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

re evaluation of turbulent mixing vertical structure in the bussol strait and its impact on water masses in the okhotsk sea and the north pacific abstract distribution of the turbulent kinetic energy dissipation rate e across the bussol strait was re evaluated by applying an improved method using density inversions to tide resolving density observations the improved estimates without excessive rejection of density inversions provide about three times higher mean values of e 1 45 10 7 w kg vertical diffusivity k 153 10 4 m2 s and depth integrated e 187 mw m2 in comparison with previous estimates one day mean vertical profiles of e in the potential density co ordinate allows us to estimate diapycnal velocity at 3 10 5 m s downwards through the 26 85 isopycnal surface and was almost zero through 26 7 suggesting the thinning of okhotsk sea mode water or of the core of north pacific intermediate water as the water flows through the bussol strait from the sea of okhotsk to the north pacific the re evaluated turbulence and current distributions confirmed following previous knowledge but with quantitative improvements and or expansion of coverage 1 all averaged e and k show distinctive mid depth maxima at 800 1600 m 26 9 27 6 and at a height of 300 400 m above the bottom and enhanced e within 500 m of the bottom corresponding to the enhanced shear and low richardson number at vertical scales of less than 50 m 2 a significant amount of the e variance 14 is explained by the 50 m scale vertical shear composed of mean and diurnal tidal currents 3 the diurnal tidal currents are well approximated by six low mode topographically trapped waves

vertical turbulent iron flux sustains the green belt along the shelf break in the southeastern bering sea 1 to evaluate the impact of vertical turbulent iron flux on the summertime biological productivity in the bering sea green belt gb we conducted the concurrent observations of dissolved iron d fe and turbulence in the bering sea for the first time we show that the gb can be sustained by iron supply from iron rich subsurface thick layer distributed along the southeastern shelf break where the gb is located via strong turbulent vertical mixing the flux ratio of d fe and nitrate was within the range of the n fe uptake ratio by gb phytoplankton suggesting this flux of nutrients can sustain gb productivity we also analyzed historical hydrographic data and suggest the thick subsurface layer along the gb is formed by the mixing of relatively warm water with some iron from the aleutian passes and iron rich outer shelf cold water in which the d fe derived from seafloor sediment is suspended due to strong vertical mixing

tidal exchange through the kuril straits abstract the tidal exchange between the okhotsk sea and the north pacific ocean is studied numerically with particular emphasis on the predominant k1 barotropic component the calculated harmonic constants of the k1 tide in and around the okhotsk sea agree well with those obtained from extensive tide gauge observations the features of the simulated tidal fields are similar to those reported in the literature since the k1 tide is subinertial in the okhotsk sea topographically trapped waves are effectively generated contributing to strong tidal currents with a maximum amplitude of over 1 5 m s 1 in the kuril straits the structures of tide induced mean flows in most passages of the straits are characterized by bidirectional currents in which the mean flow exhibits a reversal in direction across the passages this feature is clearly indicated in noaa infrared imagery the mean transport shows significant net exchange of water via several straits in the kuril islands a transport of about 5 0 sv 1 sv

observational analysis of a gust front to bore to solitary wave transition within an evolving nocturnal boundary layer abstract the evolution of a gust front to bore to solitary wave transition and comprehensive information on the evolving nocturnal boundary layer nbl associated with this change are described with analysis of radar and profiler measurements the observations were obtained on 21 june 2002 in the oklahoma panhandle during the international h2o project the evolution of this system from a strong bore initiated by a vigorous gust front to a solitary wave was observed over a 4 h period with doppler radar and surface measurements detailed information on the mature bore structure was obtained by a cluster of profiling instruments including two boundary layer wind profilers a lidar ceilometer and a microwave profiling radiometer a strong bore was initiated by an extensive gust front that perturbed an incipient nbl whose development prior to sunset was enhanced by shading from the parent mesoscale convective system at the time of bore formation the nbl was about 300 m deep and exhibited a surface t

pacific bidecadal climate variability regulated by tidal mixing around the kuril islands 1 18 6 year period variability has been detected in various aspects of the climate especially in and around the pacific ocean although it is believed to be caused by 18 6 year period tidal cycle no study has directly shown how the tidal cycle regulates such variability using a state of the art climate model we show that the 18 6 year cycle in strong tidal mixing localized around the kuril islands induces 18 6 year periodicity in el nino southern oscillation like pacific climate variability influence of the tidal mixing propagates along the pacific western rim as coastally trapped waves temperature anomaly is generated in the subsurface western equatorial pacific which propagates along the equatorial thermocline and eventually excites 18 6 year periodicity in the equatorial sea surface temperature

strong vertical mixing in the urup strait 1 microstructure measurements were conducted in one of the kuril straits in the summer of 2007 over the course of 1 day of repeated observations across the pacific side of the steep sill of the urup strait extremely strong mixing was observed during periods of pacific ward down sill flows and during the transition from pacific ward to okhotsk ward up sill flows with a turbulent energy dissipation rate of 10 6 to 10 5 w kg 1 and vertical diffusivity of 10 1 to 5 10 1 m2 s 1 during the period of strong mixing we observed homogeneous layers with a thickness of 300 600 m and potential density of 26 6 26 7 occupying the entire water column in one case high values of within this layer indicate the injection of diapycnal flows from the upper and lower layers possibly contributing to southward intrusion of intermediate water into the subtropical gyre

assessment of the effects of tidal mixing in the kuril straits on the formation of the north pacific intermediate water abstract to assess accurately the effect of tidal mixing in the kuril straits on the formation of the north pacific intermediate water npiw the spatial distribution of diapycnal diffusivity recently obtained by the present authors is incorporated into an eddy permitting ogcm it is shown that the npiw is successfully reproduced although the diapycnal diffusivity averaged over the entire kuril straits is an order of magnitude less than has previously been assumed as a tuning parameter to reproduce the npiw in low resolution ogcms this strongly suggests that the effect of tidal mixing in the kuril straits on the formation of the npiw is relatively minor and that the physical processes omitted by the low resolution ogcms such as isopycnal mixing along the kuroshio extension region are much more important this suggestion gives warning of the danger that some misleading conclusions might be derived from ogcms that employ diapycnal diffusivity just as a tuning parameter to reproduce the observed features

role of localized mixing around the kuril straits in the pacific thermohaline circulation 1 we investigate the pacific thermohaline circulation induced by the locally enhanced vertical mixing around the kuril straits by using a general circulation model when the strong vertical mixing reaches the sea surface localized upwelling is induced from the depth to the surface on the contrary in the cases where the strong vertical mixing does not reach the sea surface downwelling of surface water is induced in the shallow layer while upwelling of deep water is induced below the structure of the meridional overturning circulation in the pacific ocean significantly differs depending on whether the surface buoyancy flux is large enough to sustain upwelling of deep water or not the mixing induced downwelling of shallow water is not associated with the sea surface cooling and the source of dense water is in the deep ocean among the non surface reaching mixing cases the depth that separates the downwelling and upwelling is found to be relatively insensitive to the depth where the vertical diffusivity sharply changes

cross tropopause mixing of ozone through gravity wave breaking observation and modeling in the companion paper langford et al this issue clear signatures of ozone modulation by gravity waves in the lower and middle troposphere have been described from lidar observations over fritz peak observatory 39 9 n 105 3 w during september 3 4 1993 and analyzed using a linear model it is emphasized in that paper that the linear analysis breaks down at the tropopause level the purpose of this paper is to interpret the ozone observation in the upper troposphere using a high resolution mesoscale model and analyze the physical processes responsible for the structures in the upper troposphere and lower stratosphere in particular it is shown that topographically excited gravity waves that break at the tropopause level are responsible for an irreversible exchange of ozone from the stratosphere to the troposphere

taphonomic and paleoecologic investigations of the late cretaceous santonian iharkut vertebrate assemblage bakony mts northwestern hungary abstract the iharkut vertebrate locality an open pit mine in the bakony mountains western hungary has provided a rich and diverse assemblage of late cretaceous santonian continental vertebrates the isolated and associated remains represent 31 different taxa including fish amphibians turtles lizards pterosaurs crocodilians non avian dinosaurs and birds sedimentologic investigations suggest that the iharkut depositional environment was represented by the floodplain of a very low gradient river the 10 50 cm thick bonebed of site sz 6 is the most important fossiliferous layer in the open pit mine and analysis of this site indicates alternating energy conditions during the bone accumulation which resulted in fossils of different states of preservation being deposited together the vertebrate assemblage of site sz 6 includes three main different subsets with widely different taphonomic history the characteristics and the preservation mode high rate of abrasion and the spherical shape of the bone pebbles suggest that this type of the isolated bones was more exposed to abrasion and probably the remains were transported from farther away than the other isolated bones the second group includes 88 of the iharkut collection containing most of the identified isolated bones and teeth and represents polytypic attritional remains transported and deposited by high density flow during ephemeral flood events meanwhile the monospecific ankylosaur skeletal material from iharkut site sz 6 may represent a mass death assemblage because seven skeletons of hungarosaurus were discovered from an area of approximately 400 m 2 and in many cases close to each other in the same layer the iharkut vertebrate assemblage is dominated by bones of aquatic semi aquatic animals while the number of terrestrial animal remains is subordinate the taphonomic analysis of the ankylosaur material from iharkut locality further strengthens the previously suggested hypothesis that some of the ankylosaurs preferred wetland habitats e g areas along fluvial systems while the other two herbivorous dinosaur groups from iharkut ornithopods and ceratopsians were probably living in distal habitats

chemistry microstructure petrology and diagenetic model of jurassic dinosaur bones dinosaur national monument utah abstract the fossil bone mineral in dinosaurs from the morrison formation is well crystallized stoichiometric francolite the closely packed subparallel francolite crystals have equidimensional cross sections mostly 10 40 nm wide in contrast crystallites in unaltered mammal bone tissue are poorly crystallized nonstoichiometric carbonate hydroxyapatite a few nanometers thick and plate rod or needle shaped the diagenetic francolite crystals are elongated in the c axis direction as are bone tissue crystallites along permeable cracks francolite crystals grew to 250 nm wide compared to unaltered crystallites in mammal bones the francolite has higher concentrations of ba ce cr f la mn ni pb rb sr th u v and y and perhaps zr na and mg are lower in concentration diagene ic francolite grew from groundwater enriched in ions from silicic ashes in the brushy basin member and from dissolution of bone tissue crystallites after burial francolite grew on crystallite seeds filling the space formerly occupied by collagen perhaps half the tissue volume and dissolved crystallites the micron scale structures such as haversian canals and laminae are preserved because the diagenetic francolite retains the orientations of the seeds the laminae 1 10 m thick commonly preserve an orthogonal plywood structure the diagenetic growth of francolite during this type of bone fossilization implies that oxygen isotopic ratios measured in dinosaur bones even those that appear fresh and unaltered may dominantly reflect groundwater temperature rather than dinosaur body temperature trace element concentrations in the francolite may reflect groundwater composition rather than dinosaur diet pore filling cements precipitated in the sands and bones at shallow burial depths as evidenced by the 35 52 minus cement porosities of the sandstones and numerous uncompacted oversize pores filled by cements gypsum and calcite were precipitated from shallow alkaline groundwater as the groundwater became increasingly dominated by ions from silicic ash argentite chalcopyrite native gold native silver tiemannite and uraninite replaced areas of bone a few microns to tens of microns in size along cracks a thin chlorite crust commonly mantled francolite crystals along bone cracks and lined openings in bones and sandstones pervasive precipitation of a chalcedony crust followed with pseudomorphs of chalcedony after gypsum in larger cancellous openings the remaining space was fi led by the various forms of silica the bones are brown due to goethite filled cracks that cut pore filling minerals

taphonomic modes on fluvial deposits of the monte hermoso formation early pliocene buenos aires province argentina abstract the sedimentary deposits of the monte hermoso formation outcropping at its type locality farola monte hermoso buenos aires province argentina accumulated through fluvial processes acting on highly sinuous rivers the monte hermoso formation comprises a rich vertebrate fauna corresponding to the montehermosan stage age early pliocene which includes numerous and diverse vertebrate remains comparative taphonomic analysis indicated that the faunal assemblages coming from two different fossiliferous levels fl 1 and fl 2 recognized in floodplain deposits and channel deposits respectively are composed of remains affected by diverse taphonomic processes and therefore representing distinct taphonomic histories the variations recorded between both fossiliferous levels with respect to their taphonomic attributes and sedimentary context allowed the recognition of two distinct taphonomic modes floodplain in the fl 1 and channel lag in the fl 2 these taphonomic modes represent different conditions within the range of taphonomic histories for the monte hermoso formation assemblage formed by attritional accumulation of remains at the moment continental systems linked to fluvial environments have been poorly analyzed for the south american neogene this study contributes new information on taphonomic and paleoenvironmental characteristics of this type of deposit

effects of temporal variation in tide induced vertical mixing in the kuril straits on the thermohaline circulation originating in the okhotsk sea abstract tidally induced vertical mixing is important for thermohaline circulation previous estimations of tidal mixing have aimed to obtain time averaged values and ocean general circulation models ogcms typically parameterize such mixing using a temporally constant strength however tidal mixing is known to vary temporally during tidal or spring neap cycles here we investigate the effects of temporal change in tidally induced vertical diffusivity t in the kuril straits using an ogcm the results demonstrate that variations of vertical mixing on diurnal 2 week and 1 2 year timescales induce significant differences in the net effect of mixing and therefore in the thermohaline circulation originating in the okhotsk sea for diurnal and 2 week variations the strength of the tidal mixing effect depends on 1 the period and length of the duration over which t is larger than the temporal average and 2 the amplitude of the temporal variation of t even if the time averaged values are the same this is explained by the relative importance of two states in a quasi equilibrium state a larger t results in weaker stratification and vice versa and thus the net tidal mixing effect is weaker when t is variable than when it remains constant conversely in an adjustment stage just after an increase in t a larger t acts on stronger stratification and vice versa resulting in a stronger mixing effect for a 1 2 year variation the strength of the tidal mixing effect also depends on the phase relationship with seasonal variation in stratification these results imply the necessity of considering temporal change when estimating tidal mixing from observations specifying it in ogcms and understanding its effects

influence of okhotsk sea intermediate water on the oyashio and north pacific intermediate water 1 the volume transport between the okhotsk sea and western subarctic north pacific is estimated on the basis of direct current measurements made by a lowered acoustic doppler current profiler ladcp and hydrographic data taken in august and september 1999 near the kuril islands the estimated southwestward oyashio transport was 11 12 sv 106 m3 s in the density range of 26 7 27 4 the net transport of the okhotsk sea water osw was 3 4 sv of which 1 3 sv was coming out through the kruzenshterna strait and 2 1 sv was coming out through the bussol strait a bidirectional flow was observed in the bussol strait inflow in the northern part of the strait and outflow in the southern part 0 6 sv of osw recirculated along the western subarctic gyre the remaining 2 8 sv of osw could contribute to the formation of north pacific intermediate water as a cross subarctic front transport along the coast 1 4 sv and across the offshore saf 1 4 sv the production rate of the dense shelf water dsw through sea ice formation was estimated to be at least 1 1 sv when the intermediate osw is formed through the mixing between cold and fresh dsw and warm and salty waters from the pacific and japan sea 16 8 tw 1012 w of heat 0 007 sv of freshwater and 2 3 105 kg s of salt are exchanged the net flux of oxygen and anthropogenic co2 ex co2 from the okhotsk sea into the pacific in 26 7 27 4 is estimated to be 10 5 and 2 1 tmol yr 0 025 gtc yr respectively the ex co2 transported by osw accounts for about 10 of the accumulation of ex co2 in the subarctic and subtropical pacific

climatological features of cutoff low systems in the northern hemisphere this study presents the first multidecadal climatology of cutoff low systems in the northern hemisphere the climatology was constructed by using 41 yr 1958 98 of ncep ncar reanalysis data and identifying cutoff lows by means of an objective method based on imposing the three main physical characteristics of the conceptual model of cutoff low the 200 hpa geopotential minimum cutoff circulation and the specific structure of both equivalent thickness and thermal front parameter fields several results were confirmed and climatologically validated 1 the existence of three preferred areas of cutoff low occurrence the first one extends through southern europe and the eastern atlantic coast the second one is the eastern north pacific and the third one is the northern china siberian region extending to the northwestern pacific coast the european area is the most favored region 2 the known seasonal cycle with cutoff lows forming much more frequently in summer than in winter 3 the short lifetime of cutoff lows most cutoff lows lasted 2 3 days and very few lasted more than 5 days and 4 the mobility of the system with few cutoff lows being stationary furthermore the long study period has made it possible i to find a bimodal distribution in the geographical density of cutoff lows for the european sector in all the seasons with the exception of winter a summer displacement to the ocean in the american region and a summer extension to the continent in the asian region and ii to detect northward and westward motion especially in the transitions from the second to third day of occurrence and from the third to fourth day of occurrence the long term cutoff low database built in this study is appropriate to study the interannual variability of cutoff low occurrence and the links between cutoff lows and jet stream systems blocking or major modes of climate variability as well as the global importance of cutoff low in the stratosphere troposphere exchange mechanism which will be the focus of a subsequent paper

a northern hemispheric climatology of cross tropopause exchange for the era15 time period 1979 1993 1 a 15 year climatology of cross tropopause exchange in the extratropical northern hemisphere is presented based upon a previously developed lagrangian methodology and reanalysis data from the european centre for medium range weather forecasts ecmwf for the years 1979 1993 for this time period no apparent trends exist for upward troposphere to stratosphere tst and downward stratosphere to troposphere stt cross tropopause transport the seasonal cycles of hemispherically integrated tst and stt and the zonally integrated meridional exchange distributions show relatively little interannual variability the 15 year averaged geographical distribution of stt reveals significant deviations from zonal symmetry and pronounced seasonal variability stt occurs predominantly over the atlantic and pacific storm track regions during winter spring and autumn and also over the mediterranean in winter and spring in contrast during summer stt maxima are located over the continents particularly over southeastern europe and central asia tst is less variable and is strongest near the southern tip of greenland and the aleutian islands during all seasons aspects of the interannual variability of the geographical exchange distributions are investigated over the atlantic stt varies significantly in line with the changing storm tracks during different phases of the north atlantic oscillation nao whereas tst does less so special consideration is given to vertically deep exchange where the exchange air parcels transfer rapidly from the lowermost stratosphere to the boundary layer or vice versa these processes occur mainly during winter and exhibit pronounced maxima over the north american west deep stt and east deep tst coasts

latitudinal dependence of diapycnal diffusivity in the thermocline observed using a microstructure profiler 1 the un tethered free fall microstructure profiler turbomap d collected 53 velocity microstructure profiles in the interior pacific ocean the data between 1000 m and 1600 m depth was used to infer diapycnal diffusivity in the main thermocline we found diapycnal diffusivity at 20 30 n was roughly proportional to the logarithm of locally available energy density of the semidiurnal internal tide and reached more than 10 4 m2 s 1 near the izu ogasawara ridge in contrast diapycnal diffusivity was found to remain at 10 5 m2 s 1 equatorward of 20 n and poleward of 30 n irrespective of the amount of locally available semidiurnal internal tide energy the observed mixing hotspots were a factor of 2 3 less intense than predicted based on fine scale parameterizations although further microstructure measurements are needed to better quantify them the present study has confirmed the existence of a latitudinal dependence of diapycnal diffusivity which must be taken into account in global circulation models

numerical study on the impact of the 18 6 year period nodal tidal cycle on water masses in the subarctic north pacific 1 a series of numerical experiments is performed to test the hypothesis that temporal variations in localized strong tidal mixing related to the 18 6 year period nodal tidal cycle induce water mass variations it is suggested that enhanced mixing around the bering sea as that around the okhotsk sea have an impact on water masses broadly in the north pacific including the bering sea and the okhotsk sea oscillatory tidal mixing with a 18 6 year period reproduces water mass variations in salinity and isopycnal potential temperature around the subarctic north pacific that are qualitatively consistent with observed variations when the amplitude of oscillatory vertical diffusivity is 15 of the long term mean and even when the amplitude is as small as 3 cm2 s as obtained for a long term mean of 20 cm2 s the amplitude of the salinity variation near regions of strong mixing is smaller than but on the same order of magnitude as that observed the induced salinity anomaly spreads broadly over a distance of several hundreds of kilometers by mean currents with a short lag time of less than 3 years and is suggested to influence the model winter mixed layer over broad regions these results support the hypothesis stated above and suggest that it is necessary to clarify spatial and temporal variations in tidal mixing to reproduce both the mean states of and temporal variations in water masses of the subarctic north pacific

fine and microstructure observations in the urup strait kuril islands during august 2006 1 for the first time we performed continuous observations of turbulent mixing upon the sill of the urup strait kuril islands for a period of 1 day during august of 2006 time series of velocity profiles water properties and isopycnal depths show variability with a period of about 1 day however the water mass variability is not explained by simple water exchange between the sea of okhotsk and the north pacific empirical orthogonal function eof analysis of isopycnal coordinates extracted variability presumed to represent tidal flows as major eofs in profiles of the residual flow after subtracting the mean flow and major eofs we detected phase propagations consistent with internal gravity waves with an approximate period of 9 1 11 4 h the turbulent energy dissipation rate and vertical diffusivity k ranged from 1 10 9 to 3 10 8 w kg 1 and from 3 10 5 to 2 10 3 m2s 1 respectively occurrences of high dissipation rates generally corresponded to either strong shear or weak stratification a significant contribution of shear s to the dissipation rate was indicated with a relationship of s1 4 s1 8 probably related to propagating internal waves a strong mixing event was observed within the water column with extremely weak stratification and a richardson number below the critical value of 0 25 when the flow direction changed from up sill to down sill

late permian vertebrate community of the pranhita godavari valley india abstract the kundaram formation of the pranhita godavari valley yields the only late permian multispecies terrestrial vertebrate assemblage from india this includes various medium and small dicynodonts such as endothiodon oudenodon kingoria emydops cistecephalus and pristerodon at present two species of endothiodon e mahalanobisi and e uniseries are known apart from these dicynodonts the kundaram vertebrate fauna also contains a medium sized gorgonopsian and a small captorhinid the material from the red mudstone dominated kundaram formation includes numerous isolated disarticulated skulls and lower jaws postcranial elements are relatively rare except for a few broken limb ends and vertebrae the bones are encrusted by iron rich matrix and most of them had suffered deformation this skull dominant accumulation is attributed to prolonged aerial exposure prior to burial resulting in disarticulation of the skeletons and subsequent inundation by floodwater the limb bones and other postcranial elements of the already disarticulated skeletons were winnowed out by shallow competent flow while the relatively heavier skulls and lower jaws resisting transportation were buried near the site of death the late permian scenario of the pranhita godavari valley was characterised by the dominance of herbivores this abundance of herbivores at the base and the presence of relatively few carnivores and omnivores at the top of the kundaram food pyramid indicate a trophic structure similar to that of the modern day terrestrial ecosystem

chlorofluorocarbons in the sea of okhotsk ventilation of the intermediate water 1 ventilation of the intermediate layer in the sea of okhotsk is studied with regard to the ventilation of north pacific intermediate water npiw measurements of chlorofluorocarbons cfcs from 1998 to 2000 reveal that the okhotsk intermediate water is ventilated in two ways the first consists of dense water formation in the polynyas that form on the northern shelves during winter measurements show that on the northwestern shelf because of atmospheric cooling and brine rejection the cold water that forms is dense enough to enter the intermediate layer the cfc concentration in this dense shelf water dsw is high and almost saturated with respect to atmospheric cfcs indicating that the dsw experiences active air water gas exchange during its formation away from the shelves the cfc distribution shows that the dsw directly ventilates the upper level of the okhotsk sea intermediate water osiw the second ventilation process is driven by the strong tidal mixing around the bussol strait the observed distribution of cfcs at the 27 4 level suggest that diapycnal mixing around the strait transports cfcs from the surface to this deeper layer ventilating the osiw combination of both processes means that the osiw is more ventilated than pacific water at the same density levels

cyclone anticyclone asymmetry concerning the height of the thermal and the dynamical tropopause abstract the differences between upper tropospheric cyclones and anticyclones are investigated regarding the height of the thermal and the dynamical tropopause the problem is addressed in an idealized framework by analyzing axisymmetric balanced flows which are characterized by a radial scale r and a tropopause potential temperature anomaly where cyclones and anticyclones differ only by the sign of the height of the thermal tropopause significantly differs from the height of the dynamical tropopause unless the anomaly is shallow there is a pronounced asymmetry in that the differences are much larger and more likely to occur in the case of cyclones two factors contribute to this asymmetry first for a given amplitude cyclones and anticyclones have different aspect ratios in geometric space second for a high latitude winter scenario the critical lapse rate of the wmo thermal tropopause is asymmetric with respect to typical tropospheric and stratospheric lapse rates simulated station s

remote impacts of the 18 6 year period modulation of localized tidal mixing in the north pacific 1 the impact of the 18 6 year period modulation of the localized strong tidal mixing on the annual mean sea surface temperature sst in the open north pacific ocean is analyzed in a numerical experiment using an ocean general circulation model oscillatory sst anomalies induced in this model move eastward along the boundary between the subarctic and the subtropical gyres from the western boundary to the central pacific in about 10 years with a speed slower than that of the surface currents anomalous currents in the upper 300 m play an important role in inducing sst anomalies these anomalous currents are coupled to subsurface density anomalies and could be related to eastward moving low mode second or higher baroclinic long rossby waves these results suggest that the 18 6 year modulation of localized strong tidal mixing can influence large scale sst and or heat flux and thus climate as a result of remote impacts associated with changes in the mid depth density structure induced locally where mixing is strong that move horizontally into the open ocean

taphonomy of the late cretaceous dinosaur bearing beds of the lano quarry iberian peninsula abstract the lano quarry located in the northern part of the iberian peninsula basque cantabrian region has yielded a diverse continental vertebrate assemblage from the late cretaceous late campanian to early maastrichtian the fossil assemblage consists of almost 40 species including bony fish amphibians lizards snakes turtles crocodilians dinosaurs pterosaurs and mammals lano is the most productive european vertebrate locality hitherto known from the late cretaceous the sedimentology of the lano section shows that the three associated fossiliferous beds known as l1a l1b and l2 were deposited in an alluvial system composed primarily of fluvial sands and silts the sedimentary structures are consistent with channel areas within an extensive braided river the l1a level was excavated in detail and mapped following a square metre grid system the main features of the multispecies vertebrate assemblage are as follows wide range of body size including microfossils large proportion of adult individuals rare articulated skeletal parts size sorting and dominance of small elements high spatial density long bones showing some preferential orientation variable dip variable degree of breakage and large proportion of splintering wide range of weathering and abrasion no evidence of predatory activity or chemical alteration on the basis of these features we suggest that the lano association lies between the taphonomic modes for attritional vertebrate assemblages in fluvial channels though it tends more toward the channel fill than the channel lag mode the l1a sample of lano is a heterogeneous assemblage of elements ranging from isolated bones and teeth to articulated skeletons with allochthonous and para autochthonous characteristics it consists of a mixture of vertebrates from different palaeocommunities and includes aquatic or semi aquatic elements and remains transported from a variety of habitats on the alluvial plain the dinosaur bones are commonly broken and show a greater degree of abrasion than those of freshwater vertebrates indicating that they may be allochthonous however actinopterygians amphibians pleurodiran turtles and eusuchian crocodilians are interpreted as being para autochthonous palaeobatrachid frogs bothremydid turtles and alligatoroid crocodilians are the most relatively abundant vertebrates of the lano fossil assemblage the occurrence of pelomedusid turtles and crocodilians is indicative of an intertropical warm climate

estimates of tidal energy dissipation and diapycnal diffusivity in the kuril straits using topex poseidon altimeter data the kuril straits separating the okhotsk sea from the north pacific ocean are representative regions of strong tidal mixing in the world s oceans in the present study we first carry out numerical simulation of the barotropic tidal elevation field in the okhotsk sea using a horizontally two dimensional primitive equation model it is found that to reproduce realistic tidal elevations in the okhotsk sea the energy lost by the incoming barotropic tides to internal waves within the kuril straits should be taken into account the numerical experiments show that the model predicted tidal elevations in the okhotsk sea best fit the topex poseidon altimeter data when we take into account the baroclinic energy conversion in the kuril straits 16 gw for the k 1 tidal constituent and 37 gw for the major four tidal constituents k 1 o 1 m 2 s 2 for this baroclinic energy conversion diapycnal diffusivity averaged over the whole area of the kuril straits is estimated to be 8 x 10 4 m 2 s 1 this value is about 1 order of magnitude less than assumed for the kuril straits in previous ocean general circulation models we offer this study as a warning against using diapycnal diffusivity just as a tuning parameter to reproduce large scale phenomena

persistently declining oxygen levels in the interior waters of the eastern subarctic pacific abstract fifty years of measurements at ocean station papa osp 50 n 145 w show trends in the interior waters of the subarctic pacific that are both impacted by short term few years to bi decadal atmospheric or ocean circulation oscillations and by persistent climate trends between 1956 and 2006 waters below the ocean mixed layer to a depth of at least 1000 m have been warming and losing oxygen on density surfaces found in the depth range 100 400 m 26 3 27 0 the ocean is warming at 0 005 0 012 c y 1 whereas oxygen is declining at 0 39 0 70 mol kg 1 y 1 or at an integrated rate of 123 mmol m 2 y 1 decrease of 22 over 50 years during this time the hypoxic boundary defined as 60 mol o 2 kg 1 has shoaled from 400 to 300 m in the alaska gyre the 26 2 isopycnal occasionally ventilates whereas at osp 26 0 has not been seen at the ocean surface since 1971 as the upper ocean continues to stratify to interpret the 50 year record at osp the isopycnal transport of oxygenated waters within the interior of the subarctic pacific is assessed by using a slightly modified no parameter broecker w 1974 no a conservative water mass tracer earth and planetary science letters 23 100 107 the highest nitrate oxygen signature in interior waters of the north pacific is found in the bering sea gyre western subarctic gyre and east kamchatka current region as a consequence of winter mixing to the 26 6 isopycnal by mixing with low no waters found in the subtropics and okhotsk sea this signature is diluted as waters flow eastward across the pacific evidence of low no waters flowing north from california is seen along the coasts of british columbia and se alaska oxygen in the subsurface waters of the alaskan gyre was supplied 60 by subarctic and 40 by subtropical waters during woce surveys whereas such estimates are shown to periodically vary by 20 at osp other features discernable in the osp data include periods of increased ventilation of deeper isopycnals on an 18 year cycle and strong short term few month variability caused by passing mesoscale eddies the potential impacts of declining oxygen on coastal ecosystems are discussed

the fossil vertebrates from lano basque country spain new evidence on the composition and affinities of the late cretaceous continental faunas of europe a newly discovered fossil locality at lano basque country has yielded a vertebrate assemblage of probably maastrichtian age comprising fishes amphibians reptiles and mammals it considerably enlarges our knowledge of the late cretaceous continental faunas of europe hitherto based on a much less complete record some taxa are recorded for the first time in europe and the fauna also contains the oldest known representatives of some groups amphisbaenians salamandrids the lan assemblage reveals an original fauna comprising both forms related to asian and north american groups and elements with gondwanan affinities

taphonomic modes in the maastrichtian continental deposits of the haţeg basin romania palaeoecological and palaeobiological inferences abstract the uppermost cretaceous continental deposits of the ha eg basin sw romania have yielded a high diversity vertebrate assemblage including the dwarf insular dinosaurs of nopcsa in 1902 franz nopcsa was the first to comment on the preservation patterns of vertebrate fossils suggesting that the most important fossil accumulations which he simply referred to as fossiliferous pockets were the result of the predatory activity of crocodilians crocodilian feeding grounds recent investigations of the fossil occurrences within the ha eg basin revealed a much wider range of taphonomic modes from microfossil bonebeds to isolated partially articulated skeletons than previously believed the survey of the vertebrate accumulation types and their sedimentary context documents a wide range of processes responsible for their genesis operating within a fluvial dominated upland setting study of the individual fossil accumulations yields important information on the palaeoecology composition of local biocenoses trophic interactions and palaeobiology social behaviour habitat preferences of the ha eg fossil assemblage

taphonomy of jack s birthday site a diverse dinosaur bonebed from the upper cretaceous two medicine formation of montana jack s birthday site is a diverse vertebrate assemblage from the upper two medicine formation of western montana age is roughly 74 ma the site covers roughly 3000 m2 and excavations over 140 m2 a large bone sample 1600 skeletal elements allowed statistical evaluation of the preservational and compositional variation within the site evidence including sedimentary facies plant and invertebrate fossils and bone orientation and condition indicates jack s birthday site represents part of a small shallow floodplain lake lithologies and fossil preservation vary from northwest to southeast over a distance of 50 m this variation represents a transition from lake through shoreline to marginal shoreline floodplain environments containing ten dinosaur taxa and a variety of non dinosaurs jack s birthday site provides one of the best single faunal samples of the region the vertebrate assemblage includes two taphonomic fractions the first consisting of attritional predominantly isolated and allochthonous elements represents a time averaged assemblage the other consists of associated parautochthonous remains restricted to a single horizon taxa represented by associated remains include three iguanodontoids hypacrosaurus prosaurolophus and gryposaurus and the theropod troodon associated individuals of these taxa have non random distributions within the site fisher s exact test p 0 01 and observed taxonomic clustering may reflect group behavior and or event mortality the four or more troodon represent the first described multi individual troodontid occurrence the diversity and spatial complexity of the parautochthonous fraction of the birthday site assemblage is difficult to explain discussion of possible event mortality mechanisms focuses on three drought botulism and cyanobacterial toxicosis these share an ability to act over an ecologically significant period of time affect a variety of species and concentrate mortality along water sources aspects that may have been important in generating the birthday site assemblage evidence at the site favors drought or perhaps a drought botulism hypothesis however taxonomic clusters could represent completely separate events with a variety of causes

the 18 6 year period moon tidal cycle in pacific decadal oscillation reconstructed from tree rings in western north america 1 time series of pacific decadal oscillation pdo reconstructed from tree rings in western north america is found to have a statistically significant periodicity of 18 6 year period lunar nodal tidal cycle negative positive pdo tends to occur in the period of strong weak diurnal tide in the 3rd and 5th 10th 11th and 13rd year after the maximum diurnal tide mean pdo takes significant negative positive value suggesting that the aleutian low is weak strong western central north pacific in 30 50 n is warm cool and equator eastern rim of the pacific is cool warm this contributes to climate predictability with a time table from the astronomical tidal cycle

water exchange and tidal currents through the bussol strait revealed by direct current measurements 1 an outflow from the sea of okhotsk to the north pacific was measured at the bussol strait the largest strait connecting these basins from 31 august to 11 september 2001 yo yo casts of a lowered acoustic doppler current profiler were performed at 13 stations across the narrowest part of the strait time series covering more than approximately 24 hours were obtained for each station and the semidiurnal and diurnal tides were separated the diurnal tide at the spring tide shows a remarkable peak of the amplitude of 1 1 m s 1 at the depth below 1000 m in the western channel of the strait the upper part of the mean component flows toward the pacific and the lower part flows in the opposite direction the outflow is in excess of the inflow and net transport through the strait is 8 2 to 8 8 sv 1 sv 106 m3 s 1 the outflow is strong in two density ranges the upper layer peak around 26 8 corresponds to the density of north pacific intermediate water and the temperature salinity characteristics of this outflow were actually observed in this density range across downstream the oyashio off the southeastern coast of hokkaido net heat and salt exchanges between the sea of okhotsk and the north pacific are estimated net heat flux of 34 tw and net salt flux of 1 9 106 kg s 1 are exchanged from the sea of okhotsk to the north pacific

quantitative evaluation of iron transport processes in the sea of okhotsk abstract comprehensive observations of the iron fe distribution in the western sea of okhotsk were conducted and revealed the existence of two fe transport processes in the sub polar marginal sea one transport process is fe loading from the amur river and transport by the east sakhalin current esc and the other is fe transport by the intermediate water part of which was reported by nishioka et al 2007 here we report on quantitative evaluations of these two fe transport processes the surface dissolved fe diss fe and low salinity water distribution clearly indicate the influence of fe discharge from the amur river and the fe that is transported by the east sakhalin current the amounts of total dissolvable fe td fe and diss fe that cross the surface of the northeast sakhalin coastal area are estimated at 9 0 108 1 3 109 g yr 1 and 1 0 108 1 5 108 g yr 1 respectively although the esc surface transport system along the sakhalin coast is effective the length scale estimation of td fe transport indicated that only 1 5 of the fe at the mouth of the amur river reached 52 n which may be due to scavenging by biological particulates high fe anomalies were observed at the bottom of the continental shelf and the shelf break along the sakhalin coast the extremely low temperature and low n water indicate that fe resuspension due to the reducing properties of sediment occurred on the shelf and that the fe was introduced to dense shelf water dsw by tidal mixing we estimate that the amounts of td fe and diss fe involved in the dsw on the continental shelf are 8 8 1010 2 5 1011 g yr 1 and 2 3 109 6 6 109 g yr 1 respectively length scale estimates of td fe transport indicate that 20 of the td fe on the continental shelf remained in the kuril basin thus the td fe in the intermediate water was efficiently transported to the kuril basin these results indicate that two orders of magnitude more fe is derived from the continental shelf by the intermediate water than by surface water and that fe is transported a greater distance by intermediate water than by the surface layer additionally the fe that reached the kuril straits was mixed by intensive tidal mixing and influenced the vertical profiles of the water columns on both sides of the kuril straits in the kuril basin and the oyashio region our quantitative evaluation also indicates other fe inputs around the kuril strait

vertebrate preservation in fluvial channels abstract two taphonomic modes for attritional vertebrate assemblages in channels are proposed based on the sedimentary context of the vertebrate remains and taphonomic features of the bones themselves the channel lag mode includes bones that are buried with coarse lithologies near the bases of active channels the channel fill mode occurs in fine grained to mixed fills of abandoned channels the extreme for a channel lag assemblage would be a cluster of allochthonous abraded unidentifiable fragments and the extreme for a channel fill assemblage would be a cluster of autochthonous unbraded complete skeletons between these extremes there is a broad spectrum of possible taphonomic histories for bones in channels but distinct channel lag vs channel fill modes can be recognized in fluvial deposits in different tectonic and climatic settings throughout the phanerozoic physical and biological processes that affect the different modes produce different samples of vertebrate paleocommunities with bones in the channel lag mode representing transported remains from a variety of habitats whereas channel fill assemblages are more autochthonous and habitat specific channel facies channel pattern and alluvial architecture are used to develop hypotheses concerning how the taphonomic modes relate to different scales of fluvial processes fluvial systems with numerous abandoned channels provide more sites for preservation of relatively complete fossil vertebrates in channel fills while systems that continually rework sediments by lateral migration preserve more vertebrate remains as channel lags large scale physical controls on channel pattern and fluvial architecture probably have had significant effects on the quality and quantity of the vertebrate record throughout the history of land vertebrates taphonomic modes provide a basis for comparing faunas with similar preservational histories throughout the geologic record and they can help to minimize biases in important paleobiological parameters such as diversity estimates and the timing of appearance and extinction events

direct breaking of large amplitude internal waves in the urup strait abstract observations and model data have been analyzed for the urup strait one of the kuril straits focusing on processes driving the extremely strong vertical mixing observations over 1 day on the pacific side of the sill of the urup strait show the generation of a large amplitude internal wave laiw characterized by the depression of potential density surfaces caused by a strong off sill flow when the laiw developed the potential density surface of 26 7 was depressed downward by more than 300 m and vertical mixing was markedly elevated within the 400 m thick layer 26 6 26 7 with a layer mean maximum energy dissipation rate and vertical diffusivity of 1 2 10 6 7 9 10 6 w kg 1 and 4 0 10 1 2 8 m2 s 1 respectively a three dimensional model simulation of the kuril straits driven by the diurnal barotropic tide reproduces well the observed features relevant to the generation of laiws in and around the urup strait the structure and generation pattern of laiws in the urup strait are consistent with those of the arrested lee waves observed in the hawaiian ridge and luzon strait although the depth at the top of the sill is far shallower in the urup strait it is suggested that barotropic tidal energy with diurnal frequency is converted into laiws through the excitation of topographically trapped waves with hydraulically supercritical velocity near the sill top and it is these waves that are responsible for the extremely strong mixing on the sill flanks of the shallow kuril straits

global abyssal mixing inferred from lowered adcp shear and ctd strain profiles abstract internal wave wave interaction theories and observations support a parameterization for the turbulent dissipation rate e and eddy diffusivity k that depends on internal wave shear vz2 and strain z2 variances its latest incarnation is applied to about 3500 lowered adcp ctd profiles from the indian pacific north atlantic and southern oceans inferred diffusivities k are functions of latitude and depth ranging from 0 03 10 4 m2 s 1 within 2 of the equator to 0 4 0 5 10 4 m2 s 1 at 50 70 diffusivities k also increase with depth in tropical and subtropical waters diffusivities below 4500 m depth exhibit a peak of 0 7 10 4 m2 s 1 between 20 and 30 latitudes where semidiurnal parametric subharmonic instability is expected to be active turbulence is highly heterogeneous though the bulk of the vertically integrated dissipation e is contributed from the main pycnocline hotspots in e show some correlation with small scale bottom roughness and near bottom flow at sites where st

thermal versus dynamical tropopause in upper tropospheric balanced flow anomalies this paper systematically investigates differences between the thermal and the dynamical tropopause for upper tropospheric balanced flow anomalies idealized cyclonic and anticyclonic anomalies are considered which are either axisymmetric or plane symmetric given a distribution of potential vorticity pv the inversion problem is solved numerically to obtain the corresponding balanced flow i e wind and temperature the control parameter is the aspect ratio of the pv anomaly which governs the partitioning into a thermal and a dynamical anomaly for pv anomalies of intermediate and tall aspect ratios the location of the thermal tropopause differs significantly from the location of the dynamical tropopause the thermal tropopause is rather indistinct for intermediate aspect ratios while it is sharp and well defined for both tall and shallow anomalies a barotropic deformation flow field superimposed on a plane symmetric anomaly induces an ageostrophic wind which modifies the static stability throughout the pv anomaly such that the thermal and dynamical tropopauses evolve differently recent observations concerning the correlation between the thermal and ozone tropopauses can be interpreted consistently in terms of the present results

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

dynamical ocean response controlling the eastward movement of a heat content anomaly caused by the 18 6 year modulation of localized tidally induced mixing

possible explanation linking 18 6 year period nodal tidal cycle with bi decadal variations of ocean and climate in the north pacific 1 bi decadal climate variation is dominant over the north pacific on inter decadal timescale however the mechanism has not been fully understood we here find that the bi decadal variations in the north pacific climate and intermediate waters possibly relate to the 18 6 year period modulation of diurnal tide in the period of strong diurnal tide tide induced diapycnal mixing makes surface salinity and density higher and the upper layer shallower along the kuril islands and the east coast of japan simple model results suggest that the coastal depth adjustment by baroclinic kelvin waves enhances the thermohaline circulation the upper layer poleward western boundary current and associated heat transport by about 0 05pw this could also explain the warmer sst in the kuroshio oyashio extension regions where positive feedback with aleutian low might amplify the bidecadal variations the 18 6 year tidal cycle hence could play a role as a basic forcing for the bi decadal ocean and climate variations

numerical study of k1 internal tides in the kuril straits 1 tide induced strong diapycnal mixing in the kuril straits is thought to be one of the essential processes controlling water mass formation in the north pacific in order to make a definite quantification of diapycnal diffusivity in the kuril straits we drive a three dimensional numerical model and examine the generation propagation and dissipation features of internal waves which play an essential role in transferring energy from the predominant k1 barotropic tide to diapycnal mixing processes it is shown that most of the internal wave energy subtracted from the k1 barotropic tide is dissipated within the kuril straits such that the local dissipation efficiency becomes 0 8 1 0 about three times the value previously employed this is because the k1 tidal frequency is subinertial in this area so that significant amount of k1 tidal energy is fed into coastal trapped waves ctws which stay around each island without propagating away from the straits ctws induce strong velocity shear near the ocean bottom causing bottom confined intense mixing with a vertical decay scale 200 m less than half the value previously employed although there remains some uncertainties resulting from the employed parameterizations of viscosity and diffusivity the average diapycnal diffusivity in the kuril straits becomes 25 10 4 m2 s 1 about three times the value previously estimated although it is still an order of magnitude less than assumed for the kuril straits in the existing ocean general circulation models

internal tides and turbulent mixing observed in the bussol strait abstract repeated observations with a period of about 24 h of hydrography current velocity and microstructures were performed at three stations surrounding a seamount in the middle of the bussol strait the deepest and widest one of the kuril straits to reveal spatial and temporal variability of internal tides and associated turbulent mixing it is found that isopycnal displacements are dominated by diurnal tidal components which show phase differences namely time lags between the three stations that can be explained by a first mode topographically trapped wave ttw propagating clockwise around the seamount furthermore at the station located near the center of the strait where energy dissipation rates are largest diurnal variations of isopycnals and velocities are amplified toward the ocean bottom consistent with the vertical structure of the first mode ttw at that station vigorous turbulent mixing with the energy dissipation rate exceeding 10 6 m 2 s 3 and diapycnal diffusivity exceeding 10 1 m 2 s 1 was observed in deep layers when the diurnal tidal current consisting of the first mode ttw flows from the okhotsk sea to the north pacific enhancing the mean current these spatial and temporal variation patterns are confirmed to be reproduced by a previous numerical model successfully for the isopycnals and velocities and partially for the turbulent mixing the total energy dissipation rate is however by up to a factor of 3 10 smaller than predicted by the numerical model although the observations were performed during spring tides suggesting that the actual diapycnal mixing is overall weaker than the previous model estimate and or that extremely strong mixing occurs within highly localized areas

deep intense vertical mixing in the bussol strait 1 to reveal the intensity of deep mixing in the bussol strait we performed the direct observations of turbulence for the first time vigorous vertical mixing with a turbulent energy dissipation rate e above 10 6 w kg and diapycnal diffusivity k above 103 cm2 s were observed at depths of 600 1300 m potential densities of 27 0 27 5 at the western gap of the bussol strait possibly affecting water mass transformation and thermohaline circulation the strong vertical mixing with a diurnal period occurred when the diurnal tidal current flowed toward the okhotsk sea corresponding to a period of enhanced shear consisting of the mean flow with a two layered structure and the large amplitude diurnal tidal current with a vertical structure explained by a low vertical mode topographically trapped wave the empirical relationship ofe 10 1 46 1 91 s2 16 0 72 is obtained between e and the shear sreconstructed from the 50 m scale mean diurnal and semi diurnal tidal currents

the origin of the north pacific intermediate water possible source regions of the north pacific intermediate water npiw were investigated with synoptic conductivity temperature depth surveys in the okhotsk sea kuril basin a pycnostad referred to as the okhotsk sea mode water osmw was found in the density range of 26 6 27 the pycnostad is not seen in the western subarctic gyre wsag thus it is an indicative water peculiar to the okhotsk sea the maximum thickness is at 26 7 26 9 centered at 26 8 which coincides with the npiw density range in the north pacific subtropical gyre in the oyashio area east of the southern kuril islands and hokkaido waters that have intermediate temperature salinity and potential vorticity between the osmw and the wsag water were distributed suggesting a following transport route of the npiw source water the thick thus low q q is potential vorticity and low salinity water mass outflowing from the okhotsk sea mixes with the relatively warm saline and high q wsag water to form the oyashio water a coastal part of the oyashio water flows southwestward along the east coast of the southern kuril islands and hokkaido retaining the pycnostad q minimum a large part of the low q oyashio water flows further southward and merges with the kuroshio extension and then flows eastward forming new npiw in this process a salinity minimum develops and the q minimum disappears because of the mixing with a saline kuroshio water old npiw without a pycnostad in the npiw density range these results suggest that the origin of npiw is the water mass in the okhotsk sea osmw and the density of the water mass primarily determines the npiw density centered at around 26 8

intensive mixing along an island chain controls oceanic biogeochemical cycles 1 the subarctic pacific is a high nutrient low chlorophyll hnlc region in which phytoplankton growth is broadly limited by iron fe availability however even with fe limitation the western subarctic pacific wsp has significant phytoplankton growth and greater seasonal variability in lower trophic levels than the eastern subarctic pacific therefore differences in fe supply must explain the west to east decrease in seasonal phytoplankton growth the fe flux to the euphotic zone in the wsp occurs at a moderate value in that it is significantly higher than its value on the eastern side yet it is not sufficient enough to cause widespread macronutrient depletion that is hnlc status is maintained although we recognize several fe supply processes in the wsp the mechanisms that account for this moderate value of fe supply have not previously been explained here we demonstrate the pivotal role of tidal mixing in the kuril islands chain kic for determining the moderate value a basin scale meridional fe section shows that fe derived from sediments in the sea of okhotsk is discharged through the kic into the intermediate water masses 800 m of the western north pacific the redistribution of this fe rich intermediate water by intensive mixing as it crosses the kic is the predominant process determining the ratio of micronutrient fe to macronutrients e g nitrate in subsurface waters this ratio can quantitatively explain the differences in surface macronutrient consumption between the western and eastern subarctic as well as the general formation and biogeochemistry of hnlc waters of the subarctic north pacific

simulations of temperature and turbulence structure of the oceanic boundary layer with the improved near surface process an improved model for the oceanic boundary layer is presented in view of the recent observation of the microstructure of the upper ocean including the high dissipation rate near the sea surface in the new model the surface boundary conditions for both the turbulent kinetic energy flux and the roughness length scale are modified the parameterization of stratification effects on turbulence is improved and the convective process is reformulated on the basis of the observation of uniform temperature and velocity profiles within the convective mixed layer evolutions of the profiles of both the dissipation rate and temperature of the observation data patches experiment as well as the time series of the sea surface temperature over the observation days are successfully simulated during a diurnal cycle for the first time it is also shown that the model reproduces various important features of the oceanic boundary layer for example the formation of a diurnal thermocline the profiles of buoyancy flux and the magnitudes of the buoyancy gradients both within the mixed layer and at the diurnal thermocline performance of the model is compared with that of the widely used mellor yamada model

forcing of low frequency ocean variability in the northeast pacific abstract an ocean model is used to examine and compare the forcing mechanisms and underlying ocean dynamics of two dominant modes of ocean variability in the northeast pacific nep the first mode is identified with the pacific decadal oscillation pdo and accounts for the most variance in model sea surface temperatures ssts and sea surface heights sshs it is characterized by a monopole structure with a strong coherent signature along the coast the second mode of variability is termed the north pacific gyre oscillation npgo this mode accounts for the most variance in sea surface salinities ssss in the model and in long term observations while the npgo is related to the second eof of the north pacific sst anomalies the victoria mode it is defined here in terms of ssh anomalies the npgo is characterized by a pronounced dipole structure corresponding to variations in the strengths of the eastern and central branches of the subpolar and subtropical gyres in the north pacific it is found tha

bidecadal variability in the intermediate waters of the northwestern subarctic pacific and the okhotsk sea in relation to 18 6 year period nodal tidal cycle 1 on the basis of historical oceanographic data we investigated the long term variations of the intermediate waters in the four regions in the northwestern subarctic pacific oyashio okhotsk sea mode water upstream oyashio and east kamchatka current we found bidecadal oscillations in these water properties that are synchronized with the 18 6 year period nodal cycle in periods when the diurnal tide is strong the following characteristics are found apparent oxygen utilization and phosphate are low in oyashio and okhotsk sea mode water the thickness of the intermediate layers is large and thus potential vorticity is correspondingly low in oyashio okhotsk sea mode water and upstream oyashio around the mesothermal temperature maximum water isopycnal potential temperature are low in the areas on the pacific side and high in the intermediate layer of okhotsk sea mode water the mixing ratio of okhotsk sea mode water in the upstream oyashio water is high these bidecadal oscillations can be explained by changes in the vertical mixing around the kuril straits induced by the diurnal tide whose amplitude is modulated with the 18 6 year nodal cycle higher sea surface salinity water around the kuril straits caused by stronger tidal mixing is possibly transported northward along the cyclonic okhotsk sea gyre and possibly enhances the formation of the dense shelf water this makes apparent oxygen utilization phosphate and potential vorticity lower in okhotsk sea mode water and oyashio

bidecadal variability in the bering sea and the relation with 18 6 year period nodal tidal cycle 1 bidecadal variations are investigated in the bering sea especially in the southeastern basin adjacent to the aleutian passes where vertical mixing may be strong because of the diurnal tide those variations found in this region are synchronized with the 18 6 year period nodal tidal cycle and the temporal patterns are similar to ones around the northwestern subarctic pacific near the kuril straits reported by a previous study salinity and density in the upper layer are high in the periods when the diurnal tide is strong in the intermediate layer layer thickness is large and isopycnal potential temperature and apparent oxygen utilization are low in the same periods it is shown that these variations are consistent with the patterns expected from the nodal modulation of vertical mixing and a simple two dimensional model assuming a balance between anomalous vertical mixing and advection of anomaly by the mean current succeeds to some extent in explaining the variations of the upper layer salinity and isopycnal temperature and apparent oxygen utilization in the intermediate layer

tropospheric intrusions associated with the secondary tropopause 1 deep intrusions of tropospheric air into the lower stratosphere above the subtropical jet are investigated using new observations and meteorological analyses these intrusions are characterized by low ozone concentration and low static stability the low ozone layer is consistently observed from ozonesonde profiles and satellite remote sensing data from aura hirdls the intruding layer occurs along and under the poleward extending tropical tropopause which becomes the secondary tropopause in middle to high latitudes the association of the ozone and the thermal structure provides evidence for the physical significance of the subtropical tropopause break and the secondary tropopause the core of the intruding layer is typically between 370 and 400 k potential temperature 15 km but the vertical extent of the intrusion can impact ozone above 400 k the lower boundary of the overworld two intrusion events over the continental united states in the spring of 2007 are analyzed to show the spatial extent and the temporal evolution of the intruding air mass these examples demonstrate the effectiveness of potential temperature lapse rate i e static stability as a diagnostic for the intrusion event comparison with the potential vorticity field is made to show the complementarity of the two dynamical fields the static stability diagnostic provides a tool to map out the horizontal extent of the intruding layer and to investigate its evolution furthermore the diagnostic makes it possible to forecast the intrusion event for field studies

taphonomical and palaeoecological investigation of the late cretaceous maastrichtian tustea vertebrate assemblage romania haţeg basin insights into a unique dinosaur nesting locality abstract the tustea vertebrate locality at oltoane hill northwestern part of the ha eg basin romania has provided a rich and diverse assemblage of late cretaceous maastrichtian continental vertebrates more than 800 vertebrate fossils were recovered from this locality the isolated and associated remains represent 21 different taxa including amphibians turtles lizards snakes crocodyliforms pterosaurs dinosaurs and mammals the local assemblage is overwhelmingly dominated by dinosaurs with the rhabdodontid zalmoxes as the most abundant taxon the bonebeds that yielded this fossil material occur in a stacked series of mudstone calcrete units belonging to the middle member of the densus ciula formation the taphonomical investigations suggest that the tustea assemblage is made up of attritionally accumulated politaxic remains and that it is a parautochthonous assemblage with no evidence for significant bone transport or reworking according to the synthesis of all available field data two outstanding fossiliferous levels can be identified within the tustea locality where megaloolithus eggs and hadrosauroid hatchling material are preserved together recognized here as two superposed nesting grounds such co occurrence was considered controversial since there is a long standing and quasi general consensus that eggs of the megaloolithus oogenus were laid by titanosaurian sauropods we present several alternative scenarios to account for the co occurrence of telmatosaurus hatchling remains and megaloolithid eggs in the nesting horizons and explore these alternative hypotheses by weighing the arguments supporting or contradicting them the burden of evidence derived from our sedimentological taphonomical and palaeoecological investigations at tustea is still in favour of the autochthony of the hatchlings preserved within their own nesting grounds whereas there is no such support for a titanosaurian origin of the tu tea megaloolithid eggs

tidally induced diapycnal mixing in the kuril straits and its role in water transformation and transport a three dimensional nonhydrostatic model experiment 1 baroclinic processes generated by the k1 tidal flow around the kuril straits and their role in the linkage between the okhotsk sea and the north pacific are investigated using a three dimensional nonhydrostatic model large amplitude unsteady lee waves are generated around sill tops all along the kuril island chain and induce significant density inversions from the sea surface down to the 27 6 density layer along with this wave breaking a large flow of energy takes place from the swift tidal flow regions to greater depths as a result of the clockwise propagation of both the topographically trapped waves around the islands and the remaining unsteady lee waves such wave generation and energy exchange eventually cause intense diapycnal mixing over the shallow topographic features and near the bottom leading to a maximum diapycnal diffusivity of over 103 cm2 s 1 even in the deep bussol strait which is thought to be the main exit of the okhotsk sea water considerable mixing corresponding to diapycnal diffusivity values of between 10 50 cm2 s 1 occurs vigorous mixing in the shallow regions produces low potential vorticity pv water in the upper layer and high pv water below accordingly pv fronts are formed along the island chain and sustain instabilities that in turn release baroclinic eddies with low core pv values these features are indicated in recent satellite imagery and in situ observations suggesting that the tide is the controlling factor in the formation of fronts observed in the kuril straits tidally induced mean transport across the straits is estimated to reach 26 sv 1 sv 106 m3 s 1 which is much larger than in the barotropic case however most of the exchanged water tends to circulate around the islands due to the effect of bottom topography whereas eddies pinched off from the tidal fronts carry the exchanged water offshore the amount of eddy driven offshore transport away from the islands reaches 14 sv with roughly half being directed to the north pacific this significant offshore transport spreads the effect of the diapycnal mixing taking place in the straits over wider areas of the north pacific and the okhotsk sea for example the pv values generated in the eddies differ by 30 40 from the ambient water on average whereas sea surface salinity within the eddies is 0 1 psu higher than the surroundings corresponding to the density increase of 0 08 thus the eddy transport provides significant pv and salinity fluxes to both the north pacific and the okhotsk sea hence we infer that a combination of tidally driven processes taking place at the passages leads to the formation of eddies that play a central role in water transport and transformation and are an essential aspect of the physical interplay between the okhotsk sea and the north pacific

the relative roles of diapycnal and isopycnal mixing on subsurface water mass conversion abstract fluid motion in the sea is known to occur predominantly along quasi horizontal neutral surfaces but the very small diapycnal i e across isopycnal velocities often make a significant contribution to the conversation equations of heat salt and tracer by eliminating the diapycnal advection term between the conservation equations for i heat and ii salt an equation is derived for the rate of change lagrangian derivative of potential temperature on a neutral surface which has terms caused by a turbulent mixing along isopycnal surfaces i e isopycnal mixing b diapycnal turbulent mixing and c double diffusive convection bemuse of the nature of the isopycnal reference frame the diapycnal mixing terms do not take their expected forms for example the diapycnal turbulent mixing term is proportional to the diapycnal eddy diffusivity d multiplied by the curvature of the s curve d2s d 2 rather than the usual form d x x if the s curve is locally straight small scale turbulen

overturning circulation that ventilates the intermediate layer of the sea of okhotsk and the north pacific the role of salinity advection dense shelf water dsw formation in the northwestern continental shelf of the sea of okhotsk is the beginning of the lower limb of the overturning circulation that ventilates the intermediate layer of the north pacific ocean the upper limb consisting of surface currents in the okhotsk sea and the subarctic gyre has not been clarified using a high resolution north pacific ocean model with a curvilinear grid as fine as 3 km 3 km in the sea of okhotsk we succeeded in representing the three dimensional structure of the overturning circulation including the narrow boundary currents and flows through straits that constitute the upper limb as well as the lower limb consisting of dsw formation and ventilation in particular pathways and time scales from the bering sea to the intermediate layer via the ventilation in the sea of okhotsk were examined in detail using tracer experiments further we found that the overturning circulation that connects the surface and intermediate layer is sensitive to wind stress in the case of strong winds the coastal current under polynyas where dsw forms is intensified and consequently diapycnal transport from the surface layer to the intermediate layer increases strong winds also induce a positive sea surface salinity anomaly in the subarctic region causing a significant decrease in the density stratification and increase in the dsw salinity i e density these processes act together to produce intense overturning circulation and deep ventilation which may subduct even to the bottom of the sea of okhotsk if the wind is strong

stratosphere to troposphere transport revealed by ground based lidar and ozonesonde at a midlatitude site 1 this paper presents ozone structures measured by a ground based ozone lidar and ozonesonde at huntsville alabama on 27 29 april 2010 originating from a stratosphere to troposphere transport event associated with a cutoff cyclone and tropopause fold in this case the tropopause reached 6 km and the stratospheric intrusion resulted in a 2 km thick elevated ozone layer with values between 70 and 85 ppbv descending from the 306 k to 298 k isentropic surface at a rate of 5 km day 1 the potential temperature was provided by a collocated microwave profiling radiometer we examine the corresponding meteorological fields and potential vorticity pv structures derived from the analysis data from the north american mesoscale model the 2 pvu pv unit surface defined as the dynamic tropopause is able to capture the variations of the ozone tropopause estimated from the ozonesonde and lidar measurements the estimated ozone pv ratio from the measured ozone and model derived pv for the mixing layer between the troposphere and stratosphere is 41 ppbv pvu with an uncertainty of 33 within two days the estimated mass of ozone irreversibly transported from the stratospheric into the troposphere is between 0 07 tg 0 9 1033 molecules and 0 11 tg 1 3 1033molecules with an estimated uncertainty of 59 tropospheric ozone exhibited enormous variability due to the complicated mixing processes low ozone and large variability were observed in the mid troposphere after the stratospheric intrusion due to the westerly advection including the transition from a cyclonic system to an anticyclonic system this study using high temporal and vertical resolution measurements suggests that in this case stratospheric air quickly lost its stratospheric characteristics once it is irreversibly mixed down into the troposphere

evolution and modulation of a poleward propagating anticyclonic eddy along the japan and kuril kamchatka trenches to investigate the relationships between the movement of an eddy and its interior structure and water properties four profiling floats were deployed in an anticyclonic eddy in the western north pacific in 2013 april october daily float profiles showed rapid changes in temperature and salinity corresponding to strong interactions between eddies north of the subtropical kuroshio extension after the first interaction with a warm core eddy in april the isolation of the winter mixed layer from the surface was observed forming a subsurface remnant layer another interaction with a cold fresh eddy at middepths in may resulted in the formation of a multilayer structure the eddy then moved poleward along the japan and kuril kamchatka trenches indicating changes in its propagation pattern coupled to its interior structure the eddy then moved northward june july stalled july august and moved eastward august october in addition to a general declining trend the properties of the warm saline core changed over a short time period coinciding with changes in propagation a density anomaly at middepths of the eddy changed location during the stalled period however denser waters were continuously observed in the southeast part of the eddy during its northward and eastward movement this unidirectional density anomaly pattern was consistent with the structure of the poleward propagating eddy which interacted with the western topographic boundary meridional exchanges of heat and material were potentially elevated by the eddy s advection and movement as well as by water modifications in the eddy associated with exchanges along its perimeter

bioerosion on vertebrate remains from the upper cretaceous of the haţeg basin romania and its taphonomic implications abstract bioerosion on fossil bones offers significant insights into both trophic relationships of ancient ecosystems and vertebrate taphonomy here we report six distinct trace fossil categories identified on isolated turtle crocodyliform and dinosaur remains from the upper cretaceous sinpetru formation of the ha eg basin romania for which five different probable tracemakers are identified 1 termites 2 dermestid beetles 3 multituberculate mammals 4 ziphodont theropod dinosaurs or crocodyliforms and 5 plants this extraordinary diversity of bioerosional trace fossils on vertebrate remains reveals insect vertebrate as well as vertebrate vertebrate interactions previously undocumented in the continental uppermost cretaceous of romania the association between different traces especially since many of these are superimposed on top of each other allows the reconstruction of the detailed taphonomic history of the specimens indicating four different taphonomic pathways the vertebrate remains with trace fossils described here were most likely exposed to post mortem biotic interactions for a prolonged time period before they were transported and or trampled and finally buried in the palaeoenvironmental context of a heterogeneous braided river system with low lying wetlands and more elevated drylands the death of the vertebrates as well as the scavenging likely occurred on the drylands

distribution and formation of okhotsk sea intermediate water an analysis of isopycnal climatological data 1 in order to clarify the distribution and formation of okhotsk sea intermediate water osiw an isopycnal climatological data set based on all of the available historical observations is developed and examined the isopycnal maps clearly show that there are two direct ventilation sources for osiw dense shelf water dsw with cold and fresh properties influenced by sea ice formation in the northwest shelf region and forerunner of soya warm current water fscw which has warm and saline properties originating in the japan sea the cold and fresh water extends southward from the northwest shelf to the shelf slope off sakhalin island it suggests that dsw is transported southward by the east sakhalin current the dsw enters the kuril basin and mixes with fscw and western subarctic water wsaw originating from the north pacific to form osiw the annual mean production rate of dsw estimated from the total volume of dsw over the shelf in spring and summer is 0 67 sv 1 sv 106 m3 s the annual mean volume transport of fscw is estimated to be 0 08 sv on the basis of its cross section area and the current speed assumption of isopycnal mixing yields a mixing ratio of 1 1 0 1 among dsw wsaw and fscw to form osiw we estimate the annual production rate of osiw to be 1 4 sv the corresponding osiw s renewal time is 7 years continued assumption of isopycnal mixing yields a mixing ratio of 0 6 0 4 between wsaw and osiw to form oyashio intermediate water oyiw

stable isotope composition and rare earth element content of vertebrate remains from the late cretaceous of northern spain lano did the environmental record survive abstract oxygen and carbon isotope measurements have been performed on phosphatic remains from faunal associations dinosaurs crocodiles turtles and fish of the late cretaceous continental and marine sediments from northern spain basque country the environmental meaning of the oxygen isotope record in fossil reptiles is discussed on the basis of known paleoecology modern fauna analogs and apatite chemistry rare earth elements ree co32 and po43 contents fossil remains in sandstones and argillites from two localities urria and cuezva have low down to 16 and scattered 18o po4 co3 and 13c values with ree patterns characterized by strong middle ree enrichments these geochemical compositions of the biogenic apatites have most likely been acquired during a multi stage late diagenesis involving complete recrystallization of the apatite in the presence of aqueous fluids ree contents of fossils preserved in the clayey sands from the site of lano suggest that samples have only been affected by early diagenesis despite the diversity of analyzed taxa and the close association of marine sharks and rays and freshwater species crocodiles and turtles evolving in a littoral environment the narrow range of phosphate 18o values is interpreted as reflecting the temperature and isotopic composition of groundwaters that prevailed in the burial environment the potential information relative to the physiology and thermal regime of the vertebrates has been erased during the process of early diagenesis if all oxygen in the phosphate has exchanged with groundwaters the oxygen isotope composition of vertebrate remains suggests that a warm climate t 20 25 c prevailed in northern spain during the late cretaceous

seasonal variation in the in and outflow of the okhotsk sea with the north pacific abstract this paper examines the seasonal variation in the in and outflow of the okhotsk sea with the pacific mainly based on profiling float and satellite altimeter data the motions of the floats at depths of 500 750 m show that the waters of the okhotsk tend to flow out to the pacific through the southern kuril straits mostly bussol strait in winter seasons november march based on data from the floats exiting the sea the mean residence time of the intermediate water in the kuril basin is estimated as about one year isopycnal analysis from the profiling data shows that in the mid eastern area of the okhotsk sea potential temperature of the intermediate water with 26 6 27 2 increases by 0 2 0 5 c in every spring suggesting the inflow from the pacific in the preceding season these suggest that the in and outflow predominantly occurs during winter with the inflow at the northern straits and outflow at the southern straits the surface current field inferred from satellite altimeter data also shows that the inflow to the sea of okhotsk through the northern straits is strengthened in winter linked with strengthening of the east kamchatka current ekc from yearly anomalies of the altimeter data the winter inflow to the okhotsk through the northern straits is significantly correlated with the ekc and sverdrup transport over the north pacific further interannual variations in property of okhotsk sea intermediate water appear to be related with the ekc and wind stress over the north pacific in winter possibly through the change in inflowing pacific water transport these suggest that the seasonal and interannual variations of the in and outflow are to some extent controlled by the large scale wind stress over the north pacific being consistent with island rule qualitatively