estimation of the agulhas ring impacts on meridional heat fluxes and transport using argo floats and satellite data 1 a method that combines vertical profiles from the argo floats program and satellite sea surface height ssh data is used to reconstruct the vertical structure of the agulhas rings all eddies shed by the agulhas retroflection in the period between january 2005 and december 2008 were successfully reconstructed the velocity structures obtained are tilted and phase shifted in relation to the temperature anomalies resulting in an annual mean eddy meridional heat flux across the ring paths of 0 062 0 012 pw northward a first order estimate indicates 0 07 pw entering the atlantic from the indian ocean through agulhas rings the volume transport by agulhas rings is believed to play a central role in the overturning circulation being the main process responsible for the leakage of indian ocean waters to the atlantic the new estimates of the time mean ring volume transport of 9 8 sv from the indian to the atlantic ocean fall in the range obtained by previous works these estimates include a better representation of the trapped water region in the eddies a large inter annual variability in the volume transport was observed with a maximum of 11 21 sv in 2007 this variability is related to the number of structures shed by the agulhas retroflexion per year the ring shapes play a secondary though important role

wind control of storm triggered shallow landslides 1 heavy rainstorms are a major control of shallow landsliding in mountainous areas the influence of three dimensional 3 d variability of precipitation is analyzed by coupling a fine resolution atmospheric model rams with a fine resolution topographic model dem to represent the 3 d precipitation flux generating the catastrophic flood that occurred in versilia central italy on 19 june 1996 matching of this flux with the observed scars and debris shows that 92 of the mass movements occurred where the normalized precipitation flux exceeds 0 80 and less then 2 where this is null these results give an insight of the detected role of exposure in explaining the spatial variability of observed landslides as emerging from multivariate statistical analysis the interaction of the wind driven precipitation field with topography is an important control of shallow landslides triggered by convective storms in upland catchments

eddies in the labrador sea as observed by profiling rafos floats and remote sensing abstract data from profiling rafos floats topex poseidon altimetry and the alongtrack scanning radiometer atsr aboard ers 1 have been used to describe the spatial and seasonal patterns of eddy variability in the labrador sea peaks in sea surface height ssh variability appear in two regions off the west greenland shelf near 61 5 n 52 w where the 3000 m isobath separates from the shelf and in the center of the basin at 58 n 52 w both locations show seasonal ranges in ssh variability of up to 40 mm with the greenland site having largest variability in january march leading the central site by 50 days a sea surface temperature image from the atsr at the greenland site shows numerous eddies both cyclonic and anticyclonic being formed by injection of west greenland current water into the labrador sea interior data from profiling rafos floats launched in 1997 as part of the labrador sea deep convection experiment are used to describe three of the west greenland current eddies in detail one of

fumarolic incrustations at kudryavy volcano kamchatka as a guideline for high temperature 850 c extinct hydrothermal systems abstract our knowledge of active magmatic hydrothermal system or magmatic vapors is largely related to the modeling of geochemical processes including heterogeneous equilibrium calculations with variable bulk composition temperature or pressure with the aim to constrain the characteristics of extinct hydrothermal systems it is necessary to look for petrogenic evidence in active ones the kudryavy volcano in the kurile islands russia provides a unique natural laboratory to study the formation of fumarolic rocks from high temperature fluids measured temperature for the fumaroles up to 940 c by studying the minerals chemistry and assemblages and by computing a thermodynamical modeling we investigated the mineralogical evidence for such high temperature we confirm the documented occurrence of ca fe rich minerals as isolated patches veins or incrustation in cavities and their formation during the alteration of primary minerals we describe and documented secondary na al rich minerals davyne nepheline sodalite and their occurrence together with ca fe minerals in cavities we also documented the presence of fe wollastonite a relatively rare mineral suggesting high t formation and we observed assemblages including wollastonite andradite magnetite suggesting high temperature decomposition of andradite this natural laboratory provides a series of concordant petrologic evidences for high temperature fumarolic rocks and offers guidelines for the study of ancient high temperature hydrothermal environments on earth and other planets like mars

surface generated mesoscale eddies transport deep sea products from hydrothermal vents atmospheric forcing which is known to have a strong influence on surface ocean dynamics and production is typically not considered in studies of the deep sea our observations and models demonstrate an unexpected influence of surface generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern east pacific rise transport by these deep reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat flux into the deep ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities because the eddies interacting with the east pacific rise are formed seasonally and are sensitive to phenomena such as el nino they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea

vertical structure of mesoscale eddies in the eastern south pacific ocean a composite analysis from altimetry and argo profiling floats 1 the mean vertical structure of mesoscale eddies in the peru chile current system is investigated by combining the historical records of argo float profiles and satellite altimetry data a composite average of 420 526 profiles acquired by argo floats that surfaced into cyclonic anticyclonic mesoscale eddies allowed constructing the mean three dimensional eddy structure of the eastern south pacific ocean key differences in their thermohaline vertical structure were revealed the core of cyclonic eddies ces is centered at 150 m depth within the 25 2 26 0 kg m 3 potential density layer corresponding to the thermocline in contrast the core of the anticyclonic eddies aes is located below the thermocline at 400 m depth impacting the 26 0 26 8 kg m 3 density layer this difference was attributed to the mechanisms involved in the eddy formation while intrathermocline ces would be formed by instabilities of the surface equatorward coastal currents the subthermocline aes are likely to be shed by the subsurface poleward peru chile undercurrent in the eddy core maximum temperature and salinity anomalies are of 1 c and 0 1 with positive negative values for aes ces this study also provides new insight into the potential impact of mesoscale eddies for the cross shore transport of heat and salt in the eastern south pacific considering only the fraction of the water column associated with the fluid trapped within the eddies each ce and ae has a typical volume anomaly flux of 0 1 sv and yields to a heat and salt transport anomaly of 1 3 1011 w and 3 8 103 kg s 1 respectively

cyclonic and anticyclonic motion in the upper ocean 1 upper ocean variability is highly energetic and contributes to key processes such as heat transport and water mass formation here the distribution of ocean surface cyclonic and anticyclonic motion is computed from global drifter observations for scales from large eddies to submesoscale two zonal bands of small scale motion are recovered a known anticyclonic band at 30 40 latitude mostly wind induced and an unexpected cyclonic band at 10 20 latitude it is suggested that this is due to submesoscale processes related to salinity front instabilities these results provide a first global view of the upper ocean including these motions

hydrogen isotope geochemistry and heat balance of a fumarolic system kudriavy volcano kuriles abstract the temperature and hydrogen isotope composition of the fumarolic gases have been studied at kudriavy volcano kurile islands which is unique for investigating the processes of magma degassing because of the occurrence of numerous easily accessible fumaroles with a temperature range of 100 940 c there are several local fumarolic fields with a total surface area of about 2600 m 2 within the flattened crater of 200 600 m each fumarolic field is characterized by the occurrence of high and low temperature fumaroles with high gas discharges and steaming areas with lower temperatures we have studied the thermal budget of the kudriavy fumarolic system on the basis of the quantitative dependences of the hydrogen isotope ratio d h and tritium concentration on the temperature of fumarolic gases and compared them with the calculated heat balance of mixing between hot magmatic gas and cold meteoric water hydrogen isotope composition d and 3 h shows a well expressed correlation with the gas temperature since d h ratio and 3 h are good indicators of water sources in volcanic areas it suggests that the thermal budget of the fumarolic system is mostly controlled by the admixing of meteoric waters to magmatic gases the convective mechanism of heat transfer in the hydrothermal system governs the maximum temperatures of local fumaroles and fumarolic fields low temperature fumaroles at kudriavy are thermally buffered by the boiling processes of meteoric waters in the mixing zone at pressures of 3 12 bar these values may correspond to the hydrostatic pressure of water columns about 30 120 m in height in the volcanic edifice and hence to the depth of a mixing boiling zone conductive heat transfer is governed by conductive heat exchange between gases and country rocks and appears to be responsible for the temperature distribution around a local fumarolic vent the temperature and pressure of shallow degassing magma are estimated to be 1050 c and 2 3 bar respectively the length of the main fumarolic gas conduit is estimated to be about 80 m from the linear correlation between maximal temperatures of fumarolic fields and distances to the highest temperature f 940 fumarole this value may correspond to the depth of an apical part of the magmatic chamber the geometry of the crater zone at the kudriavy summit and the model of convective gas cooling suggest different hydrostatic pressures in the hydrothermal system at the base of high and low temperature gas conduits the depths of gas sources for low temperature fumaroles are evaluated to be about 200 m at the periphery of the magma chamber

a census of eddy activities in the south china sea during 1993 2007 1 numerous mesoscale eddies occur each year in the south china sea scs but their statistical characteristics are still not well documented a pacific basin wide three dimensional physical biogeochemical model has been developed and the result in the scs subdomain is used to quantify the eddy activities during the period of 1993 2007 the modeled results are compared with a merged and gridded satellite product of sea level anomaly by using the same eddy identification and tracking method on average there are about 32 9 2 4 eddies predicted by the model and 32 8 3 4 eddies observed by satellite each year and about 52 of them are cyclonic eddies the radius of these eddies ranges from about 46 5 to 223 5 km with a mean value of 87 4 km more than 70 of the eddies have a radius smaller than 100 km the mean area covered by these eddies each year is around 160 170 km2 equivalent to 9 8 of the scs area with water depths greater than 1000 m linear relationships are found between eddy lifetime and eddy magnitude and between eddy vertical extent and eddy magnitude showing that strong eddies usually last longer and penetrate deeper than weak ones interannual variations in eddy numbers and the total eddy occupied area indicate that eddy activities in the scs do not directly correspond to the el nino southern oscillation events the wind stress curls are thought to be an important but not the only mechanism of eddy genesis in the scs

discrete eddies in the northern north atlantic as observed by looping rafos floats abstract rafos float trajectories near the 27 5 density level were analyzed to investigate discrete eddies in the northern north atlantic with the objective of determining their geographical distribution and characteristics floats that made two or more consecutive loops in the same direction loopers were considered to have been in an eddy overall 15 24 float years of the float data were in loopers one hundred and eight loopers were identified in 96 different eddies roughly half of the eddies were cyclonic 49 and half were anticyclonic 51 although the percentages varied in different regions a few eddies were quasi stationary for long times one for over a year in the iceland basin and many others clearly translated often in the direction of the general circulation as observed by non looping floats several floats were trapped in eddies in the vicinity of the north atlantic current just upstream west of the charlie gibbs 52 n and faraday 50 n fracture zones which seem to be preferred routes for flow crossing the mid atlantic ridge five floats looped in four anticyclones that translated southwestward away from the eastern boundary near the goban spur 47 50 n these could have been weak meddies forming from remnants of warm salty mediterranean water advected northward along the eastern boundary

the structure dynamics and origin of a small scale lens of water in the western north atlantic thermocline abstract a small scale isolated anticyclonically rotating lens of water was observed in the western north atlantic thermocline during the polymode local dynamics experiment using a combination of sofar float hydrographic nutrient and moored current and temperature data we deduce that the lens was about 20 km across with a thickness not greater than 300 m centered on 750 m that its shape was not dissimilar to that of a vertical radial gaussian eddy and that at its center the lens had strong anomalies of salinity dissolved oxygen nitrate and vortex stretching the water mass properties within the eddy are not inconsistent with an origin for the feature near 15 n 54 w several thousand kilometers from where it was observed in the western north atlantic although an unambiguous origin cannot be discerned from the data if such features are not uncommon they may be an important mechanism for large scale mixing of water properties in the ocean

non gaussian velocity probability density functions an altimetric perspective of the mediterranean sea abstract velocity probability density functions pdfs are a key tool to study complex flows and are of great importance to model particle dispersion the pdfs of geostrophic velocities derived from sea level anomalies maps for the mediterranean sea have been computed and analyzed guided by recent results found in studies of two dimensional and geostrophic turbulence at the basin scale results show that the geostrophic velocity pdf derived from sla maps is non gaussian to understand the origin of this non gaussianity a topological partition of the flow based on the okubo weiss parameter is applied to separate the contribution of coherent vortices from the background field after such separation the non gaussian part of the pdf appears mostly associated with the presence of such structures only about 20 of the vortices identified in the dataset are mainly responsible for this deviation these vortices called intense vortices in previous works are those vortices with values of the amplitude larger t

faster spreading or greater ridge length in the archean dissipation of more heat from a hotter early earth by the plate tectonics mechanism would require subduction of on average younger lithosphere in principle this could be achieved equally well by faster spreading by having greater ridge length or some combination thereof present day evidence however suggests that younger oceanic lithosphere subducts more slowly than older if this applied in the archean then the greater ridge length alternative prevailed a quantitative expression is derived which indicates that oceanic heat loss is proportional to the cube root of ridge length this relationship means that if archean heat flow was 3 times that of the present 27 times as much ridge would have been required which would suggest that the archean earth was covered by many small plates moving slowly

three dimensional structure of a swarm of the salp thalia democratica within a cold core eddy off southeast australia 1 swarms of the salp thalia democratica periodically occur off southeast australia following the austral spring bloom of phytoplankton in october 2008 a filament of upwelled water was advected south by the adjacent east australian current and formed a 30 km diameter cold core eddy cce the three dimensional structure of a subsurface swarm of t democratica within the eddy was examined using both oblique and vertical hauls and an optical plankton counter opc deployed on a towed body the cce displayed distinct uplift of the nutricline and elevated fluorescence net samples show the zooplankton community was dominated by t democratica comprising 73 88 of zooplankton abundance the size distribution of t democratica measured from net samples was 0 5 5 mm and was used to interpret the opc transects which showed the swarm formed a 15 km diameter disc located 20 40 m deep in the center of the eddy the maximum salp abundance was in the pycnocline and coincided with the subsurface fluorescence maximum the mean abundance of t democratica size particles within the disc was 5003 individuals m 3 ind m 3 contrasted with only 604 ind m 3 at the outer edge of the eddy the vertically concentrated and horizontally constrained disc shaped salp swarm occurred at the interface of salp bearing inner shelf water and nutrient rich upwelled water in a cce the physical processes that formed the cce on the inshore edge of the western boundary current led to the largest density of salps recorded

eddies in the canada basin arctic ocean observed from ice tethered profilers five ice tethered profilers itps deployed between 2004 and 2006 have provided detailed potential temperature and salinity s profiles from 21 anticyclonic eddy encounters in the central canada basin of the arctic ocean the 12 35 m thick eddies have center depths between 42 and 69 m in the arctic halocline and are shallower and less dense than the majority of eddies observed previously in the central canada basin they are characterized by anomalously cold and low stratification and have horizontal scales on the order of or less than the rossby radius of deformation about 10 km maximum azimuthal speeds estimated from dynamic heights assuming cyclogeostrophic balance are between 9 and 26 cm s 1 an order of magnitude larger than typical ambient flow speeds in the central basin eddy s and potential vorticity properties as well as horizontal and vertical scales are consistent with their formation by instability of a surface front at about 80 n that appears in historical ctd and expendable ctd xctd measurements this would suggest eddy lifetimes longer than 6 months while the baroclinic instability of boundary currents cannot be ruled out as a generation mechanism it is less likely since deeper eddies that would originate from the deeper reaching boundary flows are not observed in the survey region

coherent eddies in the labrador sea observed from a mooring abstract during june november 1994 a mooring in the central labrador sea near the former ocean weather station bravo recorded a half dozen anomalous events that prove to be two different types of coherent eddies comparisons with simple analytical models are used to classify these events as coherent eddies on the basis of their velocity signatures the first clear examples of long lived convectively generated eddies are reported these four small radius 5 15 km eddies are exclusively anticyclonic with cold fresh middepth potential temperature and salinity s cores surrounded by azimuthal currents of 15 cm s 1 their s properties identify them unambiguously as the products of wintertime deep convection in the interior labrador sea compared with eddies in other regions these anticyclones are unusual for their strong surface expressions and composite s cores two warm cyclones are also seen these are larger radius 15 km than the anticyclones and about as energetic currents 15 cm s 1

energetics of a global ocean circulation model compared to observations 1 the majority of the eddy kinetic energy eke in the ocean is found on scales of 50 km to 500 km encompassed by mesoscale eddies and the meanders and rings of the boundary currents mesoscale eddies play a critical role in the dynamics of the ocean circulation with instabilities of the strong mean currents generating eddies in the upper ocean interactions between eddies transfer energy from the upper ocean to the deep ocean where eddies interact with bottom topography to generate abyssal mean flows and eddies transfer momentum back to the mean currents the kinetic energy in a global hybrid coordinate ocean circulation model hycom is compared with long term observations from surface drifters geostrophic currents from satellite altimetry subsurface floats and deep current meter moorings hycom configured at 1 12 5 9 km typical of the present generation of high resolution models is deficient in eke in both the upper and abyssal ocean depths greater than 3000 m by 21 and 24 respectively compared to surface drifting buoys and deep current meters increasing the model resolution to 1 25 4 4 km or injecting mesoscale eddies through the assimilation of surface observations in a 1 12 5 model increases the surface and the abyssal eke to levels consistent with the observations in these models the surface abyssal eke is increased by 23 51 and 15 46 for the higher resolution or data assimilative models respectively compared to the 1 12 5 non assimilative model while data assimilation increases the eke in both the upper and abyssal ocean the kinetic energy of the mean flow in the upper ocean is decreased in the data assimilative hindcast

evolution movement and decay of warm core leeuwin current eddies abstract characteristics of eddies originating in the leeuwin current lc have been investigated using 10 day sea level anomaly maps of combined topex poseidon and ers altimeter data for the period 1995 2000 during these 6 years 37 long lived anticyclonic eddies were tracked from the west coast of australian to 90 e between three and nine eddies were spawned each year and their trajectories are described in detail most long lived eddies are generated in may june when the lc is most intense and at three preferred locations 20 21 5 s 24 25 s and 28 31 s the temporal evolution and latitudinal variations of the sea level anomalies and their radius and drift speed are discussed topography plays an important role in the evolution and structure of the eddies interactions with topography can induce splitting or merging of eddies which further affects the eddy decay

skarn manto and breccia pipe formation in sedimentary rocks of the cananea mining district sonora mexico skarns mantos and breccia pipes occur at cananea in a 2 by 4 km horst of paleozoic carbonate rock and minor quartzite surface mapping and core logging reveal a sequence of events beginning with early metamorphism that converted impure carbonate lithologies to iron poor garnet pyroxene or idocrase hornfels subsequent metasomatism formed garnet py roxene skarn along the pre cretaceous elisa fault contact between carbonate rock and mesozoic volcanic rock skarn is zoned from an andradite rich center through a zone containing both andraditic garnet and salitic pyroxene to a mineralogic sequence near the marble front which is largely a function of the sedimentary protolith chert nodules are rimmed by wollastonite dolomite is converted to massive phlogopite magnetite skarn calc silicate hornfels is over printed by veins of skarn garnet and relatively pure marble is replaced by coarse blades of iron and manganese rich pyroxene multiple generations of garnet and pyroxene can be distinguished by subtle variations in color and texture age classification on the basis of crosscutting vein and overgrowth relationships indicates that late pyroxenes are more iron and manganese rich than the early generations garnets show a less regular iron enrichment with time the spatial distribution of the different garnet and pyroxene generations is irregular garnet and pyroxene in late veins have iron rich compositions both near the skarn center and near the marble front pyrite and minor chalcopyrite are the only sulfides associated with this stage of metasomatism following the main stages of garnet and pyroxene formation veins and orbicular patches of amphibole or quartz or calcite occur replacing pyroxene and in some cases garnet most of the amphibole is actinolitic in composition and is associated with pyrite and minor amounts of chalcopyrite about 20 percent of the amphibole is subcalcic and is associated with or replaced by massive calcite the alteration of prograde skarn to amphibole or quartz or calcite can be best explained by a general temperature decline the destruction of skarn by alteration related to brecciation and breccia pipe formation and the replacement of previously unaltered carbonate rocks by stratiform blankets mantos of iron oxides and sulfides resulted in some of the highest grade orebodies breccia pipe and manto formation appears to have been largely contemporaneous with emplacement and subsequent sericitic alteration of a series of quartz monzonite porphyry stocks where breccia pipes crosscut skarn garnet pyroxene and amphibole are converted to mixtures of calcite quartz chlorite hematite siderite and sulfides where breccia pipes or porphyries crosscut previously unaltered carbonate rock mixtures of magnetite sulfides chlorite siderite calcite quartz and serpentine form massive mantos veinlets of chlorite and magnetite or pyrite or serpentine extend tens of meters beyond the zones of massive replacement there is a rough vertical and lateral zonation of sulfide minerals with respect to the democrata breccia pipe from chalcopyrite or bornite or pyrite in the core and at depth to sphalerite pyrite chalcopyrite to pyrite sphalerite galena distal to the center of mineralization mineral stability relations suggest that brecciation and mineralization took place at lower temperatures 275 degrees 25 degrees c and possibly under lower x sub co 2 conditions than the earlier skarn formation the high zn cu ratios in skarn the zonation of most hypogene mineralization relative to the breccia pipes which crosscut skarn and the lack of skarn spatially associated with the quartz monzonite porphyry stocks which intrude carbonate rock all suggest that unlike skarn in most porphyry copper districts skarn at cananea is not related to the quartz monzonite porphyry stocks that are mined elsewhere in the district for disseminated supergene enriched sulfide mineralization rather the skarn may be related to a deeper magmatic system which has not yet been encountered in subsurface exposures

high temperature gold copper extraction with chloride flux in lava tubes of tolbachik volcano kamchatka subvolcanic environments in supra subduction zones are renowned for hosting epithermal deposits that often contain electrum and native gold including bonanza examples this study examined mineral assemblages and processes occurring in shallow crust volcanic settings using recent eruption 2012 2013 of the basaltic tolbachik volcano in the kamchatka arc the tolbachik eruptive system is characterized by an extensive system of lava tubes after cessation of magma input the tubes maintained the flow of hot oxidized gases that episodically interacted with the lava surfaces and sulphate chloride precipitates from volcanic gases on these surfaces the gas rock interaction had strong pyrometamorphic effects that resulted in the formation of molten salt oxidized tenorite hematite cu rich magnesioferrite and skarn like silicate mineral assemblages by analogy with experimental studies we propose that a combination of these processes was responsible for extraction of metals from the basaltic wall rocks and deposition of cu fe and cu fe oxides and native gold

formation of jasper and andradite during low temperature hydrothermal seafloor metamorphism ongeluk formation south africa andradite and andradite grossular solid solutions have repeatedly been described as minor constituents of weakly metamorphosed ocean floor metabasites and associated calcareous or siliceous sediments the conditions of garnet formation however have remained rather elusive here wedescribe the discovery of andradite as a minor but widespread constituent of chert and jasper closely associated with only very weakly metamorphosed basaltic andesites of the early paleoproterozoic ongeluk formation transvaal supergroup south africa the andradite is most commonly fine grained and forms skeletal crystals that poikilotopically enclose and replace quartz and hematite macroscopically coarse grained andradite is scarce and was recognized at one locality only up to 3 mm largeandradite grains occur closely associated with quartz in short veins that crosscut thin beds of andradite bearing jasper the cogenetic association of quartz and andradite was studied in detail to constrain the conditions of garnet formation our results indicate that andradite crystallized at temperatures well below 200 c in the sub seafloor environment in siliceous sediments of hydrothermal origin that provided an ample source of sio2 and fe2o3 andradite formed when hydrothermally modified seawater introduced ca that was leached when seawater interacted with plagioclase and clinopyroxene in the surrounding volcanic pile other important preconditions for garnet formation were the lack of mixing between the hydrothermal fluid and cold seawater and low fco2 it appears reasonable to extend the findings of this study to other recorded occurrences of andradite in modern and ancient ocean floor metabasites

global observations of large oceanic eddies 1 ten years of sea surface height ssh fields constructed from the merged topex poseidon t p and ers 1 2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean the higher resolution of the merged dataset reveals that more than 50 of the variability over much of the world ocean is accounted for by eddies with amplitudes of 5 25 cm and diameters of 100 200 km these eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies respectively the vast majority of the eddies are found to be nonlinear

impact of an unusually large warm core eddy on distributions of nutrients and phytoplankton in the southwestern canada basin during late summer early fall 2010 1 recent freshening of the arctic ocean due to melting of sea ice and enhanced ekman pumping has deepened the nutricline over the canada basin and reduced nutrient concentrations in the euphotic zone cold core eddies frequently transport nutrient rich shelf water to the canada basin but the eddies are much deeper than the euphotic zone because warm core eddies appear near the surface or at a depth range shallower than that of the cold core eddies they may play a crucial role in determining nutrient distributions in the euphotic zone and hence may affect primary production during late summer early fall 2010 we conducted detailed surveys of a warm core eddy which was unusually large 100 km in diameter we suggest that this warm core eddy which contained high ammonium shelf water could supply ammonium to the euphotic zone in the southwestern canada basin and may sustain 30 higher biomass of picophytoplankton 2 m than that in the surrounding water in the basin the role of warm core eddies in supplying nutrients to the euphotic zone and controlling phytoplankton distributions seems to be more important than previously because the recent deepening of the nutricline in the canada basin has decreased the nutrient supply to the euphotic zone

a three dimensional eddy census of a high resolution global ocean simulation 1 a three dimensional eddy census data set was obtained from a global ocean simulation with one tenth degree resolution and a duration of 7 years the census includes 6 7 million eddies in daily data which comprise 152 000 eddies tracked over their lifetimes using a minimum lifetime cutoff of 28 days variables of interest include eddy diameter thickness vertical extent minimum and maximum depth location rotational direction lifetime and translational speed distributions of these traits show a predominance of small thin short lived and slow eddies still a significant number of eddies possess traits at the opposite extreme thousands of eddies larger than 200 km in diameter appeared in daily data each year a tracking algorithm found hundreds of eddies with lifetimes longer than 200 days a third of the eddies are at least 1000 m tall and many penetrate the full depth of the water column the antarctic circumpolar current contains the thickest and highest density of eddies thick eddies are also common in the gulf stream kuroshio current and agulhas ring pathway the great majority of eddies extend all the way to the surface confirming that eddy censuses from surface observations are a good proxy for the full depth ocean correlations between variables show that larger diameter eddies tend to be thicker and longer lived than small eddies

eddy characteristics in the eastern south pacific 1 the main eddy characteristics length scales rotation period swirl and translation velocities are determined in the eastern south pacific region 10 35 s and 70 100 w based on surface drifter measurements satellite altimetry and hydrographic data from the woce p19 section the chile peru current eddies have a typical diameter of order of 30 km smaller than the typical rossby radii observed in the region they are principally formed near the south american coast and propagate seaward with a translation velocity varying from 3 cm s 1 in the southern part of the study domain to 6 cm s 1 north of 15 s long lived anticyclonic eddies propagate northwestward with a mean angle of around 333 t whereas cyclonic vortices propagate westward consistent with the vortices propagation theory on a plane the radial distribution of the swirl velocity shows that the chile peru current eddies have a maximum diameter of order 200 km with a swirl velocity of around 14 cm s 1 and a rotation period of 50 days hydrographic data reveal a vertical extent down to around 2000 m for energetic eddies no significant difference is observed between the tangential velocities of cyclonic and anticyclonic eddies geostrophic balance can be considered for large radii whereas ageostrophic dynamics may play an important role near the eddy centers

eddy transport of heat and thermocline waters in the north pacific a key to interannual decadal climate variability abstract high resolution xbt transects in the north pacific ocean at an average latitude of 22 n are analyzed together with topex poseidon altimetric data to determine the structure and transport characteristics of the mesoscale eddy field based on anomalies in dynamic height 410 eddies are identified in 30 transects from 1991 to 1999 including eddies seen in multiple transects over a year or longer their wavelength is typically 500 km with peak to trough temperature difference of 2 2 c in the center of the thermocline the features slant westward with decreasing depth by 0 8 of longitude on average from 400 m up to the sea surface this tilt produces a depth varying velocity temperature correlation and hence a vertical meridional overturning circulation in the mean 3 9 sv sv 106 m3 s 1 of thermocline waters are carried southward by the eddy field over the width of the basin balanced mainly by northward flow in the surface layer corresponding northward heat transport is 0 086 0 012 pw

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