fine structure microstructure and vertical mixing processes in the upper ocean in the western weddell sea the upward flux of heat from the subsurface core of warm deep water wdw to the perennially ice covered sea surface over the continental slope in the western weddell sea is estimated using data obtained during february june 1992 from a drifting ice station through the permanent pycnocline the diapycnal heat flux is estimated to be about 3 w m 2 predominantly because of double diffusive convection there is no evidence that shear driven mixing is important in the pycnocline the estimated mean rate of heat transfer from the mixed layer to the ice is 1 7 w m 2 although peak heat fluxes of up to 15 w m 2 are found during storms it is hypothesized that isopycnal mixing along sloping intrusions also contributes to the loss of heat from the wdw in this region however we are unable to quantify the fluxes associated with this process intrusions occur intermittently throughout this experiment but are most commonly found near the boundary of the warm core current and the shelf modified water to the east these heat fluxes are significantly lower than the basin averaged value of 19 w m 2 fahrbach et al 1994 that is required to balance the heat budget of the weddell gyre other studies suggest that shelf processes to the west of the ice station drift track and more energetic double diffusive convection in the midgyre to the east could account for the difference between our flux estimates for this region and those based on the basin scale heat budget

turbulent mixing near the yermak plateau during the coordinated eastern arctic experiment during the ice camp component of the coordinated eastern arctic experiment cearex in march april 1989 1500 profiles of temperature conductivity and velocity shear microstructure were obtained near the yermak plateau the dominant signal in isopycnal displacements was the diurnal variability near the plateau consistent with the enhanced diurnal currents found in this region previously from the fram iii and fram iv ice camps the dissipation rate of turbulent kinetic energy e reached maximum values of about 10 6 w kg 1 in two distinct regions the surface mixing layer and the pycnocline between 120 and 220 m there was a significant component of diurnal variability in e in each region in the surface layer e was proportional to the cube of the ice relative current speed at 30 m below the ice and it decayed approximately exponentially with increasing depth major mixing events in the pycnocline were correlated with large amplitude short duration isopycnal displacements the lowest dissipation rates were recorded over the deep nansen basin north of the plateau and in the subsurface core of a submesoscale baroclinic eddy in northern fram strait the time averaged vertical eddy diffusivity near the slope of the plateau was about 2 5 10 4 m2 s 1 in the pycnocline above the atlantic layer implying an upward heat flux of 25 w m 2 although only a small fraction of this heat reached the base of the mixed layer the results confirm that current interactions with steep topography are critical to the modification of atlantic water in the eastern arctic ocean

calabrian eopleistocene micromammal assemblages from the lacustrine and fluvial deposits of the southern trans urals and chronological position of some regional stratigraphic units abstract in the southern trans urals the quaternary deposits dated back to the early pleistocene 2 58 0 77 ma are scarce incomplete and often severely eroded data scarcity is a major challenge for accurate geological correlation and for integration of regional data into continent wide stratigraphic frameworks we provide a review of stratotypes and type localities for regional stratigraphic subdivisions of the eopleistocene the units correlated with the calabrian stage of the western european stratigraphical timescale 1 8 0 77 ma with particular focus on small mammals and their biochronological significance subdivisions of the eopleistocene which have been officially accepted in russia include three regional chronostratigraphic units horizons starting from uvel ka to chumlyak and sarykul we show that the calabrian deposits are characterized in the southern trans urals by sequential changes in the evolutionary level of micromammal assemblages that could be directly correlated with the mammal based biochronological zones mqr of russia vangengeim and tesakov 2008 tesakov and titov 2013 within the interval from mqr 10 to mqr 8 analysis of micromammal assemblages reveals incongruent positioning of the officially accepted uvel ka chumlyak and sarykul horizons in the regional stratigraphic chart the revealed incongruences appear to be a result of the difficulty to delineate chronostratigraphic units using the highly eroded and reworked sediments of fluvial origin the complete cycles of alternating fluvial lacustrine sedimentation and subaerial exposure provide the most reliable sections to establish the chronostratigraphic units of the calabrian stage of the early pleistocene in the southern trans urals the position of chumlyak and sarykul horizons in the regional stratigraphic chart of the southern trans urals is proposed to be changed the validity of the uvel ka formation as a chronostratigraphic unit should be further verified with a particular focus on faunal proxies mollusks ostracods and small mammals

calculating tidal current profiles from vertically integrated models near the critical latitude in the barents sea the method of extracting current profiles from vertically integrated hydrodynamic models is extended to incorporate more general boundary conditions and the consistency of the method is investigated using this method the tidal current profiles for semidiurnal and diurnal constituents are studied in high latitudes near the critical latitude where the coriolis frequency equals the tidal frequency for the semidiurnal tide the current profiles are computed at stations in the barents sea where current measurements exist at up to six different depths the observation stations are located close to the critical latitude for the largest semidiurnal constituents and the current profiles are therefore sensitive to variations of magnitude and vertical distribution of the eddy viscosity at this latitude the current is strongly depth dependent and in deep water the tidal ellipse changes direction of rotation near the seabed at four of the stations there are under ice measurements and the effects of an ice covered ocean upon the tidal current profiles are also investigated

instability of baroclinic tidal flow in a stratified fjord abstract the taylor goldstein equation is used to investigate the stability of a baroclinic tidal flow observed in a stratified fjord the flow is analyzed at hourly intervals when turbulent dissipation measurements were made the critical gradient richardson number is often close to the miles howard limit of 0 25 but sometimes it is substantially less although during 8 of the 24 periods examined the flow is marginally stable it is either very stable or very unstable in others for the unstable flow the e folding period of the fastest growing disturbances is 83 455 s about 46 of the buoyancy period at the levels where the fastest growing disturbances have their maximum amplitude these disturbances to the flows have wavelengths about 20 72 of the water depth and have mostly a second mode structure simultaneous measurements of the flow and turbulence allow for testing of the hypothesis that the growth rates of the most unstable disturbances are related to the turbulent dissipation rates dissipati

a barotropic inverse tidal model for the arctic ocean 1 we describe high resolution 5 km grid linear dynamics and inverse models of arctic ocean barotropic tides obtained with the osu tidal inversion software otis package the 8 constituent dynamics based model uses the latest ibcao bathymetry and open boundary forcing from the recent tpxo 6 2 global barotropic tidal solution this model performs significantly better than the present benchmark arctic tidal model 14 km grid by z kowalik and a proshutinsky as judged by comparisons with 300 coastal tide gauges the greatest improvements are found in the canadian arctic archipelago nares strait and the baffin bay and labrador sea and can be explained by the higher resolution of the new model in these topographically complex regions the new arctic inverse model assimilates coastal and benthic tide gauges and topex poseidon and ers altimetry for further improvements of the 4 dominant constituents m2 s2 k1 and o1

mixing in the west spitsbergen current abstract twenty eight profiles of temperature and salinity down to 1 km depth have been measured in the area north from the coast of svalbard to latitude 84 40 n between 0 and 32 e longitude they show atlantic waters of the west spitsbergen current entering the arctic ocean in a bifilimentary mode one filament following the coastline and the other 300 km farther north apparently following the continental shelf break the profiles show these filaments mixing into the ambient water in a series of intrusive layers which are remarkably uniform over distances of hundreds of kilometers a triple peak structure at the atlantic water maximum is the dominant oceanographic characteristic of the area with salt fingering occurring on the upper surface of the cold intrusions and indications of double diffusive exchanges through the lower surface a system or eddies or meanders is postulated as the mechanism for the production of multiple fronts allowing the intrusive layers to extend to distances much greater t

vertical mixing at intermediate depths in the arctic boundary current microstructure and hydrographic observations during september 2007 in the boundary current on the east siberian continental slope document upper ocean stratification and along stream water mass changes a thin warm surface layer overrides a shallow halocline characterized by a 40 m thick temperature minimum layer beginning at 30 m depth below the halocline well defined thermohaline diffusive staircases extended downwards to warm atlantic water intrusions found at 200 800 m depth observed turbulent eddy kinetic energy dissipations are extremely low epsilon 10 6 w m 3 such that double diffusive convection dominates the vertical mixing in the upper ocean the diffusive convection heat fluxes f dc h 1 w m 2 are an order of magnitude too small to account for the observed along stream cooling of the boundary current our results implicate circulation patterns and the influence of shelf waters in the evolution of the boundary current waters

shear and baroclinic energy flux on the summer new england shelf observations are presented of internal wave properties and energy fluxes through a site near the 70 m isobath on the new england shelf in late summer data collected from a shipboard adcp and microstructure profiler over a three week period and projected onto dynamic vertical modes reveals large variations in the magnitude and vertical structure of internal waves baroclinic energy and shear were primarily associated with low mode near inertial and semidiurnal waves and at times high frequency solibores the energies in each mode varied by factors from 2 to 10 over several days and were not significantly correlated with one another the associated shear variance was concentrated in the thermocline however the strength and vertical range of shear varied significantly throughout the research period and depended sensitively on both the magnitude and evolving vertical mode content of the wave field shear during the quasi two layer solibores was strong enough to temporarily lower the 4 m richardson number below the threshold for shear instability energy flux through the site came primarily from the mode 1 internal tide in both linear and nonlinear solibore forms the average energy flux from the first five baroclinic modes was 130 w m 21 a comparison of energy fluxes from each mode and locally measured average dissipation rates suggests that near inertial and high mode waves were generated near the experimental site

the contribution of salt fingers to vertical mixing in the north atlantic tracer release experiment abstract the north atlantic tracer release experiment natre was performed in an area moderately favorable to salt fingers however the classic finger signature of a distinct thermohaline staircase caused by upgradient density flux was absent this is likely because mixing by turbulence was sufficiently strong to disrupt the formation of permanent step and layer systems despite the lack of a staircase optical shadowgraph profiles revealed that small scale tilted laminae previously observed in a salt finger staircase were abundant at the natre site using microstructure observations the strength of salt finger mixing has been diagnosed using a nondimensional parameter related to the ratio of the diffusivities for heat and buoyancy the dissipation ratio by examining the dissipation ratio in a parameter space of density ratio r and richardson number ri the signal of salt fingers was discerned even under conditions where turbulent mixing also occurred while the model for turbulence descr

microstructure observations of turbulent heat fluxes in a warm core canada basin eddy abstractan intrahalocline eddy was observed on the chukchi slope in september of 2015 using both towed ctd and microstructure temperature and shear sections the core of the eddy was 6 c significa

boundary layer upper ocean and ice observations in the greenland sea marginal ice zone during the 1984 marginal ice zone experiment a coordinated ocean boundary layer and mixed layer experiment was carried out in concert with a complete heat and mass balance study in the summer marginal ice zone miz of the greenland sea the measurements were made at two drifting ice stations and included observations of ocean boundary layer turbulence profiles of water temperature salinity and velocity ice ablation ice concentration solar radiation and spectral albedos ocean conditions were found to be extremely variable the ice and water velocities were heavily influenced by tidal and inertial motions with amplitudes from 6 to 12 cm s 1 in the course of the drift a 30 km eddy was crossed wherein ice and water velocities exceeded 15 cm s 1 the northern extension of the east greenland polar front was encountered and a northward flow of atlantic water into the arctic basin was observed below the eastern edge of the front but the drift station never moved quite far enough west to be caught in the southward transport of arctic surface water heat from the ocean was a major factor in ice melt and when the ice was over atlantic water it was the dominant factor the events that had the greatest impact on the ice were two outbreaks during which off ice winds blew the ice across warm ice edge ocean fronts once south of these fronts and over surface water as warm as 1 c the ice bottom melted at rates up to 100 kg m 2 d 1 the rapid changes in stratification associated with the outbreaks had a dramatic impact on the drag and heat transfer coefficients the drag coefficient relative to the square of the relative water velocity at 30 m ranged from 0 002 to 0 02 and averaged 0 006 the heat transfer coefficient relative to the friction velocity u and the mixed layer temperature elevation above freezing ranged from 0 0025 to 0 009 and averaged 0 0038 in agreement with the idea that stratification inhibits turbulent exchange the heat transfer coefficient decreased when stratification increased in fact the observed melt rates can be simulated well if molecular heat and salt transfer through a thin near surface laminar boundary layer are accounted for as well as transfer through the turbulent outer boundary layer also in agreement with turbulent boundary layer theory the drag coefficient decreased when stratification increased slightly above neutral however for the large increases in surface stratification the drag coefficient increased this was due to the generation of internal gravity waves by ice bottom roughness because the surface exchange coefficients are so sensitive to surface stratification which is in turn highly variable in the miz accurate simulations of ice motion and ice melt will require realistic estimates of stratification and a good understanding of the relation between the ice ocean interactions and upper ocean conditions

internal wave mixing in the baltic sea near inertial waves in the absence of tides 1 the dynamics of near inertial motions and their relation to mixing is investigated here with an extensive data set including turbulence and high resolution velocity observations from two cruises conducted in 2008 summer and 2010 winter in the bornholm basin of the baltic sea in the absence of tides it is found that the basin scale energetics are governed by inertial oscillations and low mode near inertial wave motions that are generated near the lateral slopes of the basin these motions are shown to be associated with persistent narrow shear bands strongly correlated with bands of enhanced dissipation rates that are the major source of mixing inside the permanent halocline of the basin in spite of different stratification near inertial wave structure and atmospheric forcing during summer and winter conditions respectively the observed dissipation rates were found to scale with local shear and stratification in a nearly identical way this scaling was different from the gregg henyey type models used for the open ocean but largely consistent with the mackinnon gregg scaling developed for the continental shelf

a magnetostratigraphic reassessment of correlation between chinese loess and marine oxygen isotope records over the last 1 1 ma abstract we present a magnetic polarity based paleoclimatic correlation between chinese loess and marine oxygen isotope stage mis records over the last 1 1 ma this revised land ocean comparison indicates that inconsistent occurrence of the matuyama brunhes boundary which lies in mis 19 in marine sediments and occurs either at the base lower part of loess l8 or the uppermost part of soil s8 in chinese loess is due to regional and or local climate variability across the chinese loess plateau and does not need to be attributed to lock in effects of loess remanence acquisition associated with pedogenesis this result implies that the geomagnetic polarity boundaries in chinese loess in general are reliable chronostratigraphic time markers therefore astronomically tuned timescales for chinese loess that presume a downward shift of polarity boundaries due to a time lag in remanence acquisition may have overestimated ages of certain loess paleosol units

soilscape evolution of west tien shan during the late pleistocene based on humus properties of the obi rakhmat archaeological site analysis of the pedogenic humus properties of sediments at the obi rakhmat archaeological site is the basis for reconstructing soil forming processes as records of climatic fluctuations in the region of west tien shan the stratigraphic section has 10 zones of pedogenesis that are distinguishable by pedogenic humus and other features and consequently by the character of ancient soil forming processes we found that most of the sediments accumulated in an environment where serozem soils form that is in an arid subtropical landscape desert steppe zone the scheme of the altitudinal landscape sequence and the structure of the soil cover also changed according to climatic changes and regular displacements of the altitude zones occurred when analogs of modern dark serozems dominated near the site the altitude sequence was characterized by the most complexity with humid as well as arid landscapes occupying areas of the slopes climatic change trends both to humidity and to aridity simplified the altitude scheme when climate was arid humid landscapes were ousted mountain brown forest soils occurred only on the slope tops in contrast when climate was humid arid landscapes disappeared from the altitude sequence and forest and meadow zones were dominant

the matuyama brunhes boundary in loess sections in the south of the east european plain and their correlation on the basis of palaeomagnetic and palaeopedologic data abstract the matuyama brunhes boundary mbb in loess sections of the east european plain one of the greatest areas of global loess distribution is a highly debatable issue the ambiguity of the mbb position here results from the complexity of loess soil magnetization processes and an apparent delay in loess remanence acquisition and from the uncertainties of pedostratigraphic interpretations in the don glaciation area the mbb is unanimously placed below the don moraine although the exact position is still controversial in the sites of the northern azov sea the mbb is however placed in the loess horizon considered to be the equivalent of the don moraine in the north the inconsistency of this interpretation is demonstrated by detailed magnetostratigraphic and pedostratigraphic studies in the western sites of zaporozh e dnieper basin novaya etuliya lower danube basin and roxolany lower dniester basin in all these sites albeit with certain minor discrepancies the mbb is found two or three interglacial palaeosols below the don loess which is overlain by the good stratigraphic marker of the vorona pedocomplex a thick polygenetic red brown palaeosol formed supposedly in a mediterranean climate here the mbb is placed in a quadruple soil unit termed roxolany loess soil suite which consists of four closely spaced strongly calcareous soils occupying an interval between the don loess on top and the earlier well developed bobrov loess with reversed matuyama magnetization the roxolany suite can possibly be correlated with the three palaeosols of the pre don ilyinka unit of the russian unified stratigraphic scheme and thus confirms the interpretation of the mbb in the central areas of the east european plain as to the interval between the ternovka second pre don palaeosol and the troitsk third pre don palaeosol

observations of upper ocean boundary layer dynamics in the marginal ice zone 1 vertical profiles of turbulent kinetic energy dissipation and small scale hydrography were collected in the upper ocean boundary of both ice covered and ice free stations in the marginal ice zone of the barents sea in spring 2005 together with shipboard wind measurements and current profiles the mixed and mixing layer dynamics are studied during the survey shear production by the stress at the surface or under the ice dominated large upward turbulent heat fluxes 300 500 w m 2 were calculated for the mixing layers overlying the warm atlantic water which compared well with those obtained from an independent parameterization at the top of the pycnocline corresponding heat fluxes were 10 20 w m 2 significant stabilizing buoyancy fluxes were estimated for ice drift stations owing to the melting of ice in response to the large heat fluxes the mean dissipation profile in the ice free reference station agreed with the constant stress wall layer scaling within 30 on the contrary the observed dissipation profiles were enhanced in the upper half of under ice mixing layer or within 2 5 times the assessed pressure ridge keel depth deeper in the mixing layer the profiles relaxed toward the wall scaling the variability of dissipation in the mixed layer was better captured by the shear production profile when local friction speed was used together with a mixing length profile modified by buoyancy fluxes significant correlations were found between dissipation integrated over the mixing layer and work done by stress under the ice and the wind work at 10 m height the low correlation between the mixed layer depth and length scale for neutral conditions significantly increased when the reduction in the mixing length due to buoyancy fluxes was accounted for the mixing depth is observed to be strongly correlated with the outer neutral planetary length scale

sarykul paleosol in southern urals sediments russia abstract sarykul paleosols in the southern urals russia with a stable position in geological sediments are considered the brunhes matuyama boundary was found in these paleosols and they were used as a source of information on the environment data were obtained during the study of the sarykul paleosols in four sections located in the mountain part of the southern urals on the miass river erosion accumulation terrace and at the eastern edge on the trans uralian peneplain saykul paleosols have a relatively thick and compact humic horizon with a tongued lower boundary the paleosols are dark grey with high toc content that is not usual for the early pleistocene paleosols the materials showed that sarykul paleosols formed on different parent rocks may have various characteristics of the mineral part texture ph magnetic susceptibility carbonate content ratio of exchangeable cations while their humic substances characteristics humic and fulvic acid ratio humic acid characteristics of elemental composition and structure are very similar climate conditions during sarykul paleosol formation changed from relatively warm and humid to less warm and more humid the study of southern urals sarykul paleosols has shown that they can serve as a reliable marker of the final early pleistocene due to their specific characteristics not analogous to the modern soils

changes in temperature and tracer distributions within the arctic ocean results from the 1994 arctic ocean section abstract major changes in temperature and tracer properties within the arctic ocean are evident in a comparison of data obtained during the 1994 arctic ocean section to earlier measurements 1 anomalously warm and well ventilated waters are now found in the nansen amundsen and makarov basins with the largest temperature differences as much as 1 c in the core of the atlantic layer 200 400 m thus thermohaline transition appears to follow from two distinct mechanisms narrow order 100 km topographically steered cyclonic flows that rapidly carry new water around the perimeters of the basins and multiple intrusions 40 60 m thick which extend laterally into the basin interiors 2 altered nutrient distributions that within the halocline distinguish water masses of pacific and atlantic origins likewise point to a basin wide redistribution of properties 3 distributions of cfcs associated with inflows from adjacent shelf regions and from the atlantic demonstrate recent ventilation to depths exceeding 1800 m 4 concentrations of the pesticide hch in the surface and halocline layers are supersaturated with respect to present atmospheric concentrations and show that the ice capped arctic ocean is now a source to the global atmosphere of this contaminant 5 the radionuclide 129i is now widespread throughout the arctic ocean although the current level of 129i level poses no significant radiological threat its rapid arrival and wide distribution illustrate the speed and extent to which waterborne contaminants are dispersed within the arctic ocean on pathways along which other contaminants can travel from western european or russian sources

pedohumic method in paleoenvironmental reconstructions abstract paleopedology can be an instrument to better understand problems in natural and humanitarian sciences a new pedohumic method involving diagnosis and reconstruction of paleoenvironments is suggested the reconstruction of the kazantsevo r w interglacial paleoenvironment in the chulymo yenisei depression middle siberia is considered as an example the trend of environmental conditions within the r w interglacial is similar to that of the current southern taiga steppe

matuyama brunhes boundary in key sections of the loess paleosol glacial formations on the east european plain abstract multidisciplinary studies of two key sections parastratotypes of the loess soil glacial formation strelitsa and sebryakovo mikhailovka sections located in the central part of the east european plain placed the matuyama brunhes reversal well below the lower pleistocene till the till attributed to the don glaciation maximum glaciation on the east european plain is separated from the m b reversal by several units as follows 1 a horizon of humified loam of still uncertain stratigraphic position 2 a loess horizon and 3 a paleosol complex rzhaksa the polarity reversal is within a transitional zone which includes the base of the lower bobrov loess and the upper portion of the underlying soil complex balashov the primary constituent of remanent magnetization has been identified using two methods demagnetization by heating and by alternating magnetic field such a technique ensures a high degree of reliability

roxolany and novaya etuliya key sections in the western black sea loess area magnetostratigraphy rock magnetism and paleopedology abstract loess paleosol sequences in the western black sea area at roxolany 48 m thick and novaya etuliya 30 m thick were studied using paleo and rock magnetic methods in conjunction with micromorphology and mossbauer investigations although seemingly complete the sites show variability in the type and number of loess paleosol cycles and inconsistency of the matuyama brunhes boundary mbb stratigraphic position at roxolany nine pedocomplexes pk and several incipient paleosols alternating with thick loesses were observed with the mbb being located between pk 6 and pk 7 at novaya etuliya 13 pks occur upon terrace xii with khapry fauna and with the mbb in the upper part of pk 7 and the jaramillo subchron within the lower part of pk 8 the depth functions of rock magnetic properties organic carbon content c org both for bulk samples and for clay extracts along with micromorphology and mossbauer spectra allowed objective identification of individual soils within pks and maximizing the resolution of paleopedological reconstructions of global climatic stages the mossbauer studies demonstrate that paleosols are basically enriched in ferric montmorillonite oxidized magnetite ultrafine iron hydroxides and hematite are intimately associated with clay minerals in contrast fe compounds in loess consist mainly of ferrous silicates these data indicate that the paleosol magnetism is basically of bio chemogenic origin and is related to pedogenic transformation of fe compounds in a changing environment while loess magnetism is primarily detrital pedogenic magnetically soft and partly oxidized magnetite may also originate during or even after burial this ensuing transformation of fe minerals in paleosols seems to be crucial for the understanding of the timing of natural remanent magnetization nrm in subaerial sediments given that paleosols formed on the similar parent material loess their typological variability seems to depend on climate and or chronology hence the different paleosol types from roxolany and novaya etuliya provide key information for intra and inter regional correlation of loess soil sequences and represent valid paleoclimatic proxies

interannual variability in the hydrography of atlantic water northwest of svalbard using data from 1910 to 1997 we study the mean structure as well as the interannual variability in the autumn hydrography of the part of the west spitsbergen current wsc confined over the upper continental slope and of its continuation the svalbard branch this is known to provide a major pathway for warm and saline atlantic water to the arctic ocean we focus our study on the area northwest of svalbard around 80 n the time series of subsurface hydrography 100 300 m layer show interannual variations which are in the 1980s and 1990s quite coherent with hydrographic time series obtained upstream in the wsc around 76 n as well as with variations in the large scale atmospheric patterns as indicated by the north atlantic oscillation nao index however in the 1970s the coherence is poorer our results suggest that it may be important to focus on the narrow domain of the part of the wsc confined over the upper continental slope in order to get consistent estimates of the arctic ocean inflow signal in the fram strait the warming in this inflow signal in 1970 1996 does not seem to have been as strong as previously suggested

some chemical characteristics of paleosol humic acids humic acids ha s were extracted from six paleosols in southern italy ranging in radiocarbon ages from 6 000 to 30 000 yr each ha was characterized by a number of chemical elemental and functional group analyses and spectroscopic e4e6 ratios 13c nmr ir esr methods and by chemical degradation followed by separation and identification of the products by gas chromatography mass spectrometry the chemical characteristics of the paleosol ha s were then compared with those of more recent ha s the chemical and spectroscopic methods failed to show any effect of age on the chemical structure of the paleosol ha s only oxidative degradation showed differences between the six paleosol ha s the oxidation of paleosol ha s 22 000 yr old and older produced significantly greater quantities of benzenetetra penta and hexacarboxylic acids than did the oxidation of the younger paleosol ha s and of ha s extracted from soils of volcanic origins these findings indicate that the molecular complexity of the paleosol ha s increased with increasing time of burial

turbulent upper ocean mixing affected by meltwater layers during arctic summer abstractevery summer intense sea ice melt around the margins of the arctic pack ice leads to a stratified surface layer potentially without a traditional surface mixed layer the associated strengthening of near surface stratification has important consequences for the redistribution of near inertial energy ice ocean heat fluxes and vertical replenishment of nutrients required for biological growth the authors describe the vertical structure of meltwater layers and quantify their seasonal evolution and their effect on turbulent mixing in the oceanic boundary layer by analyzing more than 450 vertical profiles of velocity microstructure in the seasonal ice zone north of svalbard the vertical structure of the density profiles can be summarized by an equivalent mixed layer depth hbd which scales with the depth of the seasonal stratification as the season progresses and melt rates increase hbd shoals following a robust pattern implying stronger vertical stratification weaker vertical eddy diffusivit

shear and strain in santa monica basin by injecting a cloud of sf6 into santa monica basin at a depth of 790 m and observing its vertical spread ledwell and watson 1991 estimate the average diapycnal diffusivity between 750 and 850 m as kp 2 5 10 5 m2 m 1 this diffusivity is higher than inferred from microstructure measurements in the open ocean thermocline for typical internal wave levels gregg and sanford 1988 to examine shear and strain in the basin we dropped expendable current profilers xcps and calculated strain from conductivity temperature and depth ctd casts shear and strain are above the gm76 model spectrum garrett and munk 1975 cairns and williams 1976 and comparisons with published parameterizations indicate more than enough shear variance to account for the high diffusivity reported by ledwell and watson thus the eddy diffusivity in santa monica basin is not at odds with lower values estimated from microstructure measurements in the open ocean but is due to an elevated internal wave field the spectral shapes however differ from typical open ocean spectra

decrease of sea ice thickness at hopen barents sea during 1966 2007 1 seasonal fast ice thickness at the island of hopen barents sea was monitored over 40 years sea ice thickness variability as a climate indicator provides more quantitative information on the state of the ice cover than solely sea ice extent usually starting to form just before december hopen fast ice reaches maximum thickness in may on average 0 99 m before the ice starts to decay swell currents and winds interrupt the fast ice development at hopen during several of the winters observed leading to ice removal and new ice formation since 2000 no ice thicker than 1 0 m was observed we find a trend in the ice thickness anomalies of 0 11 m per decade coinciding with decreasing seasonal maximum ice thickness and an increase in local surface air and water temperatures this is consistent with the decreasing sea ice extent in the barents sea and the entire arctic

halocline water formation in the barents sea hydrographic data from the first phase of the coordinated eastern arctic experiment cearex are analyzed the data consist of temperature and salinity measurements made by a ship based conductivity temperature depth ctd instrument and by a drifting salargos buoy these data were collected in the autumn and early winter of 1988 1989 in the northern barents sea mostly in ice covered conditions and then across the marginal ice zone miz the data show that relatively warm salty water of atlantic origin is modified by air cooling and ice melting to produce lighter water that has properties identical to lower halocline water found in the arctic ocean this occurs mostly at the miz and to a lesser degree within the ice pack itself at the miz the halocline water subducts underneath the lighter meltwater that resides directly under the ice pack geostrophic velocity calculations indicate that it then turns eastward and flows toward the kara sea in keeping with previous chemical tracer analyses a rough calculation reveals that the amount of halocline water formed in this way in the barents sea and fram strait is 30 50 of that formed by ice growth in eastern arctic polynyas

mixing in the romanche fracture zone the romanche fracture zone is a major gap in the mid atlantic ridge at the equator which is deep enough to allow significant eastward flows of antarctic bottom water from the brazil basin to the sierra leone and guinea abyssal plains while flowing through the romanche fracture zone bottom water properties are strongly modified due to intense vertical mixing the diapycnal mixing coefficient in the bottom water of the romanche fracture zone is estimated by using the finestructure of ctd profiles the microstructure of high resolution profiler data and by constructing a heat budget from current meter data the finestructure of density profiles is described using the thorpe scaleslt it is shown from microstructure data taken in the bottom water that the ozmidov scale lo is related to lt by the linear relationship lo 5 0 95lt similar to other studies which allows an estimate of the diapycnal mixing coefficient using the osborn relation the thorpe scale and the diapycnal mixing coefficient estimates show enhanced mixing downstream eastward of the main sill of the romanche fracture zone in this region a mean diapycnal mixing coefficient of about 1000 3 1024 m2 s21 is found for the bottom water estimates of cross isothermal mixing coefficient derived from the heat budgets constructed downstream of the current meter arrays deployed in the romanche fracture zone and the nearby chain fracture zone are in agreement with the finestructure estimates of the diapycnal mixing coefficient within the romanche fracture zone although the two fracture zones occupy only 0 4 of the area covered by the sierra leone and guinea abyssal plains the diffusive heat fluxes across the 1 4 8c isotherm in the romanche and chain fracture zones are half that found over the abyssal plains across the 1 88c isotherm emphasizing the role of these passages for bottom water property modifications

barents sea tidal and inertial motions from argos ice buoys during the coordinated eastern arctic experiment a harmonic analysis constrained to estimate separately ice motions forced by tides and inertial oscillations was applied to observed positions of argos buoys deployed on drifting multiyear sea ice in the eastern arctic ocean and barents sea during the coordinated eastern arctic experiment 1988 1989 individual tidal components were estimated at 15 day intervals and inertial oscillations were estimated at 3 day intervals the s2 tidal component was distinguishable from inertial motions south of 79 n and the m2 tidal component was distinguishable from the inertial motion north of 77 5 n computed ice velocities of up to 70 cm s 1 for m2 tidal motion over spitsbergen bank southeast of svalbard agreed reasonably well with the regional tidal models no ice cover of gjevik and of kowalik regional differences in the energy distribution in the arctic basin low barents shelf high and spitsbergen bank extreme were emphasized by this technique the m4 tidal component in the ice motion was typically as large over the barents shelf as the inertial oscillation

the middle and late pleistocene loess soil record in the iskitim area of novosibirsk priobie south eastern west siberia the pleistocene loess soil sequence from west siberia has provided a continuous record of quaternary climate change in northern asia the middle late pleistocene loess paleosol stratigraphy of west siberia has become recently a subject of discussion after a considerable revision was suggested by equating the shipunovo pedocomplex to the late pleistocene stage 5 mis 5 instead of the previous correlation with the middle pleistocene stage mis 9 the revision however was made using data from a single sampled section marble quarry site without proper reference to the local geology to links of the loess and soil units traceable between the lozhok and marble quarries and to deposition hiatuses we compare the loess soil stratigraphy at the marble quarry site iskitim area novosibirsk priobie plateau upper ob reaches with the continuous record of the nearby lozhok quarry and evidence from boreholes in the quarry bottom to show that the shipunovo pedocomplex does correlate with mis 9 mis 5 is the time of the berdsk complex formation the two complexes have many features of difference thickness and maturity of soil profiles thickness and expression of humus and illuviation horizons distribution of calcium carbonate concentrations within the soil profiles patterns of soil formation processes and cryoturbation and stratigraphy the lozhok quarry section comprising five pedocomplexes intercalated in loess is continuous and almost free from hiatuses the marble quarry section in the berd high terrace in contrast does not contain some stratigraphic units including the berdsk and koinikha pedocomplex the gaps being indicated by coarse sand and gruss at the base of loess layers therefore the study has demonstrated the previously suggested pleistocene loess soil stratigraphy in southeastern west siberia

impact of nonlinear waves on the dissipation of internal tidal energy at a shelf break the vertical and temporal structure of the dissipation of turbulent kinetic energy within the internal tide at a location 5 km shoreward of the shelf break on the malin shelf has been determined using a combination of the free falling light yo yo profiler and acoustic doppler current profilers two distinct internal wave regimes were encountered period i in which large amplitude high frequency nonlinear internal waves niws occurred around neap tides and period ii in which the internal wave spectral continuum was not dominated by any particular frequency band around spring tides empirical orthogonal function analysis shows that for the low frequency waves 76 of the variance was described by mode 1 rising to 95 for the high frequency waves during period i the dissipation and vertical mixing were characterized by the niws and 70 of the dissipation occurred in the bottom boundary layer during period ii the depth integrated dissipation was more evenly distributed throughout the tidal cycle whereas vertical mixing was greatly enhanced during a single hour long episode of elevated thermocline dissipation coincident with weakened stratification during both periods i and ii 30 of the total measured dissipation occurred within the thermocline when averaged over 12 4 hours the remainder occurred within the bottom boundary layer bbl tidal average values for depth integrated dissipation and vertical eddy diffusivity for period i ii were 1 1 10 2 w m 2 4 0 10 2 w m 2 and 5 cm2 s 1 12 cm2 s 1 respectively decay rates and internal damping are discussed and vertical heat fluxes are estimated observed dissipation rates are compared with a simple model for bbl dissipation

post depositional remanent magnetization lock in and the location of the matuyama brunhes geomagnetic reversal boundary in marine and chinese loess sequences article i nfo pdrm lock in loess paleosol bioturbation disturbs detrital magnetic particles after deposition so accurate recording of the ancient geomagnetic field in bioturbated sediments is widely attributed to acquisition of a post depositional remanent magnetization pdrm whereby the geomagnetic field exerts a torque on a magnetic particle and aligns it with the field after the final mixing event experienced by the particle the relationship between the matuyama brunhes boundary mbb and oxygen isotope age tie points in marine sediments has been widely used to determine the depth at which the paleomagnetic signal is locked in however such analyses can be badly affected by age discrepancies among different paleoclimatic proxies and by varying isotopic compositions of seawater in different locations and from the presence of different water masses at different depths at the same location it is therefore necessary to separately compare paleomagnetic data with respect to either benthic or planktonic foraminiferal oxygen isotope records for sites from the same water mass to avoid inadvertently introducing age differences to the analysis when the global data set is subjected to such a rigorous analysis few reliable data remain for the mbb using two complementary approaches we estimate that the mbb is on average shifted 20 cm below its true position in marine sediments this offset is the sum of the thickness of the bioturbated surface mixed layer which is possibly dominant and the pdrm lock in depth there is also controversy concerning observed differences in the position of the mbb relative to paleoclimatic proxies in marine sediments and chinese loess deposits for the chinese loess quartz grain size is insensitive to pedogenic alteration and is a useful parameter for determining the true position of the mbb with respect to paleoclimatic boundaries we conclude that the mbb occurs late in marine oxygen isotope stage 19 and in the upper part of chinese paleosol unit s8 rather than at the mid or lower part of loess unit l8 our results require adjustment of the generally accepted positions for the mbb and resolve a longstanding chronological conundrum for marine and chinese loess sequences

observations of turbulent mixing and hydrography in the marginal ice zone of the barents sea 1 measurements of hydrography currents microstructure shear and temperature were made at ice drift stations in the marginal ice zone miz of the northern barents sea highly variable mixing regimes were observed within and below the pycnocline elevated turbulent dissipation 5 15 10 7 w kg 1 was associated with strong vertical shear between the surface layer and the subsurface currents as well as strong tidal flow over shallow topography dissipation in the pycnocline was enhanced at stations with strong wind forcing during drifts under relatively calm wind and away from strong fronts and abrupt topography station mean dissipation values were up to a factor 50 lower and double diffusion contributed significantly to the vertical heat flux where hydrography favored diffusive layering independent measures of turbulent length scale from density overturns compared well with those inferred from the dissipation measurements the variability of dissipation was better captured using a scaling by shear suggested for shelves rather than shear variance models appropriate to the deep open ocean sufficiently resolved patches of enhanced temperature microstructure used in combination with dissipation measurements suggest mixing efficiency of rf 0 2 for patches stable to double diffusion comparable to the conventional upper bound of rf 0 17 mixing efficiency for double diffusive convection favorable cases is found to be significantly larger rf 0 36 water mass modification and fluxes of nutrients and dissolved carbon were found to have large local variability in accordance with the observed variability of vertical mixing in the miz

on the horizontal extent of the canada basin thermohaline steps abstract microstructure profiles of temperatures through the diffusive thermohaline staircase above the atlantic layer core in the canada basin of the arctic ocean are used to investigate the horizontal scales of layers daily profiles during two periods 23 march 3 april and 17 26 april 1985 show that diffusive steps are present throughout the 200 km drift track a 20 hour series on 22 april sampled at about 5 profiles per hour indicates that particular diffusive layers can be traced for at least 600 m the temperature of some layers varies by up to 0 01 c h 1 30 m lateral motion therefore we cannot reliably trace steps in this location if the sampling distance is larger than about 15 m analysis of a longer time series with variable spacing from 0 4 to 5 km indicates that layers can rarely be traced between profiles more than 1 km apart

an observational and numerical study of wind stress variations within marginal ice zones published studies of ocean mesoscale processes in marginal ice zones mizs using numerical coupled ice ocean models usually assume that the surface wind speed is constant over the model domain and that wind stress variations are simply proportional to surface roughness variations we show that this assumption is not realistic in most situations because the surface wind stress is also significantly affected by mesoscale pressure variations by changes in the surface wind vector and by changes in surface layer stability two numerical case studies utilizing detailed surface and atmospheric measurements examine the factors affecting small scale 5 km variations in wind stress within mizs these case studies and surveyed observational and modeling results demonstrate that wind stress fields are qualitatively different from the surface roughness fields a realistic wind stress scenario consists of a maximum just inside the ice edge and another maximum in the open ocean stress minima occur within the pack ice region away from the miz and over grease ice if present the effect of the rougher miz ice is counteracted when wind stresses over the open ocean are enhanced by large surface heat fluxes over the ocean by a strong low level inversion over the ice or by a sharp atmospheric front with surface winds paralleling the ice edge such situations are common in miz regions some simple methods for including first order atmospheric effects on wind stress variations which could be incorporated into current ice ocean mesoscale models of miz regions are suggested

variations in apparent mixing efficiency in the north atlantic central water abstract microstructure data from the north atlantic tracer release experiment natre are presented providing detailed profiles of the thermal variance in the upper 360 m of the canary basin for the fall and spring seasons the osborn cox model is used to compute the diffusivity kt the diffusivity for the depth range 240 340 m is found to be 1 0 0 04 10 5 m2 s 1 in the fall and 2 2 0 1 10 5 m2 s 1 in the spring in good agreement with dye inferred diffusivities at similar depths measured turbulent kinetic energy tke dissipation rates were found to be contaminated by hydrodynamic noise so the osborn dissipation method was not used to compute k however data segments for which the tke dissipation rate e was large enough to be unaffected by noise were used to compute the apparent mixing efficiency d the computed d values are used to investigate variations in apparent mixing efficiency with respect to density ratio r and turbulence reynolds number e n2 in an attempt to eluci

mixing of the storfjorden overflow svalbard archipelago inferred from density overturns observations were made of the dense overflow from storfjorden from a survey conducted at closely spaced stations in august 2002 the field data set consists of conventional ctd conductivity temperature depth profiles and short term moored current meters and thermistor strings finestructure estimates were made by calculating thorpe scales over identified overturns using 0 1 dbar verticallyaveraged density profiles dissipation rate of turbulent kinetic energy per unit mass e is estimated assuming proportionality between thorpe and ozmidov length scales vertical eddy diffusivity kz is estimated using osborn s model assuming a constant mixing efficiency survey averaged profiles suggest enhanced mixing near the bottom with values of kz and e when averaged within the overflow equal to 10x10 4 m 2 s 1 and 3x10 8 w kg 1 respectively kz is found to decrease with increasing buoyancy frequency as n 1 2 0 3 albeit values of n covered only 0 5 8 cph 1 cph 2 3600 s 1 values of heat flux obtained using kz suggest that the plume gains a considerable amount of heat 45 25 w m 2 when averaged over the thickness of the plume from overlying waters of atlantic origin this value is lower than but considering the errors in estimates of kz comparable with 100 w m 2 the rate of change of heat in the overflow derived from sections across the sill and 80 km downstream

the paks loess paleosol sequence a record of chemical weathering and provenance for the last 800 ka in the mid carpathian basin abstract the paks loess paleosol sequence is one of the most important terrestrial records of middle and late pleistocene environmental changes in east central europe spanning the last ca 0 8 ma while geochemical proxies demonstrate a general decreasing chemical weathering trend over the last 0 8 ma in the carpathian basin mineralogy and derived indices reflect intensifying physical erosion in theory the observed chemical weathering trend can be accounted for both by enhanced input of relatively unweathered material and by climate deterioration during the quaternary as the proxies such as cia are not capable of distinguishing between pre and post depositional weathering enhanced physical erosion of the source areas driven by tectonism and resulting increased sedimentation of fresh mineral dust at the depositional site are demonstrated by increasing dolomite illite and chlorite contents and sme ill sme ill chl ratios from older to younger sediments in the profile together with increasing thickness of loess layers towards the youngest part of the sequence at the same time constant smectite contents 30 40 in paleosols appear to disprove progressive aridization of interglacials through time and suggest that the duration of pedogenesis played an important role in determining soil types further the increasing proportion of inherited phyllosilicates illite and chlorite would in theory raise the possibility that the decreasing values of chemical weathering indices are just artifacts of enhanced physical erosion and resulting increased dust deposition by a dilution effect the above findings highlight the fact that the general view on chemical weathering is oversimplistic as its equation includes two basic variables tectonism and time beyond climate and the interplay of these equally important factors will eventually determine its final value to get a better grasp of these processes needs further data more age control in loess profiles data on uplift in and around sedimentary basins and more sophisticated proxies as the mineralogical data presented here can be considered only semiquantitative regarding the provenance of sediments in the paks profile geochemical data demonstrate that felsic rocks dominated the source areas and there have been only very little variations in provenance over the last ca 0 8 ma significant contributions from mafic ultramafic rocks to the sediments can be ruled out as revealed by lower abundances of ferromagnesian trace elements the appearance of amphiboles and high dolomite contents suggest that loess material was at least partly sourced from local rocks and geochemical data reveal a genetic link between floodplain sediments and loess deposits

topographic enhancement of tidal motion in the western barents sea a high resolution numerical lattice is used to study a topographically trapped motion around islands and shallow banks of the western barents sea caused both by the semidiurnal and diurnal tidal waves observations and model computations in the vicinity of bear island show well developed trapped motion with distinctive tidal oscillatory motion numerical investigations demonstrate that one source of the trapped motion is tidal current rectification over shallow topography tidal motion supports residual currents of the order of 8 cm s 1 around bear island and shallow spitsbergenbanken the structures of enhanced tidal currents for the semidiurnal components are generated in the shallow areas due to topographic amplification in the diurnal band of oscillations the maximum current is associated with the shelf wave occurrence residual currents due to diurnal tides occur at both the shallow areas and the shelf slope in regions of maximum topographic gradients surface manifestation of the diurnal current enhancement is the local maximum of tidal amplitude at the shelf break of the order of 5 to 10 cm tidal current enhancement and tidally generated residual currents in the bear island and spitsbergenbanken regions cause an increased generation of ice leads ridges and trapped motion of the ice floes