modification of the intermediate waters in the northeastern subpolar pacific the modification of the intermediate layers in and around the alaskan gyre are investigated in relation to general circulation features of the region using tracer data from the world ocean circulation experiment p17n line the alaskan gyre ag core lies between the north pacific current and the alaskan stream as in the 52 54 5 n range and to the west of 144 w the north pacific current feeds the transition zone tz and the western subpolar waters wsw which consequently constitute the inflow to the region from the northwestern pacific the alaska current ac is observed to the west of 144 w between the north american coast and the ag the ac halocline 26 7 has distinct property distributions low chlorofluorocarbon and oxygen saturations and high nutrient concentrations which are correlated with eddies that are characterized by higher salt content and warmer temperatures most significantly at 26 0 the ag is found to act as a reservoir where water mass modification takes place and the as transports a mixture of waters from the ag and the ac west ward out of the region the residence time estimate for the intermediate and upper layer water in the ag 27 2 is about 2 years which corresponds to a volume exchange between the gyre and the surrounding circulation of 4 7 sv in the 0 1000 m range the layers above 26 9 0 200 m are modified by vertical mixing mostly of wsw in the ag the flux of modified waters out of the ag is approximately 0 9 sv comparison of the present data with the 1984 1989 period suggests that mixing of water from different regimes has not changed dramatically

poleward reach of the california undercurrent extension 1 the california undercurrent is known to transport relatively warm high salinity nutrient rich water from the equatorial pacific to vancouver island along the western continental slope of north america this transport helps maintain the high productivity of the eastern boundary california current system in this study we use several decades of water property survey data for the coasts of oregon washington british columbia and alaska to show that equatorial pacific water carried poleward by the undercurrent can eventually reach the aleutian islands roughly 11 000 km from the source region long term current meter records confirm the undercurrent as far north as vancouver island where the current is found to be weakest in spring but then to strengthen through the summer and fall before merging with the wind forced poleward flowing davidson current in winter the core depth of the equatorial water increases from 150 m 25 m off northwest washington near the northern end of the western north america coastal upwelling domain to 225 m 25 m off southeast alaska near the southern end of the gulf of alaska coastal downwelling domain

cross shelf transport of terrestrial al enhanced by the transition of northeasterly to southwesterly monsoon wind over the east china sea aluminum al is one of the key parameters of geotraces in spring 2011 we examined the distribution of dissolved al in the east china sea ecs to assess the potential passage of coastal water across the shelf to the western pacific measurement of dissolved al in coastal shelf and shelf break waters indicated decreasing concentrations with distance from the coast however the northward increase of dissolved al in the upper 100 m along the shelf break transect corresponding to the northward flow of kuroshio water along the okinawa trough from the north of taiwan to the tokara strait indicates contributions of terrestrial material the presence of an al plume indicated cross shelf transport at the subsurface at a potential density of 23 3 24 0 kg m3 this plume originates from the near bottom layer along the coast off zhejiang and fujian provinces and first moves southeastward to the north of taiwan and then northeastward to shelf break with export at 29 n 127 e we calculated the cross shelf fluxes of water and dissolved al based on simulation results of the 3 d massachusetts institute of technology general circulation model mitgcm the calculated cross shelf fluxes of al at the subsurface layer indicate that the ecs is highly efficient in pumping al rich coastal waters northward to the japan sea east sea and or eastward into the western pacific we also identified an important role of the monsoon with a change from northeasterly wind to southwesterly wind in spring on the cross shelf transport of al by use of numerical tracer experiments

zooplankton distribution and dynamics in a north pacific eddy of coastal origin ii mechanisms of eddy colonization by and retention of offshore species abstract mesoscale anticyclonic eddies form annually in late winter along the eastern margin of the subarctic north pacific eddies that originate off the southern tip of the queen charlotte islands near 52 n 132 w are called haida eddies during the subsequent 1 3 years they propagate westward into the alaska gyre enroute the eddies are colonized by zooplankton originating from the central british columbia continental shelf the continental slope and along slope boundary current and the oceanic alaska gyre eddies also gradually lose kinetic energy water properties and biota to the surrounding ocean in this paper we analyze zooplankton samples from haida eddies obtained in late winter early summer and autumn of 2000 and in early summer and autumn of 2001 and compare the within eddy zooplankton distributions abundances and community composition of the oceanic origin species to observations from the continental margin and alaska gyre source regions most between region comparisons were consistent with a hypothesis that the eddy zooplankton are a mixture intermediate in abundance and community composition between the bc continental margin and offshore alaska gyre source regions although usually closer to the alaska gyre however about 30 of the comparisons showed within eddy abundances higher than in either source region this outcome cannot arise from mixing alone aggregation and retention appear to be linked to vertical distribution behavior most of the successful taxa spend much of their time below the surface mixed layer this minimizes their exposure to wash out by three physical processes slow upwelling and surface divergence that accompanies weakening of the anticyclonic geostrophic currents rapid but intermittent flushing of the surface layer by ekman transport during strong wind events exchange across the eddy margin geostrophic streamlines caused by temporary displacement by wind driven inertial currents

heat and fresh water transport by eddies into the gulf of alaska abstract anticyclonic mesoscale eddies form in winter along the continental margin of canada and southeast alaska between the latitudes of 51n and 60n and drift westward into the gulf of alaska carrying warmer fresher water away from the continental margin detailed measurements of temperature and salinity between 1995 and 2001 were examined to determine the amount of heat and fresh water transported seaward by several eddies that formed west of the queen charlotte islands eddies formed in a typical winter carry about 30 10 18 j of heat into the gulf which is about 35 to 60 of the heat transported northward each winter along the continental margin toward this region the observed range of eddy heat transport is 10 19 to 10 20 j largest observed eddy heat transport coincided with increased northward heat flow along the continental margin during the el nino winter of 1997 1998 fresh water volume was determined by evaluating the amount of fresh water required to reduce the salinity from a reference level to that observed in eddies this volume varied from 0 to 70 km 3 and was largest during the 1997 1998 el nino winter eddies formed in a typical winter transport 50 km 3 of fresh water seaward which is about 15 of the estimated fresh water input to the continental margin in winter between the columbia river and 54n attributed to local runoff plus direct rainfall and flow in major rivers

the shedding of an anticyclonic eddy from the alaskan stream as observed by the geosat altimeter the evolution of a meander into an anticyclonic eddy which separates from the alaskan stream in the vicinity of the central aleutian islands is observed in two years of sea surface height anomalies computed from geosat exact repeat mission altimeter data the trajectory of the center of mass is estimated using a modified perpendicular bisector method eddy separation is inferred to occur where the trajectory makes a distinct turn to the southwest the observed region of meander growth and eddy separation agrees with that predicted by theory the evolution of meander eddy height and radius is estimated from least squares fits of the data to an axially symmetric gaussian profile the heights and radii are used to calculate the strength vorticity and energetics of the meander eddy ekman dynamics are assumed to govern the eddy decay spin down times based on vorticity are much longer than those based on energetics this is consistent with an eddy s ability to maintain its integrity as it decays representative height diameter and velocity scales of the eddy are characteristic of rings spawned by other current systems assuming a ring structure for this eddy the estimated ring volume represents a 21 transport anomaly referenced to the mean annual transport into the bering sea

mesoscale eddies in the south atlantic bight 1 satellite derived sea level anomaly fields constructed by combining measurements from simultaneously operating altimeters are used to quantify properties and propagation characteristics of eddies in the south atlantic bight sab eddy detection and eddy tracking algorithms are applied to 19 years of high resolution observations available at weekly intervals inshore of the 800 m isobath eddies are most frequently observed at and downstream of the charleston bump a major topographic feature located at 31 32 n a region where the amplitude of most eddies is increased the bump is also a preferred region for eddy generation the amplitude of eddies is found to increase with water depth eddies generated in the sab tend to propagate westward toward the coast and to the northeast presumably due to the influence of the strong mean northeastward flow of the gulf stream those eddies are highly nonlinear with potential to trap water in their interior as they propagate since a large fraction of the eddies that at some point in their histories are found inshore of the 800 m isobath experience large bathymetric changes along their trajectories they can potentially serve as efficient mechanisms for cross isobath transport in the sab analysis of temporal variability in eddy activity suggests that cross isobath transport due to nonlinear eddies may be significant during all seasons but will likely be characterized by large interannual variability

multi year meanders and eddies in the alaskan stream as observed by topex poseidon altimeter the birth life and decay of long lived anticyclonic eddies or meanders in the alaskan stream are observed from topex poseidon t p satellite their surface height anomalies approach 72 cm average diameter is about 160km and they live for 1 to 3 years propagating along the stream with mean speed of 2 5 km d 1 of the six observed the last three were formed after the first t p observations in september 1992 of these two evolved from eddies near alaskan panhandle in winter drifting across the northern gulf of alaska before entering the alaskan stream while another formed in the stream west of shelikof strait

submesoscale features and turbulent mixing of an oblique anticyclonic eddy in the gulf of alaska investigated by marine seismic survey data

swirling in the ocean immature loggerhead turtles seasonally target old anticyclonic eddies at the fringe of the north atlantic gyre abstract in a highly heterogeneous open ocean swirling oceanographic structures such as eddies drive ocean productivity and aggregate many predators including oceanic sea turtles during early life juvenile loggerhead turtles can spend more than a decade feeding on gelatinous zooplankton in the open ocean but the way they use mesoscale eddies is still poorly understood here we investigated the relationships between 1 the distribution and 2 the diving behaviour of immature loggerhead turtles of the north east atlantic and mesoscale eddies for this purpose 28 turtles were satellite tracked from the azores archipelago using the residence time rt analysis as a proxy to identify high use areas the tracks and dive data of the turtles as well as drifter trajectories were analysed in relation to eddy characteristics which include eddy radius amplitude type cyclonic vs anticyclonic lifetime and region inner core outer core periphery the turtles dispersed widely using many distinct high use areas although there were always more cyclones than anticyclones over the study region the individuals seasonally associated more with the inner cores of old anticyclonic eddies likely due to the higher productivity of decaying anticyclones the comparison between passive drifters and turtles movements showed an active swimming behaviour from the turtles rather than a passive advection through currents three dive types were identified and the one associated with the highest rt was characterized by dives of medium duration and depths in the inner cores of eddies this study is the first to highlight strong affinities of oceanic loggerhead turtles for old anticyclonic eddies around the azores suggesting a greater complexity of these warm core eddies that appear to be much more productive than cyclones

low frequency variability in the gulf of alaska from coarse and eddy permitting ocean models 1 an eddy permitting ocean model of the northeast pacific is used to examine the ocean adjustment to changing wind forcing in the gulf of alaska goa at interannual to decadal timescales it is found that the adjustment of the ocean model in the presence of mesoscale eddies is similar to that obtained with coarse resolution models local ekman pumping plays a key role in forcing pycnocline depth variability and to a lesser degree sea surface height ssh variability in the center of the alaska gyre and in some areas of the eastern and northern goa westward rossby wave propagation is evident in the ssh field along some latitudes but is less noticeable in the pycnocline depth field differences between ssh and pycnocline depth are also found when considering their relationship with the local forcing and leading modes of climate variability in the northeast pacific in the central goa pycnocline depth variations are more clearly related to changes in the local ekman pumping than ssh while ssh is marginally correlated with both pacific decadal oscillation pdo and north pacific gyre oscillation npgo indices the pycnocline depth evolution is primarily related to npgo variability the intensity of the mesoscale eddy field increases with increasing circulation strength the eddy field is generally more energetic after the 1976 1977 climate regime shift when the gyre circulation intensified in the western basin where eddies primarily originate from intrinsic instabilities of the flow variations in eddy kinetic energy are statistically significant correlated with the pdo index indicating that eddy statistics may be inferred to some degree from the characteristics of the large scale flow

impact of haida eddies on chlorophyll distribution in the eastern gulf of alaska mesoscale haida eddies influence the distribution of surface phytoplankton in the eastern gulf of alaska through two processes enhanced productivity in central eddy water and seaward advection of highly productive coastal waters in the outer rings of eddies these two processes were observed in a sequence of monthly images over five years for which images of seawifs derived chlorophyll distributions were overlaid by contours of mesoscale sea surface height anomaly derived from topex and ers 2 satellite observations satellite measurements were supplemented with ship based chlorophyll observations through one of the eddies haida eddies are deep anticyclonic mesoscale vortices that normally form in winter and early spring near the southwest coast of the queen charlotte islands high levels of chlorophyll observed in eddy centres indicated that they supported phytoplankton blooms in spring of their natal years with timing of these blooms varying from year to year and exceeding in magnitude the chlorophyll concentrations of surrounding water elevated chlorophyll levels also were observed in eddy centres in late summer and early autumn of their natal year enhanced chlorophyll biomass is attributed to higher levels of macro nutrients and higher levels of iron enclosed within eddies than in surface deep ocean water by late spring and summer when coastal water supported higher chlorophyll biomass than did oceanic offshore regions eddies that straddled the continental margin entrained high chlorophyll coastal water into their outer rings and carried it several hundred kilometres into the gulf of alaska along their southern sides on some occasions a deep ocean eddy would entrain chlorophyll from an adjacent eddy located closer to the coast forming a conveyor belt transport process to inject coastal biota into the deep sea region of the gulf this process extended the coastal region of high chlorophyll surface water and therefore phytoplankton rich water several hundred kilometres seaward and dominated the shelf to deep ocean exchange of chlorophyll from late winter to the following autumn

incised palaeo channels of the late middle pleistocene thames age origins and implications for fluvial palaeogeography and sea level reconstruction in the southern north sea basin abstract multidisciplinary investigations of the infills of steeply incised buried channels on the coast of essex england provide important insights into late middle pleistocene climate and sea level change and have a direct bearing on the differentiation of mis 11 and mis 9 in terrestrial records new data are presented from rochford and burnham on crouch where remnants of two substantial palaeo channels filled with interglacial sediment can be directly related to the terrace stratigraphy of the thames the sediments in both channels accumulated in an estuarine environment early in an interglacial when mixed oak forest was becoming established lithological evidence suggests that the interglacial beds post date the brackish water infill of an older palaeo channel ascribed to the hoxnian and correlated with part of mis 11 and pre date terrace gravels barling gravel ascribed to mis 8 an mis 9 attribution is supported by molluscan biostratigraphy palaeo salinity and amino acid racemization data the relative sea level record in this area thus includes evidence for two major marine transgressions during mis 11 and mis 9 with local maxima of 10 m o d both are associated with sediments that show hoxnian palynological affinities the wider significance of these findings and of an intermediate phase of pronounced fluvial incision during mis 10 is discussed

observations from a yakutat eddy in the northern gulf of alaska 1 the impingement of deep basin eddies on the shelf in the gulf of alaska has been implicated as an important mechanism for cross shelf exchange the influence of eddies on biological processes has been confirmed with data from the sea viewing wide field of view sensor showing elevated chlorophyll associated with eddies altimetry data suggest that an eddy formed in the winter of 2003 near yakutat alaska and propagated along the shelf break reaching the head of the gulf by spring this eddy was sampled during may and september of 2003 the eddy core water was warm salty and high in nitrate relative to basin water of the same density but was similar to historical water properties from the shelf near yakutat this suggests a shelf origin for the eddy core water

lagrangian study of mesoscale circulation in the alaskan stream area and the eastern bering sea abstract the alaskan stream is the western boundary current in the subarctic north pacific the alaskan stream area is characterized by a significant temperature salinity and density differences between the coastal and open ocean waters and strong mesoscale dynamics in this paper we demonstrate the transport pathways of the alaskan stream water in the eastern subarctic pacific and its extension into the eastern bering sea from 1 october 1994 to 12 september 2016 with the help of altimetry based lagrangian maps mesoscale eddy activity along the boundary between the shelf and deep basin in the alaskan stream region and the eastern bering sea is shown to be related to the wind stress curl in the northern north pacific in winter a significant correlation is found between the concentration of chlorophyll a in the alaskan stream area and eastern bering sea in august september and the wind stress curl in the northern north pacific in november march the mesoscale dynamics forced by the wind stress curl in winter may influence not only lower trophic level organism biomass but also salmon abundance and catch in the study area

seaglider surveys at ocean station papa circulation and water mass properties in a meander of the north pacific current a seaglider autonomous underwater vehicle augmented the ocean station papa osp 50 n 145 w surface mooring measuring spatial structure on scales relevant to the monthly evolution of the moored time series during each of three missions from june 2008 january 2010 a seaglider made biweekly 50 km 50 km surveys in a bowtie shaped survey track horizontal temperature and salinity gradients measured by these surveys were an order of magnitude stronger than climatological values and sometimes of opposite sign geostrophically inferred circulation was corroborated by moored acoustic doppler current profiler measurements and aviso satellite altimetry estimates of surface currents confirming that glider surveys accurately resolved monthly scale mesoscale spatial structure in contrast to climatological north pacific current circulation upper ocean flow was modestly northward during the first half of the 18 month survey period and weakly westward during its latter half with rossby number 0 01 this change in circulation coincided with a shift from cool and fresh to warm saline oxygen rich water in the upper ocean halocline and an increase in vertical finestructure there and in the lower pycnocline the anomalous flow and abrupt water mass transition were due to the slow growth of an anticyclonic meander within the north pacific current with radius comparable to the scale of the survey pattern originating to the southeast of osp this article is protected by copyright all rights reserved

a diagnostic model for mixed layer depth estimation with application to ocean station p in the northeast pacific abstract this paper presents a simple diagnostic model for estimating mixed layer depth based solely on the one dimensional heat balance equation the surface heat flux and the sea surface temperature the surface fluxes drive heating or cooling of the upper layer whereas the surface temperature acts as a thermostat that regulates the vertical extent of the layer daily mixed layer depth estimates from the diagnostic model and two standard bulk mixed layer models are compared with depths obtained from oceanic profiles collected during the 1956 80 canadian weathership program at station p and more recent 2001 07 profiles from the vicinity of this station from argo drifters summer mixed layer depths from the diagnostic model agree more closely with observed depths and are less sensitive to heat flux errors than those from bulk models for the weathership monitoring period the root mean square difference between modeled and observed monthly mean mixed layer depths is 6 m for the diagnostic model an

iron transport by mesoscale haida eddies in the gulf of alaska abstract a two year study of the iron distributions in anticyclonic mesoscale haida eddies of the eastern north pacific ocean has shown that such eddies are a major source of iron to the high nitrate low chlorophyll hnlc waters of the central gulf of alaska basin these eddies which are typically about 100 km in diameter form off the west coast of canada in winter and then track roughly westward into the open ocean therefore they carry large quantities of iron rich coastal waters into iron limited waters of the oligotrophic gyre when the eddies had first formed their dissolved iron concentrations were nearly two orders of magnitude higher than is typically observed at station papa 50 n 145 w 3 n m versus less than 0 05 n m and the total iron in the eddies surface waters 10 40 m was more than 13 n m higher than open ocean waters of the alaska gyre 14 n m versus 0 5 n m while the overall iron content of the eddies decreased rapidly during the first year after they formed the eddy we were able to track the longest still contained 1 5 2 times more iron than the surrounding waters 16 months after its formation therefore although iron concentrations in the surface mixed layers of the eddies drop to levels observed outside very rapidly within 4 months upward transport along isopycnals and upwelling due to eddy decay as well as vertical advective and diffusive transports typical of north pacific waters probably provide steady fluxes of iron into the euphotic zone from the still iron rich eddy core waters throughout the lifetime of the eddy

the influence of coastal origin eddies on oceanic plankton distributions in the eastern gulf of alaska abstract mesoscale anticyclonic eddies that form along the eastern continental margin of the gulf of alaska in winter transport large quantities of coastal water to the open ocean the continuous plankton recorder cpr sampled repeated transects that passed close to or through these eddies in 2000 and 2001 shelf species of diatoms and calanoid copepods were recorded in cpr samples within or in close proximity to eddies and they persisted through the sampling period several oceanic taxa also showed higher concentrations within the eddies significantly reduced occurrences of shelf taxa in oceanic samples were seen in 2001 coinciding with a weaker eddy than observed in 2000 images of ocean temperature and chlorophyll a prepared from satellite observations reveal changes in offshore transport mechanisms by eddies between winter and spring and between southern and northern eddies in this region these effects may also explain some of the seasonal and geographical variability in the cpr samples between april and june of 2000 the haida eddy straddled the low chlorophyll a waters of the gulf and the high chlorophyll a waters of the continental margin and entrained each water type into the neighbouring region the resulting swirling patterns were clearly observed in seawifs imagery sitka eddies failed to penetrate into low chlorophyll a waters during these months and were less effective in stirring high and low chlorophyll a concentrations surface currents in surrounding waters simulated by the ocean surface current simulations oscurs model were used to provide some insights into the likely fate of planktonic organisms once they leave the eddies we show that these eddies may play a significant role in distributing plankton species

physical processes that enhance nutrient transport and primary productivity in the coastal and open ocean of the subarctic ne pacific abstract in comparison to the open ocean several additional processes including coastal upwelling river discharge tidal mixing estuarine circulation and benthic remineralization enhance nutrient supply to the surface waters of the continental shelf in general coastal waters become nitrate limited during the phytoplankton growing season whereas iron and dissolved silicate limit phytoplankton growth in the less productive oceanic waters of the gulf of alaska if coastal processes supply ample amounts of macro and micro nutrients during the growing season diatom communities dominated by species such as skeletomema costatum chaetoceros spp and thalassiosira spp will bloom growth rates of these bloom populations typically range from 0 5 to 1 5 doublings per day which place a high demand on nutrients any transport of coastal waters away from the shelf will enhance productivity in oceanic waters the general circulation of the eastern subarctic pacific does not allow for offshore transport except in special circumstances these include anticyclonic mesoscale eddy formation which can export as much as 5000 km 3 of nutrient rich waters from the shelf in a single eddy and recirculation of waters away from southwestern alaska due to the cyclonic circulation around the western edge of the alaskan gyre recirculation can carry nutrient rich water from the coast to the vicinity of ocean station papa 50 n 145 w within a few months for both eddies and gyre recirculation much of the water being carried into the open ocean lies below the euphotic zone iron enrichment occurs to a depth of at least 1000 m in the gulf of alaska as a result periods of enhanced eddy formation or recirculation may supply iron that enriches the open ocean for several years damming of the columbia river and human uses of its waters have resulted in more winter and less summer discharge of fresh water and dissolved si coastal currents in this area flow north in winter and south in summer as a consequence there has been a net temporal change in si inputs to the ocean since the mid 1970s with about 4 10 9 mol more si flowing north in winter and 9 10 9 mol less si flowing south in summer compared with the early 1900s since silicate limits diatom growth and diatoms are responsible for most carbon export in phytoplankton implications for ocean productivity are significant

physical characteristics and dynamics of the coastal latex09 eddy derived from in situ data and numerical modeling 1 we investigate the dynamics of a coastal anticyclonic eddy in the western part of the gulf of lion gol in the northwestern mediterranean sea during the latex campaign in the summer 2009 latex09 the sampling strategy combines sea surface temperature satellite imagery hull mounted acoustic doppler current profiler data conductivity temperature depth casts and drifter trajectories our measurements reveal an anticyclonic eddy latex09 eddy with a diameter of 23 km and maximum depth of 31 m centered at 3 34 e 42 33 n we use a high resolution three dimensional primitive equation numerical model to investigate its generation process and evolution the model is able to reproduce the observed eddy in particular its size and position the model results suggest that the latex09 eddy is induced by a large anticyclonic circulation in the northwestern part of the gol pushed and squeezed toward the coast by a meander of the northern current this represents a new generation mechanism that has not been reported before the post generation dynamics of the eddy is also captured by the model the collision of the latex09 eddy with cape creus results in a transient structure which is depicted by the trajectories of two lagrangian drifters during latex09 the transient structure and its advection lead to a transfer of mass and vorticity from the gol to the catalan shelf indicating the importance of mesoscale structures in modulating such exchanges in the region

the mid cenozoic succession and evolution of the mut basin southern turkey and its regional significance abstract the hitherto poorly known mut basin occupies a position that is critical to our understanding of the later cenozoic history of south central turkey the biostratigraphic and sedimentological study reported here reveals an extended and complex pattern of basin evolution and enables the history of this basin to be compared in detail with that of adjacent south turkish basins the oldest basin fill deposits are demonstrated to be oligocene to earliest miocene in age and comprise alluvial redbeds thick lacustrine deposits and thin lagoonal sediments mainly supplied from northern tauride sources this mainly terrestrial megasequence resulted from an early oligocene phase of crustal extension leading to rapid trap door subsidence and the formation of narrow e w trending troughs this phase was terminated by a minor marine incursion and through reactivation of basement faults during renewed extension in the earliest miocene the overlying miocene succession thus rests with local angular discordance upon tilted and gently deformed oligocene and older rocks subsequent subaerial erosion created an irregular pre burdigalian palaeotopography that strongly influenced the nature thickness and distribution of the early miocene basin fill in palaeotopographic depressions the miocene sequence commences with alluvial fan braidplain and meander belt redbeds formed in river systems that flowed mainly south and southeast these pass up and laterally into more extensive lagoonal and shallow marine mixed clastic carbonate units yielding late burdigalian to early langhian microfaunas marking the inception of the main miocene marine transgression in this area episodic northwards marine advance led to isolation of the northerly source of siliciclastic detritus and resulted in periodic onlap of mid to inner shelf fine grained carbonates with thin clastic intercalations that include isolated coralgal build ups calcarenite mounds and sand waves at the peak of miocene transgression mid serravallian thick reefal limestones were deposited far to the north and also formed on top of basement highs forming the southern and eastern flanks of the basin significant influxes of coarse and fine siliciclastics from the north attest to periodic progradational events that are more conspicuous and protracted in the late serravallian and tortonian however muddy deeper shelf conditions prevailed throughout the middle miocene in the central part of the basin while stronger currents and unstable slopes characterise the constricted marine strait in the southeast of the basin near silifke in terms of their sequential arrangement palaeoenvironmental and tectonic evolution the oligo miocene sediments of the mut basin closely resemble coeval sequences in the adjacent ecemis aktoprak and karsanti northern adana basins and share a similar history involving complex interplay between regional tectonics and eustasism deeper water oligo miocene sequences in the outboard troughs such as the southern adana basin and the kyrenia misis andirin complex yield more subtle signatures of these tectonic and eustatic events the differences between these basins are attributable to the influence of regional kinematic elements generated during the reorganisation of plate boundaries in the northeast mediterranean that followed final suturing of the arabian and anatolide plates in the mid cenozoic

intense submesoscale upwelling in anticyclonic eddies observations from around the global ocean show that enhanced biological activity can be found in anticyclonic eddies this may mean that upwelling of nutrient rich water occurs within the eddy but such upwelling is not captured by models that resolve mesoscale processes high resolution simulations presented here show intense submesoscale upwelling from the thermocline to the mixed layer in anticyclonic eddies the properties of the upwelling are consistent with a process known as symmetric instability a simple limiting nutrient experiment shows that this upwelling can drive much higher biological activity in anticyclonic eddies when there is a high nutrient concentration in the thermocline an estimate for the magnitude of upwelling associated with symmetric instability in anticyclonic eddies in the sargasso sea shows that it may be of comparable magnitude to other processes though further work is required to understand the full implications for basin scale nutrient budgets

intrinsic and forced interannual variability of the gulf of alaska mesoscale circulation abstract the response of the gulf of alaska goa circulation to large scale north pacific climate variability is explored using three high resolution 15 km regional ocean model ensembles over the period 1950 2004 on interannual and decadal timescales the mean circulation is strongly modulated by changes in the large scale climate forcing associated with pdo and enso intensification of the model gyre scale circulation occurs after the 1976 1977 climate shift as well as during 1965 1970 and 1993 1995 from the model dynamical budgets we find that when the goa experiences stronger southeasterly winds typical during the positive phase of the pdo and enso there is net large scale ekman convergence in the central and eastern coastal boundary the geostrophic adjustment to higher sea surface height ssh and lower isopycnals lead to stronger cyclonic gyre scale circulation the opposite situation occurs during stronger northwesterly winds negative phase of the pdo along the eastern side of the goa basin interannual changes in the surface winds also modulate the seasonal development of high amplitude anticyclonic eddies e g haida and sitka eddies large interannual eddy events during winter spring are phase locked with the seasonal cycle the initial eddy dynamics are consistent with a quasi linear rossby wave response to positive ssh anomalies forced by stronger downwelling favorable winds e g southwesterly during el nino however because of the fast growth rate of baroclinic instability and the geographical focusing associated with the coastal geometry most of the perturbation energy in the rossby wave is locally trapped until converted into large scale nonlinear coherent eddies coastally trapped waves of tropical origin may also contribute to positive ssh anomalies that lead to higher amplitude eddies however their presence does not appear essential the model ensembles which do not include the effects of equatorial coastally trapped waves capture the large haida and sitka eddy events observed during 1982 and 1997 and explain between 40 and 70 of the tidal gauges variance along the goa coast in the western side of the goa basin interannual eddy variability located south of the alaskan stream is not correlated with large scale forcing and appears to be intrinsic a comparison of the three model ensembles forced by ncep winds and a multi century long integration forced only with the seasonal cycle shows that the internal variability alone explains most of the eddy variance the asymmetry between the eddy forced regime in the eastern basin and the intrinsic regime in the western basin has important implications for predicting the goa response to climate change if future climate change results in stronger wintertime winds and increased downwelling in the eastern basin then increased mesoscale activity perhaps more or larger eddies might occur in this region conversely the changes in the western basin are not predictable based on environmental forcing eastern eddies transport important biogeochemical quantities such as iron oxygen and chlorophyll a into the gyre interior therefore having potential upscale effects on the goa high nutrient low chlorophyll region

formation of the haida 1998 oceanic eddy 1 two large mesoscale anticyclonic eddies formed along the west coast of the queen charlotte islands of western canada in early 1998 altimetry measurements from topex poseidon and ers 2 satellites suggest that these eddies first appeared near cape st james at the southern tip of the islands the eddies merged in june to form haida 1998 the highest eddy ever observed in the region currents near cape st james in winter follow complicated patterns attributed to tidal rectification and pressure driven outflow from hecate strait the adjustment of these flows to the bathymetric features likely contributes to the formation of haida eddies eddies that first appear farther north along the west coast of the queen charlotte islands are set up by other processes such as baroclinic instability

a synoptic survey of young mesoscale eddies in the eastern gulf of alaska eddies in the gulf of alaska are important sources of coastal water and associated nutrients iron and biota to the high nutrient low chlorophyll central gulf of alaska three primary eddy formation regions along the eastern boundary of the gulf have been identified from south to north haida sitka and yakutat in the spring of 2005 three eddies one of each type were sampled soon after their formation the subsurface eddy core water in all three eddies was defined by high iron concentrations and low dissolved oxygen compared with surrounding basin water the sitka and yakutat core waters also exhibited a subsurface temperature maximum mesothermal water coincident in depth with the iron maximum suggesting that eddies may play a role in the formation of temperature inversions observed throughout the gulf of alaska the data suggest different formation regions with the yakutat eddy forming in shallow shelf water with riverine input while the sitka and haida eddies appear to form in deeper water

a regression modeling approach for studying carbonate system variability in the northern gulf of alaska 1 the northern gulf of alaska goa shelf experiences carbonate system variability on seasonal and annual time scales but little information exists to resolve higher frequency variability in this region to resolve this variability using platforms of opportunity we present multiple linear regression mlr models constructed from hydrographic data collected along the northeast pacific global ocean ecosystems dynamics globec seward line the empirical algorithms predict dissolved inorganic carbon dic and total alkalinity ta using observations of nitrate no3 temperature salinity and pressure from the surface to 500 m with r2s 0 97 and rmse values of 11 mol kg 1 for dic and 9 mol kg 1 for ta we applied these relationships to high resolution no3 data sets collected during a novel 20 h glider flight and a globec mesoscale seasoar survey results from the glider flight demonstrated time space along isopycnal variability of aragonite saturations arag associated with a dicothermal layer a cold near surface layer found in high latitude oceans that rivaled changes seen vertically through the thermocline the seasoar survey captured the uplift to 100 m of dense high pco2 waters at the shelf break that had been forced by the passage of a yakutat eddy during this event the aragonite saturation horizon depth where arag 1 shoaled to a previously unseen depth in the northern goa this work is similar to recent studies aimed at predicting the carbonate system in continental margin settings albeit demonstrates that a no3 based approach can be applied to high latitude data collected from platforms capable of high frequency measurements

modelling the generation of haida eddies abstract a numerical model forced with average annual cycles of climatological winds surface heat flux and temperature and salinity along the open boundaries is used to demonstrate that haida eddies are typically generated each winter off cape st james at the southern tip of the queen charlotte islands of western canada annual cycles of sea surface elevation measured at coastal tide gauges and topex poseidon crossover locations are reproduced with reasonable accuracy model sensitivity studies show that haida eddies are baroclinic in nature and are generated by the merging of several smaller eddies that have been formed to the west of cape st james the generation mechanism does not require the existence of instability processes and is associated with the mean advection of warmer and fresher water masses around the cape from hecate strait and from the southeast these advected water masses generate plumes of buoyant flow which intensify and sustain small patches of anticyclonic circulation immediately to the northwest of the cape when the flow is stronger several of these smaller eddies can merge to generate a larger eddy the haida eddy similar to observations a typical generation shedding cycle for larger haida eddies in the model is 3 4 months consistent with previous in situ water property measurements these experiments show that the eddies are generally comprised of mixed layer water from hecate strait queen charlotte sound and the continental shelves off northern vancouver island their vertical extent during the mature stage is roughly 1000 m

vertical velocity estimates in the north pacific using argo floats abstract vertical velocity in the oceans is critical for maintenance of the structure of the main thermoclines and the transport of nutrients from deepwater towards the surface and thus is an important variable for understanding the dynamics of the ocean and the transport of scalar variables in the mid 1970s the author was engaged in discussions with tom rossby about how sofar floats might be used to observe the vertical component of velocity this paper in some sense follows on from those discussions almost 40 years later in this paper the argo array is used to compute the horizontal volume divergence in a control volume in the north pacific divergence is found and this must be related to a volume flux through the base of the control volume the implied vertical velocity is large and various tests are proposed to determine whether or not the estimate is plausible the first test shows that a vertical velocity this large is necessary to close the salt budget the second test shows that the vertical velocity balances about half of the observed heat divergence the remainder is then accounted for by heat flux at the sea surface finally the time variable vertical velocity is computed and used to compute the evolution of the salt content in the control volume thus though the estimated vertical velocity is surprisingly large it passes plausibility tests

stable carbon and nitrogen isotope variation in the northern lampfish and neocalanus marine survival rates of pink salmon and meso scale eddies in the gulf of alaska abstract northern lampfish nlf stenobrachius leucopsarus myctophidae the dominant pelagic fish taxon of the subarctic north pacific ocean were sampled opportunistically in mocness tows made on continental slope waters of the gulf of alaska goa as well as in deep areas of prince william sound pws during 1997 2006 the overall mean whole body lipid corrected stable carbon isotope value of nlf from the goa was 21 4 sd 0 7 whereas that from pws was 19 5 sd 0 9 this pattern is similar to that observed for late feeding stage neocalanus cristatus copepods thus confirming a mean cross shelf carbon stable isotope gradient as well there was a statistically significant positive correlation between the considerable temporal variation in the monthly mean carbon stable isotope composition of goa neocalanus and goa nlf r 0 69 p r 0 84 p neocalanus in may were also positively correlated to salmon marine survival r 0 82 p neocalanus carbon stable isotope values point to processes taking place at the slope i e interactions driven by meso scale eddies when at the edge of the shelf as being the driving force to inter annual variability in the coastal gulf of alaska study area

subthermocline eddies over the washington continental slope as observed by seagliders 2003 09 abstractin the california current system subthermocline lenslike anticyclonic eddies generated within the california undercurrent cu are one mechanism for lateral transport of the warm saline waters of the cu garfield et al established the name cuddies for eddies of this type and hypothesized that they account for a significant fraction of the offshore transport of cu water this study presents observations of subthermocline eddies collected from a time series of seaglider surveys in the northern california current system gliders made 46 crossings of subthermocline anticyclones and 17 crossings of subthermocline cyclones over 5 5 yr close inspection grouped these into 20 distinct anticyclones and 10 distinct cyclones water properties at the core of anticyclonic eddies were similar to those in the core of the cu over the continental slope these anticyclones are examples of cuddies anticyclonic cyclonic eddies had average radii of 20 4 20 6 km peak azimuthal current speeds of 0 25 0 23

cold core anticyclonic eddies south of the bussol strait in the northwestern subarctic pacific abstract summer hydrographic surveys from 1993 to 1997 in the area south of the kuril islands in the northwestern subarctic pacific showed the existence of anticyclonic eddies south of the bussol strait at almost the same location but with variable sizes and intensities depending on the year every eddy had a cold low salinity and low potential vorticity core suggesting a strong influence from the okhotsk sea water two formation processes and annual variations were found with satellite data analyses one is the case where eddies are locally formed south of the bussol strait and intensified from summer to fall with the supply of okhotsk sea water as observed in 1993 in the other case kuroshio warm core rings that had translated northeastward are arrested near the bussol strait and amplified with the supply of okhotsk sea water as seen from summer to autumn in 1995 in winter eddies tend to move northeastward with decay the 1992 eddy moved northeastward then northward in winter and was eventually

mesoscale variability and nutrient phytoplankton distributions off central southern chile during the upwelling season the influence of mesoscale eddies abstract mesoscale features are recurrently found in the coastal transition zone ctz off central southern chile 35 40 s a region characterized by seasonal wind driven coastal upwelling in this study oceanographic data from two consecutive cruises carried out during the upwelling season january 2009 were combined with satellite time series data in order to characterize the structure and evolution of mesoscale eddies and to explore their influence on phytoplankton structure and nutrient distribution in the context of organic carbon exchanges between the coastal upwelling zone and the ctz two coastally generated contiguous mesoscale eddies 2 months old were characterized a surface cyclonic eddy cc1 and a subsurface anticyclonic eddy aa1 the distributions of salinity and dissolved oxygen together with nutrients suggested that both eddies were sites of vertical injection of high nutrient concentrations from the equatorial subsurface water mass essw into the upper layer in the ctz in addition eddy aa1 in combination with an upwelling plume was involved in the offshore advection of nutrients from the core of the essw located in the coastal zone at shallow depths

the continental margin is a key source of iron to the hnlc north pacific ocean here we show that labile particulate iron and manganese concentrations in the upper 500m of the western subarctic pacific an iron limited high nutrient low chlorophyll hnlc region have prominent subsurface maxima between 100 200 m reaching 3 nm and 600 pm respectively the subsurface concentration maxima in particulate fe are characterized by a more reduced oxidation state suggesting a source from primary volcagenic minerals such as from the kuril kamchatka margin the systematics of these profiles suggest a consistently strong lateral advection of labile mn and fe from redox mobilized labile sources at the continental shelf supplemented by a more variable source of fe from the upper continental slope this subsurface supply of iron from the continental margin is shallow enough to be accessible to the surface through winter upwelling and vertical mixing and is likely a key source of bioavailable fe to the hnlc north pacific

mesoscale eddies dominate surface phytoplankton in northern gulf of alaska abstract the hnlc waters of the gulf of alaska normally receive too little iron for primary productivity to draw down silicate and nitrate in surface waters even in spring and summer our observations of chlorophyll sensed by seawifs north of 54 n in pelagic waters 500 m depth of the gulf found that on average more than half of all surface chlorophyll was inside the 4 cm contours of anticyclonic mesoscale eddies the ratio approaches 80 in spring months yet these contours enclosed only 10 of the total surface area of pelagic waters in the gulf therefore eddies dominate the chlorophyll and phytoplankton distribution in surface pelagic waters we outline several eddy processes that enhance primary productivity eddies near the continental margin entrain nutrient and fe rich and chlorophyll rich coastal waters into their outer rings advecting these waters into the basin interior to directly increase phytoplankton populations there in addition eddies carry excess nutrients and iron in their core waters into pelagic regions as they propagate away from the continental margin as these anticyclonic eddies decay their depressed isopycnals relax upward injecting nutrients up toward the surface layer we propose that this transport brings iron and macro nutrients toward the surface mixed layer where they are available for wind forced mixing to bring them to surface these mesoscale eddies decay slowly but steadily perhaps providing a relatively regular upward supply of macro nutrients and iron toward euphotic layers they might behave as isolated oases of enhanced marine productivity in an otherwise iron poor basin we note that much of this productivity might be near or just below the base of the surface mixed layer and therefore poorly sampled by colour sensing satellites it is possible then that eddies enrich phytoplankton populations to a greater extent than noted from satellite surface observations only

the anticyclonic baroclinic eddy off sitka alaska in the northeast pacific ocean abstract among the many mesoscale eddies found in the northeast pacific ocean is a well developed anticyclonic baroclinic eddy situated within a few hundred kilometers of sitka alaska 57 n 138 w it has definitely been observed during spring and summer 1958 summer 1960 and summer 1961 observations made at other times show some evidence of its occurrence also the trajectories of three norpax drifting buoys for april may 1977 also indicated the probable presence of an eddy there the eddy whose diameter ranges from 200 to 300 km and whose depth extends to 100 m and probably to as much as 2000 m recurs at the same location the center of the eddy is characterized by the following features the surface water is less saline and only somewhat warmer than at its periphery at depths within and below the halocline it is warmer less saline and contains more dissolved oxygen than at the periphery and a warm core is situated within the halocline the halocline is usually depressed by less than 100 m but

persistently declining oxygen levels in the interior waters of the eastern subarctic pacific abstract fifty years of measurements at ocean station papa osp 50 n 145 w show trends in the interior waters of the subarctic pacific that are both impacted by short term few years to bi decadal atmospheric or ocean circulation oscillations and by persistent climate trends between 1956 and 2006 waters below the ocean mixed layer to a depth of at least 1000 m have been warming and losing oxygen on density surfaces found in the depth range 100 400 m 26 3 27 0 the ocean is warming at 0 005 0 012 c y 1 whereas oxygen is declining at 0 39 0 70 mol kg 1 y 1 or at an integrated rate of 123 mmol m 2 y 1 decrease of 22 over 50 years during this time the hypoxic boundary defined as 60 mol o 2 kg 1 has shoaled from 400 to 300 m in the alaska gyre the 26 2 isopycnal occasionally ventilates whereas at osp 26 0 has not been seen at the ocean surface since 1971 as the upper ocean continues to stratify to interpret the 50 year record at osp the isopycnal transport of oxygenated waters within the interior of the subarctic pacific is assessed by using a slightly modified no parameter broecker w 1974 no a conservative water mass tracer earth and planetary science letters 23 100 107 the highest nitrate oxygen signature in interior waters of the north pacific is found in the bering sea gyre western subarctic gyre and east kamchatka current region as a consequence of winter mixing to the 26 6 isopycnal by mixing with low no waters found in the subtropics and okhotsk sea this signature is diluted as waters flow eastward across the pacific evidence of low no waters flowing north from california is seen along the coasts of british columbia and se alaska oxygen in the subsurface waters of the alaskan gyre was supplied 60 by subarctic and 40 by subtropical waters during woce surveys whereas such estimates are shown to periodically vary by 20 at osp other features discernable in the osp data include periods of increased ventilation of deeper isopycnals on an 18 year cycle and strong short term few month variability caused by passing mesoscale eddies the potential impacts of declining oxygen on coastal ecosystems are discussed

a note on cross shelf exchange in the northern gulf of alaska the continental shelf of the gulf of alaska goa is a complex system characterized by large freshwater runoff and strong winds the goa supports one of the world s richest ecosystems including numerous species of fishes marine mammals and sea birds the mechanisms that provide nutrients to support this ecosystem are not well understood the rivers and streams that provide freshwater to the shelf are low in nitrate and the regional winds favor downwelling high concentrations of nitrate are available in the deep basin of the goa but these must be introduced to the shelf in order to support the high productivity we present evidence for cross shelf exchange due to three different mechanisms episodes of downwelling relaxation result in a flux of saline nutrient rich water onto the shelf at depth eddies formed in the northeastern goa propagate along the shelf break influencing cross shelf exchange by carrying shelf origin water from the formation region into the basin and by interacting with the shelf break circulation bathymetric steering in the many canyons that incise the goa shelf results in flow into the canyons where strong tidal mixing results in cross isobath movement of water properties

a basin scale oceanic instability event in the gulf of alaska a composite noaa 14 satellite advanced very high resolution radiometer image of the gulf of alaska for early march 1995 reveals a sequence of six anticyclonic oceanic eddies spanning more than 1500 km of the continental margin of north america from central british columbia to central alaska although isolated mesoscale eddies have previously been documented for this eastern boundary region the composite image provides the first evidence that trains of such eddies can develop simultaneously along the entire coast the 80 km radius and 250 km spacing of these warm core eddies are consistent with a baroclinic instability event in the poleward coastal current that prevails along the northwest continental margin of north america in winter roughly october through march wind data from offshore meteorological buoys combined with partial cloud free thermal images for january and february suggest that the event was triggered in mid january by an abrupt coast wide reversal in the prevailing poleward wind the instability event disrupted the alongshore transport of relatively warm high salinity water and presumably resulted in a greatly enhanced cross shore flux of brackish nutrient rich coastal water into the open ocean on the basis of its basin scale extent and more than 2 month duration it is feasible that the event had a major impact on the early spring recruitment and survival of zooplankton and pelagic fish within the highly productive fishery zones of coastal british columbia and alaska less extensive eddy sequences found in several earlier satellite images for the region suggest that these instability events are fairly common if so this indicates that the poleward current that forms over the eastern pacific continental slope in late fall herein the northeast pacific coastal current is marginally stable and likely to deform into a series of mesoscale eddies following abrupt basin scale reversals in the seasonally dominant wind provided these wind events occur early enough in the season the coastal current could reform with the onset of poleward winter winds