midshelf to surfzone coupled roms swan model data comparison of waves currents and temperature diagnosis of subtidal forcings and response abstracta coupled wave and circulation model that includes tide wind buoyancy and wave processes is necessary to investigate tracer exchange in the shelf region here a coupled regional ocean model system roms simulating waves nearshore swan model resolving midshelf to the surfzone region of the san pedro bay california is compared to observations from the 2006 huntington beach experiment waves are well modeled and surfzone cross and alongshore velocities are reasonably well modeled modeled and observed rotary velocity spectra compare well in subtidal and tidal bands and temperature spectra compare well in the subtidal band observed and modeled mid and inner shelf subtidal velocity ellipses and temperature variability determined from the first vertical complex eof ceof mode have similar vertical structure although the modeled subtidal velocity vertical shear and stratification are weaker than observed the ratio of stratification to shear is similar suggesting model vertical mixing i

the unpredictable nature of internal tides on continental shelves abstractpackets of nonlinear internal waves nliws in a small area of the mid atlantic bight were 10 times more energetic during a local neap tide than during the preceding spring tide this counterintuitive result cannot be explained if the waves are generated near the shelf break by the local barotropic tide since changes in shelfbreak stratification explain only a small fraction of the variability in barotropic to baroclinic conversion instead this study suggests that the occurrence of strong nliws was caused by the shoaling of distantly generated internal tides with amplitudes that are uncorrelated with the local spring neap cycle an extensive set of moored observations show that nliws are correlated with the internal tide but uncorrelated with barotropic tide using harmonic analysis of a 40 day record this study associates steady phase motions at the shelf break with waves generated by the local barotropic tide and variable phase motions with the shoaling of distantly generated internal tides

modeling semidiurnal internal tide variability in the southern california bight abstractthe regional oceanic modeling system roms is applied in a nested configuration with realistic forcing to the southern california bight scb to analyze the variability in semidiurnal internal wave generation and propagation the scb has a complex topography with supercritical slopes that generate linear internal waves at the forcing frequency the model predicts the observed barotropic and baroclinic tides reasonably well although the observed baroclinic tides feature slightly larger amplitudes the strongest semidiurnal barotropic to baroclinic energy conversion occurs on a steep sill slope of the 1900 m deep santa cruz basin this causes a forced near resonant semidiurnal poincare wave that rotates clockwise in the basin and is of the first mode along the radial azimuthal and vertical directions the associated tidal mean depth integrated energy fluxes and isotherm oscillation amplitudes in the basin reach maximum values of about 5 kw m 1 and 100 m and are strongly modulated by the sprin

simulations of nearshore particle pair dispersion in southern california knowledge of horizontal relative dispersion in nearshore oceans is important for many applications including the transport and fate of pollutants and the dynamics of nearshore ecosystems two particle dispersion statistics are calculated from millions of synthetic particle trajectories from high resolution numerical simulations of the southern california bight the model horizontal resolution of 250m allows the investigation of the two particle dispersion with an initial pair separation of 500m the relative dispersion is characterized with respect to the coastal geometry bathymetry eddy kinetic energy and the relative magnitudes of strain and vorticity dispersion is dominated by the submesoscale not by tides in general headlands are more energetic and dispersive than bays relative diffusivity estimates are smaller and more anisotropic close to shore farther from shore the relative diffusivity increases and becomes less anisotropic approaching isotropy 10km from the coast the degree of anisotropy of the relative diffusivity is qualitativelyconsistentwiththat foreddy kinetic energy thetotal relative diffusivity asa functionof pairseparation distance r is on average proportional to r 5 4 additional lagrangian experiments at higher horizontal numerical resolution confirmed the robustness of these results structures of large vorticity are preferably elongated and aligned with the coastline nearshore which may limit cross shelf dispersion the results provide useful information for the design of subgrid scale mixing parameterizations as well as quantifying the transport and dispersal of dissolved pollutants and biological propagules

simulation of barotropic and baroclinic tides off northern british columbia abstract the tidal response of northern british columbia coastal waters is studied through simulations with a three dimensional prognostic primitive equation model the model is forced at the boundaries with the leading semidiurnal and diurnal constituents and experiments with stratified and homogeneous fluid are compared the barotropic response shows good agreement with previously published studies of tides in the region a comparison with tide gauge measurements indicates that average relative rms differences between observations and the model surface elevation field are less than 5 for the largest constituents an internal tide is generated in cases where the model is initialized with a vertical stratification diagnostic calculations of the baroclinic energy flux are used to identify regions of generation and propagation of internal tidal energy with a representative summer stratification the integrated offshore flux is about 0 5 gigawatts higher than previously estimated from theoretical model

energetics of m2 barotropic to baroclinic tidal conversion at the hawaiian islands abstract a high resolution primitive equation model simulation is used to form an energy budget for the principal semidiurnal tide m2 over a region of the hawaiian ridge from niihau to maui this region includes the kaena ridge one of the three main internal tide generation sites along the hawaiian ridge and the main study site of the hawaii ocean mixing experiment the 0 01 horizontal resolution simulation has a high level of skill when compared to satellite and in situ sea level observations moored adcp currents and notably reasonable agreement with microstructure data barotropic and baroclinic energy equations are derived from the model s sigma coordinate governing equations and are evaluated from the model simulation to form an energy budget the m2 barotropic tide loses 2 7 gw of energy over the study region of this 163 mw 6 is dissipated by bottom friction and 2 3 gw 85 is converted into internal tides internal tide generation primarily occurs along the flanks of the kaena ridge and

three dimensional double ridge internal tide resonance in luzon strait abstractthe three dimensional 3d double ridge internal tide interference in the luzon strait in the south china sea is examined by comparing 3d and two dimensional 2d realistic simulations both the 3d simulations and observations indicate the presence of 3d first mode semi diurnal standing waves in the 3 6 km deep trench in the strait as in an earlier 2d study barotropic to baroclinic energy conversion flux divergence and dissipation are greatly enhanced when semidiurnal tides dominate relative to periods dominated by diurnal tides the resonance in the 3d simulation is several times stronger than in the 2d simulations for the central strait idealized experiments indicate that in addition to ridge height the resonance is only a function of separation distance and not of the along ridge length that is the enhanced resonance in 3d is not caused by 3d standing waves or basin modes instead the difference in resonance between the 2d and 3d simulations is attributed to the topographic blocking

internal tide energy over topography 1 the method used to separate surface and internal tides ultimately defines properties such as internal tide generation and the depth structure of internal tide energy flux here we provide a detailed analysis of several surface internal tide decompositions over arbitrary topography in all decompositions surface tide velocity is expressed as the depth average of total velocity analysis indicates that surface tide pressure is best expressed as the depth average of total pressure plus a new depth dependent profile of pressure which is due to isopycnal heaving by movement of the free surface internal tide velocity and pressure are defined as total variables minus the surface tide components corresponding surface and internal tide energy equations are derived that contain energy conversion solely through topographic internal tide generation the depth structure of internal tide energy flux produced by the new decomposition is unambiguous and differs from that of past decompositions numerical simulations over steep topography reveal that the decomposition is self consistent and physically relevant analysis of observations over kaena ridge hawaii and the oregon continental slope indicate o 50 w m 1 error in depth integrated energy fluxes when internal tide pressure is computed as the residual of pressure from its depth average while these errors are small at major internal tide generation sites they may be significant where surface tides are larger and depth integrated fluxes are weaker e g over continental shelves

trapped diurnal internal tides propagating semidiurnal internal tides and mixing estimates in the california current system from sustained glider observations 2006 2012 abstract from 2006 2012 along 3 repeated cross shore transects california cooperative oceanic fisheries investigations lines 66 7 80 and 90 in the california current system 33 609 shear and 39 737 strain profiles from 66 glider missions are used to estimate mixing via finescale parameterizations from a dataset containing over 52 000 profiles elevated diffusivity estimates and energetic diurnal d1 and semidiurnal d2 internal tides are found a within 100 km of the coast on lines 66 7 and 80 and b over the santa rosa cortes ridge srcr in the southern california bight scb on line 90 while finding elevated mixing near topography and associated with internal tides is not novel the combination of resolution and extent in this ongoing data collection is unmatched in the coastal ocean to our knowledge both d1 and d2 internal tides are energy sources for mixing at these latitudes the d1 internal tide is subinertial on line 90 d1 and d2 tides are equally energetic over the srcr the main site of elevated mixing within the scb numerous sources of internal tides at the rough topography in the scb produce standing and or partially standing waves on lines 66 7 and 80 the dominant energy source below about 100 m for mixing is the d1 internal tide which has an energy density of the d2 internal tide on line 80 estimated diffusivity estimated dissipation and d1 energy density peak in summer the d1 energy density shows an increasing trend from 2006 to 2012 its amplitude and phase are mostly consistent with topographically trapped d1 internal tides traveling with the topography on their right the observed offshore decay of the diffusivity estimates is consistent with the exponential decay of a trapped wave with a mode 1 rossby radius of 20 30 km despite the variable mesoscale it is remarkable that coherent internal tidal phase is found

observations of the semidiurnal internal tide on the southern california slope and shelf 1 we give a detailed description of the semidiurnal band current and temperature variability observed during the internal waves on the continental margin iwaves field experiments of 1996 and 1997 off of mission beach california this variability was dominated by the internal tide and the structure of the internal tide on the slope and shelfbreak region was different from that on the narrow shelf on the slope and shelfbreak the internal tide was dominated by alongshore propagating coastal trapped waves in this region semidiurnal band currents were predominantly oriented in the alongshore direction in the lower half of the water column at a water depth h of 350 m current and temperature variability were consonant with a short wavelength 8 km bottom trapped wave propagating in the alongshore direction to the north in the upper 120 m of the water column above the depth of the shelfbreak slope and shelfbreak currents were highly coherent with a zero phase lag that is there was no phase propagation in the cross shore direction on the narrow 10 km shelf cross shore currents u were much more energetic than on the slope and had the structure of a mode one internal wave the alongshore currents v decreased monotonically from the surface to the bottom of the water column with a phase that did not change with depth the near bottom u signal propagated toward the coast during all mooring deployments faster in the summer than in the fall the near bottom u and mid column temperature relative phase was neither consistent with a purely progressive nor a purely standing mode one internal wave we conclude that the internal tide on the shelf was partially reflected

structure of the baroclinic tide generated at kaena ridge hawaii repeat transects of full depth density and velocity are used to quantify generation and radiation of the semidiurnal internal tide from kaena ridge hawaii a 20 km long transect was sampled every 3 h using expendable current profilers and the absolute velocity profiler phase and amplitude of the baroclinic velocity pressure and vertical displacement were computed as was the energy flux large barotropically induced isopycnal heaving and strong baroclinic energy flux divergence are observed on the steep flanks of the ridge where upward and downward beams radiate off ridge directly above kaena ridge strong kinetic energy density and weak net energy flux are argued to be a horizontally standing wave the phasing of velocity and vertical displacements is consistent with this interpretation results compare favorably with the merrifield and holloway model

scattering of internal waves at finite topography in two dimensions part i theory and case studies abstract the scattering of internal gravity waves at finite topography in two dimensions is studied theoretically and numerically for a finite depth ocean a formal solution is derived using a mapping function based on ray tracing the solution satisfies radiation conditions energy is conserved the incoming energy flux is redistributed in physical and modenumber space numerical solutions are calculated for a single plane wave propagating from the ocean side onto slope shelf configurations where a flat shallow shelf is connected to a flat deep ocean by linear slopes staircases convex or concave parabolic profiles and half cosine slopes the fraction of the incoming energy flux transmitted onto the shelf and reflected back to the deep ocean and the distribution of these fluxes in modenumber space are calculated the results depend on the parameters of the incident wave and of the topography especially important is the distinction between supercritical topography where the slope of the topography exc

the impact of subtidal circulation on internal tide generation and propagation in the philippine sea abstractthis study examines the effects of the subtidal circulation on the generation and propagation of the m2 internal tide in the philippine sea using a primitive equation model barotropic to baroclinic conversion at the luzon strait is found to vary due to the background circulation changes over the generation site and the changing influence of remotely generated internal tides from the mariana arc the varying effect of remotely generated waves results from both changing generation energy levels at the mariana arc and variability in the propagation of the internal tides across the philippine sea the magnitude and direction of the depth integrated baroclinic energy fluxes vary temporally due to a combination of changing generation propagation and dissipation spatial patterns of internal tide propagation near the luzon strait are influenced by the locations of mesoscale eddies to the east and west of the strait the results provide insight into the mechanisms of variability of the baroclinic tide

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

evidence for enhanced boundary mixing in the santa monica basin transients in the heat content in santa monica and san pedro basins imply a basin wide diapycnal eddy diffusivity greater than 1 cm sup 2 s this is significantly larger than the value for sf sub 6 of 0 25 0 08 cm sup 2 s determined for the interior of santa monica basin for september 1985 to february 1986 by ledwell and watson however the exodus of sf sub 6 from santa monica basin after february 1986 by which time the tracer had mixed to the boundaries of the basin was fast enough to be consistent with a greatly enhanced vertical flux since the kinetic energy in the basin had not changed significantly it is unlikely that a temporal increase in forcing resulted in enhanced fluxes in the interior of the basin the most likely interpretation is that diapycnal fluxes in the basin are dominated by processes in the boundary regions temperature and sf sub 6 profiles from near the edges of the basin do not give conclusive evidence either for or against such enhanced mixing 20 refs 19 figs 5 tabs

double ridge internal tide interference and its effect on dissipation in luzon strait abstractluzon strait between taiwan and the philippines features two parallel north south oriented ridges the barotropic tides that propagate over these ridges cause strong internal waves and dissipation the energy dissipation mechanisms and the role of the baroclinic wave fields in this dissipation are investigated using numerical simulations with the massachusetts institute of technology general circulation model mitgcm the model is integrated over two dimensional configurations along a zonal transect at 20 6 n for a maximum duration of a spring neap cycle nearly all dissipation occurs at the steep ridge crests due to high mode turbulent lee waves with horizontal scales of several kilometers and vertical scales of hundreds of meters the spatial structure and timing of the predicted velocities and dissipation agree with observations and confirm the existence of these lee waves the lee wave strength is greatly affected by the internal waves generated at the other ridge when semidiurnal barotropic

model estimates of m2 internal tide generation over mid atlantic ridge topography abstract the conversion of barotropic to baroclinic m2 tidal energy is examined for a section of the mid atlantic ridge in the brazil basin using a primitive equation model model runs are made with different horizontal smoothing 1 5 6 and 15 km applied to a 192 km 183 km section of multibeam bathymetry to characterize the influence of topographic resolution on the model conversion rates in all model simulations barotropic to baroclinic conversion is highest over near and supercritical slopes on the flanks of abyssal hills and discordant zones from these generation sites internal tides propagate upward and downward as tidal beams the most energetic internal tide mode generated is mode 2 consistent with the dominant length scales of the topographic slope spectrum 50 km the topographic smoothing significantly affects the model conversion amplitudes with the domain averaged conversion rate from the 1 5 km run 15 1 mw m 2 4 and 19 higher than for the 6 km 14 5 mw m 2 and 15 km runs 12

diagnosing a partly standing internal wave in mamala bay oahu 1 an internal partly standing wave in mamala bay hawaii is studied using new observations and the princeton ocean model pom previous work suggested a convergence in the bay of east and westbound waves emanating from kaena ridge and makapuu point respectively new energy flux measurements with shipboard adcp ctd confirm that makapuu point is the eastern source after validating the pom results against observations the model output is modally decomposed and compared with the expected theoretical patterns of kinetic and available potential energy energy flux and group velocity for a partly standing wave agreement is seen for the first baroclinic mode which also contains most of the energy the results confirm previous suggestions of standing wave dynamics in mamala bay

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

shear and strain in santa monica basin by injecting a cloud of sf6 into santa monica basin at a depth of 790 m and observing its vertical spread ledwell and watson 1991 estimate the average diapycnal diffusivity between 750 and 850 m as kp 2 5 10 5 m2 m 1 this diffusivity is higher than inferred from microstructure measurements in the open ocean thermocline for typical internal wave levels gregg and sanford 1988 to examine shear and strain in the basin we dropped expendable current profilers xcps and calculated strain from conductivity temperature and depth ctd casts shear and strain are above the gm76 model spectrum garrett and munk 1975 cairns and williams 1976 and comparisons with published parameterizations indicate more than enough shear variance to account for the high diffusivity reported by ledwell and watson thus the eddy diffusivity in santa monica basin is not at odds with lower values estimated from microstructure measurements in the open ocean but is due to an elevated internal wave field the spectral shapes however differ from typical open ocean spectra

mid to inner shelf coupled roms swan model data comparison of currents and temperature diurnal and semidiurnal variability abstractaccurately representing diurnal and semidiurnal internal variability is necessary to investigate inner shelf to midshelf exchange processes here a coupled regional ocean model system roms simulating waves nearshore swan model is compared to observed diurnal and semidiurnal internal tidal variability on the mid and inner shelf 26 8 m water depth near san pedro bay california modeled mean stratification is about one half of that observed modeled and observed baroclinic velocity rotary spectra are similar in the diurnal and semidiurnal band modeled and observed temperature spectra have similar diurnal and semidiurnal band structure although the modeled is weaker the observed and modeled diurnal and semidiurnal baroclinic velocity and temperature dominant vertical structures are similar and consistent with mode one internal motions both observed and modeled diurnal baroclinic kinetic energy are strongly correlated to diurnal wind forcing and enhanced by subtidal vorticity induced reduc

internal tide generation and destruction by shoaling internal tides 1 internal tide generation is usually predicted from local topography surface tides and stratification however internal tides are often observed to be unrelated to local spring neap forcing appearing intermittently in 3 5 day bursts here we suggest a source of this intermittency by illustrating how remotely generated shoaling internal tides induce first order changes in local internal tide generation theory numerical simulations and observations show that pressure perturbations associated with shoaling internal tides can correlate with surface tide velocities to generate or destroy internal tides where shoaling internal tides have random phase such as on the new jersey slope time averaged internal tide generation is unaffected but instantaneous internal tide generation varies rapidly altering internal tide energy and possibly affecting nonlinear internal waves across shelf transport and mixing where shoaling internal tides are phase locked to the local surface tide such as in double ridge systems time averaged internal tide generation is affected and may result in resonance

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

characterizing storm water dispersion and dilution from small coastal streams characterizing the dispersion and dilution of storm water from small coastal creeks is important for understanding the importance of land derived subsidies to nearby ecosystems and the management of anthropogenic pollutants in southern california creek runoff is episodic intense and short lived while the plumes are buoyant all of which make the field sampling of freshwater plumes challenging numerical modeling offers a viable way to characterize these systems the dilution and dispersion of freshwater from two creeks that discharge into the santa barbara channel california is investigated using regional ocean modeling system roms simulations with a horizontal resolution of 100 m tight coupling is found among precipitation hydrologic discharge wind forcing and submesoscale flow structures which all contribute to plume evolution during flooding plumes are narrow and attached to the coast due to downwelling onshore wind forcing and intense vorticity filaments lying parallel to the shelf as the storm passes the winds typically shift to offshore upwelling favorable conditions and the plume is advected offshore which enhances its dilution plumes reach the bottom nearshore while they form thin layers a few meters thick offshore dilution field of passive tracers released with the runoff is strongly anisotropic with stronger cross shelf gradients than along shelf dispersion analysis of statistical moments of the passive tracer distribution results in scale dependent diffusivities consistent with the particle pair analysis of romero et al 2013 model validation the roles of submesoscale processes and wind forcing on plume evolution and application to ecological issues and marine resource management are discussed

on the generation and evolution of nonlinear internal waves in the south china sea the nonhydrostatic regional ocean modeling system is applied to the nonlinear internal waves or solitons that are generated at the luzon ridge in the south china sea the luzon ridge near the batan islands is represented by an idealized ridge with a height of 2 6 km on a flat bottom model runs are performed for various ridge shapes and a symmetric tidal forcings the model is in the mixed tidal lee wave regime the barotropic tide over the ridge generates first mode waves through the internal tide release mechanism westward traveling solitons emerge from these first mode waves through nonlinear steepening in the internal tide release mechanism asymmetric tides with strong eastward currents can generate strong westward solitons the eastward current creates an elevation wave with a higher energy density west of the ridge and as soon as the current slackens the wave is released westward on its backslope strong solitons develop the energy density is further enhanced by nonlinearities such as differences in phase speeds and energy fluxes related to lee waves a modal and harmonic decomposition shows the generation of vertical modes and higher temporal harmonics and indicates significant wave wave interaction e g triads in the mixed tidal lee wave regime more energy is contained in the first mode compared to the higher modes hence linear internal tide beams are less well defined and strong solitons develop

a tracer study of mixing in the santa cruz basin a tracer release experiment to study diapycnal and isopycnal mixing was performed in santa cruz basin in 1988 1989 approximately 1450 g of sulfur hexafluoride were injected close to an isopycnal surface at 1500 m depth in may 1988 this depth is midway between the bottom of the basin at 1920 m and the sill at 1084 m the diapycnal dispersion measured during the first few months while the tracer was still mixing to the walls of the basin yielded a diapycnal eddy diffusivity of 1 0 cm2 s 1 within a factor of 1 5 this is approximately 4 times larger than the diffusivity found by ledwell and watson 1991 in the interior of santa monica basin where the buoyancy frequency was 5 times greater the tracer was well mixed to the walls 6 months after the injection and at that time the diapycnal spread of the tracer was greater near the walls than in the interior the rate of diapycnal dispersion of the tracer increased dramatically after the tracer had mixed to the walls of the basin indicating enhanced boundary mixing an effective basin wide diapycnal diffusivity of 10 cm2 s 1 would be required to support the fluxes of tracer observed a one dimensional model for tracer and heat diffusion does not simulate the results very well however probably because of the finite mixing time between the boundary region and interior and because of the complexity of the processes in the boundary region

integrated modeling framework to quantify the coastal protection services supplied by vegetation vegetation can protect communities by reducing nearshore wave height and altering sediment transport processes however quantitative approaches for evaluating the coastal protection services or benefits supplied by vegetation to people in a wide range of coastal environments are lacking to begin to fill this knowledge gap we propose an integrated modeling approach for quantifying how vegetation modifies nearshore processes including the attenuation of wave height mean and total water level and reduces shoreline erosion during storms we apply the model to idealized seagrass sand and mangrove mud cases and illustrate its potential by quantifying how those habitats reduce water levels and sediment loss beyond what would be observed in the absence of vegetation the integrated modeling approach provides an efficient way to quantify the coastal protection services supplied by vegetation and highlights specific research needs for improved representations of the ways in which vegetation modifies wave induced processes

circulation and multiple scale variability in the southern california bight abstract the oceanic circulation in the southern california bight scb is influenced by the large scale california current offshore tropical remote forcing through the coastal wave guide alongshore and local atmospheric forcing the region is characterized by local complexity in the topography and coastline all these factors engender variability in the circulation on interannual seasonal and intraseasonal time scales this study applies the regional oceanic modeling system roms to the scb circulation and its multiple scale variability the model is configured in three levels of nested grids with the parent grid covering the whole us west coast the first child grid covers a large southern domain and the third grid zooms in on the scb region the three horizontal grid resolutions are 20 km 6 7 km and 1 km respectively the external forcings are momentum heat and freshwater flux at the surface and adaptive nudging to gyre scale soda reanalysis fields at the boundaries the momentum flux is from a three hourly reanalysis mesoscale mm5 wind with a 6 km resolution for the finest grid in the scb the oceanic model starts in an equilibrium state from a multiple year cyclical climatology run and then it is integrated from years 1996 through 2003 in this paper the 8 year simulation at the 1 km resolution is analyzed and assessed against extensive observational data high frequency hf radar data current meters acoustic doppler current profilers adcp data hydrographic measurements tide gauges drifters altimeters and radiometers the simulation shows that the domain scale surface circulation in the scb is characterized by the southern california cyclonic gyre comprised of the offshore equatorward california current system and the onshore poleward southern california countercurrent the simulation also exhibits three subdomain scale persistent i e standing cyclonic eddies related to the local topography and wind forcing the santa barbara channel eddy the central scb eddy and the catalina clemente eddy comparisons with observational data reveal that roms reproduces a realistic mean state of the scb oceanic circulation as well as its interannual mainly as a local manifestation of an enso event seasonal and intraseasonal eddy scale variations we find high correlations of the wind curl with both the alongshore pressure gradient apg and the eddy kinetic energy level in their variations on time scales of seasons and longer the geostrophic currents are much stronger than the wind driven ekman flows at the surface the model exhibits intrinsic eddy variability with strong topographically related heterogeneity westward propagating rossby waves and poleward propagating coastally trapped waves albeit with smaller amplitude than observed due to missing high frequency variations in the southern boundary conditions

internal hydraulic jumps and overturning generated by tidal flow over a tall steep ridge abstract recent observations from the hawaiian ridge indicate episodes of overturning and strong dissipation coupled with the tidal cycle near the top of the ridge simulations with realistic topography and stratification suggest that this overturning has its origins in transient internal hydraulic jumps that occur below the shelf break at maximum ebb tide and then propagate up the slope as internal bores when the flow reverses a series of numerical simulations explores the parameter space of topographic slope barotropic velocity stratification and forcing frequency to identify the parameter regime in which these internal jumps are possible theoretical analysis predicts that the tidally driven jumps may occur when the vertical tidal excursion is large which is shown to imply steep topographic slopes such that dh dxn 1 the vertical length scale of the jumps is predicted to depend on the flow speed such that the jump froude number is of order unity the numerical results agree with the theoreti

mechanisms of mid to outer shelf transport of shoreline released tracers abstracttransport of shoreline released tracer from the surfzone across the shelf can be affected by a variety of physical processes from wind driven to submesoscale with implications for shorelin

temperature and currents on the southern california shelf a description of the variability abstract temperature and horizontal current observations at three water depths 15 30 and 60 m over the southern california shelf are reported for four discrete periods during 1978 79 roughly corresponding to each of the principal seasons the vertical structure of temperature changes markedly during the year the water over the shelf is weakly stratified in the winter n 50 cpd but stratification is stronger in the summer n 250 cpd seasonal changes in vertically averaged temperature are comparatively unimportant long term averages of the longshore currents are to the south near the surface in all seasons with amplitudes ranging up to 10 cm s 1 in the winter during spring and summer the stratification is accompanied by shear in the vertical structure of these long term current averages with surface currents sweeping to the south but with deeper colder water flowing in the opposite direction currents fluctuating at subtidal frequencies are predominantly alongshore and are strongest durin

energetics and spatio temporal variability of semidiurnal internal tides in the bay of bengal and andaman sea abstract energetics of semidiurnal barotropic and internal tides in the bay of bengal bob and andaman sea as are studied using the simulations from a high resolution ocean general circulation model barotropic m 2 tide which is the largest tidal constituent in this region loses about 65 5 gw of energy in the bob and as most of this barotropic energy 46 5 gw is dissipated by means of bottom friction in the shallow regions such as the head of the bay and the gulf of martaban due to the interaction of barotropic tides with bottom topography about one third of the barotropic m 2 energy 19 1 gw gets converted into internal tides and most of this conversion 84 occurs over the andaman nicobar an ridge on the contrary to the estimates in earlier studies our results show that a large part 59 of this internal tide energy in the bob and as gets dissipated far away from the generation sites compared to the bob energy dissipation rates are found to be large over the entire as and it could result in enhanced vertical mixing in this region further analysis of the temporal variability of conversion within the model domain shows that energy conversion in the semidiurnal band varies between 11 to 27 gw over a spring neap cycle seasonal variability in the stratification due to river runoff significantly changes the conversion of tidal energy at the generation sites in the northern bob and as our study revealed that westward radiating internal tides from an ridge undergo path alteration refraction due to the time varying mesoscale circulation and such path alterations cause large intraseasonal variability in internal tide activity and redistribution of internal tide energy available for mixing in the remote areas such as the continental margins of the western bob

interference pattern and propagation of the m2 internal tide south of the hawaiian ridge abstract most of the m2 internal tide energy generated at the hawaiian ridge radiates away in modes 1 and 2 but direct observation of these propagating waves is complicated by the complexity of the bathymetry at the generation region and by the presence of interference patterns observations from satellite altimetry a tomographic array and the r p flip taken during the farfield program of the hawaiian ocean mixing experiment home are found to be in good agreement with the output of a high resolution primitive equation model simulating the generation and propagation of internal tides the model shows that different modes are generated with different amplitudes along complex topography multiple sources produce internal tides that sum constructively and destructively as they propagate the major generation sites can be identified using a simplified 2d idealized knife edge ridge model four line sources located on the hawaiian ridge reproduce the interference pattern of sea surface height and energy fl

local and remote forcing of currents and temperature in the central southern california bight 1 a comprehensive study of the central southern california bight shows that subtidal currents are dominated by relatively long time scales 10 25 days large alongshore scales and significant offshore and upward phase propagation a one dimensional model shows that observed fluctuating poleward propagating speeds 140 260 cm s 1 alongshore pressure gradient disturbances account for a much larger fraction of the alongshore velocity variance than local wind stress at least 40 in both seasons and have the longer periods of the dominant currents with the addition of local wind stress about half the velocity variance can be accounted for and overall about 5 more variance in spring than in summer results are consistent with generation of disturbances by remote wind stress several hundred kilometers equatorward of the bight and alongcoast propagation as low mode coastally trapped waves the large scale remote forcing is also responsible for much of the velocity variance on the adjacent shelf the semienclosed santa monica bay a nonlinear three dimensional model shows that water is pushed into the bay initially as part of a throughflow later becoming an eddy that gradually fills the bay producing counterflow on its shoreward side on the shelf local alongshore wind stress accounts for only 25 of the velocity variance in spring and none in summer the large scale disturbances also produce significant temperature fluctuations throughout the region via lateral advection of the mean alongshore temperature gradient local wind driven coastal upwelling is responsible for temperature fluctuations on the inner shelf during several 2 4 day events in spring but only very near the coastal wall

internal tide scattering at the line islands ridge 1 scattering of the m2 mode one internal tide from the line islands ridge is examined with a primitive equation numerical model model runs with baroclinic and barotropic forcing are performed to distinguish scattered from locally generated internal tides tpxo 5 tidal model sea surface elevations provide barotropic forcing while for the run with baroclinic forcing a mode one m2 energy flux of 1000 w m 1 is used to represent energy fluxes emanating from the hawaiian ridge scattering redistributes more energy flux from mode one than is locally generated in mode one for the higher modes scattering and generation contribute equally in terms of the overall energy flux spatial and modal distributions of energy density and flux show internal tide scattering dominates at hutchinson seamount while higher modes are generated locally at sculpin ridge hutchinson seamount s slopes are steeper over a greater continuous area than sculpin ridge scattered energy is found downstream of the steepest topographies similar to simulations with idealized gaussian ridges at the line islands ridge 37 of the incident mode one energy flux is lost because of scattering into modes 2 5 19 dissipation by the model s turbulence parameterization 15 and nonlinear transfer to the m4 internal tide 3 two topex ground tracks pass through the model domain roughly normal to the ridge topography and confirm the general features of the modal and spatial distribution found in the model in the topographically rough western pacific internal tide scattering may be a significant source of energy for mixing away from topography