an approach to estimate the freshwater contribution from glacial melt and precipitation in east greenland shelf waters using colored dissolved organic matter cdom changes in the supply and storage of freshwater in the arctic ocean and its subsequent export to the north atlantic can potentially influence ocean circulation and climate in order to understand how the arctic freshwater budget is changing and the potential impacts it is important to develop and refine empirical approaches for tracing freshwater contributions this in turn can help develop and validate model simulations arctic rivers are an important source of freshwater and stable oxygen isotope measurements are used to separate contributions from meteoric water river glacial and precipitation and sea ice melt we develop this approach further and investigate the use of an additional tracer colored dissolved organic matter cdom which is largely specific to freshwater originating from arctic rivers a robust relationship between the freshwater contribution from meteoric water and cdom is derived from 4 years of measurements in fram strait 2009 2012 combined with measurements from the east greenland shelf and dijmpha sound ne greenland results confirm a high contribution of riverine cdom in arctic halocline waters with salinities 31 5 and indicate the importance of shelf processes riverine input and sea ice formation while previously these waters where thought to be derived from open sea processes cooling and sea ice formation in the northern barents and kara seas in greenlandic coastal waters the meteoric water contribution is influenced by greenland ice sheet meltwater and deviations from the cdom meteoric water relationships found are applied to quantify meltwater contribution along the east greenland shelf waters 0 13

low calcium carbonate saturation state in an arctic inland sea having large and varying fluvial inputs the hudson bay system the hudson bay system hbs is a shallow inland sea in the arctic composed of hudson strait foxe basin channel james bay and hudson bay dissolved inorganic carbon dic and total alkalinity ta measurements were used to investigate the state of ocean acidification specifically calcium carbonate saturation states and ph the freshwater sources were identified from the relationship between oxygen isotope composition 18o and salinity to understand the role of freshwater in ocean acidification the saturation state of seawater with respect to calcium carbonate in surface water 10 the watershed characteristics however influenced the alkalinity of river runoff in different parts of hudson bay which contributed to variation in the coastal region in southwestern hudson bay where the watershed is dominated by limestone was higher compared to eastern hudson bay where the watershed consists of an igneous rock formation in deeper waters low is caused by remineralization of organic matter the highest dic concentrations 2300 mol kg were observed in the depths of central hudson bay with a phtotal of 7 49 and arg of 0 37 over 67 and 22 of the bottom water of hudson bay was undersaturated with respect to aragonite and calcite respectively despite hudson bay being very shallow less than 250 m deep the aragonite saturation horizon in the central hudson bay was around 50 m

the nutrient salinity and stable oxygen isotope composition of bering and chukchi seas waters in and near the bering strait seawater nutrient salinity and oxygen 18 data collected from 1990 to 1993 in the bering and chukchi seas were used to identify potential sources of nutrients and water masses that result in formation of the arctic ocean upper halocline and its associated nutrient maximum water matching the delta sup 18 o values of the arctic ocean upper halocline and containing sufficient or a nearly sufficient nutrient and salinity concentration was collected in subsurface waters in the summer in portions of the bering sea particularly the gulf of anadyr however nutrient concentrations significantly declined in this north flowing water over the shallow continental shelf before it reached the bering strait as a consequence of biological utilization and dilution with nutrient poor and oxygen 18 depleted fresh water therefore it does not appear likely that the flow of unaltered water through the bering strait in the summer plays a critical role in the formation of the arctic ocean upper halocline the role of other mechanisms for contributing pacific derived waters to the arctic ocean nutrient maximum is considered copyright 1997 american geophysical union

north atlantic nordic seas exchanges abstract the northeastern part of the north atlantic is unique in the sense that it is much warmer in the surface than other ocean areas at similar latitudes the main reason for this is the large northward transport of heat that extends to high latitudes and crosses the greenland scotland ridge to enter the nordic seas and the arctic there the warm atlantic water is converted to colder water masses that return southwards over the ridge partly as surface outflows and partly as overflows through the deep passages across the ridge in this paper the state of knowledge on the exchanges especially across the eastern part of the greenland scotland ridge is reviewed based on results from the ices nansen north atlantic norwegian sea exchanges project from the nordic woce project and from other sources the accumulated evidence allows us to describe the exchanges in fair detail the origins of the waters the patterns of their flow towards and over the ridge and their ultimate fate there is also increasing information on temporal variations of the exchanges although dynamical changes are still not well understood quantitative estimates for the volume transport of most of the overflow branches seem reasonably well established and transport measurements of the atlantic inflows to the nordic seas are approaching acceptable levels of confidence which allows preliminary budgets to be presented the deep overflows are driven by pressure gradients set up by the formation of deep and intermediate water the dominance of deep overflows over surface outflows in the water budget argues that this thermohaline forcing also dominates over direct wind stress and estuarine forcing in driving the atlantic water inflow across the greenland scotland ridge while wind stress seems to influence the characteristics and distribution of the atlantic water north of the ridge

composition of freshwater in the spring of 2014 on the southern labrador shelf and slope the labrador current is an important conduit of freshwater from the arctic to the interior north atlantic subpolar gyre here we investigate the spatial variability of the freshwater sources over the southern labrador shelf and slope during may june 2014 using measurements of seawater properties such as temperature salinity nutrients and oxygen isotopic composition we estimate the respective contributions of saline water of atlantic and pacific origins of brines released during sea ice formation and of freshwater from sea ice melt and meteoric water origins on the southern labrador shelf we find a large brine signal and pacific water influence indicating a large contribution of water from the canadian arctic the brine signal implies that more than 4 m of sea ice formed upstream either in the arctic or in baffin bay and the northern labrador sea over the midshelf and slope at 52 n we find a stronger influence of slope water from the west greenland current with a smaller contribution of pacific water and no brine signal thus there is advection of water from the slope region to the midshelf between 55 n and 52 n very freshwater with high meteoric content is found close to the coast in june 2014 observations from 1995 and 2008 suggest a higher fraction of brine and pacific water on the shelf compared to that observed in 2014

two circulation regimes of the wind driven arctic ocean the major goal of this paper is to demonstrate the existence in the arctic ocean of two regimes of wind forced circulation we simulated the vertically averaged currents sea level heights and ice drift in the arctic ocean from 1946 to 1993 using a two dimensional wind forced barotropic model that includes frictional coupling between the ocean and ice the model has a spatial resolution of 55 5 km and is driven by winds river runoff and an imposed but realistic sea level slope between the pacific and the atlantic oceans there is a good agreement between velocities from observed buoy motions and velocities of modeled ice drift even though the model lacks ocean baroclinicity and ice thermodynamics the results indicate that wind driven motion in the central arctic alternates between anticyclonic and cyclonic circulation with each regime persisting for 5 7 years based upon our analysis of the modeled sea level and ice motion anticyclonic wind driven motion in the central arctic appeared during 1946 1952 1958 1963 1972 1979 and 1984 1988 and cyclonic motion appeared during 1953 1957 1964 1971 1980 1983 and 1989 1993 shifts from one regime to another are forced by changes in the location and intensity of the icelandic low and the siberian high the two regimes may help explain the significant basin scale changes in the arctic s temperature and salinity structure observed recently the great salinity anomaly and the variability of ice conditions in the arctic ocean

laboratory experiments on the interaction of a buoyant coastal current with a canyon application to the east greenland current this paper presents a set of laboratory experiments focused on how a buoyant coastal current flowing over a sloping bottom interacts with a canyon and what controls the separation if any of the current from the upstream canyon bend the results show that the separation of a buoyant coastal current depends on the current width w relative to the radius of curvature of the bathymetry rc the flow moved across the mouth of the canyon i e separated for w rc 1 in agreement with previous results the present study extends previous work by examining both slope controlled and surface trapped currents and using a geometry specific to investigating buoyant current canyon interaction the authors find that although bottom friction is important in setting the position of the buoyant front the separation process driven by the inertia of the flow could overcome even the strongest bathymetric influence application of the laboratory results to the east greenland current egc an arctic origin buoyant current that is observed to flow in two branches south of denmark strait suggests that the path of the egc is influenced by the large canyons cutting across the shelf as the range of w rc in the ocean spans those observed in the laboratory what causes the formation of a two branched egc structure downstream of the kangerdlugssuaq canyon 688n 328w is still unclear but potential mechanisms are discussed

freshwater balance and the sources of deep and bottom waters in the arctic ocean inferred from the distribution of h218o data from sections across the eurasian basin of the arctic ocean occupied in 1987 and 1991 are used to derive information on the freshwater balance of the arctic ocean and on sources of the deep waters of the nansen amundsen and makarov basins using salinity h218o and mass balances we estimate the river runoff and the sea ice melt water fractions contained in the upper waters of the arctic ocean and infer pathways of the river runoff signal from the shelf seas across the central arctic ocean to fram strait the average mean residence time of the river runoff fraction contained in the arctic ocean halocline is determined to be about 11 to 14 years pacific water entering through bering strait is traced using silicate and its influence on the halocline waters of the canadian basin is estimated water column inventories of river runoff and sea ice melt water are calculated for a section just north of fram strait and implications of these inventories for sea ice export through fram strait are discussed comparison of the 18o 16o ratios of shelf water atlantic water and the deep waters of the arctic ocean indicate that the sources of the deep and bottom waters of the eurasian basin are located in the barents and kara seas

physical and geochemical properties across the atlantic pacific water mass front in the southern canadian basin temperature salinity nutrients oxygen and halocarbon data collected in the arctic ocean reveal a frontal structure previously unrecognized in the hydrography of the canadian basin samples were collected on a 1300 km section extending from the beaufort sea in the canada basin to the east siberian sea in the makarov basin these data collected in 1993 aboard the ccgs henry larsen reveal a lateral boundary between water masses of atlantic and pacific origin the term water mass assembly is introduced to describe the basic arrangement or vertical stacking of water masses found in the arctic ocean recognizing that water mass components within each assembly may differ from basin to basin using historical data two primary water mass assemblies are defined each consisting of three layers an upper layer an atlantic layer and a deep layer these two assemblies are marked by important differences one assembly here defined as the western arctic wa assembly is characterized by an upper layer of relatively fresh high nutrient water of pacific origin below this by an atlantic layer with a core temperature generally below 0 5 c and finally by a deep layer of higher salinities and colder temperatures about 0 5 c than found in the overlying atlantic layer the second assembly here defined as eastern arctic ea assembly is characterized by the absence of pacific water in the upper layer below this by an atlantic layer core as warm as 2 to 3 c and by a colder about 0 9 c deep layer because the presence or absence of pacific origin water is a key characteristic distinguishing the two assemblies we will refer to the water mass boundary between the two assemblies as the atlantic pacific front earlier research indicated that water masses in the arctic ocean were separated by a front above the lomonosov ridge into the canadian and eurasian basins although all larsen 93 stations from the canada basin a1 d1 display classic wa assembly characteristics the makarov basin station e1 shows ea assembly characteristics in the upper and atlantic layers and a wa assembly deep layer this suggests a relocation in the position of the atlantic pacific boundary away from the lomonosov ridge further larsen 93 data show the transition region between the atlantic and deep layers is fresher in the makarov basin than corresponding water in either the canada or eurasian basins implying a source of cold low salinity water perhaps from the laptev and east siberian shelves the front separating these two assemblies lies above the mendeleyev ridge and is marked by large lateral gradients in all measured properties in particular the penetration of anthropogenic halocarbons is 2 to 3 times deeper in the makarov basin than in the canada basin implying enhanced rates of ventilation this suggests that direct exchange between the canadian and eurasian basins has occurred recently near the perimeter and that physical and chemical properties including contaminants may have been transported by boundary currents more quickly from one basin to the other

water masses and circulation in the eurasian basin results from the oden 91 expedition the oden 91 north pole expedition obtained oceanographic measurements on four sections in the nansen and amundsen basins of the eurasian basin and in the makarov basin of the canadian basin thereby proving the feasibility of carrying out a typical oceanographic program using an icebreaker in the arctic ocean the data show greater spatial variability in water structure and circulation than was apparent from previous data the results show that a clear front exists between the eurasian and canadian basins such that upper halocline water in the canadian basin is almost absent from the eurasian basin the lower halocline water produced in the barents kara sea region permeates much of the eurasian basin and flows along the continental slope into the canadian basin the deeper circulation is strongly influenced by topography three return flows of the atlantic layer are identified one over the nansen gakkel ridge one over the lomonosov ridge and a third flowing from the canadian basin the slight differences observed in salinity and temperature characteristics of the deeper waters of the nansen and amundsen basins do not lead to an obvious explanation of their origin or flow pattern

inorganic carbon in a high latitude estuary fjord system in canada s eastern arctic abstract rapidly changing conditions in the arctic can have a significant impact on biogeochemical cycles and can be particularly important in high latitude estuary fjord systems with abundant and diverse freshwater sources this study provides a first look into the inorganic carbon system and its relation to freshwater sources in cumberland sound in the east coast of baffin island nunavut canada these data contribute to the very limited set of inorganic carbon measurements in high latitude estuary fjord systems during the ice free conditions in august 2011 the meteoric freshwater fractions mw in the upper 40 m ranged from 11 to 21 and no sea ice melt sim was present in the sound surface waters were undersaturated with pco 2 260 and 300 atm and dic and ta ranged between 1779 and 1966 mol dic kg 1 and 1922 and 2140 mol ta kg 1 respectively aragonite saturation ar state ranged from 1 9 in the surface to 1 4 in the subsurface waters data show decreasing ta and ar with increasing mw fraction and suggest that cumberland sound waters would become aragonite undersaturated ar 18 o 19 2 and ta 174 mol ta kg 1 end members indicate mw was most likely a mixture of river water and glacial melt in august 2012 mw fractions at the surface were between 8 and 11 5 and sim between 7 and 23 significant interannual variability of summertime sim could potentially result in ar undersaturation

tracing pacific water in the north atlantic ocean 1 in the arctic ocean pacific source water can be distinguished from atlantic source water by nitrate phosphate concentration relationships with pacific water having higher phosphate concentrations relative to those of nitrate furthermore pacific water originally from the inflow through bering strait is clearly recognizable in the outflows of low salinity waters from the arctic ocean to the northern north atlantic ocean through the canadian arctic archipelago and through fram strait in the canadian arctic archipelago we observe that almost all of the waters flowing through lancaster and jones sounds most of the water in the top 100 m in smith sound containing the flow through nares strait and possibly all waters in hudson bay contain no water of atlantic origin significant amounts of pacific water are also observed along the western coast of baffin bay along the coast of labrador and above the 200 m isobath of the grand banks there is a clear signal of pacific water flowing south through fram strait and along the east coast of greenland extending at least as far south as denmark strait pacific water signature can be seen near the east coast of greenland at 66 n but not in data at 60 n temporal variability in the concentrations of pacific water has been observed at several locations where multiple year observations are available

varieties of shallow temperature maximum waters in the western canadian basin of the arctic ocean the properties and spreading pathways of shallow temperature maximum waters stms in the western canadian basin are investigated using ctd and mooring data obtained in 1997 98 as part of the sheba surface heat budget of the arctic ocean drift experiment and available historical data three distinct varieties of stm are recognized on the basis of salinity range 1 surface mixed layer water smlw with s 32 psu these stms carry sufficient heat within the upper layers of the ocean to significantly affect the rates of ice cover and decay for example during the winter of 1997 98 anomalously warm stm 0 c originating from ecsw was observed to spread northwards along the northwind ridge and chukchi plateau where the maximum reduction of the ice covers was subsequently observed in late summer 1998 maslanik et al 1999 regional climate variability and ice cover in the western canadian basin are thus affected not only by anomalous atmospheric circulation patterns but also by the circulation of upper ocean water masses

the spatial and temporal variability of the east greenland coastal current from historic data analysis of historic hydrographic data collected between 1932 and 1997 show a freshwater jet flowing southward along the east greenland shelf between denmark strait and cape farewell with a typical baroclinic transport of between 0 5 and 2 sv this jet has been labelled the east greenland coastal current egcc the depth of the jet is a function of transport but the lateral extent of the jet is mainly defined by the position of the shelf break comparing section transports from different times and locations it is seen that significant short term variability masks both longer term variability and latitudinal variations the data suggest an increase in egcc transport during the early 1930s greenland warm period followed by reduced average fluxes thereafter but there is insufficient data for this result to be considered statistically significant in addition there is no evidence of significant growth in the transport as the jet progresses south as might be expected with the addition of run off from the se greenland fjords

calcium carbonate saturation states in the waters of the canadian arctic archipelago and the labrador sea 1 ocean acidification is predicted to occur first in polar oceans we investigated the saturation state of waters with respect to calcite cal and aragonite arg in six sections along an arctic outflow pathway through the canadian arctic archipelago caa and into the northwestern atlantic using dissolved inorganic carbon and total alkalinity measurements from 2003 to 2005 the study area a key region connecting the arctic and the north atlantic includes smith sound barrow strait baffin bay davis strait hudson strait and the labrador sea the average arg in the arctic outflow was 1 18 0 17 in barrow strait and 1 31 0 14 in smith sound with areas where arg 1 the arctic outflow through the caa has a high content of pacific waters which have a low saturation state these waters can be traced along the western baffin bay to davis strait south of davis strait this outflow is modified by mixing with slope and offshore waters of atlantic origin and with the outflow from hudson strait despite the mixing low saturation state water can still be identified on the southern labrador shelf the aragonite saturation horizon is found at 150 m in barrow strait at 200 m in baffin bay davis strait and hudson strait and at 2300 m in the labrador sea this study provides baseline data of the saturation states for the waters of the caa and the northwest atlantic it also illustrates the downstream evolution of low saturation state arctic outflow in the northwest atlantic

distribution of atlantic and pacific waters in the upper arctic ocean implications for circulation the atlantic and pacific oceans provide source waters for the arctic ocean that can be distinguished by their differing nitrate and phosphate concentration relationships using these relationships we estimate the amount of atlantic and pacific waters in the surface layer top 30 m of the arctic ocean atlantic source water is dominant in most of the eurasian basin and is present in significant amounts in the makarov basin north of the east siberian sea pacific source water is dominant in most of the canadian basin and is present in significant amounts in the amundsen basin north of greenland we deduce circulation patterns from the distributions of atlantic and pacific source waters in the surface layer of the arctic ocean and conclude that the flow within the surface layer differs from ice drift along the north american and european boundaries of the polar basin

freshwater composition of the waters off southeast greenland and their link to the arctic ocean 1 the freshwater composition of waters on the southeast greenland shelf and slope are described using a set of high resolution transects occupied in summer 2004 which included hydrographic velocity nutrient and chemical tracer measurements the nutrient and tracer data are used to quantify the fractions of pacific water sea ice melt and meteoric water present in the upper layers of the east greenland current egc and east greenland coastal current egcc the egc egcc system dominates the circulation of this region and strongly influences the observed distribution of the three freshwater types sea ice melt and meteoric water fractions are surface intensified reflecting their sources and generally increase southward from denmark strait to cape farewell as well as shoreward significant fractions of pacific water are found in the subsurface layers of the egcc supporting the idea that this inner shelf branch is directly linked to the egc and thus to the arctic ocean a set of historical sections is examined to investigate the variability of pacific water content in the egc and egcc from 1984 to 2004 in the vicinity of denmark strait the fraction of pacific water increased substantially in the late 1990s and subsequently declined to low levels in 2002 and 2004 mirroring the reduction in pacific water content reported previously at fram strait this variability is found to correlate significantly with the arctic oscillation index lagged by 9 years suggesting that the arctic ocean circulation patterns bring varying amounts of pacific water to the north atlantic via the egc egcc

the east greenland coastal current structure variability and forcing abstract the subtidal circulation of the southeast greenland shelf is described using a set of high resolution hydrographic and velocity transects occupied in summer 2004 the main feature is the east greenland coastal current egcc a low salinity high velocity jet with a wedge shaped hydrographic structure characteristic of other surface buoyancy driven currents the egcc was observed along the entire greenland shelf south of denmark strait while the transect north of the strait showed only a weak shelf flow this observation in conjunction with water mass considerations and other supporting evidence suggests that the egcc is an inner branch of the east greenland current egc that forms south of denmark strait it is argued that bathymetric steering is the most likely reason why the egc apparently bifurcates at this location repeat sections occupied at cape farewell between 1997 and 2004 show that the alongshelf wind stress can have an influence on the structure and strength of the egcc and egc on timescales of 2 3 days accounting for the wind induced effects the volume transport of the combined egcc egc system is roughly constant 2 sv over the study domain from 68 n to cape farewell near 60 n the corresponding freshwater transport increases by roughly 60 over this distance 59 96 msv referenced to a salinity of 34 8 this trend is consistent with a simple freshwater budget of the egcc egc system that accounts for meltwater runoff melting sea ice and icebergs and net precipitation minus evaporation

last century changes in ocean wind wave height from global visual wave data 1 centennial time series of visually observed wave height were derived from the international comprehensive ocean atmosphere data set along the major ship routes in the world ocean and homogenized they demonstrate positive trends in significant wave height over the north pacific with a maximum of 8 10 cm decade in the northeast pacific in the north atlantic and other basins significant upward changes up to 14 cm decade are observed only for the last 50 years and not for centennial records long term changes in wind wave height are closely associated with the north atlantic oscillation in the atlantic and with north pacific oscillation and el nino southern oscillation in the pacific

freshwater fluxes through the western fram strait two hydrographic and d18o transects across fram strait aug sept 1997 1998 are used to examine freshwater contributions to the east greenland current egc the egc featured up to 16 meteoric water in both years but was made comparatively more saline through the formation of up to 11 m of sea ice we derive meteoric water fluxes of 3680 km3yr 1 in aug sept 1997 and 2000 km3yr 1 in aug sept 1998 the 1997 and 1998 data show a long term me m sea ice flux through fram strait around half the long term mean meteoric water flux a 1991 d18o section bauch et al 1995 yielded a very similar ratio our 1998 section reveals fresh 1ow 6180 water on the east greenland shelf whose comparatively large volume constitutes a potentially significant contribution to the total freshwater flux through fram strait such fluxes are important to the regional and global thermohaline circulation we suggest that efforts towards monitoring both the egc and east greenland shelf waters are thus required

river runoff sea ice meltwater and pacific water distribution and mean residence times in the arctic ocean hydrographic and tracer data collected during ark iv 3 fs polarstern in 1987 arctic91 ib oden and aos94 ccgs louis s st laurent expeditions reveal the evolution of the near surface waters in the arctic ocean during the late 1980s and early 1990s salinity nutrients dissolved oxygen and 18 o data are used to quantify the components of arctic freshwater river runoff sea ice meltwater and pacific water the calculated river runoff fractions suggest that in 1994 a large portion of water from the pechora ob yenisey kotuy and lena rivers did not flow off the shelf closest to their river deltas but remained on the shelf and traveled via cyclonic circulation into the laptev and east siberian seas river runoff flowed off the shelf at the lomonosov ridge and most left the shelf at the mendeleyev ridge arctic91 and aos94 pacific water fraction estimates of upper halocline water the traditionally defined core of the pacific water mass document a decrease in extent compared to historical data the front between atlantic water and pacific water shifted from the lomonosov ridge location in 1991 to the mendeleyev ridge in 1994 the relative age structure of the upper waters is described by using the 3 h 3 he age the mean 3 h 3 he age measured in the halocline within the salinity surface of 33 1 0 3 is 4 3 1 7 years and that for the 34 2 0 2 salinity surface is 9 6 4 6 years lateral variations in the relative age structure within the halocline and atlantic water support the well known cyclonic boundary current circulation

disappearance of pacific water in the northwestern fram strait 1 water of pacific origin entering the arctic ocean through the bering strait exits the arctic ocean through the canadian archipelago and the fram strait the amount and timing of pacific water export through these gates depend on the upper circulation of the arctic ocean and react accordingly on changes nutrient and hydrographic data from four cruises to the area north of the fram strait in 1984 1990 1997 and 2004 show that substantial changes have occurred lately in the amount of pacific waters delivered to the fram strait and hence further to the atlantic ocean while the data from 1984 1990 and 1997 all showed considerable amounts of pacific water above the shelf and slope northeast of greenland this strong signal had completely vanished in 2004 the arrival of a previously not observed cold halocline layer at the area can be recognized in 1997

sources and distribution of fresh water in the east greenland current abstract fresh water flowing from the arctic ocean via the east greenland current influences deep water formation in the nordic seas as well as the salinity of the surface and deep waters flowing from there this fresh water has three sources pacific water relatively fresh cf atlantic water river runoff and sea ice meltwater to determine the relative amounts of the three sources of fresh water in may 2002 we collected water samples across the east greenland current in sections from 81 5 n to the irminger sea south of denmark strait we used nitrate phosphate relationships to distinguish pacific waters from atlantic waters salinity to obtain the sum of sea ice melt water and river runoff water and total alkalinity to distinguish the latter river runoff contributed the largest part of the total fresh water component in some regions with some inventories exceeding 12 m pacific fresh water pacific source water s 32 cf atlantic source water s 34 9 typically provided about 1 3 of the river runoff contribution sea ice meltwater was very nearly non existent in the surface waters of all sections likely at least in part as a result of the samples being collected before the onset of the melt season the fresh water from the arctic ocean was strongly confined to near the greenland coast we thus conjecture that the main source of fresh water from the arctic ocean most strongly impacting deep convection in the nordic seas would be sea ice as opposed to fresh water in the liquid phase i e river runoff pacific fresh water and sea ice meltwater

the east greenland spill jet high resolution hydrographic and velocity measurements across the east greenland shelf break south of denmark strait have revealed an intense narrow current banked against the upper continental slope this is believed to be the result of dense water cascading over the shelf edge and entraining ambient water the current has been named the east greenland spill jet it resides beneath the east greenland irminger current and transports roughly 2 sverdrups of water equatorward strong vertical mixing occurs during the spilling although the entrainment farther downstream is minimal a vorticity analysis reveals that the increase in cyclonic relative vorticity within the jet is partly balanced by tilting vorticity resulting in a sharp front in potential vorticity reminiscent of the gulf stream the other components of the irminger sea boundary current system are described including a presentation of absolute transports

freshwater budget of the canada basin arctic ocean from salinity δ18o and nutrients 1 the contribution of freshwater components e g meteoric sea ice and pacific water in the canada basin is quantified using salinity 18o and nutrient data collected in 2003 and 2004 the penetration depth of sea ice meltwater is limited to the upper 30 m and brine rejected during sea ice formation is observed from 30 to 250 m depth the fraction of meteoric water is high in the upper 50 m and decreases with depth pacific water entering via bering strait is the main source of freshwater below 50 m depth bering strait throughflow which transports pacific water with salinity 32 5 together with meteoric water supplied upstream of the bering strait contributes up to 75 of freshwater input 3200 km3 a 1 to the canada basin the mean residence time of pacific water in the canada basin is estimated to be 11 years precipitation and river runoff from both north american and eurasian continents add 800 km3 a 1 and sea ice formation removes 900 km3 a 1 0 6 m a 1 of fresh water the export of ice and liquid fresh water from the canada basin contributes 40 of the freshwater flux from the arctic ocean to the north atlantic ocean

a freshwater jet on the east greenland shelf in august 1997 rrs discovery cruise 230 world ocean circulation experiment woce section a25 ran a hydrographic section into cape farewell on the southern tip of greenland the closest approach to the shore was 2 nm in a water depth of 160 m over the east greenland shelf analysis of the hydrographic data conductivity temperature depth ctd vessel mounted acoustic doppler current profiler and thermosalinograph has revealed a current flowing southwestward 15 km wide 100 m deep and centered 10 km offshore we believe it to be driven by meltwater runoff from greenland this feature which we call the east greenland coastal current egcc carries a little less than 1 sv 106 m3 s 1 with peak current speeds of 1 m s 1 at the surface the center of the egcc lies on a salinity front with maximum salinity contrast 4 practical salinity units psu between coast and shelf break and between surface and bottom a spot value of freshwater transport is 0 06 sv 1800 km3 yr 1 which is equivalent to 30 of the arctic freshwater gain the presence of the egcc and its continuity up the east greenland coast as far as denmark strait is confirmed in satellite sea surface temperature images and surface drifter tracks we estimate the sensitivity of its freshwater flux to changes in melt season mean surface air temperature to be 25 per 1 c

arctic ocean water mass balance from isotope data the distributions of the oxygen 18 and tritium isotopes and of salinity yield a residence time of 10 years for the surface and halocline waters of the arctic basin we find a yearly net production of 0 59 m of sea ice and an input of 1 16 m of freshwater from continental river runoff local precipitation and bering strait salinity deficiency using the basin area value with these numbers gives long term average total net production and transport rates of 0 15 sv of ice and 0 18 sv of meteoric component bering strait water not included if in addition a reasonable depth profile of relative current velocity is assumed for the outflow a yearly input of 2 8 sv of atlantic and bering strait water is needed to replenish the upper and halocline waters these numbers should be good to 20 and are multiyear averages the isotope data clearly indicate that the barents sea is an inflow area for atlantic water to the basin but that net export of ice occurs there

the influence of wind forcing on the chesapeake bay buoyant coastal current observations of the buoyant coastal current that flows southward from chesapeake bay are used to describe how the thickness width and propagation speed vary in response to changes in the along shelf wind stress three basic regimes were observed depending on the strength of the wind for weak wind stresses from 0 02 to 0 02 pa the buoyant coastal current was relatively thin the front slope was not steep and the width was variable 1 20 km for moderate downwelling southward wind stresses 0 02 0 07 pa wind driven cross shelf advection steepened the front causing the plume to narrow and thicken for stronger downwelling wind stresses greater than 0 07 pa vertical mixing dominated bulk richardson numbers were approximately 0 25 isopycnals were nearly vertical and the plume front widened but the plume width did not change plume thickness and width were normalized by the theoretical plume scales in the absence of wind forcing normalized plume thickness increased linearly from 1 to 2 as downwelling wind stresses increased from 0 to 0 2 pa normalized plume widths were approximately 1 for downwelling wind stresses from 0 02 to 0 2 pa the observed along shelf propagation speed of the plume was roughly equal to the sum of the theoretical propagation speed and the wind driven along shelf flow

baffin island and west greenland current systems in northern baffin bay abstract temperature salinity and direct velocity observations from northern baffin bay are presented from a summer 2003 survey the data reveal interactions between fresh and cold arctic waters advected southward along baffin island and salty and warm atlantic waters advected northward along western greenland geostrophic currents estimated from hydrography are compared to measured ocean currents above 600 m depth the baffin island current is well constrained by the geostrophic thermal wind relation but the west greenland current is not furthermore both currents are better described as current systems that contain multiple velocity cores and eddies we describe a surface intensified baffin island current seaward of the continental slope off canada and a bottom intensified west greenland current over the continental slope off greenland acoustic doppler current profiler observations suggest that the west greenland current system advected about 3 8 0 27 sv sv 10 6 m 3 s 1 towards the north west at this time the most prominent features were a surface intensified coastal current advecting 0 5 sv and a bottom intensified slope current advecting about 2 5 sv in the same direction most of this north westward circulation turned southward in the baffin island current system the baffin island system was transporting 5 1 0 24 sv to the south east at the time that includes additional contributions from nares strait to the north 1 0 0 2 sv and lancaster sound to the east 1 0 0 2 sv net freshwater fluxes were 72 and 187 msv for the west greenland and baffin island currents respectively empirical uncertainty arises from unknown temporal variations at weekly time scales and pertubations introduced by unresolved eddies eddies with 10 km horizontal and 400 m vertical scales were common and recirculated up to 1 sv our 2003 observations represent conditions when the north atlantic oscillation index nao was close to zero analysis of historical hydrographic data averaged along isobaths during nao positive years reveals a baroclinic circulation in baffin bay more intense than 2003 with stronger southward flow of fresher arctic waters along baffin island and stronger northward inflow of saltier atlantic waters along greenland during negative nao years this cyclonic circulation weakens as evidenced by a 1979 synoptic survey of the hydrography along baffin island

ocean circulation and freshwater pathways in the arctic mediterranean based on a combined nd isotope ree and oxygen isotope section across fram strait the water masses passing the fram strait are mainly responsible for the exchange of heat and freshwater between the nordic seas and the arctic ocean the arctic mediterranean am disentangling their exact sources distribution and mixing however is complex this work provides new insights based on a detailed geochemical tracer inventory including dissolved nd isotope end rare earth element ree and stable oxygen isotope 18o data along a full water depth section across fram strait we find that nd isotope and ree distributions in the open am primarily reflect lateral advection of water masses and their mixing seawater particle interactions exert important control only above the shelf regions as observed above the ne greenland shelf advection of northward flowing warm atlantic water aw is clearly reflected by an end signature of 11 7 and a nd concentration nd of 16 pmol kg in the upper 500 m of the eastern and central fram strait freshening and cooling of the aw on its way trough the am are accompanied by a continuous change towards more radiogenic end signatures e g 10 4 of dense arctic atlantic water this mainly reflects mixing with intermediate waters but also admixture of dense kara sea waters and pacific derived waters the more radiogenic end signatures of the intermediate and deep waters reaching 9 5 are mainly acquired in the sw nordic seas through exchange with basaltic formations of iceland and se greenland inputs of nd from svalbard are not observed and surface waters and nd on the svalbard shelf originate from the barents sea shallow southward flowing arctic derived waters 200 m form the core of the east greenland current above the greenland slope and can be traced by their relatively radiogenic end reaching 8 8 and elevated nd 21 to 29 pmol kg these properties are used together with 18o and standard hydrographic tracers to define the proportions of pacific derived 30 based on nd isotopes and atlantic derived waters as well as of river waters 8 shallow waters 150 m on the ne greenland shelf share some characteristics of arctic derived waters but exhibit less radiogenic end values reaching 12 4 and higher nd up to 38 pmol kg in the upper 100 m this suggests local addition of greenland freshwater of up to 6 in addition to these observations this study shows that the pronounced gradients in end signatures and ree characteristics in the upper water column provide a reliable basis for assessments of shallow hydrological changes within the am

circulation of summer pacific halocline water in the arctic ocean 1 we present an analysis of arctic ocean hydrographic and sea ice observations from the 1990s with a focus on the circulation of water that originates in the north pacific ocean previous studies have shown the presence of two varieties of relatively warm summer halocline water in the vicinity of the chukchi sea i e the relatively fresh alaskan coastal water acw and the relatively saltier summer bering sea water sbsw here we extend these studies by tracing the circulation of these waters downstream into the arctic ocean we find that acw is generally most evident in the southern beaufort gyre while sbsw is strongest in the northern portion of the beaufort gyre and along the transpolar drift stream we find that this separation is most extreme during the early mid 1990s when the arctic oscillation was at historically high index values this leads us to speculate that the outflow to the north atlantic ocean through the canadian archipelago and fram strait may be similarly separated as arctic oscillation index values fell during the later 1990s acw and sbsw began to overlap in their regions of influence these changes are evident in the area north of ellesmere island where the influence of sbsw is highly correlated with a 3 year lag with the arctic oscillation index we also note the presence of winter bering sea water wbsw which underlies the summer varieties all together this brings the number of distinct pacific water types in our arctic ocean inventory to three acw sbsw and wbsw

composition and fluxes of freshwater through davis strait using multiple chemical tracers 1 freshwater transport through davis strait can supply additional buoyancy to the deep convection region of the labrador sea which influences the strength of the meridional overturning circulation and consequently the global climate the freshwater contribution from local sea ice meltwater meteoric water fluvial glaciofluvial and precipitation and the arctic outflow were quantified using oxygen isotope composition 18o salinity and nutrient relationships in september october 2004 freshwater transported by the arctic outflow was isolated using a modified nutrient relationship method and further deconvoluted into sea ice meltwater meteoric water and pacific water for the first time fluxes of individual freshwater components were estimated using observations of the velocity field derived from mooring arrays and geostrophic currents from hydrography the arctic outflow dominated in western davis strait 60 and its influence extended eastward close to the greenland slope the sea ice meltwater fraction was small 6 and attributed to glacial meltwater the freshwater inventory of the 0 100 m layer was equivalent to 7 4 m in western davis strait 8 m from the arctic outflow and 0 6 m from brine rejection in eastern davis strait the freshwater inventory was 4 m 3 m from meteoric water and 1 m from sea ice meltwater the arctic outflow contributed 82 99 msv to the southward freshwater transport about 67 81 of the total glacial meltwater contributed the largest northward transport of 10 30 msv

evolution of the freshwater coastal current at the southern tip of greenland abstractshipboard hydrographic and velocity measurements collected in summer 2014 are used to study the evolution of the freshwater coastal current in southern greenland as it encounters cape farew

environmental significance of lungfish burrows gnathorhiza within lower permian wolfcampian paleosols of the us midcontinent abstract burrows of the lungfish gnathorhiza occur in the fine grained strata of the lower permian wolfcampian blue spring shale member of the matfield formation near manhattan kansas thousands of lungfish burrows occur in three beds of a compound paleosol profile with the vast majority confined to a single bed several meters below the florence limestone member of the barneston limestone chase group the burrows a high percentage of which contain lungfish bones occur in a 145 m long lens shaped unit comprised of clayey siltstone that exhibits platy to subangular blocky peds and downward and laterally branching thin rhizoliths the uppermost paleosol horizon in each level is gleyed indicating that there was standing water for part of the year the paleoecosystem represented by these units formed in a low lying terrestrial coastal paleolandscape with subtle topography and imperfectly drained paleosols equivalent to present day aquents these paleosols are part of a pedogenic sequence recording an upward climatic trend from semi arid to monsoonal

using the nutrient ratio no po as a tracer of continental shelf waters in the central arctic ocean historical nitrate phosphate and dissolved oxygen data from the central arctic ocean are examined with particular emphasis on the conservative parameters no 9 no sub 3 o sub 2 and po 135 po sub 4 o sub 2 the no po ratio is shown to increase with depth in the canada basin being approximately 0 78 in surface and upper halocline waters and approximately 1 0 in the atlantic layer and deep waters lower halocline water is marked by no and po minima and intermediate no po no po ratios from the arctic shelf seas are examined to determine possible source regions for the various water masses the no po ration of canada basin deep water implies an upper bound of approximately 11 shelf water contribution to this water mass a slight oxygen maximum core in the lower halocline water is identified at a salinity of s double bond 34 5 in the vicinity of the alpha ridge this core appears to be diminished by diapycnal mixing and does not extend into the beaufort gyre

quantitative considerations of dissolved barium as a tracer in the arctic ocean 1 dissolved barium ba was measured along transects across fram and denmark straits as part of the 1998 ark xiv 2 polarstern expedition results are combined with other available tracer observations to analyze water mass composition at fram strait a combination of pacific water and eurasian river runoff dominated 80 and 10 of the total mass respectively the upper east greenland current egc while the remainder of the section was dominated by north atlantic water a much smaller contribution of pacific water to the egc 50 at fram strait in 1987 suggests that this component can be quite variable in time north american river water was not detectable at fram strait in 1998 presumably the eurasian river water we observed at fram strait transited eastward along shelf within the arctic mixed with pacific water in the vicinity of the east siberian sea and was borne by the transpolar drift across the arctic ocean in the absence of significant net ice formation along the way such a pathway can be expected to produce more pronounced freshening of the egc than when eurasian river water mixes more directly off shelf into salty atlantic waters and pacific water is diverted largely through the canadian archipelago existing measurements at the main arctic gateways were used to construct a ba budget for the arctic ocean under conditions of simultaneous mass heat and salt conservation this preliminary budget is statistically consistent with the steady state hypothesis on the arctic basin scale ba appears to be conservative

variability in river runoff distribution in the eurasian basin of the arctic ocean 1 the distribution of freshwater within the arctic ocean and its export from it are intimately involved in climate and climate change processes both within and outside the arctic ocean river runoff in the arctic ocean constitutes a major part of the arctic ocean freshwater budget within the arctic ocean variability in the distribution of river runoff will be reflected in the location of the cold halocline that isolates the sea ice from the warm atlantic layer outside the arctic ocean such variability will impact on the salinity of north atlantic waters great salinity anomaly and on deep convection areas of the north atlantic ocean and thereby potentially on global thermohaline circulation rivers entering the arctic ocean have high levels of total alkalinity that contribute significantly to the total alkalinity of the surface polar mixed layer we exploit total alkalinity data to trace river runoff in the surface polar mixed layer and to observe variability in the river runoff distribution in the eurasian basin over the period 1987 2001 the river runoff front changed from a position over the gakkel ridge in 1987 and 1991 to over the lomonosov ridge in 1996 and returned to a midpoint between the two ridges in 2001 wind field changes as characterized by the arctic oscillation index are considered to be a major factor in determining ice and surface water flow we note a correlation with 4 6 years delay between changes in river runoff distribution and the arctic oscillation index we show that the delay can be inferred from a geostrophic flow calculation

ocean regulation hypothesis for glacier dynamics in southeast greenland and implications for ice sheet mass changes synchronous acceleration and thinning of southeast se greenland glaciers during the early 2000s was the main contributor that resulted in the doubling of annual discharge from the ice sheet we show that this acceleration was followed by a synchronized and widespread slowdown of the same glaciers in many cases associated with a decrease in thinning rates and we propose that ice sheet ocean interactions are the first order regional control on these recent mass changes sea surface temperature and mooring data show that the preceding dynamic thinning coincides with a brief decline in the cold east greenland coastal current egcc and east greenland current we suggest this decline was partly induced by a reduction in ice sheet runoff which allowed warm water from the irminger current to reach the se greenland coast a restrengthening of the cold waters coincides with the glaciers subsequent slowdown we argue that this warming and subsequent cooling of the coastal waters was the cause of the glaciers dynamic changes we further suggest that the restrengthening of the egcc resulted in part from cold water input by increased glacier calving during the speedup and increased ice sheet runoff we hypothesize that the main mechanism for ice sheet mass loss in se greenland is highly sensitive to ocean conditions and is likely subject to negative feedback mechanisms copyright 2010 by the american geophysical union

recent changes in the freshwater composition east of greenland results from three hydrographic surveys across the east greenland current between 2011 and 2013 are presented with focus on the freshwater sources end member analysis using salinity 18o and nutrient data shows that while meteoric water dominated the freshwater content a significant amount of pacific freshwater was present near denmark strait with a maximum in august 2013 while in 2011 and 2012 the net sea ice melt was dominated by brine in 2013 it became close to zero the amount of pacific freshwater observed near denmark strait in 2013 is as large as the previous maximum in 1998 this together with the decrease in meteoric water and brine suggests a larger contribution from the canadian basin we hypothesize that the increase of pacific freshwater is the result of enhanced flux through bering strait and a shorter pathway of pacific water through the interior arctic to fram strait

gradients in seasonality and seawater oxygen isotopic composition along the early permian gondwanan coast se australia abstract oxygen isotope compositions of marine carbonates are commonly employed for understanding ancient temperatures but this approach is complicated in the very distant past due to uncertainties about the effects of diagenesis and the isotopic composition of seawater both locally and globally microsampled accretionary calcite from two species of the fossil bivalve eurydesma sowerby and morris 1845 collected from sediments of cisuralian age in high latitude marine sediments along the se coast of australia records cyclic seasonal fluctuations in shell 18 o values during growth demonstrating the primary nature of the isotope signal and thus allowing investigation of early permian seawater isotopic composition and water temperature in the high southern latitudes the mean and seasonal range of 18 o carb decreases poleward across about 10 of paleolatitude 67 s 77 s the presence of co occurring dropstones and stratigraphically associated glendonites constrains winter temperatures across the region to near freezing thus permitting calculation of realistic estimates of water composition and summer temperatures summer 18 o carb values indicate water temperatures between 5 c and 12 c with warmer values at lower latitudes the decrease in both mean sea surface temperature and seasonal amplitude with increasing latitude on the gondwanan coast is much like that observed along high latitude coastlines today calculated 18 o water decreases toward the pole likely associated with an increasing contribution of isotopically light fresh water derived from summer snow melt the gradient in 18 o water is similar to that documented over a similar span of latitude on the modern se greenland coast we infer the presence of a north flowing coastal current of cold o 18 depleted water that entrains progressively greater amounts of more typical seawater as it moves away from the pole 18 o values in se australia however are about 3 lower than those off greenland suggesting comparatively lower salinity water or more o 18 depleted glacial ice runoff in the permian gondwanan high latitudes perhaps augmented by more depleted negative global average seawater conditions in southeastern australia during the largest of the permian deglaciations were warmer than present day antarctica at similar latitudes but may approximate those of early mid miocene antarctica with frozen winters but summers closer to 10 c