arctic ocean deep water masses in the western iceland sea the icelandic danish contribution to the international greenland sea project was devoted to a study of the distribution and transport of water masses in the western iceland sea each year in september from 1987 to 1991 temperature and salinity were observed on a station net in the area off east greenland from the denmark strait in the south to 72 30 n the data reveal that the deep water column of the western iceland sea is occupied by a number of slightly different water masses which all can be traced back to a formation in the arctic ocean it is especially noticeable that in some years almost undiluted eurasian basin deep water can be observed as far south as the denmark strait

atoll reef island formation and response to sea level change west island cocos keeling islands abstract reef islands around the margin of coral atolls generally comprise unconsolidated holocene sands and gravels overlying a reef flat or cemented conglomerate platform such islands have accreted within the last 3000 4000 years since sea level has reached a level close to present and the reef flat and conglomerate platform have formed island morphology consists of an oceanward ridge a less distinct lagoonward ridge and low lying central depression several alternative models of how such reef islands might have developed are examined in relation to chronology and sediment provenance particularly in the context of the cocos keeling islands where this issue has been debated since darwin visited the atoll which of these models appears most appropriate for an elongate reef island on the atoll margin is assessed using conventional radiocarbon dating of coral shingle and accelerator mass spectrometry ams radiocarbon dating of individual sand grains from pits across west island the dating results suggest that both coral clasts and individual grains of various components are generally reliable and replicable indicators of the chronology of island accumulation implying rapid transport of skeletal material after death of the contributing organisms across the reef flat zone and relatively little reworking the central part of west island appears to have formed first with oceanward accretion up until about 2000 years bp gradual oceanward accretion with lesser lagoonward extension has continued beyond 2000 years bp at the northern and southern ends of the island and a sequence of lagoonward recurving spits has formed adjacent to the inter island passage at the southern end of the island radiocarbon dating of fossil microatolls indicates a gradual fall of sea level over this period which appears to have had little effect on the pattern of island accretion

seasonal cycle of mesoscale instability of the west spitsbergen current abstractthe west spitsbergen current wsc is a topographically steered boundary current that transports warm atlantic water northward in fram strait the 16 yr 1997 2012 current and temperature salinity measurements from moorings in the wsc at 78 50 n reveal the dynamics of mesoscale variability in the wsc and the central fram strait a strong seasonality of the fluctuations and the proposed driving mechanisms is described in winter water is advected in the wsc that has been subjected to strong atmospheric cooling in the nordic seas and as a result the stratification in the top 250 m is weak the current is also stronger than in summer and has a greater vertical shear this results in an e folding growth period for baroclinic instabilities of about half a day in winter indicating that the current has the ability to rapidly grow unstable and form eddies in summer the wsc is significantly less unstable with an e folding growth period of 2 days observations of the eddy kinetic energy eke show a p

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

post glacial sea level rise from a coral record at huon peninsula papua new guinea dating of coral reef terraces can provide a record of changes in sea level which should be pronounced during the transition between glacial and interglacial periods cores drilled from coral reefs at barbados in the equatorial west atlantic1have revealed the sea level changes that occurred during the younger dry as event at the end of the last glacial maximum 11 000 yr bp it has not been known however whether pacific coral reefs can grow at a rate sufficient to keep up with the rise in sea level during such a transition here we report results obtained from a 52 m drill core from the post glacial reef at huon peninsula papua new guinea spanning the interval from 7 000 to 11 000 14c yr bp which show that coral growth kept pace while the relative sea level rose by 50m although the tectonic environment is very different from that at barbados the two records compare well when corrections are made for local tectonic uplift showing that sea level rise was similar at both locations the rate of rise was greatest between 9 000 and 10 00014c yr bp corresponding to the time of the younger dryas

formation of denmark strait overflow water by mixing in the east greenland current abstract hydrographic data and current meter records from the east greenland current collected during theperiod 1987 to 1989 around the latitude of the central greenland sea reveal the formation of a watermass having the characteristics of denmark strait overflow water dsow the downstream southwestward transport of this newly formed water mass can be substantial amounting to roughly halfof the outflow of dsow through denmark strait as reported in the literature the formation of dsow inthe east greenland current results from isopycnic mixing of recirculated atlantic water and upper arcticintermediate water substantial formation occurs when the neccessary conditions for baroclinic instabilityare satisfied and the current variability due to mesoscale eddies is high this is subject to significantchanges from year to year

on the hydrography of denmark strait using 111 shipboard hydrographic sections across denmark strait occupied between 1990 and 2012 we characterize the mean conditions at the sill quantify the water mass constituents and describe the dominant features of the denmark strait overflow water dsow the mean vertical sections of temperature salinity and density reveal the presence of circulation components found upstream of the sill in particular the shelfbreak east greenland current egc and the separated egc these correspond to hydrographic fronts consistent with surface intensified southward flow deeper in the water column the isopycnals slope oppositely indicative of bottom intensified flow of dsow an end member analysis indicates that the deepest part of denmark strait is dominated by arctic origin water with only small amounts of atlantic origin water on the western side of the strait the overflow water is a mixture of both constituents with a contribution from polar surface water weakly stratified boluses of dense water are present in 41 of the occupations revealing that this is a common configuration of dsow the bolus water is primarily arctic origin water and constitutes the densest portion of the overflow the boluses have become warmer and saltier over the 22 year record which can be explained by changes in end member properties and their relative contributions to bolus composition

last deglaciation in the okinawa trough subtropical northwest pacific link to northern hemisphere and tropical climate 1 detailed deglacial and holocene records of planktonic delta o 18 and mg ca based sea surface temperature sst from the okinawa trough suggest that at similar to 18 to 17 thousand years before present kyr b p late spring early summer ssts were approximately 3 degrees c cooler than today while surface waters were up to 1 practical salinity unit saltier these conditions are consistent with a weaker influence of the summer east asian monsoon eam than today the timing of suborbital sst oscillations suggests a close link with abrupt changes in the eam and north atlantic climate a tropical influence however may have resulted in subtle decoupling between the north atlantic and the okinawa trough eam during the deglaciation okinawa trough surface water trends in the holocene are consistent with model simulations of an inland shift of intense eam precipitation during the middle holocene millennial scale alternations between relatively warm salty conditions and relatively cold fresh conditions suggest varying influence of the kuroshio during the holocene

observed sources and variability of nordic seas overflow the overflows from the nordic seas maintain the deep branch of the north atlantic circulation that is an important part of the global climate system an analysis of observed ocean temperatures and salinities between 1950 and 2005 shows that the atlantic water circulating in the nordic seas is the main source for change in the overflow waters

holocene sea level changes and barrier reef formation on an oceanic island palau islands western pacific abstract internal facies and development of an oceanic island s barrier reef were revealed by the stratigraphical study of six drill cores in palau islands western pacific the holocene reef development is primarily constrained at its foundation by the antecedent topography of pleistocene substratum holocene barrier reef is an increment on the pleistocene barrier reef which had been subaerially exposed during glacial stages about 8300 cal year bp calibrated calendar years b p branching acropora facies initially formed a bank on the seaward side of a pleistocene limestone surface with a vertical accumulation rate as high as 30 m ka ka 1000 years after 7200 cal year bp when the sea level rise rate decreased reef crest facies caught up with the sea surface with an accumulation rate of less than 2 2 m ka corals found in the reef crest facies are similar to the present day reef crest corals dominated by acropora digitifera and a humilis after the reef crest was formed bioclastic sand and gravel facies prograded lagoonward of the reef crest and consisted mostly of reef derived materials the construction of patch reefs post dated the barrier reef formation the mature barrier reef provided calm conditions inside the lagoon which then led to the construction of patch reefs and fringing reefs sea level changes deduced from the accumulation curves show rapid rise before 7200 cal year bp followed by a slight rise of 4 m at its maximum this change in sea level rise rate inspired the change in reef facies from branching acropora to reef crest

late holocene sea level changes in yoron island the ryukyus japan abstract several indicators of slightly elevated shorelines have been investigated along the coasts of yoron island the profiles of sea corrosion notches suggest a continuous sequence of former sea levels reaching about 1 5 m above the present sea level in situ fossil barnacles octomeris sulcata collected near the 1 5 m elevation have been dated 800 60 and 730 60 yrs b p a slightly elevated beachrock consisting mainly of calcarina has been dated 2090 60 yrs b p a curve of relative sea level variations in yoron island during the last three thousand years is given in fig 6 no evidence of a differential land uplift during the late holocene has been found along the coast

biogeography of terrestrial and freshwater vertebrates from the late cretaceous campanian western interior of north america abstract previous biogeographic studies of late cretaceous late campanian vertebrate faunas in the western interior basin wib of north america have suggested the presence of faunal and floral provincialism characterized by distinct northern and southern biomes however the provincialism hypothesis has been questioned based largely on the contention that the investigated faunas were recovered from a series of diachronous time transgressive deposits and are therefore non correlative extensive work in several fossiliferous units of late campanian age including the dinosaur park judith river two medicine kaiparowits fruitland kirtland and aguja formations has greatly increased understanding of wib vertebrate faunas and their chronostratigraphic relationships here updated and greatly expanded faunal and chronostratigraphic datasets are utilized to undertake an extensive biogeographic analysis of these six terrestrial fossiliferous formations within the wib of north america quantitative biogeographic comparisons of the formations and their constituent faunas are conducted using four statistical methods analysis of similarity q mode cluster analysis parsimony analysis of endemicity and correspondence analysis the results of this study provide strong support for highly divergent faunas in northern and southern regions of the wib with a latitudinal faunal gradient as an interface yet the nature of the interface between these faunas remains unclear with possibilities including 1 two or more discrete provinces separated by a zone or zones of faunal mixing and 2 a continuous latitudinal gradient or cline with no discrete zones of endemism lacking evidence of any physiographic barrier to north south dispersal climatic variation within the wib is regarded as the most likely explanation for the overarching biogeographic patterns observed for late campanian vertebrate taxa

recent large increases in freshwater fluxes from greenland into the north atlantic 1 freshwater fw fluxes from river runoff and precipitation minus evaporation for the pan arctic seas are relatively well documented and prescribed in ocean gcms fluxes from greenland on the other hand are generally ignored altogether despite their potential impacts on ocean circulation and marine biology here we present a reconstruction of the spatially distributed fw flux from greenland for 1958 2010 we find a modest increase into the arctic ocean during this period fluxes into the irminger basin however have increased by fifty percent 6 3 0 5 km3 yr 2 in less than twenty years this greatly exceeds previous estimates for the ice sheet as a whole the rate of increase since 1992 is 16 9 1 8 km3 yr 2 the cumulative fw anomaly since 1995 is 3200 358 km3 which is about a third of the magnitude of the great salinity anomaly gsa of the 1970s if this trend continues into the future the anomaly will exceed that of the gsa by about 2025

structure and variability of the shelfbreak east greenland current north of denmark strait abstractdata from a mooring array deployed north of denmark strait from september 2011 to august 2012 are used to investigate the structure and variability of the shelfbreak east greenland current egc the shelfbreak egc is a surface intensified current situated just offshore of the east greenland shelf break flowing southward through denmark strait this study identified two dominant spatial modes of variability within the current a pulsing mode and a meandering mode both of which were most pronounced in fall and winter a particularly energetic event in november 2011 was related to a reversal of the current for nearly a month in addition to the seasonal signal the current was associated with periods of enhanced eddy kinetic energy and increased variability on shorter time scales the data indicate that the current is for the most part barotropically stable but subject to baroclinic instability from september to march by contrast in summer the current is mainly confined to the shelf break with

holocene reef growth in the maldives evidence of a mid holocene sea level highstand in the central indian ocean radiometrically calibrated ages from three reef cores are used to develop a holocene reef growth chronostratigraphy and sea level history in the maldives central indian ocean last interglacial reef u series age 122 7 ka was encountered at 14 1 m below mean sea level an age of ca 8100 calibrated cal yr b p immediately overlying this pleistocene surface records the initiation of holocene reef growth massive in situ corals occur throughout the cores and the consistency of the three age depth plots indicate that the reef grew steadily between 8100 and 6500 cal yr b p and at a decreasing rate for the next 2 k y the position of modern sea level was first achieved ca 4500 cal yr b p and sea level reached at least 0 50 1 m higher from 4000 to 2100 cal yr b p before falling to present level emergent fossil microatolls provide evidence of this higher sea level results are significant to two long standing issues relating to maldivian sealevel history first the ambiguity of a late holocene highstand has been resolved with clear evidence of its existence reported here second the uncertainty of the regional pattern of sea level change in the central indian ocean has been clarified the maldivian results broadly agreeing with island records in the eastern rather than western indian ocean our results provide the first field evidence confirming geophysical model projections of a highstand 4 2 k y ago in the central indian ocean though the observed level 0 50 0 1 m is lower than that projected

late pleistocene and holocene melting history of the antarctic ice sheet derived from sea level variations abstract spatial and temporal variations of the late pleistocene and holocene sea levels provide important constraints on the melting history of the major ice sheets in this study we have examined the sea level variations at eight sites along the coast of antarctica to investigate the melting history of antarctic ice sheet complexes comparisons of sea level variations between observations and predictions due to glacio hydro isostatic adjustment suggest that the ice thicknesses removed from the last glacial maximum lgm around the weddell sea are significantly thicker than those around the ross embayment sea level observations also indicate that climap derived models predict too much relative sea level change and that consequently ice mass change along the coast has to be scaled down improvement of the late pleistocene antarctic ice model is required to evaluate more accurate predictions of present day geophysical observables associated with this history thus these more accurate predictions can then be subtracted from observables and the residual field can be analyzed to constrain ongoing mass changes from the ice sheet we therefore predicted present day geophysical observables such as the rate of change of solid surface gravity and crustal movement these geophysical observables based on the ice models constructed from observed sea level variations are significantly different from those based on previous models on the other hand detailed sea level observations around syowa indicate the existence of a sea level highstand of about 10 m around 40 kyr bp to investigate these sea level observations we have performed preliminary numerical calculations comparisons between these observations and predictions indicate the synchronous melting of the northern and southern ice sheets suggesting a strong link between the melting histories of both polar ice sheets

atlantic origin overflow water in the east greenland current abstractdense water masses transported southward along the east coast of greenland in the east greenland current egc form the largest contribution to the denmark strait overflow when exiting den

eddy driven recirculation of atlantic water in fram strait eddy resolving regional ocean model results in conjunction with synthetic float trajectories and observations provide new insights into the recirculation of the atlantic water aw in fram strait that significantly impacts the redistribution of oceanic heat between the nordic seas and the arctic ocean the simulations confirm the existence of a cyclonic gyre around the molloy hole near 80 n suggesting that most of the aw within the west spitsbergen current recirculates there while colder aw recirculates in a westward mean flow south of 79 n that primarily relates to the eastern rim of the greenland sea gyre the fraction of waters recirculating in the northern branch roughly doubles during winter coinciding with a seasonal increase of eddy activity along the yermak plateau slope that also facilitates subduction of aw beneath the ice edge in this area

holocene sea level record from corals reliability of paleodepth indicators at ishigaki island ryukyu islands japan abstract holocene sea level change provides direct evidence of the melting of ice sheets however our understanding of the timing and course of such change is limited by a lack of information regarding environmental condition of corals for example holocene sea level curves are compiled based on water depths estimated from the occurrence of a small number of coral species as species identification is difficult work the error associated with this method of estimating sea level exceeds 2 5 m in addition there generally occurs a difference in the living water depth of corals between high energy reefs and low to moderate energy reefs this difference in living water depth also results in an error in reconstructed sea level curves in the present study we analyzed drill core and recorded the vertical distribution of corals at the high energy ibaruma reef and low to moderate energy fukido reef ishigaki island ryukyu islands japan analyses of corymbose acropora a digitifera massive goniastrea g retiformis massive pocillopora p verrucosa massive platygyra p ryukyuensis and other corals enables the accurate reconstruction of a sea level curve because these species are distributed in a narrow range with a weighted mean m w error of between 0 5 and 2 5 m these observation data from ibaruma and fukido reefs can be used to reconstruct holocene sea level curves based on drill core data from ibaruma reef however the two reefs yield contrasting sea level curves the curve reconstructed based on data from fukido reef is several meters deeper than that reconstructed based on data from ibaruma reef this discrepancy reflects the different energy levels of the two reefs high energy at ibaruma reef and low to moderate energy at fukido reef therefore the accurate reconstruction of a holocene sea level curve requires the identification of species from drill core and observations of the vertical distribution of species at the present day reef at a location close to the drilling site the holocene sea level curve reconstructed based on drill core data from ibaruma reef reveals a rapid sea level rise of approximately 7 5 m kyr 1 between 8000 and 6000 cal years bp the rate of sea level rise decreased from 7 5 to 3 5 m kyr 1 between 6000 and 5000 cal years bp a mid holocene highstand occurred at around 5000 cal years bp at a level of approximately 3 2 5 m above the present mean sea level the increase in ocean volume corresponding to this sea level rise indicates that melting of the antarctic ice sheet continued beyond 6000 cal years bp as most of the northern hemisphere ice sheets had melted by 6000 cal years bp resulting in sea levels similar to those of the present day

high frequency variability in the circulation and hydrography of the denmark strait overflow from a high resolution numerical model abstractinitial results are presented from a yearlong high resolution 2 km numerical simulation covering the east greenland shelf and the iceland and irminger seas the model hydrography and circulation in the vicinity of denmark strait show good agreement with available observational datasets this study focuses on the variability of the denmark strait overflow dso by detecting and characterizing boluses and pulses which are the two dominant mesoscale features in the strait the authors estimate that the yearly mean southward volume flux of the dso is about 30 greater in the presence of boluses and pulses on average boluses pulses are 57 1 27 5 h long occur every 3 2 5 5 days and are more frequent during the summer winter boluses pulses increase decrease the overflow cross sectional area and temperatures around the overflow interface are colder warmer by about 2 6 c 1 8 c the lateral extent of the boluses is much greater than that of the pulses in both cases the along stra

impacts of eustasy and hydro isostasy on the evolution and landforms of pacific atolls consideration of eustatic and hydro isostatic effects on late quaternary sea levels in the tropical pacific ocean indicates that the configuration of modern atolls with emergent annular reef flats is a transient morphology not developed until post mid holocene time annular atoll reefs perched atop carbonate platforms which cap buried volcanic edifices are underlain by 8 28 m of holocene limestone disconformably overlying a substratum of last interglacial or older limestone comparable thicknesses 9 23 m of holocene sediment are present beneath atoll lagoons that are uniformly 85 m deep during glacio eustatic drawdowns in global sea level by 120 125 m carbonate platforms of modern atoll provinces rose abruptly from the sea as clusters of subaerial limestone plateaus flanked by steep cliffs modern analogues are provided by emergent atolls uplifted on the flexural arches of trench forebulges slow subsidence coupled with karstic erosion of emergent atolls during the last glaciation lowered the surfaces of last interglacial reef edifices by the amounts needed to provide accommodation space for holocene reef growth during the postglacial eustatic rise in sea level modern atoll reef caps began to grow after 9 ka when rising holocene sea level overtopped degraded remnants of interglacial reefs but remained submerged until carbonate buildups approached sea level in mid holocene time 6 4 ka classic atoll morphology with circlets of multiple islets dotting annular reefs formed in combination with late holocene hydro isostatic drawdown in tropical pacific sea level in response to equatorial ocean siphoning a facet of global isostatic adjustment gia to deglaciation early holocene eustatic rise in sea level and late holocene hydro isostatic decline in sea level combined to produce a regionally variable mid holocene highstand in tropical pacific sea level that stood 1 0 2 6 m above modern sea level cemented mid holocene paleoreef flats now stranded well above sea level serve as resistant foundations for non migratory pinned islets that were not present along atoll rims until after the local crossover date when ambient high tide level first fell below mid holocene low tide level existing atoll landforms have a time depth generally 1 2 ka

the jan mayen current of the greenland sea oceanographic measurements acquired by the usns bartlett during september 1989 in and north of the area of the jan mayen current jmc show that in terms of upper layer baroclinic flow about half of the jmc is a wide meander in the east greenland current egc and about half continues eastward to close the greenland gyre gg on the south this phenomenon has been charted in the past but has elicited no comment surface drifters and a numerical model corroborate this behavior at deeper depths 100 m the meander dissipates with the flow becoming more easterly a drifting float at 500 m depth confirms that the flow is relatively undeviated toward the east ultimately merging with the northward flowing norwegian atlantic current near the gg the fresh water content of the water column is low in the upper layers but high in the middepths where there is a substantial content of egc water e g in the jmc the converse is usually true the fwc of the gg computed for the period 1953 1966 was smaller by a factor of 2 in both layers than in 1989 indicating that 1989 is in another period of low salinity comparable to that of 1968 the period of the great salinity anomaly described by dickson et al 1988

sources to the east greenland current and its contribution to the denmark strait overflow data from the east greenland current in 2002 are evaluated using optimum multiparameter analysis the current is followed from north of fram strait to the denmark strait sill and the contributions of different source waters in mass fractions are deduced from the results it can be concluded that at least in spring 2002 the east greenland current was the main source for the waters found at the denmark strait sill contributing to the overflow into the north atlantic the east greenland current carried water masses from different source regions in the arctic ocean the west spitsbergen current and the greenland sea the results agree well with the known circulation of the western nordic seas but also add knowledge both to the quantification and to the mixing processes showing the importance of the locally formed greenland sea arctic intermediate water for the east greenland current and the denmark strait

significant role of the north icelandic jet in the formation of denmark strait overflow water the largest dense water plume feeding the lower limb of the atlantic meridional overturning circulation from the nordic seas comes from denmark strait overflow water measurements of hydrography and water velocity north of iceland and ocean model simulations indicate that a significant part of this water is supplied by the north icelandic jet

composition and variability of the denmark strait overflow water in a high resolution numerical model hindcast simulation the upstream sources and pathways of the denmark strait overflow water and their variability have been investigated using a high resolution model hindcast this global simulation covers the period from 1948 to 2009 and uses a fine model mesh 1 20 to resolve mesoscale features and the complex current structure north of iceland explicitly the three sources of the denmark strait overflow the shelfbreak east greenland current egc the separated egc and the north icelandic jet have been analyzed using eulerian and lagrangian diagnostics the shelfbreak egc contributes the largest fraction in terms of volume and freshwater transport to the denmark strait overflow and is the main driver of the overflow variability the north icelandic jet contributes the densest water to the denmark strait overflow and shows only small temporal transport variations during summer the net volume and freshwater transports to the south are reduced on interannual time scales these transports are highly correlated with the large scale wind stress curl around iceland and to some extent influenced by the north atlantic oscillation with enhanced southward transports during positive phases the lagrangian trajectories support the existence of a hypothesized overturning loop along the shelfbreak north of iceland where water carried by the north icelandic irminger current is transformed and feeds the north icelandic jet monitoring these two currents and the region north of the iceland shelfbreak could provide the potential to track long term changes in the denmark strait overflow and thus also the amoc

holocene variability of the kuroshio current in the okinawa trough northwestern pacific ocean abstract cores 255 and b 3gc from the southern and northern okinawa trough respectively were studied for determining the variability of the kuroshio current on centennial scales during the holocene based on detailed ams 14 c dates stable isotope and planktonic foraminiferal distribution the main flow of the kuroshio current was inferred to re enter the okinawa trough at 7 3 calendar cal kyr bp leading to abrupt changes in sedimentation rate remarkably increased abundance of the kuroshio current indicator pulleniatina obliquiloculata increased sea surface temperature sst and depth of thermocline dot during 4 6 2 7 cal kyr bp the abundance of p obliquiloculata sharply decreased corresponding to a decreases in sst and dot implying that the influence of the kuroshio current weakened at that time possibly as a result of the intensified winter monsoon significantly the kuroshio current proxies e g the difference in sst between the southern and northern okinawa trough display periodicities of 1500 yr and 700 800 yr ascribed to the second harmonic of the 1500 yr cycle in oceanic thermohaline circulation during the holocene the holocene events at 0 6 1 7 3 3 4 6 5 9 8 1 9 4 cal kyr bp in the okinawa trough appear to be the most recent manifestation of the millennial scale climate cycle recorded in the north atlantic arabian sea marine sediment cores and greenland ice cores suggesting global climatic tele connections

on the nature of the mesoscale variability in denmark strait abstracttime series data from a mooring in the center of denmark strait and a collection of shipboard hydrographic sections occupied across the sill are used to elucidate the mesoscale variability of the dense overflow water in the strait two dominant reoccurring features are identified that are referred to as a bolus and a pulse a bolus is a large weakly stratified lens of overflow water associated with cyclonic rotation and a modest increase in along stream speed of 0 1 m s 1 when a bolus passes through the strait the interface height of the overflow layer increases by 60 m and the bottom temperature decreases by 0 4 c by contrast a pulse is characterized by anticyclonic rotation a strong increase in along stream speed of 0 25 m s 1 a decrease in interface height of 90 m and no significant bottom temperature signal it is estimated that on average boluses pulses pass through the strait every 3 4 5 4 days with no seasonal signal to their frequency both features have the strongest along

holocene sea level change and ice sheet history in the vestfold hills east antarctica abstract a new holocene sea level record from the vestfold hills antarctica has been obtained by dating the lacustrine marine and marine lacustrine transitions that occur in sediment cores from lakes which were formerly connected to the sea from an elevation of 7 5 m 8000 yr ago relative sea level rose to a maximum 9 m above present sea level 6200 yr ago since then sea level has fallen monotonically until the present the precision of the new record makes it suitable for constraining the recent history of the ice sheet in that region using numerical models of glacio hydro isostasy simplified regional models suggest that the ice sheet margin has retreated 30 40 km since the last glacial maximum with 600 700 m of thinning occurring at the present coastline

tropical pacific climate at the mid holocene and the last glacial maximum simulated by a coupled ocean atmosphere general circulation model 1 simulations for the mid holocene 6000 years before present 6 ka and the last glacial maximum lgm 21 ka have been performed by a global ocean atmosphere coupled general circulation model gcm after the initial spin up periods both runs were integrated for about 200 years for 6 ka the model shows an enhanced seasonal variation in surface temperature and a northward shift of the african and the indian summer monsoon rain area overall circulation features in the tropics correspond to a strong walker circulation state with negative sea surface temperature sst and precipitation anomalies in the central pacific and positive precipitation anomalies over the indian and australian monsoon regions it is noted that there is about a 0 35 c cooling of the global mean sst in contrast to the 6 ka result the simulated tropical climate anomaly at 21 ka corresponds to a weak walker circulation state the simulated lgm sst decrease is about 2 c over the tropical western pacific it is larger about 5 c over the caribbean sea this sst anomaly is in broad agreement with the observed proxy data interestingly the model simulates a warmer than present sst over the subtropical pacific this may be related to a weaker subtropical anticyclone due to weakened monsoon circulation at the lgm

arctic system reanalysis improvements in topographically forced winds near greenland southern greenland is home to a number of weather systems characterized by high speed low level winds that are the result of topographic flow distortion these systems include tip jets barrier winds and katabatic flows global atmospheric reanalyses have proven to be important tools in furthering our understanding of these systems and their role in the climate system however there is evidence that their mesoscale structure may be poorly resolved in these global products here output from the regional arctic system reanalysis asrv1 30 km and asrv2 15 km grid resolutions are compared to the global era interim reanalysis era i 80 km grid resolution focusing on their ability to represent winds in the vicinity of southern greenland comparisons are made to observations from surface and upper air stations as well as from research aircraft flights during the greenland flow distortion experiment gfdex the era i reanalysis has a tendency to underestimate high wind speeds and overestimate low wind speeds which is reduced in asrv1 and nearly eliminated in asrv2 in addition there is generally a systematic reduction in the root mean square error between the observed and the reanalysis wind speeds from era i to asrv1 to asrv2 the exception being low level marine winds where the correspondence is similar in all reanalyses case studies reveal that mesoscale spatial features of the wind field are better captured in asrv2 as compared to the era i or asrv1 these results confirm that a horizontal grid size on the order of 15 km is needed to characterize the impact that greenland s topography has on the regional wind field and climate however even at this resolution there are still features of the wind field that are under resolved

evolution of the east greenland current from fram strait to denmark strait synoptic measurements from summer 2012 we present measurements from two shipboard surveys conducted in summer 2012 that sampled the rim current system around the nordic seas from fram strait to denmark strait the data reveal that along a portion of the western boundary of the nordic seas the east greenland current egc has three distinct components in addition to the well known shelfbreak branch there is an inshore branch on the continental shelf as well as a separate branch offshore of the shelfbreak the inner branch contributes significantly to the overall freshwater transport of the rim current system and the outer branch transports a substantial amount of atlantic origin water equatorward supplementing our measurements with historical hydrographic data we argue that the offshore branch is a direct recirculation of the western branch of the west spitsbergen current in fram strait the total transport of the shelfbreak egc the only branch sampled consistently in all of the sections decreased toward denmark strait the estimated average transport of dense overflow water 27 8 kg m3 and 0 c in the shelfbreak egc was 2 8 0 7 sv consistent with previous moored measurements for the three sections that crossed the entire egc system the freshwater flux relative to a salinity of 34 8 ranged from 127 13 to 81 8 msv the hydrographic data reveal that between fram strait and denmark strait the core of the atlantic origin water in the shelfbreak egc cools and freshens but changes very little in density

holocene sea level change and tectonic uplift deduced from raised reef terraces kikai jima ryukyu islands japan abstract kikai jima kikai island is surrounded by four holocene raised coral reef terraces which are thought to be an offlapping sequence of reef deposits caused by combined effects of seismic uplift and holocene sea level change many studies in this region have investigated holocene sea level changes and reef growth but there are relatively few in which reliable sea level indicators are given we have found that pocillopora verrucosa one of the most abundant coral species on the upper reef slopes of fringing reefs in the ryukyus has its peak abundance at a depth of 1 5 m therefore this species is considered ideal for the analysis of relative sea level change and can be used as a dipstick for the holocene reef deposits in this area based on the distribution of p verrucosa on the four holocene raised terraces we calculate relative paleo mean sea levels to be 10 8 11 1 and 8 5 8 9 m for terrace i 5 0 5 3 m for terrace ii 4 0 4 3 m for terrace iii and 1 9 2 5 m for terrace iv these results combined with hitherto known and newly measured radiometric dates 103 total clearly show that the four terraces formed in response to repeated seismic uplifts at 6 3 4 1 3 1 and 1 4 ka and that sea level was higher than present between 7 0 and 6 3 ka

timing of the last glacial maximum from observed sea level minima during the last glacial maximum ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today but few direct estimates exist of the volume of the ice sheets or the timing and rates of change during their advance and retreat here we analyze four distinct sediment facies in the shallow tectonically stable bonaparte gulf australia each of which is characteristic of a distinct range in sea level to estimate the maximum volume of land based ice during the last glaciation and the timing of the initial melting phase we use faunal assemblages and preservation status of the sediments to distinguish open marine shallow marine marginal marine and brackish conditions and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio hydroisostatic modelling our results indicate that from at least 22 000 to 19 000 calendar years before present land based ice volume was at its maximum exceeding today s grounded ice sheets by 52 5 x 10 exp 6 cu km a rapid decrease in ice volume by about 10 percent within a few hundred years terminated the last glacial maximum at 19 000 250 years

reef coralgal assemblages as recorders of paleobathymetry and sea level changes in the indo pacific province the coralgal framework within the outer reef margin of many indo pacific reefs exhibits three main shallow water communities the environmental significance of which can be inferred by comparison with their modern counterparts a community dominated by tabular acropora gr hyacinthus cytherea with branching pocillopora damicornis p eydouxi montipora digitata occasional domal faviids and mm thick crusts of the coralline algae lithophyllum and mesophyllum mainly typical of the 6 15 m paleodepth range a community including robust branching acropora gr danai robusta a humilis a digitifera and subordinate favia stelligera echinopora gemmacea associated to vermetid gastropods and thick coralline crusts of hydrolithon cf onkodes and neogoniolithon cf fosliei flourishing in depths less than 6 m in medium to high water energy settings a community composed of domal porites cf lutea and p cf lobata with occasional acropora gr danai robusta and cm thick crusts of coralline algae in sheltered habitats in depths less than 10 m these biological assemblages allow us to determine relationships between reef growth and paleobathymetry and consequently to reconstruct regional relative sea level curves high water energy reefal assemblages provide stronger evidence for reconstructing sea level curves than low energy buildups because they have generally been controlled by a keep up growth mode subsiding reef sites seem to be more reliable indicators of sea level variations because they usually present expanded reef sequences

the production of north atlantic deep water sources rates and pathways updating an earlier account by dickson et al 1990 this paper reviews the initial development phase of north atlantic deep water nadw production from the points where the dense inflows from nordic seas cross the greenland scotland ridge to the point off south greenland where the buildup of new production appears almost complete in particular three long term current meter arrays totaling 91 instruments and set at 160 km intervals south from the denmark strait sill are used to validate earlier short term arrays by others and in combination with these earlier arrays to describe the downstream evolution of mean speed depth and entrainment the variability of the overflow current in space and time and the likely contribution of the other three main constituents of nadw production at densities greater than 27 8 from the points of overflow 5 6 sv the transport within this range increases by entrainment and confluence with other contributory streams to around 13 3 sv at cape farewell while recirculating elements prevent us from determining the net southgoing transport a nadw transport of this order appears consistent with recent estimates of net abyssal flow passing south through the north and south atlantic