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

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

lagrangian assessment of simulated surface current dispersion in the coastal ocean 1 a purely lagrangian assessment of dispersion from modeled surface current trajectories in the coastal ocean is presented modeled trajectories come from roms simulations for the southern california bight during the 1996 through 1999 period data are from surface current trajectories collected primarily in the santa barbara channel with code style drifters distributions of particle positions from trajectories emanating from launch locations within 10 kilometers of the coast throughout the santa barbara channel that advect for one through four days lagrangian pdfs are evaluated descriptively and quantitatively the two dimensional kolmogorov smirnov k s statistical test for comparing discrete sampled data with a known probability distribution is the quantitative basis in general dispersion distributions from observations are similar to lagrangian pdfs computed from modeled trajectories and the k s statistic quantifies this accordingly a few specific regions of poor model data agreement are indicated and discussed the purely lagrangian assessment elucidates an improved understanding of model performance and ocean circulation beyond that offered in a eulerian sense and is necessary when modeled trajectories are utilized for applied oceanographic and marine ecology problems

island wakes in deep water abstract density stratification and planetary rotation distinguish three dimensional island wakes significantly from a classical fluid dynamical flow around an obstacle a numerical model is used to study the formation and evolution of flow around an idealized island in deep water i e with vertical island sides and surface intensified stratification and upstream flow focusing on wake instability coherent vortex formation and mesoscale and submesoscale eddy activity in a baseline experiment with strong vorticity generation at the island three types of instability are evident centrifugal barotropic and baroclinic sensitivities are shown to three nondimensional parameters the reynolds number re rossby number ro and burger number bu the dependence on re is similar to the classical wake in its transition to turbulence but in contrast the island wake contains coherent eddies no matter how large the re value when re is large enough the shear layer at the island is so narrow that the ver

characteristic patterns of the circulation in the santa barbara channel the subtidal near surface circulation in the santa barbara channel sbc and on the shelf north of point conception is described based on observations obtained during the 3 year period from 1993 to 1995 near surface currents in the channel are a superposition of a larger than sbc scale flow and a cyclonic circulation of variable intensity located inside the channel on seasonal timescales the larger than sbc scale flow near the surface is equatorward in spring and poleward from summer through winter the increase in equatorward flow in spring occurs concurrently with the increase in equatorward wind stress and the decrease in near surface temperatures and synthetic subsurface pressures ssps the flow reverses in late spring simultaneously with the increase in the along channel ssp difference and months before wind stress has reached its peak the period during which the cyclonic circulation within the sbc is strongest coincides with the period of strongest poleward flow through the eastern entrance a synoptic description of the circulation in the sbc is presented in terms of six characteristic patterns labeled upwelling relaxation cyclonic propagating cyclones flood east and flood west an analysis of the 5 and 45 m currents into empirical orthogonal functions eofs isolates 50 53 of the 5 m 45 m low frequency current variance into three two modes combining these modes with the mean current fields the modes have spatial patterns that correspond to the characteristic flow patterns subjectively deduced from inspection of daily averages of the near surface currents from late spring through fall the two largest 5 m current modes produce a repeating pattern of circulation in which the sequence of four states namely upwelling cyclonic relaxation and quiescent is traversed roughly every 16 days in addition to the large scale cyclonicity in the central sbc smaller cyclonic eddies form frequently in the eastern channel and travel toward the west with an average speed of 0 06 m s 1 the patterns described here develop in response to the wind stress and the along channel ssp gradient

sea level variations induced by heating and cooling an evaluation of the boussinesq approximation in ocean models in this paper a sigma coordinate ocean model is modified to remove the commonly used boussinesq approximation so that the effect of thermal expansion is exactly included in the basic equations in order to cope with the seasonal heating cycle and the detection of climate change through variation in sea level height tests are performed to evaluate the differences between boussinesq and non boussinesq calculations under different heating and cooling conditions and different model domains for an idealized case of a flat bottom shallow ocean basin without wind forcing simulations of a warm eddy show that the non boussinesq dynamics have only a minor effect on the baroclinic current field however vertically averaged velocities though small compared with the baroclinic velocities are cyclonic for the boussinesq calculation and anticyclonic for the non boussinesq calculation the results indicate that global or closed basin boussinesq models should be able to simulate most of the observed steric sea level changes on seasonal or climate timescales when corrected by a spatially uniform time dependent factor calculated from the volume averaged density change the seasonal variation of the globally averaged sea level calculated from climatological data is small about 1 cm variations in steric sea level in regional models both boussinesq and non boussinesq may differ from those of global models owing to the unknown transport across their boundaries associated with the local heating and cooling a spatially uniform time dependent correction similar to that associated with thermal expansion is proposed to account for transport across open boundaries of regional models variations of sea level obtained from a boussinesq model of the atlantic ocean approximate the seasonal signal due to the heating cooling cycle of each hemisphere as observed by satellite altimeter data

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

the california current system in the southern california bight and the santa barbara channel recent observations in the santa barbara channel and over the california cooperative oceanic fisheries investigations calcofi southern california grid are used to examine seasonal circulation patterns in and near the southern california bight defined as the region east of the santa rosa ridge and including the santa barbara channel poleward flow relative to 500 m is found throughout the bight in all seasons except for spring and all subregions except the western part of the santa barbara channel in spring there is equatorward flow throughout the bight at all depths to 500 m though it tends to be surface or midcolumn intensified equatorward flow offshore of the bight present in all seasons narrows and accelerates into a jet like feature and simultaneously moves close to the santa rosa ridge in summer current meter data from the eastern entrance to the santa barbara channel are consistent with the seasonal results from the calcofi data and further show an upward propagation of phase at annual period with a phase speed of 1 to 2 m d 1 comparison with the calcofi ship winds suggests that poleward flow in the bight may be the result of positive wind stress curl through a sverdrup balance though the observed transport is only about 75 of that expected from the curl amplitude equatorward flow in the bight may be the result of coastal upwelling though the transport is larger than expected from the relatively weak winds in the bight and the offshore extent of the equatorward flow is about 10 rossby radii farther than might be expected for linearized coastal upwelling equatorward flow outside the bight cannot be explained as a sverdrup flow because the wind stress curl is positive throughout most of the region upward propagation of phase and downward propagation of energy may be indicative of forcing by remote wind equatorward of the bight given the complexity of possible forcing mechanisms for circulation in and near the bight a model that includes effects of remote wind forcing ekman pumping and topography is needed to explain the observations in a satisfactory way

dating transcurrent terrane accretion an example from the meguma and avalon composite terranes in the northern appalachians the polygenetic minas geofracture separates the meguma and avalon composite terranes of the maritime appalachians dynamically recrystallized muscovite and biotite occur within d3 shear zones which developed during dextral movement along the geofracture these record 40ar 39ar plateau ages between circa 360 and 370 ma comparable plateau ages are recorded by micas within undeformed portions of granitic plutons and their low pressure contact metamorphic aureoles these are similar to u pb ages previously reported for igneous monazite therefore indicating relatively rapid postmagmatic cooling at shallow crustal levels the d3 fabrics were superimposed on earlier s1 structures which formed during initial amalgamation of the meguma and avalon composite terranes whole rock slate phyllite samples collected outside high temperature portions of the plutonic contact aureoles yield 40ar 39ar plateau ages which correspond to groupings of circa 400 395 ma 390 385 ma and 380 375 ma these are interpreted to date diachronous formation of the s1 fabrics and concomitant low grade regional metamorphism in the circa 25 ma between initial amalgamation and granitic plutonism it is inferred that there was a slow rise of isotherms through the crust as a result of overthrust tectonic thickening this led to crustal melting and the production of widespread granitic magmas which were emplaced immediately prior to d3 dextral shearing

the pattern and variability of winter kuroshio intrusion northeast of taiwan the variations of the kuroshio path and velocity northeast of taiwan are analyzed based on along track satellite altimeter data as well as high resolution model experiments observations reveal that in winter the kuroshio intrusion into the east china sea ecs at this location is manifested by a secondary maximum current core smcc shoreward of the kuroshio s main path the smcc varies significantly on interannual time scale and its variability is strikingly out of phase with that of the kuroshio entering the ecs meaning that the stronger the kuroshio the weaker the smcc and vice versa model experiments corroborate the observational results and more importantly indicate that the kuroshio intrusion here follows two primary routes a large anticyclonic loop that separates from the kuroshio at the northern end of taiwan and moves forward to form the smcc and a straight northward path onto the shelf when the kuroshio turns sharply eastward along the continental slope of the ecs the intrusion is controlled by both local forcing and remote effect with its pattern and variability depending mostly on the local heat flux and the inertia of the kuroshio current

statistical aspects of surface drifter observations of circulation in the santa barbara channel argos tracked drifters are used to study the near surface circulation in the santa barbara channel the mean consists of a cyclonic cell in the western santa barbara channel with weaker flow in the eastern channel drifter mean velocities agree well with record means from near surface current meters at the eastern entrance to the channel drifter velocities are biased toward outflow eastward velocity conditions drifter variability at synoptic and seasonal scales shows a tendency for upwelling and eastward flow in spring a strong cyclonic circulation in summer poleward relaxation in fall and weak variable circulation in winter drifter estimates of eddy stress divergence indicate advective terms play a secondary role in the mean surface momentum balance lagrangian time and space scales are about 1 day and under 10 km respectively the mismatch between lagrangian and eulerian timescales indicates advective terms are important to the fluctuating circulation

an oceanic cyclonic eddy on the lee side of lanai island hawai i 1 a young cold core cyclonic eddy displaying a significant increase in surface chlorophyll was observed offshore lanai island hawai i where the marine optical buoy moby is located during one of its deployments moby broke free from its mooring in the course of its 3 day free drifting period moby followed a cyclonic eddy which is manifested by satellite remote sensing data chlorophyll data from moderate resolution imaging spectroradiometer and sea surface temperature sst from a geostationary operational environmental satellite the time series of the sst show that the cold core eddy was in a formative stage it existed as a stand alone eddy for about 9 days before it merged with cold water south of oahu island a high resolution numerical model simulation reproduces similar eddies in terms of location size and intensity an eddy detection algorithm is described and applied to locate and track the modeled eddies the results demonstrate that mesoscale and submesoscale eddies are frequently generated on and pass through the lee side of lanai island and the statistical analysis quantifies the general features of eddies in the area

the evolution and depth structure of shelf and slope temperatures and velocities during the 1997 1998 el nino near point conception california abstract moored survey and drifter observations are used to describe the evolution of temperature sea level velocity and salinity from 1997 to 1998 over the california shelf between san luis obispo bay and the eastern entrance to the santa barbara channel the dominant event during this time was the 1997 1998 el nino its relation to background seasonal and interannual variability depended on which property is considered subsurface temperature and local sea level showed extreme anomalies between march 1997 and october 1998 three distinct peaks occurred the first two are associated with the regional response to el nino while the cause of the third remains unclear the first peaked in june 1997 and decayed until august the main el nino peak reached maximum amplitude between november 1997 and january 1998 after the collapse of the regional el nino anomaly in february 1998 a final peak occurred locally during the summer of 1998 the central result presented here concerns the spatial structure of temperature during these events the initial peak was surface intensified and was barely detectable at 45 m its amplitude varied with position along the coast decaying with distance north the main peak showed a strong signal down to at least 200 m the amplitude and timing of temperature anomalies during this event were depth dependent the largest absolute amplitudes relative to seasonal cycles were in excess of 4 c and occurred between 45 and 65 m depth the anomalies reached their maximum values at later time with increasing depth between october 1997 and january 1998 the amplitude of this main peak was comparable at all mooring sites the final peak in august 1998 had a comparable amplitude at all mooring sites to a depth of 100 m temperature increases during the three events were accompanied by a corresponding rise in sea level the el nino signals in currents and salinity are more difficult to distinguish from background variability than those in temperatures and sea level however stronger than average poleward flow was observed at the eastern entrance to the santa barbara channel between 5 and 100 m depth for most of 1997 and there are indications for greater than usual poleward flow over the santa maria basin in fall 1997 surface drifter evidence although qualitative also suggests greater than usual poleward displacement in november 1997 relative to other years along with increased temperature survey observations of salinity suggest changes to the regional temperature salinity relation during november 1997 with greater than usual salinity at temperatures below 12 c

relaxation from upwelling the effect on dissolved oxygen on the continental shelf 1 continental shelves in upwelling regimes are subject to sequences of upwelling and relaxation events each on timescales of order 1 week typically these episodes have pronounced impacts on the temperature and density structure on the shelves and also on the along shore and cross shore flow regimes it had previously been demonstrated that relaxation phases advect warm water along shore poleward from regions of less intense upwelling thus adding to the heat balance in upwelling locations and providing a rectification of oscillating heat fluxes in the current paper it is shown that relaxations also modify the dissolved oxygen do budget of the lower layers on a narrow shelf this provides enhanced do values due to near surface exposure while on a wide shelf decreased do concentrations are created due to oxygen consumption on the inner shelf the resulting variations along the coast can lead to along shore advection of high or low do during a relaxation event observations are presented from moorings off san diego and del mar which show large departures from density correlated do values during relaxations and which support the proposed mechanisms

subinertial currents on the southern califoinia shelf abstract subinertial currents on the southern california shelf are investigated using observations from a current meter array deployed near san diego during the summer fall and winter of 1978 79 this region is characterized by weak winds order 1 2 m s 1 and thus other driving mechanisms for the subinertial currents may be important a simplified depth averaged longshore momentum equation consisting of a balance between current accelerations the adjusted sea level asl gradient and the wind and bottom stress is examined the asl gradient is estimated using sea level and atmospheric pressure observations separated by 350 km a linear parameterization of the bottom stress is used with a drag coefficient of 5 10 4 m s 1 during fall and winter the first order balance of terms in the longshore momentum equation over the inner shelf 15 m depth is between the wind and bottom stress over the outer shelf 60 m the primary balance is between the asl gradient and the bottom stress at midshelf 30 m bo

a petrological and geochronological study of a 360 ma metallogenic event in maritime canada with implications for lithophile metal mineralization in the canadian appalachians the occurrence of ca 360 ma greisen related molybdenite mineralization in the clayton hill biotite muscovite leucomonzongranite 1 km2 is unusual for the southwestern meguma terrane of the maritime appalachians where 380 ma granite related sn mineralization dominates the presence of extensive hornfelsing and occurrence of mineralized sn w cu zn skarns in the area suggests a larger intrusion occurs at depth the intrusion and mineralization are constrained to 361 ma based on concordant re os molybdenite and 40ar 39ar muscovite ages which equates to other ca 360 ma granites in the area hence magmatism of this age is more widespread than previously considered the intrusion is highly evolved 74 wt sio2 metaluminous a cnk 1 1 05 a cnk molar ratio al2o3 cao na2o k2o and depleted in cafemic and transition elements rare earth elements ree 106 23 ppm are strongly fractionated with light rare earth elements lree enriched la lun 10 and negative eu anomalies biotite is

thermal history of the southwestern meguma zone nova scotia from an 40ar 39ar and fission track dating study of intrusive rocks two geologically distinct regions within the meguma terrane have been studied in detail and are shown to have contrasting thermal histories this conclusion is based on 31 new 40ar 39ar age spectra on micas k feldspars and hornblendes from several of the plutons in southern nova scotia which are satellites to the much larger south mountain batholith smb in addition we report four k feldspar age spectra from a locality in the northeastern part of the smb and seven fission track ages from both the southern and northern areas the complex age spectrum of hornblende from a mafic phase associated with the bamngton passage pluton suggests a minimum intrusive age of 385 ma a result consistent with geologic evidence that this pluton represents an early less evolved magmatic pulse later intrusive activity appears to have been coeval with the intrusion of the smb at ca 370 ma ago in the southern region argon clocks in feldspars were completely reset and mica clocks variably reset by a later thermal event the cumulative geochronologic and geologic evidence constrains this event to 300 320 ma ago in the smb this alleghanianl hercynian thermal disturbance is much less pronounced and appears to be localized to small areas that are often associated with economic mineralization k feldspars from the southern plutons record an episode of argon loss 220 230 ma ago which is less evident in the smb to the north upper triassic dike injection in the southern region associated with the initial rifting phase of the canadian atlantic margin accompanied this milder thermal pulse apatites in the two regions record a mean fission track age of ca 180 ma which we attribute to the final cooling of the terrane below about 100 c the timing of this event coincides with regional uplift recorded in sedimentary sequences along much of the maritime continental shelf deux kgions gtologiques distinctes inttgkes au terrane de meguma ont ctt ctudites en dctai1 et leurs histoires thermales

numerical simulation of a synoptic event in the southern california bight 1 in the middle of march 2002 a synoptic upwelling event occurred in the southern california bight it was marked by a precipitous cooling of at least 4 c within 10 20 km of the coast by the end of the month the preevent temperatures had slowly recovered the regional oceanic model system roms is used to simulate the event with an atmospheric downscaling reanalysis for surface wind and buoyancy flux forcing lateral boundary conditions of temperature salinity velocity and sea level are taken from a global oceanic product barotropic tidal fields from a global barotropic model are imposed along the open boundaries the simulation reproduces well the upwelling process compared with observed data the sensitivity of the simulation is examined to wind resolution heat flux and tidal forcing the oceanic response to the different wind resolutions converges at the level of the 6 km resolution which is the finest scale present in the terrain elevation data set used in the atmospheric downscaling the combination of an analytical diurnal cycle in the solar radiation and the empirical coupling with the instantaneous roms sea surface temperature produces a similar oceanic response to the downscaled heat flux tidal effects are significant in the upwelling evolution due to the increase in wind energy input through a quasi resonant alignment of the wind and surface current probably by chance

sub mesoscale coastal eddies observed by high frequency radar a new mechanism for delivering nutrients to kelp forests in the southern california bight 1 sub mesoscale eddies are described along the mainland coast of the santa barbara channel based on observations from a network of high frequency hf current measuring radars and near shore moorings the eddies are 4 15 km in diameter and typically last about 2 days although some last up to 6 days most eddies within the radar coverage area are anti cyclonic with relative vorticities of 0 4 f to 0 8 f where f is the coriolis parameter but cyclonic eddies are also observed moored observations over the inner shelf 12 m water depth of a sequence of two eddies in december 2001 show an increase in nitrate plus nitrite from the background levels of 1 2 m to a maximum of 10 12 m when the eddies are present we speculate that these eddies are an important transport mechanism for nutrients and biogenic particles to inner shelf ecosystems of the southern california bight

moored observations of the current and temperature structure over the continental slope off central california 1 a basic description of the variability current meter data have been analyzed from seven moorings on the continental slope along the central california coast from point piedras blancas to point reyes the goal was to examine the subtidal variability in the 100 m to 1000 m depth range particularly with regard to alongshore propagating events and interactions with eddies and meanders of the california current offshore the 2 year time series available off point sur were first analyzed in conjunction with the local and remote surface wind stress and coastal synthetic subsurface pressure and then correlated with shorter coincident current records moored at similar depths to the north and south the poleward flowing california undercurrent was the most prominent feature at all the moorings except at one site located well into the monterey submarine canyon the strongest poleward flows over the slope occurred in 3 to 4 month bursts not phase locked with the seasons with vector speeds exceeding 40 cm s 1 south of the canyon an approximately monthly signal was identified which propagated poleward upward and offshore the behavior of this signal was consistent with that of an internal coastal kelvin wave generated at the surface by remote wind stress to the south and was likely not of equatorial origin the wave was apparently scattered by the abrupt topography of the canyon since its energy persisted to the north of the canyon but with unstable phase at least three eddy meander interaction events were observed these warm deep 1000 m anticyclonic features reversed the flow over the slope to equatorward when they moved onshore and interrupted the flow of the undercurrent one event forced anomalously strong 15 cm s 1 onshore flows off monterey bay and offshore flows off point sur while quantitative transport estimates could not be made with this sparse data set it seems apparent that such events play a significant role in the exchange of water properties between the shelf and the deep ocean

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

sensitivity of coastal currents near point conception to forcing by three different winds ecmwf coamps and blended ssm i ecmwf buoy winds previous observational and modeling studies have indicated the importance of finescale winds in determining the circulation near point conception in the santa maria basin smb and the santa barbara channel sbc california there has not been a systematic attempt however to analyze and quantify the sensitivity of the near surface circulation to different wind data here a regional circulation model of the smb and sbc is driven using three wind datasets the european centre for medium range weather forecasts ecmwf 110 km 110 km horizontal grid the coupled ocean atmosphere mesoscale prediction system coamps 9 km 9 km horizontal grid and a blended wind product that combines special sensor microwave imager ssm i ecmwf and buoy and coastal wind data and that is referred to as seb a springtime period march may 1999 in which equatorward wind dominates and wind stress curls are strong is chosen for the study two groups of experiments are conducted with and without assimilating moored temperature observations the focus is on long time scales of greater than weeks and on mean currents comparisons between these experiments and between model and observation show that the circulation driven by the ecmwf wind is much weaker than that by the other two winds on the other hand the seb dataset shows locally intensified wind stress curls behind capes and coastal bends whereas these wind stress curls are weak in coamps it is found that these small scale variations in the wind field force alongshore inhomogeneous pressure gradients that in turn can significantly affect the near coast currents the result is that modeled currents forced by seb agree better with observations than do those produced by coamps empirical orthogonal function analyses were conducted on the near surface currents sea level wind and wind stress curl the mode 1 current 40 is unidirectional i e generally equatorward or poleward and correlates well with the mode 1 wind 90 the mode 2 current 20 is cyclonic in the sbc and poleward inshore and equatorward offshore in the smb it correlates well with mode 1 sea level 70 which suggests that mode 2 currents are driven by the pressure gradient it is significant that neither mode 2 current nor mode 1 sea level correlates well with mode 1 wind stress curl 70 rather they correlate well with the time integral of the mode 1 wind stress curl these conclusions support a previous theoretical idea that cyclonic circulation in the sbc and the inshore currents of the smb are both driven by alongshore pressure setup induced by the time integral of the wind stress curl rather than by the wind stress curl itself this idea of a pressure setup is consistent with the differences found between the currents driven by coamps and seb winds

k ar and 40ar 39ar geochronology of granitoid rocks from southern nova scotia its bearing on the geological evolution of the meguma zone of the appalachians k ar and or 40ar 39ar apparent ages are reported for 28 samples of biotite and muscovite from nova scotia s south mountain batholith and associated northern satellite stocks in addition 14 mica samples from the southern satellite stocks were dated previous workers using primarily k ar and rb sr techniques have reported a spread of apparent ages ranging from 240 420 ma for these intrusive rocks the present data set is internally consistent and has been calibrated against accepted interlaboratory standards a mean age of 367 ma was obtained for the south mountain batholith and the northern stocks a value consistent with results recently obtained in an rb sr study by clarke and halliday no differences in apparent age among the various phases or clear geographic age distribution patterns were evident satellite stocks in the southern part of the province have in general younger apparent ages clustered in the range 300 320 ma we suggest that in southern areas mica argon systems record the effect

polyphase late paleozoic tectonothermal evolution of the southwestern meguma terrane nova scotia evidence from 40ar 39ar mineral ages 40ar 39ar incremental release ages of hornblende muscovite and biotite from a variety of granitic stocks and host metamorphic rocks suggest a complex late paleozoic tectonothermal evolution for the southwestern meguma terrane regional d1 folding with cleavage formation under greenschist lower amphibolite facies m1 metamorphic conditions occurred at ca 400 410 ma and was followed by emplacement of a series of granitic stocks ranging in age between ca 375 and 315 ma these were emplaced at relatively shallow crustal levels and developed contact metamorphic aureoles of variable grade these are locally superposed on m1 regional metamorphic assemblages and result in a complex isograd pattern 40ar 39ar mineral ages suggest episodes of contact metamorphism occurred at 1 360 375 ma possibly related to emplacement of the south mountain batholith or temporal equivalents 2 350 356 ma around the port mouton pluton and northeastern shelburne pluton 3 ca 315 325 ma near the wedgeport pluton and in

u pb and rb sr geochronology of the wedgeport granitoid pluton southwestern nova scotia zircons from biotite monzogranite of the wedgeport pluton intrusive into deformed metasediments of the cambrian goldenville formation in the southwestern meguma terrane of nova scotia yield concordant u pb ages of 316 5 ma this is interpreted as the time of intrusion and crystallization within the error limits the 323 12 ma rb sr whole rock isochron age is identical and gives an initial 87 sr 86 sr ratio of 0 7137 0 0056 rb sr analyses of mineral separates of biotite potassium feldspar and quartz plagioclase from several samples yield subparallel internal isochrons with an average age of 257 8 ma initial ratios of the internal isochrons range from 0 716 to 0 759 a slow cooling model for these latter data is discarded because the mineral data fall on straight lines instead a reheating event related to plutonism ca 257 ma ago which was sufficient to cause local grain to grain migration and reequilibration of strontium and rubidium but not large scale redistribution is invoked this reheating is also inferred to be responsible for the hydrothermal alteration and sn u mineralization concentrated along the northwestern margin of the pluton a dextral northeast southeast shear zone cutting the pluton is also inferred to be ca 257 ma old it may be related to the last stages of westward obduction of the meguma terrane these results provide a clear example of permo carboniferous plutonism in the southwestern meguma terrane and suggest a similar interpretation may apply to other anomalously young ages recorded in this area in light of these results the permo carboniferous age of the large east kemptville tin deposit and its location in a dextral shear zone suggest that the association of younger plutonism and shear zones may be a significant factor for economic mineralization

evaluation of trajectory modeling in different dynamic regions using normalized cumulative lagrangian separation 1 the lagrangian separation distance between the endpoints of simulated and observed drifter trajectories is often used to assess the performance of numerical particle trajectory models however the separation distance fails to indicate relative model performance in weak and strong current regions such as a continental shelf and its adjacent deep ocean a new skill score is proposed based on the cumulative lagrangian separation distances normalized by the associated cumulative trajectory lengths this skill score is used to evaluate surface trajectories implied by global hycom hindcast surface currents as gauged against actual satellite tracked drifter trajectories in the eastern gulf of mexico during the 2010 deepwater horizon oil spill it is found that the new skill score correctly indicates the relative performance of the global hycom in modeling the strong currents of the gulf of mexico loop current and the gulf stream and the weaker currents of the west florida shelf in contrast the lagrangian separation distance alone gives a misleading result the proposed dimensionless skill score is particularly useful when the number of drifter trajectories is limited and neither a conventional eulerian based velocity nor a lagrangian based probability density function may be estimated

ocean response to wind sheltering in the southern california bight 1 a particularly warm surface oceanic wake persisted during the period 6 16 june 1999 in the south eastern part of santa catalina island in the southern california bight from satellite images regional atmospheric model results and hydrographic measurements around catalina island a strong correlation appears between observed sea surface temperature wind stress and surface stratification it is suggested that the warm island wake was probably due to lower turbulent mixing rates associated with wind sheltering effect we argue that the sheltering effect may also account for a portion of the relatively warm sea surface temperature characteristic of the whole bight opposing previous arguments that temperature evolution of the surface ocean in this region is primarily driven by lateral advective fluxes

rb sr age and geochemical distinctions between the carboniferous tin bearing davis lake complex and the devonian south mountain batholith meguma terrane nova scotia the davis lake complex dlc composed of biotite monzogranite leucomonzogranite and cassiterite topaz greisen hosts the east kemptville tin mine in southwestern nova scotia the dlc monzogranite contains glomeroporphyritic biotite with ilmenite and many rare earth element ree bearing accessory minerals zircon bearing quartz phenocrysts and xenoliths of biotite granite primary muscovite is rare major and trace element geochemical trends indicate well defined but limited magmatic differentiation trends ree patterns of the least evolved granites are flat and show a ce yb ratio of 10 the dlc was previously considered cogenetic with the devonian south mountain batholith smb on the basis of its location lithologies and similarities in major and trace element geochemistry however new rb sr whole rock isotopic data indicate an rb sr date of 330 7 ma mean square of weighted deviates mswd 2 8 for the dlc implying that it is at least 35 ma younger than the smb the initial 87sr 86sr rat

the california current system in relation to the northeast pacific ocean circulation abstract the california current system is described in its regional setting using two modern datasets argo provides a broadscale view of the entire eastern north pacific ocean for the period 2004 2010 and the high resolution xbt network includes transects from honolulu to san francisco 1991 2010 and to los angeles 2008 2010 together these datasets describe a california current of 500 800 km width extending along the coast from 43 n to 23 n the mean southward transport of the california current is about 5 sv off central and southern california with about 2 5 sv of northward flow on its inshore side interannual variations are 50 or more of the mean transports the salinity minimum in the core of the california current is supplied by the north pacific current and by freshwater from the northern continental shelf and modified by alongshore geostrophic and across shore ekman advection as well as eddy fluxes and air sea exchange the heat and freshwater content of the california current vary in response to the fluctuating strength of the alongshore geostrophic flow on its offshore side the california current is influenced by north pacific intermediate waters at its deepest levels and by eastern subtropical mode waters on shallower density surfaces in total the sources of the california current its alongshore advection and its strong interactions with the inshore upwelling region and the offshore gyre interior combine to make this a rich and diverse ecosystem the present work reviews previous contributions to the regional oceanography and uses the new datasets to paint a spatially and temporally more comprehensive description than was possible previously

a forcing mechanism for the poleward flow off the southern california coast it is shown that when the wind distribution along a coast is anisotropic such that its cross shore scale is smaller than its alongshore scale the coastal sea level or the upper layer anomoly a of an ocean forced by both wind and wind curl is governed by a modified nondimensionalized kelvin wave equation a t a y k0 0 y t k1 y dtl where k0 and k1 are wind stress and wind stress curl at the coast respectively y is the alongshore distance and t is the time numerical experiments from a simple reduced gravity type with idealized forcing and coastline to a three dimensional primitive equation model with a realistic coastline bottom topography of the southern california bight and the santa barbara channel and observed wind stresses were carried out to show that the observed near coast near surface poleward flow in the region is primarily forced by the equatorward weakening of the wind curl k1 y 0 in the bight beta provides natural damping by weakening and widening the current through westward propagating rossby waves and causes the current to lead the coastal pressure field by 1 2 months which improves the agreement with observations of the phasing of the modeled currents but is otherwise not required in forcing the poleward flow

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

a poleward jet and an equatorward undercurrent observed off oregon and northern california during the 1997 98 el nino abstract the timing and intensity of the effects of the 1997 98 el nino on sea surface temperature sst and coastal sea level along the us west coast are examined using in situ time series measurements and the effects on upper ocean currents on the continental shelf and slope off oregon and northern california are examined using repeated shipborne adcp transects a mid shelf mooring off newport oregon and an hf surface current radar an initial transient positive anomaly was observed in both adjusted sea level and sst during may june 1997 followed by anomalously high coastal sea levels generally strongest during september 1997 through february 1998 and abruptly returned to normal in late february 1998 and by positive temperatures anomalies over the mid shelf that persisted longer into april 1998 low frequency coastal sea level anomalies propagated poleward at 2 1 m s poleward flow over the shelf and slope was enhanced at most depths during the el nino compared with following years northward currents in the upper 12 m over the continental shelf off newport oregon averaged 13 7 cm s stronger during august 1997 through february 1998 than during the same period the following year enhanced poleward flow was present at all latitudes sampled during november 1997 and february 1998 particularly over the continental slope these transects also provided clear views of a fall winter equatorward undercurrent which was both strongest and had the most alongshore similarity of form during the enso finally subsurface intensified anticyclonic eddies originating in the poleward undercurrent appear to be a recurrent feature of the circulation off newport late in the upwelling season

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

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

planetary wave propagation off california and its effect on zooplankton abstract lagged correlation of dynamic height from the gappy california cooperative oceanic fisheries investigation calcofi with monthly san diego sea level for the period 1949 2001 shows that the dynamic height propagates westward at 4 10 cm s 1 about double the speed of the large scale low frequency rossby wave 2 2 cm s 1 ocean topography experiment topex poseidon jason 1 s along track sea level height estimates since january 1993 filtered interannually propagate westward at 4 3 cm s 1 verifying that observed westward propagation is about double that expected including the effect of the mean california current on the rossby wave propagation does not explain the discrepancy but rather slightly increases it if variations in the ocean depth in the calcofi region are also taken into account the westward propagation is still only about one half that observed standard theory therefore does not explain the observations because of the westward propagation interannual variations in alongshore ge

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

the east kemptville tin deposit yarmouth county nova scotia a pb isotope study of the leucogranite and mineralized greisens evidence for a 366 ma metallogenic event pb isotopic data for whole rock leucogranite and mineral separates variably mineralized greisen and galena from the east kemptville sn cu zn ag deposit yarmouth county southwestern nova scoti

the effect of accessory minerals on the redistribution of lead isotopes during crustal anatexis a model abstract the initial pb isotopic composition of anatectic granites is modelled as a mixture of pb derived from major minerals that have characteristically low 238 u 204 pb and 232 th 204 pb ratios i e feldspars biopyroboles etc with pb contributed from dissolved accessory minerals with characteristically high 238 u 204 pb and 232 th 204 pb ratios i e zircon monazite etc the initial pb isotopic composition of anatectic granites is a function of a the age type modal distribution and heterogeneity in the initial u and th content of the accessory minerals b variation in melt composition and temperature during anatexis c the fraction of the source melted and d the extent to which the melt was homogenized prior to crystallization the differential behavior of accessory minerals during anatexis can explain the common yet enigmatic decoupling of the pb isotopes from other chemical and isotopic systems in granite rocks granitic plutons derived by anatexis of the same source material are not required to have the same initial pb isotopic composition low temperature peraluminous granites are more likely to exhibit homogeneous initial pb isotopic compositions dominated by the pb contained within the major mineral assemblage of the source material in contrast the initial pb isotopic composition of higher temperature metaluminous or peralkaline anatectic granites is more likely to be heterogeneous unless the melts are homogenized during emplacement and will record a larger fraction of the radiogenic pb component contained in the accessory mineral assemblage of the source material heterogeneity in the initial pb isotopic composition of individual granites or granitic suites can preserve the weighted average age of the radiogenic pb present in the accessory mineral assemblage of the source region even if these minerals are entirely dissolved during anatexis the use of isotopic tracer studies in terrane analysis will be optimized by the isotopic characterization of granitic suites

a multivariate approach to geochemical distinction between tin specialized and uranium specialized granites of southern nova scotia like most granitoid bodies that host significant granophile deposits the south mountain batholith smb of nova scotia consists of an earlier suite intruded by a later suite of smaller plutons that are more silicic and peraluminous the latter generally show a range of other geochemical features that readily identify them as specialized and allow for their separation from the earlier non specialized granites in the case of mineralization associated with the smb we can go one step further and clearly separate the specialized granites into stanniferous and uraniferous series which can be identified even where no sn or u enrichment is present although this can be done successfully using simple histograms of a number of elements li p sn and f we show that combining all elements in discriminant analysis guarantees 100 success in separating the two groups r mode factor analysis aids in accounting for the variance within each group the most important effect being a biotite factor because of bo

pb isotope constraints on the age of sulfide ore deposition and u pb age of late uraninite veining at the musoshi stratiform copper deposit central africa copper belt zaire the musoshi copper deposit is a typical ore shale type deposit located centrally in the zaire zambian copper belt cu fe sulfides are disseminated in a 20 m thick laminated black siltstone unit the ore shale which occurs above a thick approximately 1 km sequence of oxidized arkosic sediments of the roan group at the base of the katangan sedimentary basin uraninite occurs in veins which cut the ore shale and extend from major hydrothermal alteration zones in the footwall rutile accompanying this veining was dated by richards et al 1988 at 514 or 2 m y 2sigma in the present study nine analyses of five uraninite samples give a u pb age of 514 or 3 m y 2sigma in exact agreement with the rutile age information concerning the age and source of the copper mineralization at musoshi has been sought by study of pb isotopes in the cu fe sulfides and other minerals leach residue analyses of most ore samples show poor correlations on 207 pb 204 pb vs 206 pb 204 pb diagrams and scatter in a band these samples typically display mature recrystallized textures and may contain thin concordant sulfide veinlets with coarse secondary biotite quartz and carbonate however analyses of three samples from near the center of the ore shale which show less evidence for recrystallization and contain no veinlets form a wellcorrelated line mswd 2 54 15 analyses corresponding to a two stage model age of 645 or 15 m y 2sigma data from the other samples scatter below this line on the pb pb diagram and toward the secondary isochron obtained from the hydrothermal rutiles similar phenomena are observed on a 208 pb 204 pb vs 206 pb 204 pb diagram where addition of u to the disturbed samples is clearly demonstrated we conclude that the samples record disturbance of pb isotopes in a simple two stage system by the late uranium depositing hydrothermal event at 514 m y the significance of the 645 m y fractionation event is not clear however at least two interpretations may be given that the event reflects primary cu fe sulfide ore deposition or that pb isotopes were homogenized at this time in a preexisting orebody by some process which also introduced u and th into the deposit we are not able at present to distinguish between these two alternatives but whichever is correct it is clear that copper ore deposition occurred at or before 645 m y and is thus unrelated to the later 514 m y hydrothermal event a high integrated u pb source ratio mu 10 2 obtained from the 645 m y sulfide isochron suggests an evolved crustal source for pb in the orebody and rules out a significant contribution from mafic igneous rocks if cu and pb are assumed to share a common source these results do not support derivation of the metals from mantle derived materials at musoshi this u pb ratio contrasts strongly with a value of mu 9 7 calculated from the rutile analyses for the late hydrothermal overprint and further confirms that this later event was not involved in the formation of the copper deposit other than in coarsening and locally concentrating the ore the high temperature 397 degrees or 5 degrees c fluids associated with this event were probably derived from deep levels in the crust and appear to have been expelled during a late pulse of activity at the close of the lufilian orogeny

late devonian lamprophyric dykes in the meguma zone of nova scotia hornblende rich lamprophyric dykes from southeastern nova scotia are contemporaneous with the large peraluminous granitic batholiths ca 370 ma of the meguma zone and may be closely associated with their origin

the seasonal alongshore pressure gradient on the west coast of the united states the long term mean steric height 0 500 dbar data of reid and mantyla 1976 are added to relative monthly mean adjusted sea level data to obtain a seasonal time series of quasi absolute large scale 300 km sea surface elevation along the west coast of the united states from 48 n to 33 n north of 38 n the elevation slope reverses sign seasonally so that the resulting pressure gradient force is southward from october to june and northward from july to september south of 38 n the pressure gradient force is northward except during january at all latitudes and during february in the interval from 38 n to 35 n maximum northward force occurs during august and september at all latitudes the relative contributions to sea level elevation slope by seasonal heating and cooling freshwater effluent effects the alongshore component of coastal wind stress and deep ocean currents are investigated both seasonal heating and cooling and freshwater contributions to large scale elevation slope are relatively insignificant 10 in every month at all latitudes wind stress forcing determined with the barotropic steady frictional model of csanady 1978 is significant north of point conception 35 n for both the long term mean slope and its seasonal oscillation remote contributions are particularly important in the pacific northwest south of san francisco 38 n empirical evidence suggests that deep ocean currents contribute significantly to coastal elevation slope in summer and fall and in the mean deep ocean currents may also affect elevation slope along the whole coast during spring causing elevated sea level toward the north

mesoscale to submesoscale transition in the california current system part i flow structure eddy flux and observational tests in computational simulations of an idealized subtropical eastern boundary upwelling current system similar to the california current a submesoscale transition occurs in the eddy variability as the horizontal grid scale is reduced to o 1 km this first paper in a series of three describes the transition in terms of the emergent flow structure and the associated time averaged eddy fluxes in addition to the mesoscale eddies that arise from a primary instability of the alongshore wind driven currents significant energy is transferred into submesoscale fronts and vortices in the upper ocean the submesoscale arises through surface frontogenesis growing off upwelled cold filaments that are pulled offshore and strained in between the mesoscale eddy centers in turn some submesoscale fronts become unstable and develop submesoscale meanders and fragment into roll up vortices associated with this phenomenon are a large vertical vorticity and rossby number a large vertical velocity relatively flat horizontal spectra contrary to the prevailing view of mesoscale dynamics a large vertical buoyancy flux acting to restratify the upper ocean a submesoscale energy conversion from potential to kinetic a significant spatial and temporal intermittency in the upper ocean and material exchanges between the surface boundary layer and pycnocline comparison with available observations indicates that submesoscale fronts and instabilities occur widely in the upper ocean with characteristics similar to the simulations

the flow of the undercurrent over the continental borderland off southern california 1 iniroduction 2 background the bottom topography off southern california has been the cc a slow had equatornard flow is the eastern limb of termed a continental borderland to distinguish it from the ordinary the large scale anticyclonic gyre of the temperate north pacific shelf slope morphology found along most continental margins ocean the cc carries relatively cool low salinity waters of shepard and emuy 19411 islands shallow banks basins and subarctic origin to lower latitudes on average the core of the cc troughs form a complex bathymetric region extending from the has velocities of 0 10 to 0 15 m s and traces a path roughly coast to 200 lon offshore the southern california coastline has a parallel to the california baja california coastline localized concave curvature between the headland at point conception to measurements of flow can exceed 0 5 m s davis 19851 an the u s mexican border as a whole this region is referred to as instantaneous realization of the cc includes a tangle of meanders the california bight the geographic bathymetric dguration eddies and narrow jetlike flows and counterllows the cc lies at of the bight exm a pronounced influence upon the local circula varying distances off the coast and at the latitude of the tion patterns and heme upon the distributions of physical e u s mexican border there is a strong shoreward component to sverdrup and fleming 19411 and biological quantities e g the flow in most seasons especially summa the flow splits one allen 1945 owen 19801 during 1985 we conducted an oceano branch turns and flows northward into the california bight graphic survey off southern california the sampling grid was becoming the eastern limb of a cyclonic eddy centered about the designed to reveal the mumce of the geographic bathymetric offshore banks seasonally fall and winter a weak inshore features upon the circulation of the california current system countercurrent ic develops at the surface along various portion6 ccs especially the flow of the california undercurrent cu of the coastline reid et d 19581 at depth the cu cdes the survey grid also includes station lines mss the core of the waters of subtropical origin poleward along the continental slope california current cc and transects an offshore dipole eddy these waters are relatively warm and saline and have low mm simpson and lym this issue the station grid of this study trations of dissolved oxygen the cu also demonstrates a welldiffers considerably from that used by the california cooperative defined seasonality and at times opposes the overlying dace oceanic fisheries investigations calcofi surveys in both its flow maps and sections of the long term seasonal means of relaspatial resolution and depth of sampling the objectives of thic tive geostrophic velocity and distributions of ocean characteristics report are 1 to examine the spatial continuity of the cu through for the ccs are available in calcofi atlas 30 lym et d 19821 the complex bathymeny of the bight 2 to trace the poleward for a comprehensive review of the long term seasonal large scale paths and offshore spread of waters of southern origin transported description of the ccs the readex is referred to recent papas by by the cu 3 to contrast this subsurface flow with the surface hickey 1979 chelton 19841 and lynn andslnpsm 19871 and flow and 4 to compare these results with the long term calcofi to important references of pioneering work given therein mean conditions

coastal perturbations of marine layer winds wind stress and wind stress curl along california and baja california in june 1999 abstract month long simulations using the fifth generation pennsylvania state university national center for atmospheric research mesoscale model mm5 with a horizontal resolution of 9 km have been used to investigate perturbations of topographically forced wind stress and wind stress curl during upwelling favorable winds along the california and baja california coasts during june 1999 the dominant spatial inhomogeneity of the wind stress and wind stress curl is near the coast wind and wind stress maxima are found in the lees of major capes near the coastline positive wind stress curl occurs in a narrow band near the coast while the region farther offshore is characterized by a broad band of weak negative curl curvature of the coastline such as along the southern california bight forces the northerly flow toward the east and generates positive wind stress curl even if the magnitude of the stress is constant the largest wind stress curl is simulated in the lees of point conception and the santa ba

seasonal dynamics of the surface circulation in the southern california current system abstract the seasonal dynamics of the southern california current scc is investigated using a primitive equation ocean model with real coastlines and topography the model is tested with different wind forcing and the resulting flow fields are compared to the mean and seasonal circulation inferred from long term in situ observations california cooperative oceanic fisheries investigation calcofi the model integration forced with the output winds of a regional atmospheric model rsm best captures the statistics of the observed circulation with a 0 9 correlation coefficient for the streamlines and 0 5 for the velocity fields the model integrations reveal a pronounced linear response of the flow field to changes in winds on the shelf region a dynamical feature inferred from calcofi hydrography also suggested in topex ers maps is an annually recurrent westward propagation of ssh anomalies originated in the southern california bight scb during the upwelling season the rsm integration is the only one to capture the correct timing and spatial evolution of this process we therefore use this model integration for guidance in constructing a dynamical framework to interpret the observed circulation and its variability during the upwelling season in spring there is an upward tilt of the isopycnals along the coast directly forced by the winds in the bight as the spring transitions to the summer the upwelling winds relax in the bight but are still strong in the region offshore approximately in correspondence of the continental slope positive wind stress curl condition anomalous denser waters in the location of the southern california eddy are maintained and reinforced by the combined interaction of the coastal islands geometry and the wind stress curl through ekman dynamics the adjustment process to the denser water initiates a westward propagation of ocean density anomaly through rossby waves and reinforces the cyclonic gyre like circulation of the sce increasing positive vorticity surface poleward flow maintained by the positive wind stress curl is also reinforced in proximity of point conception as a consequence of the adjustment during the summer the cyclonic gyre becomes increasingly unstable as the core of the ocean anomalies crosses the continental slope instability processes within the cyclonic region characterized by a sharp increase in eke shed eddies that leave the region either drifting to the west or interacting with existing eddies in the region offshore the eke reaches a seasonal maximum at the end the summer in the cyclonic region and in late fall further offshore where the eddies are fully developed the shedding of eddies cannot be directly seen in the calcofi observations because of the sampling aliasing for this point we rely on the strong suggestion of the model which we assume is able to capture the leading order dynamics additional integrations with a linearized version of the model are also presented to reinforce our interpretation of the westward propagation of the isopycnal anomalous displacement associated with rossby wave dynamics

a sulfur isotope study of main stage tin and base metal mineralization at the east kemptville tin deposit yarmouth county nova scotia canada evidence for magmatic orgin of metals and sulfur

island wakes in the southern california bight 1 wind and current induced island wakes were investigated using a multiplatform approach of in situ remote sensing and numerical model simulations for the southern california bight scb island wind wakes are a result of sheltering from the wind with weak wind mixing strong heat storage and consequent high sea surface temperature sst wind wakes around santa catalina island are most persistent during spring and summer months current wakes caused by the disruption of the poleward traveling california countercurrent induce eddies to form off the north end of catalina island and these move poleward every 9 12 days current wake eddies induce strong mixing with low sst and high density sea surface signatures whereas wind wakes induce high sea surface temperature signatures associated with the formation of a well defined shallow thermocline current wake eddies vary from 1 to 30 km in diameter from numerical solutions we predicted the frequency of occurrence of current induced wakes off santa catalina island wind wakes were also observed off all the other islands of the scb as seen from the analysis of synthetic aperture radar data time series analysis of the island mass effect phenomenon has shown a concurrence of low sst and high sea surface chlorophyll for santa catalina san nicholas and san clemente islands that might be related to the seasonality of the california current and california countercurrent future oceanographic research in the scb should not ignore the occurrence of wind and current induced island features since they may be important in the transport and or retention of nutrients pollutants and plankton

low frequency waves in the santa barbara channel observed by high frequency radar are antisymmetric with a mean propagation speed of 5k m d 1 and relative vorticity of order 0 1 f complex empirical orthogonal function decomposition in the 10 20 day passband partitions variance into two dominant modes the first mode represents the vortices with an average period of 14 4 days the second mode represents alongshore fluctuations with an average period of 13 3 days amplitude functions of the two modes correlate with in situ current time series at 5 and 45 m depths obtained from moorings at the east and west channel entrances suggesting coupling with the larger scale circulation of the northern southern california bight the observations support interpretation of mode 2 as a coastal trapped wave since the period and alongshore flow are consistent with previous observations and predictions we hypothesize that mode 1 is a resonant response of the santa barbara basin in the form of a trapped topographic rossby mode the spatial mode resembles the predicted pattern based on a simplified analytical model of the fundamental mode the amplitude of mode 1 is consistently large when the frequencies of modes 1 and 2 converge suggesting that the vortices are a basin scale resonant response to coastal trapped waves index terms 4520 oceanography physical eddies and mesoscale processes 4512 oceanography physical currents 4508 oceanography physical coriolis effects 4516 oceanography physical eastern boundary currents 4544 oceanography physical internal and inertial waves keywords propagating eddies santa barbara channel coastal trapped waves citation beckenbach e and l washburn 2004 low frequency waves in the santa barbara channel observed by high frequency radar j geophys res 109 c02010 doi 10 1029 2003jc001999

late paleozoic collision delamination short lived magmatism and rapid denudation in the meguma terrane nova scotia canada constraints from 40ar 39ar isotopic data the meguma terrane consists of 8 15 km of early paleozoic stratified rocks deposited on a continental basement that were deformed and metamorphosed during the late paleozoic as a result of lithospheric plate collision the oldest cleavage previously published whole rock 40ar 39ar plateau ages of 415 395 ma dates the onset of crustal thickening which was followed by voluminous but short lived late devonian granitic and minor mafic magmatism 380 370 ma this magmatism may have been the product of delamination of the lower lithosphere and upwelling of asthenosphere which effected melting above the new moho and resulted in intrusion at depths of 5 12 km 40ar 39ar plateau ages of hornblende muscovite and biotite indicate that at the present erosion level most of the meguma terrane cooled through 300 c by 368 360 ma slightly earlier than for the southwestern meguma terrane ca 345 ma the present erosion level was exhumed by the latest devonian early carboniferous visean the age of the

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

geochronological evidence for multiple tectono thermal overprinting events in the east kemptville muscovite topaz leucogranite yarmouth county nova scotia canada the east kemptville muscovite topaz leucogranite located in yarmouth county nova scotia canada is host rock to the only producing primary tin deposit in north america 56 mt 0 165 sn previous geochronological studies include i rb sr whole rock analyses of the quartz topaz greisens which indicated a date of 337 5 ma and ii 40ar 39ar analyses of greisen muscovite which indicated apparent plateau dates of ca 300 ma however the pervasive development of deformational fabrics at east kemptville suggests that both the rb sr whole rock and 40ar 39ar muscovite ages are at best minimum estimates for the inferred time of mineralization in the present study rb sr whole rock and mineral muscovite plagioclase k feldspar analyses and 40ar 39ar incremental step heating of a muscovite separate indicate the following i diffusion of sr on the whole rock scale terminated at 344 5 ma 11 point isochron date coincident with closure of muscovite to intracrystalline diffusion of ar apparent plat

airborne synthetic aperture radar observations of spiral eddy slick patterns in the southern california bight 1 repeat sampling on hourly time scales using an airborne synthetic aperture radar sar is used to investigate the occurrence and evolving characteristics of spiral shaped slick patterns commonly presumed to be indicators of submesoscale ocean eddies in the area around santa catalina island california 33 4 n 118 4 w simultaneous sar imagery and boat survey data are examined over two 5 h long periods spaced 3 days apart in april 2003 the sar imagery reveals several spiral like patterns roughly 5 km in diameter occurring downstream of the western end of catalina we believe that the most likely formation mechanism for these patterns is current wake instability related to the flow of the southern california countercurrent along the north shore of catalina in one case there is an observed cold core eddy and vortex sheet attached to the tip of the island similar to island wake simulations done by dong and mcwilliams 2007 in another case the sar imagery shows a series of slick patterns that at least initially resemble spiral eddies but the data show no clear evidence of actual ocean eddies being present either at depth or through a rotating surface expression a speculation is that such features signify island wake eddies that are relatively weak and dissipate quickly an unexpected finding was how quickly a spiral slick pattern could deteriorate suggesting a time scale for the surface feature of the order of only several hours an implication of this result is that care is needed when interpreting a single satellite sar imagery for evidence of active submesoscale eddies recommendations are made for future field studies

extreme convection of the near equatorial americas africa and adjoining oceans as seen by trmm abstractthis study documents the preferred location and diurnal cycle of extreme convective storms that occur in the tropical band containing the east pacific ocean central and south america the atlantic ocean and northern africa data from the tropical rainfall measuring mission trmm precipitation radar show three types of convective stratiform structures that constitute extreme convective events deep convective cores dccs wide convective cores wccs and broad stratiform regions bsrs interim ecmwf re analysis era interim data show the associated synoptic environmental factors associated with the occurrence of extreme convective features the dcc wcc and bsr echoes are associated with early middle and late stages of convective system development respectively and the statistics and timing of their occurrence are related to topography and life cycle behavior of the convection storms containing dcc occur primarily over the sudanian savannas of africa and near the mountains in northern

poleward flow off central california during the spring and summer of 1981 and 1984 currents and winds measured over the continental shelf and upper continental slope during the first half of 1984 are analyzed to determine the character of the flow off central california point conception to san francisco the mean flow was poleward from point conception to point sur in opposition to the equatorward wind stress the mean flow was equatorward north of point sur fluctuations in alongshore currents over the shelf were highly correlated with local winds everywhere except off point conception where currents were not only uncorrelated with wind but also poorly correlated with currents farther north north of point buchon there is evidence for poleward propagation of shelf current variability at 175 200 cm s the correlation between currents and local wind forcing dropped considerably beyond the shelf break only 10 15 km offshore from the shelf moorings during extended periods of weak equatorward winds the poleward shelf flow south of point sur spreads farther offshore over the continental slope a three week period of calm winds in july 1984 resulted in a 100 km wide tongue of poleward flow extending 300 km along the california coast similar but somewhat weaker poleward surface flow occurred during the same period in 1981 a 2 to 3 week period of calm winds in late june and early july 1981 resulted in a 100 km wide tongue of poleward flow extending at least 150 km along the california coast in contrast to the poleward flow on the shelf which appears to be normal during spring and summer the poleward surface flow observed over the slope in july 1981 and 1984 is unusual based on historical hydrographic surveys off the central california coast poleward surface flow over the continental slope occurs seasonally in the winter but is not generally observed after february

subtidal inner shelf circulation near point conception california 1 we discuss connections between inner shelf and mid shelf circulation near point conception california as well as the wind forcing of inner shelf circulation point conception marks the southern edge of a major upwelling zone that extends from oregon to central california the coastline makes a sharp eastward turn at point conception and the santa barbara channel to the east is generally assumed to be an upwelling shadow consistent with this regional division inner shelf currents are strongly correlated with wind north of point conception but not in the santa barbara channel one exception to this generalization is a location in the santa barbara channel near a pass that cuts through the coastal mountains where local winds have a dominant cross shore component and directly drive cross shore currents over the inner shelf inner shelf currents in the santa barbara channel when compared with mid shelf currents in that area are weaker but strongly correlated by contrast inner shelf currents north of point conception show a far greater incidence of poleward flow than is seen over the mid shelf in that area poleward flow events lasting 1 5 days transport warm water from the santa barbara channel around point conception to the central california coast these events are associated with relaxation of the generally equatorward wind but not always with mid shelf flow reversals

three dimensional oceanic eddy analysis in the southern california bight from a numerical product with eight islands complex coastlines and bottom topography strong wind curls and frequent upwelling fronts the southern california bight scb is an area with strong eddy activity by applying an automated eddy detection scheme to a 12 year high resolution numerical product of the oceanic circulation in the scb a three dimensional eddy data set is developed it includes information for each eddy s location polarity intensity size boundary and moving path at nine vertical levels through a series of statistical analyses applied to the eddy data set three dimensional statistical characteristics of mesoscale and submeoscale eddy variations in the scb are elucidated these shed light on how eddies are generated evolve and terminate a significant percentage of eddies is found to be generated around islands and headlands along the coastline which indicates that islands in the scb play a vital role in eddy generation three types of eddies based on shape are identified from the numerical product bowl lens and cone a dynamic analysis shows that some submesoscale eddies with finite local rossby numbers tend to be ageostrophic balanced while mesoscale eddies are in geostrophic balance the present research results are useful for the interpretation of data sets obtained during the interdisciplinary santa barbara channel radiance in a dynamic ocean radyo field experiment conducted on september 3 25 2008