identification of the kuroshio extension its bifurcation and northern branch from altimetry and hydrographic data during october 1992 august 1999 spatial and temporal variability a methodology is proposed using altimter derived upper layer thickness and baroclinic transport to identify the kuroshio extension the bifurcation point and the northern branch by combining topex poseidon altimeter and climatological data within a two layer reduced gravity model results obtained from the japanese coast to 175 w show that the location of the bifurcation point presents interannual variability that is related with upstream conditions the longitude of the bifurcation point ranged from 147 to 160 e estimates of baroclinic transport at the kuroshio extension and its northern branch decrease steadily to the east trough the region of study from 35 to 11 and from 10 to 3 sv respectively

decadal variability in the kuroshio oyashio extension simulated in an eddy resolving ogcm abstract through analysis of a hindcast integration of an eddy resolving quasi global ocean general circulation model decadal variability in the kuroshio oyashio extension region is investigated with particular emphasis on that of the subarctic oyashio and the kuroshio extension ke fronts the ke front is deep and is accompanied by a sharp sea surface height ssh gradient with modest sea surface temperature sst gradient in contrast the subarctic front is shallow and is recognized as a zone of tight gradient in sst but not ssh as a decadal scale change from a warm period around 1970 to a cool period in the mid 1980s those fronts in the model migrate southward as observed and the associated pronounced cooling is confined mainly to those frontal zones reflecting the distinctive vertical structure of the fronts the mixed layer cooling is the strongest along the subarctic front whereas the subsurface cooling and the associated salinity changes are most pronounced along the ke front concomitan

lethal sandslides from eolian dunes fossil vertebrates entombed within the upper cretaceous djadokhta formation of southern mongolia bear testimony to a heretofore unknown geologic phenomenon mass wasting of eolian dunes during heavy rainstorms evaporation of shallow penetrating rainwater led to progressive calcite accumulation in a thin layer of sand about 0 5 m below the surface of dune lee slopes during rare heavy rainstorms a perched water table developed at the top of calcitic zones positive pore water pressure led to translational slides and fast moving sediment gravity flows that overwhelmed animals on the lee slopes of large dunes and in interdune areas

near surface dynamical structure of the kuroshio extension 1 lagrangian data from 657 svp drifters cnes aviso archiving validation and interpretation of satellite oceanographic data time variable satellite altimeter sea level anomaly and levitus 98 hydrographic data are used to develop 0 25 spatial resolution maps of the mean and eddy circulations in the northwestern pacific during the 1990s drifter velocities at 15 m depth and 200 m temperature data clearly indicate in the kuroshio extension ke jet two prominent meanders that culminate in a 300 km northward deflection east of the shatsky rise at 160 e the interannual trends of aviso mesoscale variance are absent along the path of the meandering ke jet three anticyclonic recirculations can be identified south or southeast of the kuroshio the southernmost around daito island being a new discovery about 3 of the drifters with drogues attached crossed the kuroshio front the aviso currents are correlated at 0 8 with drifter geostrophic velocity the aviso geostrophic currents are adjusted in amplitude to the contemporaneous drifter observations and are further used to compute an unbiased mean geostrophic circulation and the quasi geostrophic reynolds stresses in the ke region the principal axes of the eddy reynolds stresses are oriented along the unbiased mean velocity vectors within the meandering ke jet the time mean horizontal momentum balance that includes both the mean and eddy momentum convergences is used to compute absolute sea level map and its uncertainty at 145 e the 2000 m depth absolute dynamic height referenced to the sea level reveals a heretofore unknown 70 dynamic cm drop from 25 to 42 n

dalton wells geology and significance of debris flow hosted dinosaur bonebeds in the cedar mountain formation lower cretaceous of eastern utah usa the lower cretaceous dalton wells dinosaur locality north of moab utah consists of a 2 m thick stacked succession of four fossil rich bonebeds with an estimated collective lateral extent of more than 4000 m2 to date 215 m2 of the bonebeds have been excavated and more than 4200 vertebrate fossil field specimens have been collected the site occurs at the base of the yellow cat member of the cedar mountain formation and lies unconformably on upper jurassic strata of the morrison formation the age of the assemblage is tentatively accepted as barremian nine dinosaur taxa are recognized making dalton wells one of the richest abundance and diversity lower cretaceous dinosaur localities in the world the bonebeds are rare examples of fossiliferous subaerial debris flow deposits at least four flows originated an undetermined distance up slope from an early cretaceous site of dinosaur bone concentration and flowed through the site carrying bones short distances toward an adjacent area of lakes ponds and wetlands host sediments most likely accumulated on the eastward dipping slopes of a backbulge in a foreland basin the overall depositional setting was alluvial lacustrine in a warm to hot and seasonally wet and dry climate the consistent expression and location of lacustrine facies in both the brushy basin member of the morrison formation and the yellow cat member of the cedar mountain formation indicate that high rates of subsidence typified the dalton wells area both before and after the j k transition and further suggest that there was some form of long term to episodic and localized influence on subsidence the depositional slope required to generate debris flows may have been established by forebulge crustal flexure but could also have been established or amplified by the high rates of subsidence that maintained the lacustrine paleoenvironments in the field area concretionary deposits in the yellow cat member at dalton wells are diagenetic and apparently resulted from groundwater precipitation likely enhanced by the presence of organics bones and lacustrine carbonates the regional and cross facies expression of calcretes in the yellow cat member combined with the rarity of pedogenic indicators confirms that they are not paleosols mineral precipitation likely occurred as groundwater flow was established in response to foreland basin development it remains unknown under what specific circumstances animals died and carcasses accumulated prior to being reworked by debris flows however the stratigraphic association of seasonally wet and dry facies throughout the yellow cat member suggests that drought induced mortality events were probably common in a seasonally wet and dry environment debris flows may have been triggered by intense rainfall or seismic events

hadrosaurid edmontosaurus bonebeds from the horseshoe canyon formation horsethief member at drumheller alberta canada geology preliminary taphonomy and significance three monodominant hadrosaurid bonebeds in the horsethief member of the horseshoe canyon formation uppermost campanian in southern alberta canada are documented each bonebed is hosted by a dec

late quaternary variations in water mass in the shatsky rise area northwest pacific ocean abstract oxygen isotope analysis of planktonic and benthic foraminifera in piston core s 2 collected from the shatsky rise 33 21 75n 159 07 70e water depth 3107 m provides a paleoceanographic record for the last 540 000 years in the northwestern pacific ocean although peaks in the abundance of sinistral neogloboquadrina pachyderma occur during marine isotope stage 2 and particularly 6 and 12 the southward shifting of the subarctic front did not reach the core site during these glacial periods however mass accumulation rates of total organic carbon biogenic opal and terrigenous matter contents indicate that surface productivity increased during cold periods in addition the c n ratio analyzed in organic matter reached values of up to 10 during glacial periods these results imply that delivery of eolian dust to this site was enhanced by strengthened westerly winds during glacial periods down core fluctuations in 13c values of globigerinoides ruber and globorotalia inflata nearly overlap particularly during the period from 540 to 260 ka this latter trend suggest that the subtropical surface water mass prevailed at the core site throughout that period based upon the very small vertical 13c gradient through water column in modern kuroshio current water

a coupled decadal prediction of the dynamic state of the kuroshio extension system abstractbeing the extension of a wind driven western boundary current the kuroshio extension ke has long been recognized as a turbulent current system rich in large amplitude meanders and energetic pinched off eddies an important feature emerging from recent satellite altimeter measurements and eddy resolving ocean model simulations is that the ke system exhibits well defined decadal modulations between a stable and an unstable dynamic state here the authors show that the decadally modulating ke dynamic state can be effectively defined by the sea surface height ssh anomalies in the 31 36 n 140 165 e region by utilizing the ssh based ke index from 1977 to 2012 they demonstrate that the time varying ke dynamic state can be predicted at lead times of up to 6 yr this long term predictability rests on two dynamic processes 1 the oceanic adjustment is via baroclinic rossby waves that carry interior wind forced anomalies westward into the ke region and 2 the low frequency ke variability influenc

isotopic paleoecology of mammals and the middle miocene cooling event in the madrid basin spain abstract the middle miocene underwent profound climatic perturbations detected in worldwide marine and continental records the miocene climatic optimum 17 to 14 ma a warm and humid period was followed by the middle miocene cooling 14 13 8 ma characterized by a sharp drop in temperatures and an increase in aridity triggered by the reestablishment of the eastern antarctica ice sheet the madrid basin located in the central iberian peninsula has furnished a considerable number of miocene fossil sites with a very complete succession of localities from the lower middle miocene to the upper middle miocene middle and upper aragonian mn5 and mn6 local zones db to g mammalian fossil tooth enamel of different taxa including rhinoceros equids gomphothere suids and ruminants from 16 fossil sites spanning from 15 9 ma to 13 2 ma were analyzed for 13c 18oco3 and 18opo4 values with the aim of determining regional paleoecological paleoenvironmental and paleoclimatic changes across this important climate transition the 13c values vary between 11 9 and 6 4 vpdb indicating a c3 environment ranging from woodlands to more open conditions the rhinoceros alicornops simorrense and hoploaceratherium tetradactylum the gomphothere gomphotherium angustidens the cervid heteroprox moralesi and the paleomerycid triceromeryx pachecoi may be regarded as browsers inhabiting more closed environments whereas the equid anchitherium the rhinoceros hispanotherium matritense and the bovid tethytragus langai show a mixed feeding diet related to more open conditions furthermore the variation in 13c values across the fossil sites and local zones indicates drier conditions in local zones db and dc 15 9 14 8 ma a more humid period in local zone dd 14 8 14 1 ma before a return to a drier environment in local zones e f and g 14 1 13 2 ma the 18oco3 and 18opo4 values and calculated 18ow values all track a declining trend from local zones db to dd 15 9 14 1 ma with minimum values in local zone e 18oco3 26 5 2 1 18opo4 18 4 2 4 and 18ow 5 3 2 9 the minimum in 18o values in local zone e 14 1 13 7 ma appears to coincide with a drop in temperature at the time of the middle miocene cooling 14 13 8 ma after this minimum 18oco3 18opo4 and 18ow values recover in local zones f and g 13 7 13 2 ma the calculation of 13cleaf values allowed us to determine plausible biomes that might have existed in the madrid basin during the middle miocene i e a tropical rain forest a tropical deciduous forest a temperate evergreen forest and a xeric woodland scrubland although this method was not able to detect more savanna like environments finally 13cdiet meq values were used to infer mean annual precipitation with values ranging from 250 mm yr local zone dc to 670 mm yr local zone dd which are in accordance with the proposed biomes suggested by the 13cleaf values and fossil mammal assemblages

propagation characteristics of extratropical planetary waves observed in the atsr global sea surface temperature record this paper examines the characteristics of planetary wave signatures that have been found in the along track scanning radiometer averaged sea surface temperature asst record for 1991 1996 longitude time plots for every latitude between 5 and 50 north and south reveal westward propagating wave like patterns at many locations whose speed decreases with latitude like baroclinic rossby waves a two dimensional radon transform method is used to measure the wave speed and its variation with location and time which broadly matches the rossby wave speeds predicted by the most recent theory and those measured by topex altimetry although there are some discrepancies at low latitudes the thermally detected speeds are slower than expected a possible consequence of sampling limitations wave signatures are clearest between 25 and 40 s where the meridional temperature gradient is strongest here observed speeds are 20 30 greater than theoretical predictions planetary wave speed varies considerably with longitude in general it increases toward the west of ocean basins and distinct differences between ocean basins are evident the propagation characteristics of the waves appear to change abruptly at locations consistent with latitudinal variations in seafloor bathymetry particularly midocean ridges in addition eastward propagating signatures are found in the southern ocean the results demonstrate the value of the asst data set as a tool for studying basin scale wave processes as a complement to the use of altimetry by observing the thermal signature of rossby waves the method has the potential to clarify their influence on air sea interaction processes and to contribute to climate modeling studies

unveiling the taphonomy of elusive natural tank deposits a study case in the pleistocene of northeastern brazil abstract fossiliferous natural tanks are a singular type of sedimentary deposit restricted to northeastern brazil which usually preserves a diversified late pleistocene vertebrate fauna their fossil assemblages are taxonomically well known but their taphonomy is poorly understood this work presents a detailed taphonomic analysis of a tank deposit from jirau site ceara state northeastern brazil to improve understanding of the processes that influenced fossil deposition and preservation in natural tanks and to shed light on paleoecological and paleoenvironmental aspects related to the late pleistocene vertebrate fauna from northeastern brazil tank deposits from different localities were also compared to figure out potential taphonomic patterns among them additionally comparisons with other brazilian pleistocene deposits and other debris flow deposits bearing vertebrates were undertaken the study revealed the predominance of the megamammal eremotherium laurillardi in the deposit which we attributed to its abundance in late pleistocene biocoenosis as well as bone resistance scarcity of non mammalian vertebrates is likely related to their paucity in late pleistocene biocoenosis time averaging was evidenced by the co occurrence of different weathering petrographic and color patterns and may have affected the ontogenetic profile of the accumulation relative to the original biocoenosis analyses of weathering stages tooth and trample marks indicate wide exposition of the thanatocoenosis before burial abrasion and petrographic patterns allow reworking in the assemblage to be inferred permineralization and substitution are the fossilization processes observed taphonomy indicates that floods deposited clasts and bioclasts in the tank under an arid or semiarid climate in a debris flow regime comparison with other tank deposits revealed several similar taphonomic features and differences related to sedimentology and stratigraphy taphonomic similarities suggest rather homogeneous environmental conditions in the northeastern brazil during the late pleistocene as previously suggested by taxonomic studies comparison with other brazilian pleistocene deposits shows that tanks have more temporal fidelity than caves coastal and some fluvial deposits the jirau vertebrate accumulation was produced by the reworking and transport of skeletal elements accumulated in a nearby thanatocoenosis and is similar to other better known debris flow hosted vertebrate accumulations

a laboratory experiment and numerical simulation of an isolated barotropic eddy in a basin with topographic β an initial localized eddy was generated in a rotating tank by a source sink method to study the behaviour of an isolated barotropic eddy on a plane the evolution of the eddy was compared with the laboratory experiments by firing beardsley 1976 and by takematsu kita 1985 1988 confirming the northwestward southwestward translation of a cyclonic anticyclonic isolated eddy due to nonlinear effects anticyclonic eddies were contrasted with cyclonic eddies in the tank experiment showing a cyclonic anticyclonic asymmetry due to the topographic as a substitute for the planetary the fluid experiment was simulated well by numerical simulation based on the quasi geostrophic vorticity equation numerical experiments verified the northwestward southwestward translation both for an initially gaussian and initially rankine type isolated cyclonic anticyclonic eddy

seasonal variations in planktonic foraminifera at three sediment traps in the subarctic transition and subtropical zones of the central north pacific ocean the distribution and flux of planktonic foraminifera in the north pacific ocean were studied for a 1 year period beginning in july 1993 using time series samples collected in three sediment traps deployed in a north south transect along 175 e longitude sediment trap locations allowed monitoring of faunas within the subarctic transition and subtropical water masses in this region seasonally high foraminiferal flux rates were recorded at the subarctic site during periods of intense stratification of surface water accompanied by high fluxes of organic matter and biogenic opal contents faunal composition dominated by sinistral forms of neogloboquadrina pachyderma and globigerina umbilicata at the latter site characterized the subarctic water mass feature data collected at the transitional and subtropical sites illustrate differences in seasonal flux rates and in relation to those recorded at the subarctic site faunal composition at the transitional water mass site was dominated by dextral phenotypes of n pachyderma whereas this taxon was absent at the subtropical site also during the period of warmest surface temperature october globigerinoides ruber became dominant at the transitional water mass site in contrast to the subtropical water mass site where globigerinoides sacculifer became dominant while associated with common occurrences of globigerinoides tenellus and globorotalia tumida much lower fluxes of planktonic foraminifera organic matter and biogenic opal also marked subtropical water the distinctive differences in faunal composition and flux rates at the transitional and subtropical sites suggest that little if any exchange of surface water occurred between these two sites and in particular in the area representing the distal kuroshio extension

quasi stationary jets transporting surface warm waters across the transition zone between the subtropical and the subarctic gyres in the north pacific 1 surface flow jets and associated sea surface temperature sst distribution are investigated in the northwestern north pacific using satellite derived surface currents and sst data that can resolve fine spatial scale structure the combined use of these data reveals warm tongue phenomena driven by surface geostrophic jets which extend northeastward in the kuroshio oyashio transition area they roughly coincide with the subarctic front saf defined as the 4 c isotherm at 100 m depth the phenomena appear throughout the year with seasonal cycles which do not correspond with that of the subarctic north pacific their positions are affected by bottom topography so that their quasi stationary and consistent features are suggested thus it is implied that these jets play an important role in transporting warm waters toward the subarctic region the time series of sst and current fields describe the jets year to year variability involving some changes in strength and connections with the kuroshio extension ke and demonstrate the effects of advection by the jets on sst fields when ke extends northward at its crests for 1999 2002 one of the jets along saf simultaneously strengthens resulting in high sst region directly over and along the south side of the jet hydrographic data show warm saline water intrusions along the jets their mean fields also reveal that these jets are vertically well developed forming a boundary between the subtropical and subarctic gyres in the north pacific

response of the separated western boundary current to harmonic and stochastic wind stress variations in a 1 5 layer ocean model abstract a time dependent version of the parsons model geostrophic 1 5 layer model of the ventilated thermocline has been developed to investigate the response of the midlatitude ocean to wind stress variations in a simple configuration in this model the total amount of water is kept constant and the eastern boundary thermocline depth can vary in time so as to maintain mass balance here basin modes are not investigated in contrast to many recent studies but the emphasis is on the line where the motionless second layer outcrops which represents the separated western boundary current it is shown that the position of this line only depends on the wind stress the earth rotation and the thermocline interior solution the position is not influenced by the parameterization of the dissipative processes this generalizes previous results established in the stationary case the displacement of the outcrop line in the case of harmonic or stochastic wind stress variations is computed numerically showing

physical and biological mechanisms for planetary waves observed in satellite derived chlorophyll we examine the evidence for global propagation of planetary wavelike features in sea surface chlorophyll over much of the midlatitude ocean westward propagating signals are seen that travel at the same speed as that predicted for long planetary waves we then test three mechanisms for production of this signal these are horizontal passive north south advection by the wave against a mean background gradient vertical upwelling of nitrate which is converted into chlorophyll and vertical upwelling of chlorophyll itself the tests involve comparisons of the amplitude and phase of the predicted signal with observations the horizontal advective process predicts an amplitude for chlorophyll fluctuations that is in fair agreement with the data though both overestimating and underestimating in places the predictions for the phase difference between the chlorophyll and sea surface height signatures are in good agreement with the data the upwelling biological mechanism could potentially give a large signal in the chlorophyll field but the predicted amplitude patterns and the predicted phase difference which is everywhere negative are not in accord with the observations except in a few regions the amplitude predicted by upwelling of chlorophyll is small compared with the horizontal advection mechanism we conclude that over most of the ocean the chlorophyll signal is well explained by horizontal advective processes although we cannot rule out that there exist locations where additional biological mechanisms may be responsible for at least part of the signal

effects of large scale wind on the kuroshio path south of japan in a 60 year historical ogcm simulation the effects of large scale wind forcing on the bimodality of the kuroshio path south of japan the large meander lm and non large meander nlm were studied by using a historical simulation 1948 2007 with a high resolution ocean general circulation models ogcm the kuroshio in this simulation spent much time in the nlm state and reproduced several aspects of its long term path variability for the first time in historical ogcm simulation presumably because the eddy kinetic energy was kept at a moderate level by using the simulated fields the relationships between wind forcing or kuroshio transport and path variation proposed by past studies were tested and specific roles of eddies in those variations were investigated the long term variation of the simulated net kuroshio transport south of japan was largely explained by the linear baroclinic rossby wave adjustment to wind forcing in the simulated lm events a triggering meander originated from the interaction of a wind induced positive sea surface height ssh anomaly with the upstream kuroshio and was enlarged by cyclonic eddies from the recirculation gyre the cyclonic eddy of the trigger meander was followed by a sizable anticyclonic eddy on the upstream side subsequently a weak strong kuroshio favored the lm nlm the lm tended to be maintained when the kuroshio transport off southern japan was small and increasing kuroshio transport promoted decay of an existing lm the supply of disturbances from upstream which is related to the wind induced ssh variability at low latitudes contributed to the maintenance of an existing lm

the influence of nonlinear mesoscale eddies on near surface oceanic chlorophyll oceanic rossby waves have been widely invoked as a mechanism for large scale variability of chlorophyll chl observed from satellites high resolution satellite altimeter measurements have recently revealed that sea surface height ssh features previously interpreted as linear rossby waves are nonlinear mesoscale coherent structures referred to here as eddies we analyze 10 years of measurements of these ssh fields and concurrent satellite measurements of upper ocean chl to show that these eddies exert a strong influence on the chl field thus requiring reassessment of the mechanism for the observed covariability of ssh and chl on time scales longer than 2 to 3 weeks the dominant mechanism is shown to be eddy induced horizontal advection of chl by the rotational velocities of the eddies

tracer transport in cold core rings pinched off from the kuroshio extension in an eddy resolving ocean general circulation model 1 using an eddy resolving ocean general circulation model we examine the cold core rings pinched off from the kuroshio extension ke focusing on their tracer transport the origin of the tracers in the rings and how they are trapped are directly investigated by releasing two passive tracers corresponding to the ke water and the water in the mixed water region mwr to the north of the ke the cold core rings carry the tracer in the mwr wrapped by the ke water from the surface to the bottom at the pinch off in and above the upper thermocline 26 4 these tracers are trapped in the ring and move along the ring until the rings rejoin the kuroshio even in the lower thermocline 26 4 27 2 a substantial part of the tracers moves along the ring while gradual leakage occurs vorticity balance in the rings is consistent with the passive tracer experiment indicating that water in the upper thermocline moves along the rings while the synchronous movement in and below the lower thermocline is severely contaminated by baroclinic rossby waves these direct estimations are compared with the indirect diagnoses using pv the ratio of drift velocity of ring to its tangential velocity nonlinear parameter and the largest closed contour of stream function in the comoving frame of the ring these indirect diagnoses are consistent with the direct estimation in the upper thermocline but are not good indicators below the lower thermocline the cause of their insufficient performance is discussed

on the kuroshio extension near the emperor seamounts in june july 1982 and november 1983 studies were carried out of the vertical structure of the kuroshio extension along 167 e and the path of the current as it approached the emperor seamount chain in addition records from moored current meters at three locations two at 167 e and one in the main gap of the emperor seamount chain were obtained the kuroshio extension in both 1982 and 1983 turned cyclonically meander wave length of 450 km as it approached the chain the axis of the surface current was located in deep water 3 5 km in 1982 and in relatively shallow water 0 5 km in 1983 in 1982 the horizontal temperature gradient decreased and the density surfaces down to 2000 m ascended as the kuroshio extension flowed over the emperor seamounts in neither year was there evidence of current splitting as it crossed the seamounts in 1983 in contrast to 1982 there was no weakening of the horizontal temperature gradient and the kuroshio extension went over a very shallow portion of kinmei seamount 500 m the current measurements made at the time of the hydrographic section show that the instantaneous kuroshio extended to the bottom abyssal eastward current of 2 cm s 1 the deep low frequency eddy kinetic energy values are intermediate between those measured at 152 e and those at 158 w suggesting a large scale eastward decrease in deep eddy activity zonal mean flow near 3500 m at 167 e was essentially zero 0 1 cm s 1 the mean meridional components were larger 2 1 and 0 7 cm s 1 at the southern side of the gap the deep flow was unusually steady ke km 1 and directed northeastward into the eastern basin of the north pacific low ratios o 1 were also observed in the lower thermocline compared with those at 167 e o 10 100 the frequency content of the gap kinetic energy differed from that measured at 167 e the highest frequency band 2 hours p 2 days was the most energetic whereas at 167 e the mesoscale band 20 days p 150 days was the most energetic the flow in the gap resembles in many of its characteristics that observed in two other channel flows the vema channel and the charlie gibbs fracture zone

post depositional bone destruction in cave sediments a micromorphological study of the mis 5a d cave bear strata of biśnik cave poland

a frequency dependent description of propagating sea level signals in the kuroshio extension region abstracthilbert empirical orthogonal function analysis is used to provide a frequency dependent description of observed sea level variability in the kuroshio extension region 1993 2012 inclusive the dominant high frequency mode periods between 140 and 350 days describes signals that propagate westward with the largest amplitudes in the vicinity of the shatsky rise and emperor seamounts based on the close correspondence between the variance of the high frequency variability and the underlying bathymetry it is speculated that this mode is driven by jet bathymetry interactions the dominant low frequency mode periods longer than 350 days is explained in terms of wind forced jet trapped rossby waves that propagate along the mean kuroshio extension jet one of the most surprising findings of this study is that sea level changes north of the jet in the meander region anticipate changes south of the jet by about 3 yr based on correlations of observed sea level with the pacific decadal oscillation and

decomposition of vertical velocity for nutrient transport in the upper ocean abstractwithin the pycnocline where diapycnal mixing is suppressed both the vertical movement uplift of isopycnal surfaces and upward motion along sloping isopycnals supply nutrients to the eup

pleistocene debris flow deposition of the hippopotamus bearing collecurti bonebed macerata central italy taphonomic and paleoenvironmental analysis abstract an integrated taphonomic sedimentological study provides insight into the origin preservation biases and paleobiological significance of the latest early earliest middle pleistocene bonebed of collecurti near colfiorito macerata central italy which represents an important benchmark in the european biochronological scale sedimentological evidence indicates that the bonebed is hosted in a debris flow deposit which was emplaced in a shallow lacustrine setting geologic and geomorphic controls on sedimentation in the intermontane colfiorito basin provided an ideal setting for the development of cohesive mass flows due to high relief and poorly integrated catchments along the basin margin and the abundance of detrital fines yielded by mesozoic sedimentary rocks of the local basement the fossil assemblage includes 496 bones with a minimum of 24 individuals representing 9 species and 8 genera dominated by hippopotamus antiquus the hippopotamus remains include partially articulated carcass parts as well as closely associated elements few disarticulated elements which are bones that can be more easily transported hydraulically were involved in pre debris flow winnowing and sorting and then entrained by the debris flows in nearby uplands transported a short distance down into a shallow pond or lake margin where the flow buried hippopotamus carcasses that had accumulated in the pond lake the hippopotamus carcasses were in an advanced state of decomposition when the debris flow entrained them their bones show no evidence of weathering trampling scavenging sorting or transportation prior to debris flow reworking which indicates that the animals were probably lying on the bottom of the pond where they lived or were already partially buried in mud previous palynological investigations have shown that the strata of interest at collecurti were deposited during a climatic trend toward ever increasing cooler conditions the low richness of the fauna confirms long exposure to harsh climatic and environmental conditions two are the plausible causes of the death of the collecurti animals i e severe cold and or drought taphonomic attributes rule out drought indicating that the assemblage accumulated in a short time as the result of a mass mortality event possibly due to a cold snap there are no other reported examples of quaternary debris flow hosted bonebeds in europe probably because this agent of taphonomic accumulation is rarely investigated in high energy paleogeomorphic settings it is likely that more such sedimentary events took place in the area and that similar fossil sites await to be discovered

increased sensitivity of the plio pleistocene northwest pacific to obliquity forcing abstract insolation driven changes in poleward heat transport and changes in greenhouse gas concentrations can explain aspects of the rise of obliquity paced climate variability during the pliocene pleistocene transition based on an alkenone based sea surface temperature sst reconstruction of the kuroshio current extension kce we propose here that emergence of this region as the primary locus of ocean atmosphere heat transfer in the pacific ocean promoted northern hemisphere glaciation nhg our record shows that with intensification of nhg at 2 7 ma the kce cooled 2 4 c during glacial intervals likely in nh winter spring these high amplitude 41 kyr sst cycles slightly lead o 18 variations ruling out global ice volume changes as the primary cause the lead of sst over o 18 cycles matches the phasing between these two proxies observed in the tropics supporting changes in co2 concentrations as a unifying mechanism of ocean surface temperature change however the amplitude of the kce sst cycle is twice that of the tropical records pointing to an additional regional process we infer that cooling of the north pacific sea surface by the east asian winter monsoon and associated westerlies intensified during glacial intervals this transfer of heat and moisture from the ocean to the atmosphere potentially furthered glacial formation by accelerating snow fall in north america therefore these results might also support a role for tropical extratropical heat balance in enhancing glacial growth via the obliquity pacing

life and death in a late cretaceous dune field nemegt basin mongolia for more than 70 years red sandstones of the gobi desert have yielded abundant articulated skeletons of late cretaceous dinosaurs lizards and mammals at ukhaa tolgod structureless sandstones are the only fossiliferous facies and we present new evidence for deposition on dune sand sourced alluvial fans that were built at the margins of stabilized eolian bedforms during mesic climatic episodes in laterally and vertically adjacent large scale eolian cross strata in which skeletons are absent we have found abundant tracks of dinosaurs that walked on sparsely vegetated dunes that were active under xeric conditions our study of calcareous concretions in vaguely bedded eolian sandstones suggests that bedding was nearly destroyed by burrowing invertebrates and trampling dinosaurs the accumulation of illuvial clays and pedogenic calcite in these sediments reduced infiltration of rainwater and with attendant climatic change and heavy rainfall events led to fan development

the middle miocene climatic transition east antarctic ice sheet development deep ocean circulation and global carbon cycling abstract the middle miocene represents a major change in state in cenozoic climatic evolution following the climax of neogene warmth in the late early miocene at 16 ma the early stage of this climatic transition from 16 to 14 8 ma was marked by major short term variations in global climates east antarctic ice sheet eais volume sea level and deep ocean circulation in the later stage from 14 8 to 12 9 ma climatic developments included major growth of the eais and associated antarctic cooling a distinct increase in the meridional temperature gradient large fluctuations in sea level followed by a global sea level fall and important changes in deep water circulation including increased production of southern component water east antarctic ice sheet growth and polar cooling also had large effects on global carbon cycling and on the terrestrial biosphere including aridification of mid latitude continental regions increased stability of the eais after 14 8 ma represents a crucial step in the establishment of late neogene global climate systems what controlled these changes in polar climates and the east antarctic ice sheet deep ocean circulation changes probably played a major role in the evolution and variation in polar climates as they have throughout the cenozoic oxygen and carbon isotopic evidence for warm saline deep water production in the eastern tethyan northern indian ocean indicates that meridional heat transport to the antarctic inhibited cenozoic polar cooling and eais growth during the early middle miocene from 16 to 14 8 ma inferred competition between warm low latitude sources derived from the eastern tethyan northern indian ocean and a cold high latitude source southern component water from 16 to 14 8 ma may have been associated with instability in the antarctic climate and cryosphere reduction of warm saline deep water flow to the southern ocean at 14 8 ma may have decreased meridional heat transport to the antarctic cooling the region and leading to increased production of southern component water these middle miocene climatic and cryospheric changes in the antarctic had profound effects on marine and terrestrial climates as the meridional surface temperature gradient increased boundaries between climatic zones strengthened leading to increased aridification of mid latitude continental regions in australia africa and north and south america enhancing the development of grasslands and stimulating the evolution of grazing mammals

differential formation and circulation of north pacific central mode water abstract a repeat hydrographic section along 165 e was analyzed to verify a westward extension of the formation region of the north pacific ocean central mode water cmw suggested by previous synoptic observations and to investigate the relation between the formation region and thermohaline fronts the cmw formation region extends at least as far west as 155 e much farther than recognized in a previous study based on climatology it is located in two interfrontal regions between the kuroshio extension front and the kuroshio bifurcation front kbf and between the kbf and the subarctic front where two types of cmw namely the lighter variety with potential density of 25 8 26 2 kg m 3 and the denser one of 26 3 26 4 kg m 3 are formed how this differential formation of cmw is reflected in its gyrewide distribution was examined using one time sections of the world ocean circulation experiment woce hydrographic program in the north pacific the main circulation paths of the two types of cmw diverge eas

aragonian stratigraphy reconsidered and a re evaluation of the middle miocene mammal biochronology in europe abstract the recently collected fauna of armantes 1a in chron c5br of the armantes section necessitates reinterpretation of the previous bio and magnetostratigraphical correlations between the armantes and vargas sections calatayud daroca basin central spain w krijgsman m garces c g langereis r daams j van dam a j van der meulen j agusti l cabrera a new chronology for the middle to late miocene continental record in spain earth planet sci lett 142 1996 367 380 the long reversal in the vargas section is now correlated to c5br instead of to c5cr on the basis of the biostratigraphical correlation of armantes 1a to the faunas of fuente sierra 2 and 3 in the vargas section which are situated in the basal part of the middle aragonian mn5 this leads to the revised age of 16 0 ma for the early middle aragonian mn 4 5 boundary our age estimate of the mn5 6 boundary is maintained at ca 13 75 ma the vargas section is now considered to start in chron c5cn 2r and to end in c5bn 1n as a result of the revised correlation the duration of the time gap between the fossiliferous parts of vargas and the younger aragon section previously estimated as ca 1 5 myr is now reduced to less than 200 000 years the tie points of the european mammal units mn4 mn6 to the geomagnetic polarity time scale f f steininger w a berggren d v kent r l bernor s sen j agusti circum mediterranean neogene miocene and pliocene marine continental chronologic correlations of european mammal units in r l bernor v fahlbusch h w mittmann eds the evolution of western eurasian neogene mammal faunas columbia univ press new york 1996 pp 7 46 are evaluated our age estimates of the mn4 5 and mn5 6 boundaries are compatible with the new magnetostratigraphic calibration of middle miocene mammal zones in the swiss molasse basin o kempf t bolliger d kalin b engesser a matter new magnetostratigraphic calibration of early to middle miocene mammal biozones of the north alpine foreland basin in j p aguilar s legendre j michaux eds actes du congres biochrom 97 mem trav e p h e 21 1997 547 562

a study of the kuroshio s seasonal variabilities using an altimetric gravimetric geoid and topex poseidon altimeter data the first year of topex poseidon t p altimeter data were used to study the seasonal variabilities of the kuroshio current the intercomparison between the t p and gauge sea levels at selected tide gauge stations around taiwan shows that the two have a correlation of about 0 9 at the immediate vicinity of the deep ocean and both show an annual cycle with an amplitude of 15 cm a 3 3 geoid for the western pacific was constructed by least squares collocation using gravity anomalies and sea surface gradients derived from seasat geosat ers 1 and t p altimetry to account for the oceanographic signal in the altimeter data we derived a covariance function for the gradients of the sea surface topography sst based on a global averaging concept and a spherical harmonic expansion of the levitus sst to degree 50 the accuracy of the geoid ranges from 5 to 40 cm the sst values derived from the geoid and the data along t p s descending tracks were fitted to the hyperbolic functions in a two step procedure to find the kuroshio s seasonal axes and the parameters that describe its characteristics the mean variabilities in the kuroshio s path maximum velocity baroclinic transport and width are 22 km 19 cm 8 sv and 27 km respectively the averaged percentage variability of all quantities is 25 all the variabilities are relatively large near the northeast coast of taiwan and the starting point of the kuroshio extension the large scale circulations over the western pacific were obtained by median filtering the sst at the 1334 km spatial scale the pacific s subtropical gyre is clearly visible and it shows different features over the four seasons and its kinetic energy shows possible correlations with the determined parameters over the south china sea a warm ring with a radius of 300 400 km and a center at 15 n 113 e was detected in the spring and summer

extraordinary preservation in a new vertebrate assemblage from the late cretaceous of mongolia we report here a new locality ukhaa tolgod brown hills from the upper cretaceous of the gobi desert of mongolia which shows an unmatched abundance of well preserved vertebrate fossils including the highest concentration of mammalian skulls and skeletons from any mesozoic site in the main collecting area about 4 km2 recovered and uncollected articulated skeletons of thero pod ankylosaurian and protoceratopsian dinosaurs represent over 100 individuals specimens collected also include skulls many with associated skeletons of over 400 mammals and lizards skeletons including the first known skull of the bird mononykus and nest sites that preserve the first known theropod dinosaur embryos1 in contrast to other mesozoic localities the diversity and abundance of theropods mammals and lizards are unusually high the exceptional preservation of vertebrates from the red bed facies of the gobi upper cretaceous has been attributed to arid conditions2 4 possibly involving catastrophic death and burial during major sandstorms5 although fossils are found in fluvial facies at ukhaa tolgod high concentrations of excellent specimens in aeolian facies support the argument for rapid entombment in sand this contrasts with conditions for the terrestrial upper cretaceous in north and south america where accretionary preservation of fossils in fluvial deposits predominates

amplification of a surface intensified eddy drift along a steep shelf in the eastern mediterranean sea abstract the datasets of the eddies and gyre path tracking egypt egitto program in the eastern mediterranean sea reveal a large mesoscale anticyclone traveling along the libyan shelf surface drifter trajectories combined with a ctd transect accurately quantify the horizontal velocity and the vertical structure of this surface intensified anticyclone the observed westward drift speed is significantly higher than expected from the beta effect alone to study the impact of a steep shelf topography on the propagation of compact surface intensified vortices the authors used a two layer beta plane model with steep continental slope and nearly zonal boundary a perturbation theory derived by g sutyrin for a circular vortex in the upper layer with the lower layer at rest as a basic state is generalized for nonuniform slope in the presence of the image effect an integral momentum balance is used to derive the drifting velocity of an upper layer vortex with the main assumption that a stable and steady drifti

manifestation of oceanic rossby waves in long term multiparametric satellite datasets the characteristics of westward copropagating features in satellite altimetry sea surface temperature and ocean colour data are investigated throughout the global oceans between 50 north and 50 south for the period 1998 2008 a new hybrid filtering approach allowing features with periods between 37 and 410 days to pass polewards of 20 north and south and features with periods between 37 and 205 days to pass within 20 of the equator is found to isolate features whose speed is consistent with predictions of long planetary wave theory throughout much of the oceans features with wavelengths between 300 and 800 km and periods between 205 and 410 days are shown to be a significant source of temperature and chlorophyll variability between 20 and 50 north and south whilst within 20 of the equator signals in the 800 1500 km and 37 205 days range are predominant between 15 and 50 north and south observed propagation speeds are found to closely match those predicted for first mode baroclinic rossby waves by theory in the equatorial pacific and atlantic oceans features with wavelengths 800 2000 km periods 15 40 days and phase speeds 20 50 cm s 1 characteristic of tropical instability waves are preferentially observed the amplitude and phase relationship between copropagating signals in ocean colour and altimetry and sea surface temperature and altimetry is interpreted in terms of the horizontal meridional advection of mean temperature and chlorophyll gradients by rossby waves similar to what has recently been observed for non linear eddies at shorter length scales the observed phase relationships are in good agreement with the range of phases expected for horizontal advection throughout much of the oceans and consistent with the sign of the mean meridional gradients of temperature and chlorophyll these results support the view that horizontal advection be it from waves and or eddies is the dominant mode of covariation of temperature and chlorophyll with sea surface height throughout most of the oceans although the agreement between predicted and observed amplitude and phase relationships is insufficient to completely rule out vertical mechanisms in a few regions we believe that a one size fits all approach for global rossby wave studies can no longer be considered valid and although we have modified our technique to take this into account we advocate future work to develop a fully latitudinally dependent filtering methodology

stratigraphy sedimentology and palaeoecology of the dinosaur bearing kundur section zeya bureya basin amur region far eastern russia since 1990 the kundur locality amur region far eastern russia has yielded a rich dinosaur fauna the main fossil site occurs along a road section with a nearly continuous exposure of continental sediments of the kundur formation and the tsagayan group udurchukan and bureya formations the sedimentary environment of the kundur formation evolves from lacustrine to wetland settings the succession of megafloras discovered in this formation confirms the sedimentological data the tsagayan group beds were deposited in an alluvial environment of the gravel meandering type the dinosaur fossils are restricted to the udurchukan formation scarce and eroded bones can be found within channel deposits whereas abundant and well preserved specimens including sub complete skeletons have been discovered in diamicts these massive unsorted strata represent the deposits of ancient sediment gravity flows that originated from the uplifted areas at the borders of the zeya bureya basin these gravity flows assured the concentration of dinosaur bones and carcasses as well as their quick burial such taphonomic conditions allowed the preservation of sub complete hadrosaurid skeletons unearthed at the kundur site palaeobotanical data indicate a subtropical climate during the deposition of the kundur and udurchukan formations several elements in the composition of the kundur vertebrate fauna suggest a strong influence of the north american late cretaceous vertebrate communities the abundance of corythosaur like lambeosaurines the probable presence of a nodosaurid dinosaur and of a eucosmodontid or microcosmodontid multituberculate a late maastrichtian age is tentatively proposed for the dinosaur bearing sediments in amur region by comparison with the information collected in the western interior basin of north america as it is also observed in the latter area important floristic changes diminution of angiosperm pollens and predominance of modern families and the disappearance of dinosaurs mark the end of the maastrichtian age in the amur region late maastrichtian dinosaur localities from amur region are dominated by lambeosaurines whereas these dinosaurs apparently disappeared from western north america long before the iridium horizon that defines the k p boundary this local disappearance is therefore probably due to ecological factors rather than indicating a gradual extinction of the dinosaurs long before the k p boundary

low frequency variability in regions of the kuroshio extension and the gulf stream using sea surface height data collected by the topex poseidon altimeter we studied the low frequency variability in the kuroshio extension and gulf stream the most significant signals are the basin wide background seasonal cycle and low frequency wave activity generated over major bottom bathymetry and subsequent westward propagation in both regions the spatial structures of the seasonal cycle in the two regions are quite different in the kuroshio extension the seasonal cycle has a northeast southwest orientation and lies closer to the western boundary whereas it has an east west orientation and lies more offshore in the gulf stream the close relationship between the low frequency wave activity and major bottom bathymetry features is discussed through both empirical orthogonal functional eof analysis and calculation of eddy kinetic energy and reynolds stress the spatial structures of these eddy statistics are fundamentally different from those of high frequency mesoscale variability they are not in the proximity of maximum time mean flow but rather they lie mostly to the west of major bottom bathymetry the close association of the clusters of local maximum eddy properties with major bottom topographic features in both regions wave generation over the major bottom topographic features and subsequent westward propagation and difference of the eddy statistics from that associated with high frequency mesoscale variability all suggest that unlike in the case with high frequency mesoscale variability generation in which internal dynamics of the background mean flow such as nonlinear instability plays a fundamental role external forcing through bottom topography must play a fundamental role in generating the low frequency wave activity

satellite observations of chlorophyll phytoplankton biomass and ekman pumping in nonlinear mesoscale eddies nonlinear mesoscale eddies can influence biogeochemical cycles in the upper ocean through vertical and horizontal advection of nutrients and marine organisms the relative importance of these two processes depends on the polarity of an eddy cyclones versus anticyclones and the initial biological conditions of the fluid trapped in the core of the eddy at the time of formation eddies originating in the eastern south indian ocean are unique in that anticyclones typically associated with downwelling contain elevated levels of chlorophyll a enhanced primary production and phytoplankton communities generally associated with nutrient replete environments from analysis of 9 years of concurrent satellite measurements of sea surface height chlorophyll phytoplankton carbon and surface stress we present observations that suggest eddy induced ekman upwelling as a mechanism that is at least partly responsible for sustaining positive phytoplankton anomalies in anticyclones of the south indian ocean the biological response to this eddyinduced ekman upwelling is evident only during the austral winter during the austral summer the biological response to eddy induced ekman pumping occurs deep in the euphotic zone beyond the reach of satellite observations of ocean color

oceanography the rossby rototiller planetary waves also known as rossby waves propagate throughout the world s oceans on very large scales they influence the ocean climate system and also it seems the delivery of nutrients to the ocean surface

distribution of sei whales balaenoptera borealis in the subarctic subtropical transition area of the western north pacific in relation to oceanic fronts the subarctic subtropical transition area of the western north pacific is an important summer feeding grounds of sei whales the oceanographic structure and circulation of this area are largely determined by strong oceanic fronts and associated geostrophic currents namely the polar front pf subarctic front saf and kuroshio extension front kef the relationship between the distribution of sei whales and oceanographic fronts was investigated using a generalized additive model gam and the cetacean sighting survey data and oceanographic observations in july from 2000 to 2007 were used in the analysis the number of individual sei whales was used as the response variable while the distances from the pf saf and kef to the whales were used as explanatory variables along with the longitude values sei whales were concentrated north and south of the saf and the areas from 250 to 300 km north and from 100 to 200 km south of the saf were estimated as high density areas of sei whales the entire inter frontal zone between the pf and saf featured an elevated concentration of sei whales and the area south of the pf and along the saf was identified as an important feeding ground of sei whales in july from 2000 to 2007

multiproxy reconstruction of the palaeoclimate and palaeoenvironment of the middle miocene somosaguas site madrid spain using herbivore dental enamel profound palaeoclimatic changes took place during the middle miocene the miocene climatic optimum 20 to 14 13 5 ma was followed by a sudden 200 ka decrease in temperature and an increase in aridity around the world as a consequence of the reestablishment of the ice cap in antarctica somosaguas palaeontological site madrid basin spain has provided a rich record of mammal remains coincident with this global event middle miocene biozone e 14 1 13 8 ma it contains four fossiliferous levels t1 t3 1 t3 2 and t3 3 with t1 being the oldest that span an estimated time of 105 125 ka scanning electron microscope sem and rare earth element ree analyses performed on herbivore tooth enamel gomphotherium angustidens anchitherium cf a cursor conohyus simorrensis prosantorhinus douvillei and ruminants indicate that diagenetic processes have not been intense enough as to obscure the original geochemical signal stable isotope 18oco3 13cco3 and 18opo4 analyses have been measured on the herbivore tooth enamel across these levels with the aim of determining to what extent the global cooling and aridity pattern is recorded at this site a decrease in 18oco3 and 18opo4 has been detected from t1 to t3 3 and t3 1 to t3 3 respectively indicating a progressive drop of about 6 c from around 18 c to 12 c in mean annual temperatures within t3 tooth enamel 13c values experience an increase from t3 1 to t3 3 suggesting an increase in aridity ba ca analyses have also been performed on the tooth enamel in order to detect changes in the palaeoecology of the studied taxa this ratio allows the establishment of particular feeding patterns such as a more browsing habit in the case of gomphotherium angustidens compared to anchitherium cf a cursor as suggested by higher ba ca values in the latter trace elements do not support any significant change across the succession in the dietary behaviour of the species analyzed despite the stable isotopes evidence of an important palaeoclimatic shift from t1 to t3 3

rossby wave and ocean color the cells uplifting hypothesis in the south atlantic subtropical convergence zone 1 rossbywavessignaturesonfilteredoceancolordataare detected in the subtropical convergence zone of the south atlantic ocean we investigate whether these chlorophyll anomalies can be accounted for by the uplifting mechanism of phytoplanktonic cells associated with the passage of a rossby wave we consider vertical chlorophyll profiles exhibiting a subsurface chlorophyll maximum typical of the south atlantic subtropical convergence province chlorophyll remotely sensed concentrations resulting from an academic uplifting of the three chlorophyll profiles are reconstructed with a radiative transfer model amplitude of the chlorophyll enrichments found with this hypothesis 0 06 mg chl m 3 compares well with propagative ocean color anomalies detected in the seawifs data however other processes such as the rototiller effect siegel 2001 or advection of chlorophyll gradients could also play a non negligible role index terms 4560 oceanography physical surface wavesandtides 1255 9325information related to geographic region atlantic ocean 4552 oceanography

taphonomy of debris flow hosted dinosaur bonebeds at dalton wells utah lower cretaceous cedar mountain formation usa abstract a taphonomic study of the lower cretaceous dalton wells dw dinosaur bonebeds near moab utah provides insight into the origins preservational biases and paleobiological significance of one of the richest and most diverse early cretaceous dinosaur sites known the bonebeds occur in a stacked succession of debris flows at the base of the yellow cat member of the cedar mountain formation which was deposited in a seasonally dry alluvial lacustrine setting although only 5 of the locality has been collected more than 4200 bones were recovered representing an assemblage overwhelmingly dominated by dinosaurs with a minimum of 67 individuals that represent at least eight genera the assemblage also includes eight elements from four non dinosaurian reptiles the dinosaur fauna is sauropod dominated mni minimum number of individuals 41 a basal macronarian mni 15 venenosaurus mni 3 a camarasaurid mni 2 and a large number mni 21 of generically unassigned sauropod elements other dinosaurs include the theropods utahraptor mni 9 nedcolbertia mni 2 a possible ornithomimid mni 2 plus a large iguanodontid mni 4 and the ankylosaurid gastonia mni 9 patterns of skeletal articulation and clustering ontogenetic representation and bone surface modification indicate that the assemblage accumulated and was exposed for more than a year as the result one or more multiple mass mortality events likely droughts that culled large numbers of subadults from the biocoenose carcasses and disarticulated elements were reworked then later transported a short distance and buried by a succession of debris flows skeletal representation data patterns of sorting breakage burrows abrasion and scratch marks provide evidence for sorting trampling and scavenging prior to debris flow reworking pre debris flow sorting is attributed to earlier hydraulic winnowing of easily transported elements the intensity and thoroughness of breakage involving 97 of the elements suggest highly focused high load impacts compatible with trampling by sauropods and iguanodontids lightly abraded and vertically displaced elements indicate episodes of trampling in soft mud trampling occurred before and after debris flow transport theropod tooth marks are uncommon but bone scavenging by osteophagous insects was common and severe resulting in substantial damage to articular surfaces comparisons of dw and other debris flow hosted bonebeds indicate that there are few consistent patterns among fossil assemblage and bone modification data however there are numerous similarities in the geological and spatial taphonomy datasets from these sites resulting from the similar physico hydraulic conditions under which elements were transported reworked and buried geologically and taphonomically dalton wells is similar to the blagoveshchensk monodominant hadrosaur bonebed in the udurchukan formation of eastern russia which also is interpreted as a debris flow hyperconcentrated flow deposit dalton wells also shares geologic and taphonomic characteristics with four bonebeds southeast of the town of green river utah and all occur at the base of the yellow cat member the uniform stratigraphic occurrences of the dalton wells blagoveshchensk and the green river sites resting on an unconformity and their shared sedimentologic and taphonomic features indicate that these sites originated in response to similar tectonic depositional and biostratinomic factors

models of miocene marginal lacustrine sedimentation in response to varied depositional regimes and source areas in the madrid basin central spain abstract a succession of lake complexes formed through miocene times in the madrid basin central spain the complex formed during the aragonian stage provides an outstanding opportunity to evaluate the role of source areas and depositional regimes in the construction of coeval marginal lacustrine deposits sedimentary facies of the aragonian lake indicate a shallow lake that was fringed to the nw and s by arkosic alluvium to the n by litharenitic alluvial fans and to the ne and e by alluvial fans distally dominated by large floodplains marginal lacustrine deposits in the arkosic realm mostly consist of mg smectites and dolomite sequences that laterally interfinger with sepiolite beds which were deposited in small discontinuous ponds in the distal alluvial fan areas occasionally micaceous rich sandy streams entered the lake forming sheets at their entry points in contrast the northern margin of the lake was formed by muddy flats which were influenced by fluctuation in the water table in this setting illitic mudstones are commonly interbedded with biotite rich flood sands showing a sheet like geometry meandering channels occasionally cut into the mud flats facies assemblages on this side of the lake were mainly derived from low grade metamorphic areas to the northeast the marginal lacustrine facies consist of silty clays carbonate paleosols and paludal to lacustrine limestones these facies reflect an interfingering between the lake and a wide stream floodplain system derived from a carbonate source area the mosaic of marginal lacustrine facies in the madrid basin during the aragonian is discussed in the light of lithological and geochemical factors related to variations in source areas

a comparison of surface eddy kinetic energy and reynolds stresses in the gulf stream and the kuroshio current systems from merged topex poseidon and ers 1 2 altimetric data analyses of surface eddy kinetic energy eke inferred from 5 years of merged topex poseidon and ers 1 2 altimetric data are presented in the gulf stream gs and the kuroshio ks current systems focusing on anisotropy and eke seasonal interannual and long term variations as well as reynolds stresses for both gs and ks a descriptive analysis of the eke field shows that it is anisotropic along the path of the currents and assesses the close relationship between the spatial distribution of eke high levels and bottom topography a striking ocean feature is found in the gs shaped as a zonal double blade structure in the eke field centered at 37 n 71 5 w that likely corresponds to a regular and permanent lateral displacement of the mean path of the current at this geographical location maps of eke seasonal means for years 1993 1996 and 1997 provide a detailed description of the surface variability meanders pinched off eddies etc and show strong interannual variations in the ks eke monthly mean changes in the ks reveal a well marked seasonal cycle during the first 3 years 1993 1995 with eke peaking in july august this is followed by a constant increase of its level from the beginning of year 1996 till the beginning of 1997 during this increase the zonal velocity variance u 2 is up to 30 higher than its meridional counterpart suggesting a zonal acceleration of the eastward flow eke seasonal changes are also found in the ks current 30 35 n 130 140 e and also show a regular annual cycle during the first 3 years which precedes by 2 months the eke seasonal cycle in the ks extension maximum in may june the maximum in eke in both regions precedes by 2 months the maximum surface transport found by qiu et al 1991 and zlotnicki 1991 occurring in july and late september respectively no such annual cycle is found in the gs region during the first 3 years year 1996 is anomalous in both current systems with mean eke level that increases by more than 20 compared to the other years also eke monthly mean changes in the ks reveal a well marked positive tendency in the eastern part of the current of more than 300 cm2 s 2 yr 1 and a negative tendency both in its eastern part and in the ks current this feature is absent from the gs at last eddy mean flow interaction is presented both the spatial averaging of turbulent quantities and the relative contribution of the different terms of the horizontal momentum fluxes are discussed a tentative explanation is given for the anomalously large u 2 at the end of 1996 in the ks extension

a 370 ka paleoceanographic record from the hess rise central north pacific ocean and an indistinct kuroshio extension abstract a 5 m long core np36 collected from the hess rise in the central north pacific ocean 34 11 7 n 179 15 4 e water depth 2664 m was analyzed for benthic and planktonic foraminifera this core yields a continuous record for the last ca 370 000 years according to the oxygen isotope stratigraphy cross spectral analysis of down core variations in planktonic 18o values correlates well with the specmap reference scale allowing recognition of marine isotope stages mis down to mis 10 and the 18o variations coincide well with the changes in sea surface temperature derived using the modern analogue technique time series analyses of mass accumulation rates mar of planktonic and benthic foraminifera were also performed along with analysis of variations in faunal composition mar of planktonic foraminifera display maxima during glacial periods which together with coincident changes in lightness l of sediment measured with the spectrophotometer strongly suggests increasing flux of eolian dust to the hess rise due to strengthened westerly winds however mar of benthic foraminifera including epistominella exigua a common typical phytodetritus feeder also display highest increases during some interglacial periods i e mis 5 and 7 the benthic mar maxima are thought to reflect variations in consumption patterns between benthic and planktonic species a proposed hypothesis that vigorous grazing of phytoplanktons occurred during glacial periods reducing the flux of phytodetritus to the sea floor in turn impacting and limiting production of benthic foraminifera with the opposite effect prevailing during interglacial periods down core variations in right coiling neogloboquadrina pachyderma abundance and the composition of planktonic foraminiferal faunas indicate the subarctic front did not shift southward over the study site during the past 370 000 years alternatively variations in faunal composition indicate that subtropical water prevailed in the study area throughout this period no clear faunal evidence of the presence of the kuroshio extension was found in core np36 reflecting the loss of heat and tropical faunal elements from this water mass as it flowed eastward during late quaternary climatic maxima and minima

upgradient and downgradient potential vorticity fluxes produced by forced rossby waves part i basic experiments abstractthe mean flow and potential vorticity pv flux produced by rossby waves are examined particularly by focusing on the effects of stratification and nonlinearity on upgradient and downgradi

phytoplankton pigment distribution from seawifs data in the subtropical convergence zone south of africa a wavelet analysis the agulhas system agulhas current retroflection agulhas return current arc south of africa constitutes a complex energetic system subject to high frequency mesoscale and low frequency variability using chlorophyll pigment concentration data collected by the seawifs ocean color sensor and sea surface height satellite data we demonstrate the utility of wavelet analysis in jointly analyzing ocean color and altimetric signals two distinct dynamical scenarios of the agulhas system october 1997 and january 1998 yield different dominant wavelengths 620 and 500 km for the arc rossby wave they are simultaneously retrieved from the chlorophyll and sea level anomaly signals longitudinal extension of the power resulting from the wavelet analysis also depends on the dynamical regime

decadal shifts of the kuroshio extension jet application of thin jet theory abstractmeridional shifts of the kuroshio extension ke jet on decadal time scales are examined using a 1960 2004 hindcast simulation of an eddy resolving ocean general circulation model for the earth simulator ofes the leading mode of the simulated ke represents the meridional shifts of the jet on decadal time scales with the largest southward shift in the early 1980s associated with the climate regime shift in 1976 77 a result confirmed with subsurface temperature observations the meridional shifts originate east of the date line and propagate westward along the mean jet axis a trajectory inconsistent with the traditionally used linear long rossby waves linearized in cartesian coordinates although the phase speed is comparable to that in the traditional framework the zonal scale of these westward propagation signals is about 4000 km and much larger than their meridional scale to understand the mechanism for the westward propagation of the ke jet shifts the authors consider the limit of a thin

seasonal succession vertical distribution and dissolution of planktonic foraminifera along the subarctic front implications for paleoceanographic reconstruction in the northwestern pacific abstract the regional spatial and depth distribution of planktonic foraminifera were studied through sediment trap observations at two stations stations wct 5 about 41 n 150 e and wct 6 about 42 n 155 e along the subarctic front in the northwestern pacific ocean the sediment traps were moored at 1000 and 4500 m depths at station wct 5 and 1091 2051 and 4871 m depths at station wct 6 the samples were collected from 17 august 1998 to 10 august 1999 at station wct 5 and from 15 august 1999 to 6 august 2000 at wct 6 at station wct 5 two distinct annual periods of increased total foraminiferal and species production were evident the period of highest production was in autumn with a secondary period in early summer at station wct 6 high total foraminiferal shell fluxes occurred in april may and september october the april may spring bloom of planktonic foraminifera apparently began each year as the sea surface temperature sst increased after winter and the decrease of thickness of the mixed water layer during june july in every year following the cessation of bloom the most common foraminiferal species in the study region were globigerina quinqueloba neogloboquadrina pachyderma neogloboquadrina dutertrei neogloboquadrina incompta globigerinita glutinata globigerina bulloides globigerina falconensis globorotalia theyeri globorotalia scitula and globigerinella calida foraminiferal fluxes displayed a distinct seasonality at all trap depths at both stations at station wct 5 in 1998 1999 foraminiferal species were scarce in the surface water during spring and summer and the dominant foraminiferal species were most productive during winter and autumn at station wct 6 the dominant foraminiferal species were most productive during late winter to spring and all species showed a peak in middle spring may a comparison of seasonal patterns of dominant foraminiferal species between the northwestern and northeastern pacific demonstrated that foraminiferal productivity was a good proxy for sea surface temperature and mixing of water column significant dissolution of foraminiferal tests was evident in the deepwater column and was used to estimate the foraminiferal lysocline depth 4500 m in the northeastern pacific basin

taphonomy of mammalian fossil bones from the debris flow deposits of somosaguas north middle miocene madrid basin spain abstract debris flow hosted assemblages dominated by mammalian remains are very scarce in the fossil record and few examples are reported herein we present a detailed taphonomic study of somosaguas north madrid basin spain a middle miocene mammalian dominated site embedded in debris flow deposits in order to increase our knowledge of the mode of formation of fossiliferous assemblages in this depositional context the assemblage includes 6592 large mammal remains belonging to at least 10 different species fossils are found in matrix supported poorly sorted coarse arkosic sandstones and fine conglomerates which are interpreted as the result of successive debris flow deposits breakage constitutes a pervasive taphonomic alteration in the bone assemblage however together with unidentifiable bone fragments we also found complete to almost complete skeletal elements bone remains are isolated a fact that is indicative of a time of exposure of the carcasses long enough to enable decay and complete disarticulation there are no associations of elements belonging to the same individual which suggests that prior to or during debris flow transport bones were profusely dispersed based on the taphonomic evidence we suggest that somosaguas north assemblage was formed by successive debris flow transport and burial of pre existing thanatocoenoses bones from those thanatocoenoses were modified by biostratinomic agents trampling weathering in varying degrees depending on their time of exposure debris flow transport produced further abrasion and breakage in collagen depleted bones our results are congruent with an environmental context of semiarid landscapes presenting long arid periods and highly irregular hydrological seasonality finally we compared the somosaguas north assemblage with other debris flow hosted vertebrate assemblages although somosaguas north shares taphonomic features with some of these sites it is not possible to define consistent and single taphonomic patterns for debris flow assemblages given the varied taphonomic histories of the remains prior to and during debris flow transport

annual and interannual variability in the kuroshio current system abstract individual seasonal 300 m temperature maps were constructed over the kuroshio current system from 130 e to 170 w for a 4 year period from summer 1976 through spring 1980 using transpac xbt data and jodc temperature depth data quasi stationary meanders in the kuroshic current system occurred at 137 c i e kuroshio meander at 144 e and 150 e i e lee wave meanders and near 160 e i e meander over the shatsky rise a composite of the paths of the kuroshio i e the 12 c isotherm from the individual seasonal maps and the total variance map finds nodes i e minima and anti nodes i e maxima of variability to have existed along the mean kuroshio path the anti nodes coincided with the location of the quasi stationary meanders the nodes in between zonal propagation of temperature anomalies accounted for 20 30 of the total interannual variance these temperature anomalies propagated eastward at 0 5 1 5 cm s 1 in the region 140 155 e and westward at 1 to 2 cm s 1 in the re

radiolarian assemblages in surface sediments along longitude 175 e in the pacific ocean abstract this study of 24 surface sediment samples along longitude 175 e between latitudes 48 n and 14 s in the western pacific ocean documents the relationship between the modern distribution of radiolarian assemblages and present oceanographic conditions ninety two species were classified into eight clusters by using r mode cluster analysis q mode cluster analysis was used to distinguish five geographical zones which were interpreted to represent the tropical southern subtropical northern subtropical transitional and subarctic climatic zones species richness diversity and equitability are highest in the tropical and transitional zones we attempted to formulate new regression equations considering ecological information on the vertical distribution of radiolarian species transfer functions were derived from regression analysis of radiolarian assemblages to observed sea surface temperature sst values the transfer functions have a standard error of 1 16 c in the estimate of winter sst 0 81 c in that of summer sst

interaction of barotropic vortices with coastal topography laboratory experiments and numerical simulations the interaction of a barotropic cyclonic vortex on a b plane with a strong topographic slope is studied by means of laboratory experiments and numerical simulations in the laboratory the vortex is produced in a rectangular rotating tank with a weak uniformly sloping bottom slope angle 3 58 in order to simulate the b effect the cyclonic vortex moves in the northwestward direction and interacts with an additional pronounced linear topography slope angle 358 along the western boundary of the tank the laboratory experiments revealed that the original northwestward trajectory changes to the south until the vortex is dissipated by viscous effects and bottom friction as it moves upslope the exterior ring of the vortex forms a strong current to the northeast from this current a new cyclonic vortex is created repeating approximately the behavior of the original one later two more vortices are formed in the same way a finite difference numerical model is used to solve the nondivergent barotropic equation despite the presence of the strong slope agreement between laboratory results and numerical runs suggests that conservation of potential vorticity is indeed the basic mechanism involved in the southward motion of the vortex and the northeastward meandering current

divergent eddy heat fluxes in the kuroshio extension at 144 148 e part i mean structure the kuroshio extension system study kess provided 16 months of observations to quantify eddy heat flux ehf from a mesoscale resolving array of current and pressure equipped inverted echo sounders cpies the mapped ehf estimates agreed well with point in situ measurements from subsurface current meter moorings geostrophic currents determined with the cpies separate the vertical structure into an equivalent barotropic internal mode and a nearly depth independent external mode measured in the deep ocean as a useful by product of this decomposition the divergent ehf dehf arises entirely from the correlation between the external mode and the upper ocean thermal front ehfs associated with the internal mode are completely rotational dehfs were mostly downgradient and strongest just upstream of a mean trough at 1478e the downgradient dehfs resulted in a mean to eddy potential energy conversion rate that peaked midthermocline with a magnitude of 10 3 10 23 cm 2 s 23 and a depth averaged value of 3 3 10 23 cm 2 s 23 dehfs were vertically coherent with subsurface maxima exceeding 400kwm 22 near 400 m depth the subsurface maximum dehfs occurred near the depth where the quasigeostrophic potential vorticitylateralgradientchangessignfromonelayertothenextbelowit thesteeringlevelisdeeperthanthis depth of maximum dehfs a downgradient parameterization could be fitted to the dehf vertical structure with a constant eddy diffusivity k that had values of 800 1400m 2 s 21 along the mean path the resulting divergent meridional eddy heat transport across the kess array was 0 05 pw near 35 258n which may account for 1 3 of the total pacific meridional heat transport at this latitude

features of the water mass front in the northwestern north pacific analysis of the hydrographic data taken in the northern north pacific has revealed a water mass front defined as the abrupt change of mixing rates between the two typical water masses typical water masses are situated above the main thermocline in the subtropical and subpolar gyres this front termed water mass front in the present study can be regarded as the boundary between the subtropical gyre and the subpolar gyre the index for detecting the frontal position from the temperature field is given as the 5 c isotherm at the 300 m level comparisons with data from previous studies are also made and this front appears to correspond to the subarctic front in almost every instance

messor barbarus ants as soil bioturbators implications for granulometry mineralogical composition and fossil remains extraction in somosaguas site madrid basin spain abstract few studies have inquired about the relationship between myrmecological activity and the granulometry and mineralogy of sediments of a palaeontological site the objectives of this article are to determine the sedimentological or mineralogical distinctions produced by ants of the species messor barbarus when excavating their nests and extracting grains and vertebrate fossil remains from the miocene palaeontological site of somosaguas madrid spain to evaluate the degree of taphonomic influence this myrmecological activity has on the fossil remains and to decide whether or not it can be used as a tool for palaeontological prospection results show that messor barbarus does not alter fossil remains when examined under a 10 binocular magnifying glass ants preferentially extract from the ant nest grains of medium sizes 0 25 2 mm compared to the non ant modified soils and also extract a higher quantity of feldspars these significant granulometric and mineralogical modifications should be considered when carrying out compositional sedimentological or stratigraphical studies since these can become biased and alter geological interpretations as provenance or palaeoclimatic signal grain size selection could be due to messor barbarus physical capacities or the use of clay particles as cementing elements in nests mineralogical distinction may be related to feldspars embayments and pits filled with finer material mainly smectites making transportation and pheromone impregnation easier results show that the ant mounds had increasing concentrations of fossil remains the nearer they were from the main excavation area therefore the study of ant mounds in potentially fossiliferous zones can indeed be used as a new method of palaeontological prospection

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

eddies masquerade as planetary waves the advent of satellite based remote sensing of ocean color in the late 1970s 1 provided the first largescale views of chlorophyll distributions in the upper ocean these distributions are a proxy for the biomass of phytoplankton which drive oceanic productivity more recently ocean color measurements have been combined with satellite data on sea surface height ssh and other physical properties of the ocean to elucidate the processes that regulate primary production in the sea on page 328 of this issue chelton et al 2 further advance this field by showing that ocean eddies exert a strong influence on near surface chlorophyll

covariations of sea surface temperature and wind over the kuroshio and its extension evidence for ocean to atmosphere feedback abstract satellite microwave measurements are analyzed revealing robust covariability in sea surface temperature sst and wind speed over the kuroshio extension ke east of japan ocean hydrodynamic instabilities cause the ke to meander and result in large sst variations increased reduced wind speeds are found to be associated with warm cold sst anomalies this positive sst wind correlation in ke is confirmed by in situ buoy measurements and is consistent with a vertical shear adjustment mechanism namely an increase in sst reduces the static stability of the near surface atmosphere intensifying the vertical turbulence mixing and bringing fast moving air from aloft to the sea surface south of japan the kuroshio is known to vary between nearshore and offshore paths these paths are very persistent and can last for months to years as the kuroshio shifts its path coherent wind changes are detected from satellite data in particular winds are high south of tokyo when the kuroshio takes the near

surface water hydrography of the kuroshio extension during the pliocene pleistocene climate transition abstract the pliocene pleistocene climate transition offers an opportunity to study the effect of glaciation on the ocean climate system we present a globigerinoides ruber 18 o record from ocean drilling program site 1208 kuroshio current extension kce this exclusively sub tropical foraminifer a summer fall mixed layer dweller at the kce affords the first long 3 0 ma to 1 8 ma orbital scale 2 5 kyr time step account of the sea surface in this area the section s temperature corrected benthic foraminiferal 18 o record constrains global changes in ice volume yielding a 18 o record that primarily reflects summer fall kce hydrography temperature and salinity a 0 3 decrease in 18 o values at 2 7 ma coincides with the onset of northern hemisphere glaciation indicating as much as 1 5 c warming during the summer fall to suggest that the subtropical north pacific sea surface provided heat and moisture for expanding ice sheets on the orbital scale the 41 kyr cycle that dominates high latitude climate is absent from the 18 o record indicating a stable surface water hydrographic regime on this time scale rather the 18 o record varies at and is coherent with the 19 kyr precessional component of the regional insolation curve supporting a direct response to subtropical insolation and insensitivity to extra regional forcing factors such as ice sheets

the instabilities and multiscale energetics underlying the mean interannual eddy interactions in the kuroshio extension region abstractusing a recently developed energetics diagnostic methodology namely the localized multiscale energy and vorticity analysis ms eva this study investigates the intricate nonlinear mutual interactions among the decadally modulating mean flow the interannual fluctuations and the transient eddies in the kuroshio extension region it is found that the mean kinetic energy maximizes immediately east of the izu ogasawara ridge while the transient eddy kinetic energy does not peak until 400 km away downstream the interannual variabilities which are dominated by a jet trapped rossby wave mode provide an energy reservoir comparable to the other counterparts in the upstream strong localized barotropic and baroclinic transfers from the mean flow to the eddies are observed whereas those from the interannual variabilities are not significant besides fueling the eddies the unstable mean jet also releases energy to the interannual scale processes between 144 and 154 e both transfers from the mean

origin of decadal scale eastward propagating heat content anomalies in the north pacific abstractupper ocean heat content ohc is at the heart of natural climate variability on interannual to decadal time scales providing climate memory and the source of decadal prediction skill in the midlatitude north pacific ocean ohc signals are often found to propagate eastward as opposed to the frequently observed westward propagation of sea surface height another variable that represents the ocean subsurface state this dichotomy is investigated using a 150 yr coupled gcm integration simulated ohc signals are distinguished in terms of two processes that can support eastward propagation higher baroclinic rossby wave rw modes that are associated with density perturbation and spiciness anomalies due to density compensated temperature and salinity anomalies the analysis herein suggests a unique role of the kuroshio oyashio extension koe region as an origin of the spiciness and higher mode rw signals wind forced westward propagating equivalent barotropic rws cause meridional shifts of the sub