eddy resolving observation of the north pacific subtropical mode water abstracthydrographic data obtained by high resolution shipboard observations and argo profiling floats have been analyzed to study the mesoscale structure and circulation of the north pacific subtropical mode water stmw the float data show that in the late winter of 2008 stmw having a temperature of approximately 18 8 17 7 and 16 6 c formed west of 140 e at 140 150 e and east of 150 e respectively in the recirculation gyre south of the kuroshio extension after spring the newly formed stmw gradually shift southward decreasing in thickness simultaneously the stmws of 16 6 and 17 7 c are gradually stirred and then mixed in terms of properties in late fall they seem to be integrated to form a single group of stmws having a temperature centered at 17 2 c such stmw circulation in 2008 is much more turbulent than that in 2006 which was investigated in a previous study the difference between the two years is attributed to the more variable state of the kuroshio extension in 2008 associate

resuspension measured with sediment traps in a high energy environment the near bottom sedimentation rates were measured by placing cylindrical sediment traps 10 m above the sea floor on each of six moorings deployed between 4100 and 5100 m along a transect across an energetic deep sea current in the hebble area centered at 40 n 63 w on the nova scotian rise sedimentation rates above the sea floor were monitored with additional traps at 23 54 100 200 and 500 m above the bottom mab on the mooring at 4950 m the total flux at 500 mab for the two week period consisting mostly of primary particles from surface water was 166 mg m2 day and increased exponentially towards the bottom the total flux at 10 mab increased down slope from 1160 mg m2 day at 4158 m where the mean current speed was 8 cm s to a maximum of 77 300 mg m2 day at 5022 m where the mean current speed was 32 cm s then decreased to 59 400 mg m2 day at the mooring at 5076 m the size frequency distributions of large discrete particles such as foraminifera diatoms radiolarians and fecal pellets were quantified in all trap samples to examine whether the large variation in fluxes was due to artifacts such as current velocity or trap tilt based on the source persistence and distribution of these particles we conclude that the large variations in fluxes across the rise and with distance from the sea floor are due primarily to resuspension and resettling of bottom sediments with tilt and current effects on trapping having only a secondary effect the vertical gradients of large particle fluxes suggest effective vertical eddy diffusivities of 102 104 cm2 s using a two dimensional model horizontal advection and secondary circulation probably play a large role in moving large rapidly falling up to 1 cm s particles to a height of 50 100 m above the sea floor

observation of south atlantic subtropical mode waters with argo profiling float data south atlantic subtropical mode water sastmw is detected using temperature and salinity profiles obtained by argo floats marked by low potential vorticity within its extent mode waters are identified by homogeneous temperature and salinity values both horizontally and vertically their presence is evident in three regions the brazil current recirculation gyre on the western side of the basin the eastern side of the basin and along the southern edge of the gyre formation occurs between winter and mid spring in the regions of cumulative cooling of the ocean we showed that argo profilers do not preferentially sampled eddies yet from the profiles that found sastmw inside an eddy 80 are anticyclonic furthermore the mode water layer inside anticyclonic eddies is on average thicker than inside cyclonic eddies or anywhere else we investigate the correlation between the presence of mode water with the eddy kinetic energy eke the cross spectrum shows that the eke and the layer thickness are out of phase in the annual period band we addressed the role of negative surface heat fluxes during the sastmw period of formation nearly all profiles that indicated mode water formation occurred at the time and within the region where the cumulative heat flux was negative

sediment fluxes re suspension and accumulation rates at two wind exposed coastal sites and in a sheltered bay abstract sediment fluxes measured by sediment traps placed at different heights above the sea bed at two near coastal sites and in a sheltered bay are analysed in relation to wave and current conditions traps were deployed for 13 15 coastal sites and 6 months and recovered with a mean period of 16 6 14 0 and 30 days respectively the traps with an aspect ratio of 5 were placed at 0 3 0 5 0 8 1 0 2 0 4 0 6 0 8 0 and 10 0 m above the sea bed at one location whereas an aspect ratio of 2 3 was used at the second coastal location with similar trap intervals the trap in the sheltered bay was placed at 1 0 m above the sea bed results showed that sediment fluxes varied between 505 0 and 38 9 g m 2 day 1 at 0 3 m above the sea bed at a coastal site whereas only small flux variations occurred in the sheltered bay accumulation rates were measured by 210 pb at the three sites and was 2 4 g m 2 day 1 at the same site where fluxes varied between 505 0 and 38 9 g m 2 day 1 at 0 3 m above the sea bed this shows that re suspension here is high and frequent a similar pattern was found at the other coastal site whereas accumulation rate and sediment flux were very similar in the sheltered bay analyses showed that re suspension was induced both by surface wave activity related to periods of high wind speeds and by current shear stress in more calm periods re suspension is quantified as a time series by applying the introduced depth integrated re suspension flux dirf high dirf occurred during periods of high surface wave activity and one re suspension event accounted for about 25 of the total re suspension flux at the site although the event had a very low frequency of occurrence less than 5 of the time about 50 of the total re suspension flux occurred in the interval between 0 0 and 20 0 g m 2 day 1 comparison of different time scales for measuring sediment fluxes and re suspension using sediment traps shows that a time scale of 24 12 h gives an adequate resolution

advances in marine chemistry 1979 1982 these four years saw advances in many areas further developments in sampling and analytical techniques have opened new avenues of exploration for trace elements and particulate matter the impact of the geosecs expedition was further felt in the field of marine chemistry as the results were still being published a major field effort occurred as a follow on to the geosecs work tto and intensive sampling was performed in the newly discovered submarine hydrothermal vent fields an important and unresolved controversy has arisen regarding the ability to measure preformed co2 in the seawater system in many respects the field of marine chemistry appears to be gaining a momentum spurred by both improvements in analytic techniques and an increasing social and economic relevance

impact of aleutian low activity on the stmw formation in the kuroshio recirculation gyre region 1 to understand the formation of north pacific subtropical mode water stmw in the kuroshio recirculation gyre region the cause of stmw thickness variation is investigated using temperature profiles in a historically archived data set the thickness variation is predominantly controlled by the main thermocline depth mtd when the main thermocline deepens shoals the wintertime mixed layer depth can develop not develop and consequently thicker thinner stmw is observed in summer the large scale atmospheric forcing controlling the mtd is explored using a wind driven hindcast ocean model the mtd variation stems primarily from a baroclinic response in the ocean to the aleutian low al activity especially the meridional movement of the al exerts a remarkable influence

locally enhanced wintertime air sea interaction and deep oceanic mixed layer formation associated with the subarctic front in the north pacific 1 satellite derived high resolution air sea flux data and argo float data were analyzed to reveal the fine scale spatial structures of air sea turbulent heat and momentum fluxes and their relationship with the deep oceanic mixed layer around the subarctic front saf in the north pacific an important feature inferred from the satellite derived dataset is the presence of a pair of positive and negative air sea flux anomaly bands with a width of 100 200 km on both sides of the saf such a fine scale structure in air sea fluxes has not been captured in previous datasets the saf plays a significant role in determining the fine scale structure of air sea fluxes the oceanic mixed layer is deeper to the south of the saf and the maximum mixed layer depth is observed near the positive anomaly band in air sea fluxes this study concludes that active air sea interactions due to the presence of the saf enhances upward air sea heat and momentum fluxes to the south of saf and selectively produces a deep oceanic mixed layer where the formation of transition region mode water occurs

climatology and decadal variations in multicore structure of the north pacific subtropical mode water the pycnostad of the north pacific subtropical mode water stmw often displays multiple vertical minima in the potential vorticity profile argo profile data from 2004 to 2015 are used to investigate inter annual to decadal variations of the multicore structure climatologically about 24 pycostads of stmw have multicore structure and most of them distribute in the region west of 150 e stmw cores are classified into three sub modes the cold middle and warm ones with potential temperatures of 16 0 17 c 17 18 c and 18 19 5 c respectively the kuroshio extension ke varies between stable and unstable states the unstable ke with large meanders increases the subsurface stratification and shoals the winter mixed layer east of 150 e with warmer temperatures there the dominant stmw type varies from the cold single type in stable ke years making up 72 of the profiles with stmw to the middle single one 53 in unstable years the variation of the dominant stmw type in the region east of 150 e subsequently affects the multicore structure of stmw west of 150 e in a broad region between 130 e and 180 e profiles with stmw are fewer in unstable years but the proportion of multicore profiles increases among stmw profiles this might be due to the split recirculation gyre with a chaotic ke

coupling of near bottom pelagic and benthic processes at abyssal depths in the eastern north pacific ocean a time series site was established in the eastern north pacific ocean to study the coupling between near bottom pelagic and benthic processes at abyssal depths in an area with well documented seasonality in surface water productivity particulate total mass ptm particulate organic c poc particulate total n ptn and particulate calcium carbonate p caco fluxes were measured from sediment trap collections at 600 and 50 m above bottom from february 1990 to october 199 1 606 d the sea floor at 4 100 m was concurrently monitored with a time lapse camera over a 386 d period from july 1990 to july 199 1 during this study in situ measurements of sediment community oxygen consumption scoc were made and surface sediment samples collected seasonally with a free vehicle grab respirometer ptm poc ptn and p cac0 fluxes exhibited a strong seasonal signal with episodic peaks from spring through fall and lows in winter scoc increased sharply between winter and summer coinciding with spring peaks in particulate fluxes detrital aggregates appeared on the sea floor in pulses over a 6 month period from july to december 1990 coinciding with periods when particulate fluxes were elevated but delayed 1 5 months after the initial peaks in particulate flux mobile epibenthic megafauna monitored with time lapse photography consisted primarily of holothuroids and echinoids and were twice as active when detrital aggregates were observed on the sea floor as during the rest of the year our results show a temporal relationship between the flux of particulate matter entering the benthic boundary layer the arrival and residence of detritus on the sea floor and the activity of the sediment community and mobile epibenthic megafauna

long term variations of the kuroshio extension path in winter meridional movement and path state change abstractas an indicator of the kuroshio extension ke path the ke northern boundary kenb was detected based on the position of the strong winter sea surface temperature sst gradient between 142 and 155 e using high spatial resolution satellite derived sst for the 30 winters january to march from 1982 to 2011 the ke path showed meridional movement with a period of 10 15 yr and an amplitude of about 2 latitude the changes in latitudinal position of the ke path were initiated by a north south shift of the aleutian low al negative wind stress curl anomalies around 35 n in the eastern north pacific associated with a northward shift of the al induced a deepening of the main thermocline depth and then this deepening signal propagated westward reaching the ke region after about 3 yr where it caused the ke path to move northward the path state of the ke straight path convoluted path modulated on a time scale of 8 12 yr but this was not significantly correlated with the meridional movement of

role of large particles in the transport of elements and organic compounds through the oceanic water column abstract during the past decade data from a variety of sources have been obtained which show conclusively that the relatively rare large particles sinking through the water column are responsible for the majority of the downward vertical mass flux in the sea this finding has important implications for understanding the transfer distribution and fate of elements and organic compounds in marine waters the large 100 m detrital particles responsible for vertical flux are primarily biogenic and range in size and composition from small discrete fecal pellets and plankton hard parts to large amorphous aggregates or snow which contain both organic and inorganic constituents depending on size shape and density these particles sink at rates ranging from 1000 m day 1 several methods have been developed for sampling these particles of which in situ sediment trapping has probably furnished the most comprehensive qualitative and quantitative information on the role large particles play in material transport flux studies have highlighted the importance of marine heterotrophs in packaging fine suspended particulate matter into large rapidly sinking particles which accelerate the movement of incorporated materials to depth large particle production via biological packaging is not restricted to the euphotic zone but can occur at all depths and information is now accruing on rates of production of large particles in the water column chemical analyses of sedimenting particles collected in sediment traps and those sampled by other means have allowed quantifying vertical fluxes and residence times of elements radionuclides and organic compounds natural and anthropogenic in various oceanic regimes pertinent studies dealing with the above aspects are reviewed and several areas for future research are suggested

sedimentation resuspension and chemistry of particles in the northwest atlantic abstract sediment traps were deployed to sample vertical fluxes of particulate matter both immediately above and within the nepheloid layer on the continental slope and rise of the western north atlantic the data from the traps are used to estimate the settling flux of particles and to attempt to distinguish between the primary flux settling material from the upper water column and the resuspended flux settling material that has been resuspended from some region of the sea floor from these data and from measurements of the net nepheloid standing crop of particles estimates of the mean residence time for particles resuspended in the nepheloid layer are on the order of weeks to months from 15 to 500 m above bottom horizontal advection and diffusion are more important than vertical mixing in maintaining the upper portion of the nepheloid layer the estimated flux of al to the north atlantic as atmospheric dust is one to two orders of magnitude less than the primary flux of al measured just above the nepheloid layer yet the range of accumulation rates of al measured on the sea floor with radioisotopes is close to the values we define as the primary flux horizontal transport of al rich particles mostly aluminosilicates must therefore be significant even above the nepheloid layer the size of 80 90 of the particles collected in the traps both above and within the nepheloid layer was less than 63 m the mean size of particles trapped in the nepheloid layer was about 22 m and above the nepheloid layer 11 m the particles were probably in large aggregates when they encountered the traps but identifiable fecal pellets are only a small fraction of the material collected in the traps between 6 and 15 of the primary production of particulate organic carbon in the euphotic zone was collected in floating sediment traps at the 100 m depth indicating that most particulate organic carbon is recycled in the surface water only 2 3 of primary production of organic carbon was collected as primary flux 500 m above the sea floor from an intercomparison of the composition of particles falling rapidly collected in traps falling slowly or not at all collected in water bottles and resting on the sea floor from core tops it was found that elements associated with biogenic matter such as ca sr cu and i were carried preferentially by the rapidly falling particles once these particles reached the sea floor the concentration of those elements was decreased through decomposition respiration or dissolution dissolution appears to be rapid near or on the sea floor because radiolarians diatoms and juvenile foraminifera were rare in core samples even though abundant in all traps the dynamic nature of the nepheloid layer makes it possible for particles to be resuspended many times before they are finally buried enabling sediment to be carried long distances from its origin the recycling of particles near the sea floor may also increase dissolution of siliceous and carbonate matter

fluxes of uranium and thorium series isotopes in the santa barbara basin abstract samples from the manop santa barbara basin sediment trap intercomparison were analyzed for the isotopes of uranium thorium radium lead and polonium all of the traps showed approximately the same compositions and isotopic ratios indicating that they trapped similar materials the234th flux via falling particles was very close to the flux predicted from the production and scavenging rates of234th from the water column the210pb content of the trapped particles and the surface sediments were the same however the measured flux of210pb was seven times greater than the predicted flux predicted and measured fluxes of228th and210po were similarly out of balance to explain this apparent inconsistency we suggest as others have done that the santa barbara basin is an area where scavenging from the water column is intensified and where sediments deposited initially on the margins may be physically remobilized on a short time scale these two effects increase the apparent area from which the basin derives the longer lived isotopes but does not increase significantly the supply of the short lived234th

a sediment trap intercomparison study in the santa barbara basin four sediment traps of radically different design were deployed in the santa barbara basin for approximately 45 days the measured fluxes ranged from 370 to 774 g m 2 yr 1 for the different designs these values lie within flux measurements previously determined for the basin compared to the 25 year record 920 g m 2 yr 1 however all fluxes determined in this experiment are somewhat low because this experiment was conducted during a general period of high storm activity and runoff measurement of greater than average flux was expected it is probable that the higher flux recorded by the sediments results from a significant input of detritus into the basin by near bottom transport the chemical composition of trapped material was nearly identical in all four trap designs the deep cone design however had a significantly lower mn content since this trap was the only one in which reducing conditions were produced in the sample container reduction and mobilization of manganese after collection is believed to have occurred in spite of the very different designs tested the factor of two agreement in flux determination and the compositional similarity of the material collected is encouraging for future attempts to directly measure the flux of particulates in the ocean

observations of an anticyclonic eddy of 18 c water in the sargasso sea abstract observations have been made of a lens of 18 c water in the sargasso sea near 30 n 69 w the lens was nearly isothermal and isohaline and was embedded in the more typical weakly stratified 18 c water in the area it was more than 500 m thick and 170 km in diameter the lens was moving south southwest at 3 8 km day 1 and was rotating anticyclonically with speeds up to 50 cm s 1 a smaller lens of water near 16 c was located concentrically below the major eddy the 14 c isotherm in the main thermocline was depressed 300 m below its level in the surrounding area and the 20 c isotherm in the seasonal thermocline was raised 50 m significant anticyclonic flow occurred as deep as 850 m in the thermocline these observations confirm previous sparse evidence of eddies of this type it has been suggested that they are generated near the corner rise seamounts we speculate that the observed feature is the remnant of an eddy formed by a convection cell of 18 c water possibly generated near the new england

extraordinary subsurface mesoscale eddy detected in the southeast of okinawa in february 2002 1 in february 2002 a subsurface mesoscale eddy with extraordinary features was detected at a depth of about 300 dbar in the southeast of okinawa a part of the ryukyu islands the water mass occupying this subsurface eddy is characterized as the north pacific subtropical mode water npstmw with salinity maximum and thick thermostad its temperature salinity and potential density at the core of the eddy are 18 4 c 34 81 and 25 06 respectively thickness and width of the eddy are about 300 m and 100 km respectively mixing between the eddy and the surrounding water mass is also found such eddy with the npstmw has never been detected during ten years

observations of watermass modification by mesoscale eddies in the subtropical frontal region of the indian ocean sector of southern ocean abstract two eddies one cyclonic and the other anticyclonic in the subtropical frontal region stf of the indian ocean sector of southern ocean so and their role on the watermass modification are described here using the hydrographic data collected during the austral summer february of 2012 and 2013 and also by using argo profiles sampled during the austral summer from 2004 to 2012 the cyclonic eddy transports cold fresh and deeper antarctic intermediate water aaiw to much shallower depths but the anticyclonic eddy pushes the warm more saline subtropical surface water stsw to deeper depths significant changes in the properties of watermasses in terms of temperature and salinity viz stsw colder by 1 c and less saline by 1 psu and subtropical mode water stmw temperature decreased by 0 5 c and salinity by 0 7 psu were noticeable in the centre of cyclonic eddy on the other hand no such changes were found in the stmw properties in the anticyclonic eddy region the observed changes in the properties of watermasses were confirmed with the argo profiles sampled from the cyclonic and anticyclonic eddy regions of the stf a striking feature observed both in the cyclonic eddy and the anticyclonic eddy was the freshening of aaiw and this is consistently evident both in the cruise based observations as well as in the argo profiles it is hypothesized that the freshening in the aaiw at a given depth in the cyclonic eddy is due to shoaling of the pycnocline causing further intrusion of fresh saline water from deeper depths whereas the corresponding freshening in the anticyclonic eddy is due to the conservation of potential vorticity

diatom flux in mcmurdo sound antarctica abstract quantitative floral analyses have been performed on sea ice sediment trap and surface sediment samples collected from six sites in mcmurdo sound antarctica although diatom abundances in the sea ice reach 108 109 cells m 2 maximum diatom fluxes between october december 1984 as measured in the sediment trap samples are only 105 107 individuals m 2 day 1 the cumulative flux of diatoms for this three month period is approximately 107 109 individuals m 2 possibly an order of magnitude less than the sea ice abundances implying that diatom and opal flux must significantly increase when the sea ice melts and releases those particles previously trapped in the ice five species dominate the sea ice assemblage amphiprora sp pleurosigma sp nitzschia stellata pinnularia quadratarea andnitzschia curta these species are also common in the water column along withthalassiosira spp a genus rarely found within the sea ice within the upper 250 m of the water column at a site in granite harbor diatom flux decreases between 47 79 from 34 to 220 m opal flux however decreases by only 13 40 over this same interval indicating that dissolution of thinly silicified diatom frustules has occurred at mid water depths increases in absolute diatom flux of two species in particular nitzschia curta andthalassiosira spp may indicate their transport from other areas at all sites the greatest increase in diatom flux occurs just above the sea floor resuspension of diatom tests and or lateral advection creates a near bottom nepheloid layer in which significant modification of the diatom assemblage occurs a combination of preferential dissolution of those forms which dominate the sea ice and dilution of the assemblage with resuspended and or advected diatoms representative of many year averages of the flora may be responsible for the production of a sediment assemblage primarily made up ofthalassiosira spp nitzschia curta and other robust forms ofnitzschia

influence of kuroshio path variation south of japan on formation of subtropical mode water abstractdistributions of subtropical mode water stmw in the northwestern part of the north pacific subtropical gyre were investigated using temperature salinity profiles from 2005 to 2011 with particular reference to the kuroshio meander and non meander path states south of japan in spring of meander years warm stmw with a potential temperature of 19 20 c potential density anomaly of 24 6 24 9 kg m 3 was found in the shikoku basin whereas cold stmw below 19 c was distributed throughout the southern region of japan in non meander years the warm stmw was formed in a spatially isolated and warm winter mixed layer ml in the shikoku basin where a local recirculation developed in association with the kuroshio meander path both the absence of horizontal mixing with a cold ml south of the kuroshio extension because of the spatially isolated ml and an increase in horizontal heat advection due to the westward flow associated with this local recirculation caused the ml warming in the shikoku basin a

influence of boundary scavenging and sediment focusing on 234th 228th and 210pb fluxes in the santa barbara basin abstract sediment trap samples were collected from the santa barbara basin to examine the flux of 234 th 228 th and 210 pb mean ratios of measured to predicted fluxes are 2 10 and 21 for 234 th 228 th and 210 pb respectively boundary scavenging may supply a portion of all three radionuclides however sediment focusing supplies additional 228 th and 210 pb but little 234 th sediment temporarily deposited on the shelf around the basin contains little excess 234 th due to its short half life 228 th and 210 pb fluxes to the sediments in the santa barbara basin are several times greater than predicted from their supply in the overlying water column these enhanced fluxes require lateral transport of 228 th and 210 pb to the basin through boundary scavenging and sediment focusing 234 th flux is poorly correlated with 228 th and 210 pb fluxes because individual radionuclide sources to the basin differ i e water column production boundary scavenging and or sediment focusing correlations between 228 th and 210 pb fluxes are high due to the strong influence of sediment focusing on both radionuclides there is a strong correlation between both the 228 th and 210 pb flux and total mass flux and lithogenic flux but a weak correlation with the other major sediment components e g organic carbon carbonate and biogenic opal in the santa barbara basin a large fraction of the total mass flux is lithogenic material 50 80 hence the strong correlation between 228 th and 210 pb fluxes and both total mass and lithogenic fluxes 234 th flux is poorly correlated with total mass and major sediment component fluxes

a fast high precision splitter for particle suspensions abstract samples of disaggregated particles collected from within the water column by means of sediment traps or from the seafloor by means of cores or grabs often must be split into smaller but representative portions to facilitate analysis we have designed and tested a simple precise and inexpensive sample splitter that uses air pressure to discharge a uniformly mixed particle suspension into two to six equal sized subsamples the coefficient of variation of particle concentrations in subsamples produced from sediment trap samples was less than 2 and less than 4 in subsamples from a core a sample can be split into six subsamples in less than three minutes the splitter is fabricated from acrylic and teflon to allow acid cleaning when necessary and the design isolates the sample to reduce the risk of contamination

a time series study of silica production and flux in an eastern boundary region santa barbara basin california a high resolution data set describing the annual silica cycle between january 1994 and august 1999 in the santa barbara basin sbb captures processes and events occurring in both surface and deep basin waters increases in biogenic silica bsi concentrations in the surface waters indicated strong bloom events in the early spring of each year and sporadic blooms during the summer and fall lithogenic silica lsi was present at elevated concentrations in surface waters in the winter and spring at times the siliceous biomass in the sbb is comparable to that in major global upwelling regions however anomalously low annual depth integrated bsi concentrations were observed during the e1 nino conditions of 1997 1998 a 1 5 year time series of biogenic silica production rate measurements was used to calculate the highest resolution estimate of annual silica production to date an estimated 5 5 mol si m 2 yr 1 this silica production rate approaches that estimated for the major global upwelling zones 8 3 mol si m 2 yr 1 eastem boundary regions outside of the major coastal upwelling zones would account for 30 40 of global silica production if the santa barbara basin is representative of these coastal regions since the sediments of the sbb contain a high resolution climate record an understanding of the coupling between surface processes and deep basin sedimentation events is of value fluxes of bsi and lsi to 470 m were not strongly coupled to the seasonal cycle of particulate concentrations or production rates in surface waters continuous sediment trap collections of sedimenting particles indicate that both lsi and bsi tend to be exported at the highest rates during the spring and summer as particles sink lsi becomes enriched relative to bsi and consistently dominates the mass flux of silica at 470 m brief increases in the percent contribution of bsi to si flux may create microlaminae within larger scale laminations which are thought to be annual varves a comparison of annual bsi sedimentation rates with annual silica production estimates reveal that 30 of the annual silica production is exported to a depth of 470 m this export rate is the highest observed to date and suggests the potential for large quantities of silica burial in coastal sediments

remotely propagating salinity anomaly varies the source of north pacific ventilation abstract the dense shelf water dsw produced in the sea of okhotsk causes the deepest ventilation in the north pacific and plays a key role in overturning to the depth of intermediate layers salinity determines the density of dsw in cold seas such as this however the variability of dsw salinity has yet to be quantified and its causes remain unknown because of the paucity of available observation data here we describe the variability of dsw salinity in the period from 1950 to 2005 through the analysis of a newly compiled hydrographic dataset expanded with russian measurements in the sea of okhotsk and the bering sea dsw salinity exhibits a decreasing trend of 0 0024 0 0015 y 1 over 1950 2005 in addition to decadal scale variability with a typical magnitude of 0 1 we have found that dsw variability is controlled largely by surface salinity anomalies that propagate along pathways associated with ocean currents from the bering sea to the sea of okhotsk these salt pathways can be traced farther upstream to the alaskan stream and western subarctic gyre we suggest that this is a possible pathway which consists of a previously undefined upper branch of the north pacific overturning cell along this pathway the effects of the nodal tide that has an 18 6 year period may also propagate from the kuril straits and the aleutian passes our results indicate that long term atmospheric variations and enhanced hydrological cycles over the north pacific which are associated with global climate changes are conducted to the intermediate layer through surface salt pathways and subsequent dsw ventilation and lead to variability in material circulation and biogeochemical cycles

a role of eddies in formation and transport of north pacific subtropical mode water 1 hydrographic data acquired during 2001 by argo profiling floats deployed in the kuroshio recirculation region are used to verify the inference that mesoscale eddies prevailing in the recirculation region play an important role in the formation and transport of north pacific subtropical mode water npstmw that is the deeper winter mixed layer is formed preferentially where the thermocline is deeper in association with anticyclonic eddies in the succeeding seasons mesoscale eddies retain npstmw during their southwestward movement from the npstmw formation region so that anticylonic eddies contribute substantially to the npstmw transportation the spatial distributions of the mixed layer depth in winter and the npstmw thickness in the succeeding seasons based on the float data suggest that they are affected by mesoscale eddies the float data also provide the statistical relations of these quantities against the thermocline depth which are consistent with our inference

particulate iron and manganese in the santa barbara basin california abstract particulate fe and mn may be important trace metal scavengers in the water column as well as being probable indicators of biologically mediated redox processes a study has been made of suspended particulate composition in the santa barbara basin a shallow near shore basin off southern california with sub oxic conditions below sill depth observations have revealed several interesting phenomena relating to the geochemistry of fe and mn most striking is a profound enrichment of particulate fe in samples from the bottom two hundred meters these particulates have a constant fe p mole ratio of about three and may originate at the sediment water interface or may be transported to the basin from local marshes for particulate mn enrichments are observed both in the sub sill waters and near the base of the euphotic zone a consideration of particle removal rates suggests that the sub photic zone enrichment has a biogenic origin in the sub sill waters enrichment in mn is apparently due to the precipitation of dissolved mn diffusing from the anoxic basin sediments a simple mass balance suggests that most of the mn lost from the sediments is transported from the santa barbara basin in dissolved form

biogenic sedimentation in mcmurdo sound antarctica surface sediments from eastern mcmurdo sound and fjord basins of the victoria land coast are enriched in organic carbon and opal at depths below 600 m opal contents commonly exceed 30 organic carbon contents average 1 5 and are as high as 3 5 opal and organic carbon are supplied by local production within and below sea ice and by advection from open water areas of the southwestern ross sea the distribution of organic carbon and opal at the sea floor is consistent with cyclonic clockwise water circulation in mcmurdo sound advective transport from the ross sea supplies biogenic sediment to eastern and northern mcmurdo sound the southwestern shelf is bathed by waters derived in part from beneath the ross ice shelf which transport very little allochthonous carbon the supply of biogenic debris in southwestern mcmurdo sound is further curtailed by sea ice conditions e g more prevalent multi year sea ice which reduces photosynthesis and the absence of summer basal melting and ice breakout which restricts the flux of sea ice and open water production to the sea floor consistent with this hypothesis organic carbon fluxes measured via sediment trapping beneath fast ice are one to two orders of magnitude higher in eastern versus western mcmurdo sound pronounced cross sound gradients in shallow water benthic biomass and species diversity have previously been attributed to east west variations in productivity our surface sediment data suggest that similar or even more dramatic contrasts in benthic community structure may exist in the deeper water areas of mcmurdo sound pervasive resuspension is documented by pronounced near bottom flux increases measured by sediment trapping resuspension events which may be more common during the austral winter act to winnow and transport biogenic debris and fine terrigenous sediment from shallow regions 400 m to protected shelf basins despite oxidative loss within the water column the accumulation rate of organic carbon in the deep basins of mcmurdo sound averages 45 mg c m 2 day 1 more than an order of magnitude higher than the world average organic carbon flux to continental margins and equivalent to accumulation rates observed in many anoxic settings preservation efficiency of opal during transport and deposition appears anomalously high and the most opal rich sediments of mcmurdo sound are depleted in organic carbon relative to mid and low latitude siliceous deposits despite this observation if similar patterns of biogenic sedimentation exist on many other parts of the shelf the antarctic continental margin is an important sink for sedimentary organic carbon as has been previously suggested for the silica system

carbonate variations in the northeast pacific during the late quaternary quaternary glacial interglacial changes in the carbonate compensation depth ccd have been determined from core suites in three regions of the ne pacific the cores have sedimentation rates ranging from 1 6 to 16 cm kyr based on oxygen isotope radiocarbon and or carbonate stratigraphies carbonate values are higher in glacial than interglacial times and generally follow a pattern similar to that of the central equatorial pacific the sediment s carbonate profiles can be readily intercorrelated allowing the construction of a regional carbonate stratigraphy the extent of carbonate preservation is very sensitive to small changes in water depth but does not depend on geographic location a depth transect of cores off northern california and oregon provides a detailed record of glacial interglacial shifts in the ccd through time during the late holocene intensified carbonate dissolution at 7 ka is coincident with shifts in continental climatic indicators and may suggest the onset of the modern upwelling regime along the nw u s margin during the last 45 ka the ccd has migrated more than 1800 m between glacial and interglacial times although carbonate patterns are similar to those in the equatorial pacific the amplitude of the carbonate fluctuations is much greater in the northeast pacific this suggests that regional mechanisms such as glacial deepwater formation or enhanced dissolution due to interglacial noncarbonate productivity related to coastal upwelling may modulate carbon cycling

observations of the subtropical mode water evolution from the kuroshio extension system study abstract properties and seasonal evolution of north pacific ocean subtropical mode water stmw within and south of the kuroshio extension recirculation gyre are analyzed from profiling float data and additional hydrographic and shipboard adcp measurements taken during 2004 the presence of an enhanced recirculation gyre and relatively low mesoscale eddy variability rendered this year favorable for the formation of stmw within the recirculation gyre stmw formed from late winter convection that reached depths greater than 450 m near the center of the gyre the lower boundary of stmw corresponding to 25 5 kg m 3 was set by the maximum depth of the late winter mixed layer properties within the deep portions of the stmw layer remained largely unchanged as the season progressed in contrast the upper boundary of the stmw layer eroded steadily as the seasonal thermocline deepened from late april to august vertical eddy diffusivity responsible for this erosion was estimated from a budget analysis of

the vertical flux of biogenic and lithogenic material in the ross sea moored sediment trap observations 1996 1998 abstract as part of the usjgofs aesops program we deployed an array of moored sediment traps and determined the composition and vertical flux of particulate matter through the water column of the continental shelf environment of the ross sea we deployed two moorings with two traps each one mooring was located in the southcentral ross sea along the line of aesops process studies the other mooring was located in the northcentral ross sea the flux in the southern ross sea was generally double that in the north and there was a significant increase in flux into the deep traps indicating horizontal transport and possible focusing of particulate matter the particles are primarily biogenic although lithogenic contributions can increase to over 30 of the flux in the near bottom trap nearer to the ice shelf the fluxes collected by the traps were generally low but within the range of previous observations several unique observations stand out from these data 1 the export of organic matter to 200 m during the spring and summer was extremely low consistent with observations that the ongoing phytoplankton bloom was being stored or recycled in the upper water column 2 a major pulse of biogenic silica export occurred in the fall just as ice was reforming the correlation of this event with lithogenous particles excess fe and with the early breakout of katabatic winds suggests that this event might be related to fe fertilization of diatom production and export 3 the largest flux of organic matter during 1996 1997 was carried by the pteropod limacina helicina and was observed at both moorings under the ice in the late fall just after the diatom pulse although it is difficult to estimate the proportion of these organisms that were swimmers contaminating the flux we believe that a significant fraction settled into the traps and may represent the die out of this herbivore population after the suspended pom concentration had dropped to very low levels fluxes to the upper traps were much lower than estimates of export flux made by other methods during synoptic ship studies these differences are discussed and the fluxes are compared with preliminary data from the roaverrs trap program which was simultaneously deployed in the ross sea

evolution of the north pacific subtropical mode water in anticyclonic eddies anticyclonic eddies aes trap and transport the north pacific subtropical mode water stmw but the evolution of the stmw trapped in aes has not been fully studied due to the lack of eddy tracking subsurface observations here we analyze profiles from special designed argo floats that follow two stmw trapping aes for more than a year the enhanced daily sampling by these argo floats swirling around the eddies enables an unprecedented investigation into the structure and evolution of the trapped stmw in the aes the upper lower thermocline domes up concaves downward and this lens shaped double thermocline encompasses the thick stmw within the eddy core the lighter stmw 25 0 25 2 trapped in aes dissipates quickly after the formation in winter because of the deepening seasonal thermocline but the denser stmw 25 2 25 4 remains largely unchanged except when the ae passes across the izu ridge the enhanced diapycnal mixing over the ridge weakens the denser stmw appreciably while many aes decay upon hitting the ridge some pass through a bathymetric gap between the hachijojima and bonin islands forming a cross ridge pathway for stmw transport by contrast the north pacific intermediate water npiw underneath is deeper than the eddy trapping depth 600 m and hence left behind east of the izu ridge in argo climatology the shallow stmw 400 m intrudes through the gap westward because of the eddy transport while the npiw 800 m is blocked by the izu ridge

ventilation of a monsoon dominated ocean subduction and obduction in the north indian ocean based on the characteristics of oceanic circulation in a monsoon dominated ocean a new framework of annual ventilation including subduction and obduction is postulated and applied to the north indian ocean based on both soda and godas it is revealed that besides the winter season ventilation can also occur in summer considering the horizontal resolution soda results are mainly discussed with godas results given for validity of key conclusions the annual subduction obduction rate in the north indian ocean based on soda is estimated at 10 2 sv 11 sv averaged from 1960 to 2009 with 4 2 sv 6 2 sv occurring during winter monsoon period and 6 sv 4 8 sv during summer monsoon period respectively both subduction and obduction feature great interannual variability with the vertical pumping term of decisive importance furthermore the concepts of the penetration depth through subduction and the origin depth through obduction are postulated the penetration depth in the arabian sea is on the order of 50 to 200 m the origin depth through obduction in the arabian sea is deeper than that in the bay of bengal with the deepest on the order of 200 to 250 m along the western boundary

southern california inner basin sediment trap calibration the deployment of particle interceptor traps pits in the three inner basins of the southern california bight santa barbara santa monica and san pedro where preserved laminated bottom sediments occur provides a natural calibration between the parameters determined with the pits and those derived from the historical sedimentary deposits the accumulation rates and chemical composition of the pit materials compare favorably with these recently deposited bottom sediments the ratio of the measured particle collection rate to the sediment accumulation rate for these three basins averaged0 93 0 20 radionuclide 210pb 228th 232th and trace element fe cu zn cd pb compositions of the pit materials and surface sediments agree within generally 30 in each basin an application of pits as a sampling system in an outer basin san nicolas where the sedimentary record has been obscured by bioturbation is also presented to further demonstrate the utility of pits for spatial and temporal studies of various aspects of particle transport and sediment deposition based on the calibration of the pits in the three inner basins we conclude from the comparison of the radionuclide and trace element compositions between the pit materials and surface sediments from the san nicolas basin that recently deposited sedimentary material has been mixed by bioturbation with older material from the last several hundred years excess210pb and the228th 232th activity ratio in the pit material are 6 and 15 times higher than in the surface sediment total pb and1n hno3 leachable pb are 4 and 8 fold higher in the pit material

effects of mesoscale eddies on subduction and distribution of subtropical mode water in an eddy resolving ogcm of the western north pacific abstract the effects of mesoscale eddies on the subduction and distribution of the north pacific subtropical mode water stmw are investigated using an eddy resolving ocean general circulation model ogcm first the subduction rate is calculated and the contribution of eddies to the subduction of stmw is estimated it is found that eddy subduction significantly contributes to the total subduction of stmw second eddy thickness transport and diapycnal flux are directly diagnosed to investigate the large scale eddy induced transport process of stmw the large southward eddy thickness transport in the stmw core density is consistent with eddy subduction the eddy transport on the isopycnal surface of stmw is directed down the thickness gradient and traverses the mean flow the meridional eddy transport streamfunction indicates two eddy circulation cells south of 30 n associated with the circulation of stmw these cells flatten density surfaces similar to the effect of the gent and mcwilliams gm schem

effect of mesoscale eddies on subtropical mode water variability from the kuroshio extension system study kess abstract forty eight profiling floats have been deployed in the kuroshio extension ke region since may 2004 as part of the kuroshio extension system study kess project by combining the float temperature salinity measurements with satellite altimetry data this study investigates the role played by mesoscale eddies in controlling the property changes in north pacific subtropical mode water stmw following a 3 yr period of low eddy activity in 2002 04 the ke showed a transition to a high eddy kinetic energy state in 2005 this transition is the result of delayed oceanic response to the 2002 shift in the basin scale surface wind forcing in connection with the pacific decadal oscillation the high eddy kinetic energy state of the ke is characterized by successive shedding of strong cold core rings into the recirculation gyre resulting from the interaction of the ke jet with the shatsky rise or the preexisting cutoff rings by transporting northern origin high potential vorticity pv ke water into t

an algorithm to detect isolated anomalies in three dimensional stratified data fields with an application to density fields from four deep basins of the baltic sea 1 a new approach to describe the mesoscale variability caused by eddies in terms of the integral properties of all eddies contained in a certain ocean volume is suggested for this purpose a pattern recognition algorithm to detect isolated anomalies in three dimensional stratified data fields was developed and is introduced in detail an application to 12 eddy resolving density fields acquired in the framework of the german russian project mesodyn in four deep basins of the baltic sea namely the arkona basin the bornholm basin the stolpe furrow and the eastern gotland basin demonstrates that the algorithm works properly the most remarkable finding of this application is that the volume fraction occupied by the isolated anomalies or eddies is constant it amounts to about 12 of the total volume for each data field no matter whether the stratification corresponds to a summer or a winter situation many possible applications of the pattern recognition are proposed to document its general usefulness finally the main features of the algorithm and possible extensions are discussed extensively

decadal variation in winter mixed layer depth south of the kuroshio extension and its influence on winter mixed layer temperature abstractthe long term behavior of the wintertime mixed layer depth mld and mixed layer temperature mlt are investigated in a region south of the kuroshio extension ke 30 37 n 141 155 e an area of the north pacific subtropical gyre where the deepest mld occurs using historical temperature profiles of 1968 2014 both the mld and mlt in march have low frequency variations which show significant decadal 10 yr variations after the late 1980s observational data and simulation outputs from a one dimensional turbulent closure model reveal that surface cooling is the main control on winter mld in the late 1970s and 1980s whereas there is a change in the strength of subsurface stratification is the main control after 1990 in the latter period a weak strong subsurface stratification is caused by a straight path convoluted path of the ke and by a deepening shallowing of the main thermocline depth due to oceanic rossby waves formed as a result of positive negative anomalies of wind stress

formation region of north pacific subtropical mode water in the late winter of 2003 1 the mixed layer structure and properties in the formation region of the north pacific subtropical mode water stmw east of japan in the late winter of 2003 were examined using temperature and salinity data primarily from argo profiling floats the formation region extends south of the kuroshio extension between 30n and 35n and as far east as 175e it is characterized by a mixed layer with depths greater than 200db and meridionally uniform temperature between 16 5c and 18 2c associated with a mixed layer front at its southern edge the mixed layer in the formation region becomes colder fresher and denser toward the east leading to the formation of warmer saltier and lighter stmw in the western part of the region the spatial variation of the mixed layer depth in the formation region corresponds well with the underlying permanent thermocline depth index terms 4223 oceanography general descriptive and regional oceanography 4283 oceanography general water masses 4572 oceanography physical upper ocean processes citation oka e and t suga formation region of north pacific subtropical mode water in the late winter of 2003 geophys res lett 30 23 2205 doi 10 1029 2003gl018581 2003

on determining the large scale ocean circulation from satellite altimetry to determine the surface geostrophic currents which are proportional to the slope of the dynamic topography from satellite altimetry one needs an accurate and independent estimate of the geoid currently these estimates are given in terms of spherical harmonics while the high degree terms short wavelengths are either uncertain or completely unknown the low degree terms long wavelengths are reasonably accurate furthermore in terms of spherical harmonics most of the dynamic topography s power is contained in the low degree terms if the dynamic topography is treated as the signal and the geoid uncertainty as the noise the signal to noise ratio is the highest for these low degree terms therefore a spherical harmonic expansion of the difference between the altimeter derived mean sea surface and the geoid estimate should reveal the large scale circulation of the ocean surface layer when one examines the low degree terms methods based on this principle are proposed and partially demonstrated over the pacific ocean using the mean sea surface derived from the seasat altimeter and the goddard earth model 9 earth gravity model the preliminary results show a well defined clockwise gyre in the north pacific and a much less well defined counterclockwise gyre in the south pacific when the dynamic topography so obtained is compared to wyrtki s 1975 dynamic topography derived from hydrographic data the agreement is within the limit of geoid uncertainties and satellite orbital errors to fully determine the three dimensional ocean circulation one still needs hydrography the three dimensional density distribution of the ocean a method is presented for the determination of the ocean circulation and the improvement of the geoid in the combined problem of geodesy hydrography and satellite altimetry

three dimensional structure of the wind driven circulation in the subtropical north pacific abstract the subduction rate is calculated for the north pacific based on levitus climatology data and hellerman and rosenstein wind stress data because the period of effective subduction is rather short subduction rates calculated in eulerian and lagrangian coordinates are very close the subduction rate defined in the lagrangian sense consists of two parts the first part is due to the vertical pumping along the one year trajectory and the second part is due to the difference in the winter mixed layer depth over the one year trajectory since the mixed layer is relatively shallow in the north pacific the vertical pumping term is very close to the ekman pumping while the sloping mixed layer base enhances subduction especially near the kuroshio extension for most of the subtropical north pacific the subduction rate is no more than 75 m yr 1 slightly larger than the ekman pumping the water mass volume and total amount of ventilation integrated for each interval of 0 2 unit is computed the corre

the subtropical mode water circulation in the north pacific abstract historical hydrographic data are analyzed to investigate the seasonal variation of the subsurace pycnostad in the northwestern part of the north pacific and to relate it to the circulation of subtropical mode water stmw a gyre scale scheme of stmw circulation is deduced based on its observed climatological formation area and climatological geostrophic flow fields the deduced circulation is supported by climatological features of the subsurface hydrography presented separately for the non large meander period and the large meander period of the kuroshio zonal and meridional sections and isopycnal maps of potential vorticity and apparent oxygen utilization the kuroshio countercurrent composing the kuroshio recirculation system advects stmw formed in the wintertime thick mixed layer immediately off the kuroshio and the kuroshio extension during the non large meander period the recirculation system has a single anticyclonic gyre centered near 30 n 137 e and advects stmw formed off the kurosh