen the equatorward transport in the separated jet throughout the separation process the coastal upwelling front and jet are continuous robust features separation of a coastal upwelling jet is an important mechanism for cross shelf transport from the coast to the deep ocean cape blanco appears to be the northernmost point where an equatorward jet regularly separates from the coast to become an oceanic jet and thus serves as the northern boundary of the region where an intense meandering current characteristic of the california current system

a modeling study of the three dimensional continental shelf circulation off oregon part ii dynamical analysis abstract sixty day simulations of the subinertial continental shelf circulation off oregon are performed for a hindcast study of summer 1999 in part i the model results are shown to compare favorably with in situ currents and hydrographic measurements obtained from an array of moored instruments and field surveys and high frequency radar derived surface currents in this paper the modeled three dimensional time varying circulation and dynamical balances are analyzed providing a detailed synoptic description of the continental shelf circulation off oregon for summer 1999 the circulation is clearly wind driven and strongly influenced by alongshore variations in shelf topography in the region of the coast where the alongshore topographic variations are small the upwelling circulation is consistent with standard conceptual models for two dimensional across shore circulation in the regions where the alongshore topographic variations are greater the upwelling circulation is highly three dimensional ov