the middle surface concept and its application to the elasto plastic behaviour of saturated sands an elasto plastic constitutive model for the monotonic behaviour of saturated sands under triaxial loading conditions is presented in this paper this model is capable of simulating the behaviour of sands under different densities and confining pressures using a single set of model parameters the critical state concept and the state parameter concept for sands are used in developing the model a novel modelling technique named the middle surface concept is proposed to properly incorporate the state parameter into the model within the framework of critical state soil mechanics the underlying concept of this new modelling technique is that the true stress strain response is a combined effect of two pseudo responses one pseudo response incorporates the concept of the state parameter and the other pseudo response incorporates the concept of the critical state the true yield surface is defined by the two pseudo yield surfaces and lies in between them hence the name middle surface concept by dividing

climate instability during the last interglacial period recorded in the grip ice core isotope and chemical analyses of the grip ice core from summit central greenland reveal that climate in greenland during the last interglacial period was characterized by a series of severe cold periods which began extremely rapidly and lasted from decades to centuries as the last interglacial seems to have been slightly warmer than the present one its unstable climate raises questions about the effects of future global warming

last interglacial eemian hydrographic conditions in the southeastern baltic sea ne europe based on dinoflagellate cysts abstract a rich organic walled dinoflagellate cyst and pollen record from the licze borehole in northern poland has been used to reconstruct the hydrographic history of the southeastern baltic sea during the last interglacial eemian stage late pleistocene warm saline waters ca 10 15 psu entered the site from the north sea within the first few hundred years of the eemian corresponding to the pinus betula e1 or pinus betula ulmus e2 regional pollen assemblage zones rpaz by about 300 years beginning of rpaz e3 dinoflagellate cyst assemblages were already indicating summer sea surface salinities in excess of about 15 psu and temperatures that perhaps exceeded 27 c warm and saline conditions of 15 20 psu or more at least twice present levels persisted throughout the early eemian a rise in sea level at licze appears to correlate with a similar event in eastern denmark as both coincide with the increase in corylus ca 750 years into the interglacial this sea level rise might therefore have a basinwide extent and appears to correspond to an opening of the danish belts there is little if any evidence of arctic waters throughout the sequence whereas dinoflagellate cysts reflect sustained high salinites within the upper water column a concomitant increase in abundance of the chlorococcalean alga pediastrum within the carpinus corylus alnus e5 rpaz indicates an escalating freshwater input presumably from the proto vistula whose mouth was nearby this suggests the development of a thin seasonal low salinity surface layer below which dinoflagellates lived in more saline waters increasing fluvial influence suggests shallowing through rpaz e5 this study is the first to document dinoflagellate cysts from the eemian of the southeastern baltic sea and reveals a flora with distinctive lusitanian mediterranean affinities

hafted armatures and multi component tool design at the micoquian site of inden altdorf germany abstract excavation of the micoquian site inden altdorf weisweiler 124 near the former german capital bonn in western germany has revealed the first valid open site habitation features with hut like structures and associated hearths for the middle palaeolithic in central europe it has been dated to the eemian interglacial ois 5e a warm interglacial between 128 and 115 ka bp various wear traces and especially organic residues have been detected on a large number of stone tools using microscopic use wear analysis of lithics recovered from the site a multi level analysis developed through an experimental framework and archaeological study using optical light microscopes scanning electron microscopes and energy dispersive x ray microprobes identified the adhering residues as birch pitch birch pitch is the oldest synthetically produced material and was used as an adhesive to attach lithic implements to wooden shafts while such hafting technology is commonly associated with modern humans in the upper palaeolithic the birch pitch residues found on the micoquian tools of inden altdorf suggest that hafting technologies and the frequent use of multi component tools already existed in the middle palaeolithic c 120 ka bp in central europe

modelling twentieth century global ocean circulation and iceberg flux at 48 n implications for west greenland iceberg discharge abstract we have used a coupled ocean iceberg model to study the variation in global ocean circulation and north atlantic iceberg flux from 1900 to 2008 the latter component of the study focused particularly on greenland icebergs feeding into the labrador current and past newfoundland the model was forced with daily heat freshwater and wind fluxes from the twentieth century reanalysis the reanalysis heat fluxes were shown to be offset from the shorter ncep reanalysis and a grid point correction was applied to this component of the forcing the model produces a generally realistic ocean circulation although with an enhanced atlantic meridional overturning largely due to the forcing the modelled iceberg flux at 48 n is well correlated with the long term observed flux when using a modelled iceberg discharge that varies in a similar fashion to the highly variable observed flux at 48 n from this model we infer changes in the spatial and temporal variability of iceberg calving from western greenland during the first third of the twentieth century the majority of modelled icebergs reaching 48 n derive from southern greenland while only after 1930 is the traditional perspective of a majority of such icebergs originating from baffin bay consistent with model results decadal scale changes in the dominant regional sources are found with oscillations between western greenland and northern baffin bay the latter origin was modelled to be most important in the last third of the twentieth century although west greenland sources have increased in importance in recent years the model correctly reproduces the pronounced late spring peak in flux at 48 n for southern greenland icebergs but has an approximately six month offset for icebergs from baffin bay most likely due to resolution issues leading to model icebergs not being delayed in shallow coastal waters whereas in reality they may be grounded for some time or trapped in coastal sea ice

last interglacial and holocene climatic development in the norwegian sea region ocean front movements and ice core data planktonic foraminiferal evidence suggests that the ocean front systems between polar and atlantic surface waters in the norwegian sea generally were located closer to greenland during oxygen isotope substage 5e than in the holocene during both these periods oscillations have occurred in the position of the fronts in the western norwegian sea region the substage 5e influence of warm atlantic waters was interrupted by a return to polar conditions these findings support both ice core data and evidence from europe that the last interglacial was a period of rapid climatic shifts

temporal variability of the subarctic front near the charlie gibbs fracture zone we document temporal variability of the northernmost branch of the north atlantic current known as the north subarctic front nsaf for the period 1976 1985 the front s location and temperature salinity t s parameters were determined from 120 repeat transects along three standard sections occupied by russian ships 1 ocean weather station ows c 52 75 n 35 5 w to st john s newfoundland 2 along 35 w from 52 n to 36 5 n and 3 ows c to cape st vincent portugal the nsaf exhibits significant interannual variability of its location shifting 200 km to 300 km in a few months along the ows c st john s section the front reached its southernmost location in 1976 1977 then experienced two 250 to 300 km northward shifts in 1978 1979 and 1980 1981 all of the three shifts peaked in wintertime these events nearly coincide with events of the opposite sign along the ows c cape st vincent section the northernmost location in 1976 1977 and two 200 km southward shifts in 1978 1979 and 1980 1981 the nsaf s behavior is thus coherent near the charlie gibbs fracture zone at the 500 km scale frontal time series associated with the moving front of t and s at the 200 m level for the cold side of the nsaf reveal two events an s200 minimum in the winter of 1976 1977 which might be a manifestation of the great salinity anomaly of the 1970s and a sharp drop of s200 in early 1984 which might signal the arrival of another large salinity anomaly the great salinity anomaly of the 1980s

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

the iceland faroe inflow of atlantic water to the nordic seas abstract the flow of atlantic water between iceland and the faroe islands is one of three current branches flowing from the atlantic ocean into the nordic seas across the greenland scotland ridge by the heat that it carries along it keeps the subarctic regions abnormally warm and by its import of salt it helps maintain a high salinity and hence density in the surface waters as a precondition for thermohaline ventilation from 1997 to 2001 a number of adcps have been moored on a section going north from the faroes crossing the inflow combining these measurements with decade long ctd observations from research vessel cruises along this section we compute the fluxes of water volume heat and salt for the period june 1997 june 2001 we found the average volume flux of atlantic water to be 3 5 0 5 sv 1 sv 10 6 m 3 s 1 when compared to recent estimates of the other branches this implies that the iceland faroe inflow is the strongest branch in terms of volume flux transporting 47 of the total atlantic inflow to the arctic mediterranean nordic seas and arctic ocean with shelf areas if all of the atlantic inflow were assumed to be cooled to 0 c before returning to the atlantic the iceland faroe inflow carries a heat flux of 124 15 tw 1 tw 10 12 w which is about the same as the heat carried by the inflow through the faroe shetland channel the iceland faroe atlantic water volume flux was found to have a negligible seasonal variation and to be remarkably stable with no reversals even on daily time scales out of a total of 1348 daily flux estimates not one was directed westwards towards the atlantic

centennial scale oscillations in oxygen and carbon isotopes of endogenic calcite from a 15 500 varve year record of the pianico interglacial abstract the palaeolake record from pianico southern alps comprises a sequence of 15 500 continuous calcite varves formed during peak interglacial conditions around 400 ka ago the varved nature of these deposits allows precise sub sampling of five varve year intervals for stable isotope analyses all samples consist of calcite precipitated in the epilimnion of the lake with contents of detrital carbonate below 4 four significant negative 18 o oscillations occurred during the upper half of the interglacial the most prominent of these oscillations has an amplitude of 1 1 and lasted 780 varve years the three other oscillations are shorter 125 195 varve years and of lower amplitude 0 4 0 9 an additional major drop in 18 o occurs 315 varve years before the end of continuous calcite precipitation in the lake this shift marks the end of long interglacial conditions and the beginning of harsher climate conditions and glacier advances in the southern alps in contrast the four 18 o oscillations within the period of continuous formation of calcite varves reflect natural intra interglacial climate dynamics

instability of climate and vegetation dynamics in central and eastern europe during the final stage of the last interglacial eemian mikulino and early glaciation abstract in terrestrial records from central and eastern europe the end of the last interglacial seems to be characterized by evident climatic and environmental instabilities recorded by geochemical and vegetation indicators the transition mis 5e 5d from the last interglacial eemian mikulino to the early last glacial early weichselian early valdai is marked by at least two warming events as observed in geochemical data on the lake sediment profiles of central grobern neumark nord klinge and of eastern europe ples results of palynological studies of all these sequences indicate simultaneously a strong increase of environmental oscillations during the very end of the last interglacial and the beginning of the last glaciation this paper discusses possible correlations of these events between regions in central and eastern europe the pronounced climate and environment instability during the interglacial glacial transition could be consistent with the assumption that it is about a natural phenomenon characteristic for transitional stages taking into consideration that currently observed human induced global warming coincides with the natural trend to cooling the study of such transitional stages is important for understanding the underlying processes of the climate changes

climate variations in europe over the past 140 kyr deduced from rock magnetism rapid shifts in climate during the last glacial are now well documented particularly from the oxygen isotope records of the two greenland ice cores grip1 2 and gisp23 in the grip record1 2 these climate events are also seen during the preceding eemian interglacial which may be an analogue for the future climate warmed by the greenhouse effect but these shifts are not found in the eemian section of the gisp2 core3 casting doubt on whether the rapid shifts in the grip oxygen isotope record really do represent a climate signal here we present magnetic susceptibility pollen and organic carbon records from maar lake deposits in the massif central france these data provide an independent record of past climate and we find that they correlate well with the ice core records during the last glacial during the eemian two rapid cooling events seen in our record also correlate with those seen in the grip ice core supporting the idea that rapid climate change did occur in the eemian interglacial and demonstrating that it extended to continental europe

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

interannual changes in the overflow from the nordic seas into the atlantic ocean through denmark strait the global thermohaline circulation is an important part of earth s climate system cold dense water formed in the nordic seas enters the atlantic ocean as overflows across the sills of the greenland scotland ridge the denmark strait overflow dso is one of the main sources of north atlantic deep water until now the dso has been believed to be stable on interannual timescales here for the first time evidence is presented from a 4 year program of observations showing that overflow transports in 1999 2000 were approximately 30 higher than previous estimates later transports decreased remarkably during the observation period coincident with a temporary temperature increase of about 0 5 c

was the climate of the eemian stable a quantitative climate reconstruction from seven european pollen records the aim of the present study is to estimate the range of the climatic variability during the eemian interglacial which lasted about 10 000 years marine isotopic stage 5e the modem pollen analogue technique is applied to seven high resolution pollen records from france and poland to infer the annual precipitation and the mean temperature of the coldest month the succession of pollen taxa and the reconstructed climate can be interpreted coherently the warmest winter temperatures are centred in the first three millennia of the eemian interglacial during the mixed oak forest phase with quercus and corylus as dominant trees a rapid shift to cooler winter temperatures of about 6 degrees to 10 degrees c occurred between 4000 and 5000 years after the beginning of the eemian related to the spread of the carpinus forest this shift is more obvious for the reconstructed temperatures than for precipitation and is unique and irreversible for the whole eemian period following this climatic shift of the eemian variations of temperature and precipitation during the fast 5000 years were only slight with an amplitude of about 2 degrees to 4 degrees c and 200 to 400 mm yr the estimated temperature changes were certainly not as strong as those reconstructed for the stage 6 5e termination or the transition 5e 5d this is consistent with the constantly high ratio of tree pollen throughout the eemian indicative of a succession of temperate forest types this gradual transition between different forest landscapes can be related to intrinsic competition between the species rather than to a drastic climatic change c 1998 elsevier science b v all rights reserved

measured volume heat and salt fluxes from the atlantic to the arctic mediterranean 1 the flow of warm and saline atlantic water towards the arctic crosses the greenland scotland ridge in three current branches since the mid 1990 s extensive monitoring with quasi permanent moorings and regular ctd cruises has been in operation on three sections crossing the branches averaged over the years 1999 to 2001 values of volume heat relative to 0 c and salt flux due to the total atlantic inflow across the greenland scotland ridge into the nordic seas are estimated as 8 5 sv 1 sv 106 m3 s 1 313 1012 w and 303 106 kg s 1 in this period the average temperature and salinity of the atlantic inflow were 8 5 c and 35 25 respectively within the observational uncertainty we do not find any significant seasonal variation of the volume flux but a negative correlation between the inflow flux through the faroe shetland channel and through the other two gaps was indicated

the gin sea a synthesis of its physical oceanography and literature review 1972 1985 abstract a synthesis and review of the physical oceanography of the gin sea greenland iceland and norwegian seas is presented an accompanying bibliography is included from 1972 through 1985 some 1986 works are also noted emphasis is placed on describing the gin sea as a major semi enclosed basin that plays a role unique among the world s oceans by providing a strong two way advective exchange between the ice covered polar sea and the north atlantic ocean and at the same time acting as the primary site for northern hemisphere bottom water formation the water masses for the gin sea are defined in a manner as consistent as possible with the literature the large scale oceanographic and meteorological factors influencing the water mass formation and circulation are described a sample calculation of the various horizontal and vertical thermohaline driven exchanges is given

isotope and cladocera data and interpretation from the eemian optimum and postoptimum deposits kaliska palaeolake central poland during the eemian optimum calcareous gyttja and lake marl accumulated the characteristic feature of calcareous gyttja is an occurrence of fragments of diatoms and plants while in lake marl they are absent in the carbonate rich deposits no cladocera remains are preserved based on the results of stable isotope analyses of carbonates the eight isotopic horizons is were defined and characterised in the studied deposits 15 species of subfossil cladocera were identified and 6 zones of fauna development were distinguished the defined cladocera species are similar to ones known from the other eemian site in poland the faunal taxa indicate the low trophy status of the lake initially followed by an increase to eutrophic status the cladocera and isotopic compositions suggest that the hornbeam zone e5 was a period of higher density of macrophytes as well as of an increase of biological activity associated with the low water level the fluctuations of the isotopic curves caused by a shallowing of the basin and a change of sediment lithology are characteristic for the spruce zone e6 the palaeolake transformed into a peatbog during the pine zone e7 during the early vistulian renewed carbonate accumulation and cladocera development took place indicating the repeated reservoir existence

observations of seasonal subduction at the iceland faroe front the polar front in the north atlantic is bound to the ridge between iceland and the faroe islands where about one half of the northward transport of warm atlantic water into the nordic seas occurs as well as about one sixth of the equatorward dense overflow we find a low salinity water mass at the surface of the iceland faroe front iff which in wintertime subducts along outcropping isopycnals and is found in much modified form on the atlantic side of the iceland faroe ridge ifr crest the features found on the atlantic side of the crest at depth have temperature and salinity characteristics which are clearly traceable to the surface outcrop of the iff the presence of coherent low salinity layers on the atlantic side of the ifr crest has not been previously reported warm waters above the ifr primarily feed the faroe current and injection of a low salinity water mass may play an early role in the water mass transformation taking place in the nordic seas the seasonality of the intrusive features suggests a link between winter convection mixed layer instability and deep frontal subduction these low salinity anomalies as well as a low oxygen water mass from the iceland basin can be used as tracers of the intermediate circulation over the ifr

direct velocity observations of volume flux between iceland and the shetland islands atlantic waters flowing northward into the nordic seas are important for their role as an early indicator of changes to deepwater formation as such this requires a fundamental understanding of the pathways and volume fluxes through the primary passageways from the atlantic into the nordic seas a mean annual volume transport of 6 1 0 3 sv was observed flowing in above the t 27 8 isopycnal a proxy for the lower limit of atlantic water depth through the faroe shetland channel fsc and over the iceland faroes ridge ifr from march 2008 to june 2012 using repeat velocity sections obtained from a vessel mounted acoustic doppler current profiler adcp a new vessel route has expanded the spatial coverage of fsc observations and reveals a difference in average inflow transport which most likely results from an interannual variation in the total transport through the fsc which in turn is tied to a weakening of the southerly flow over the western slope of the channel this interannual variability has increased the mean transport through the fsc from 0 9 sv observed over the first 2 years of this program by rossby and flagg 2012 to a 4 5 year mean of 1 7 0 2 sv which emphasizes the importance of knowing the flow along the faroese shelf interannual fluctuations in transport observed over the ifr are related to the width of the inflow over the faroese half of the ridge

holocene periodicity in north atlantic climate and deep ocean flow south of iceland climate fluctuations during the past millennium are relatively well documented1 on a longer timescale there is growing evidence of millennial scale variability of holocene climate at periodicities of 2 500 and 950 years possibly caused by changes in solar flux 2 3 and 1 500 years maybe related to an internal oscillation of the climate system 4 5 6 but the involvement of deep water masses in these holocene climate changes has yet to be established here we use sediment grain size data from the iceland basin to reconstruct past changes in the speed of deep water flow the study site is under the influence of iceland scotland overflow water isow the flow of which is an important component of the thermohaline circulation that modulates european climate flow changes coincide with some known climate events the little ice age and the mediaeval warm period and extend over the entire holocene epoch with aquasi periodicity of 1 500 years the grain size data indicate afaster isow flow when the climate of northern europe is warmer however a second mode of operation is observed in the early holocene when warm climate intervals are associated with slower isow flow at that time the melting remnant of land based glacial age ice may have provided a sufficient source of fresh water to the ocean to reduce isow flow south of iceland

reconstruction of environmental conditions of eemian palaeolake at studzieniec central poland on the basis of stable isotope and cladocera analyses abstract the results of isotopic and cladocera investigations of the eemian lacustrine sediments of studzieniec palaeolake central poland are presented the 12 m thick section contains silty sands and clayey silts on the bottom then gyttja and organic silts and peat in the upper part based on the results of stable isotope analysis of carbonates the 11 isotopic horizons is were defined and characterised results of isotopic analysis correlated with cladocera and pollen data enabled reconstruction of varying environment conditions the environmental changes were caused by a transition from the glaciation to the interglacial period expressed by a significant decrease in 18 o is 3 a warming of climate characterised by a positive trend in 18 o is 3 6 an increase of biological activity noted as very high positive values of 13 c above 7 is 7 the fluctuations of the isotopic values at the upper part of the section probably point to a shallowing of the lake due to sedimentary infill is 9 10 in the studied deposits 23 species of the subfossil cladocera were identified and seven zones of faunal development were distinguished the studzieniec palaeolake was sufficiently a shallow reservoir the cladocera composition indicates the initial oligotrophic status of the lake and then its subsequent increase and the periods of higher density of macrophytes during the interglacial optimum the low frequency of cladocera remains in carbonate rich deposits may be caused by a state of preservation of faunal assemblages or the fast rate of sediment accumulation

eemian and early weichselian temperature and precipitation variability in northern germany abstract dramatic changes in european vegetation occurred during the transition from the eemian interglacial to weichselian glacial climates correlative with major changes in global ice core and marine records quantitative knowledge of climate change is important for understanding of the climate system and for climate modelling for which reconstructions of this transitional period are of special interest however it has been difficult to quantify the climatic changes involved in the eemian to early weichselian transition from terrestrial archives due to the lack of modern vegetation analogues to circumvent this problem we applied a suitable multivariate probabilistic approach to pollen and plant macrofossil assemblages to reconstruct temperature and precipitation for this transition in central europe our reconstructions span the interval from the beginning of the eemian marine isotope stage mis 5e to the odderade interstadial mis 5a they indicate a relatively stable eemian with increasing precipitation reducing the continentality of the climate with time during the transition from the eemian to the herning stadial mean july and january temperatures decreased by 4 c and by as much as 20 c respectively temperatures remained high enough to support forests during the stadials and we infer that the reconstructed decrease of precipitation below 500 mm per year caused the extirpation of forests during these periods thus we conclude that precipitation although difficult to reconstruct is of vital importance for explaining vegetation change during the eemian and eemian early weichselian transition

idealized study on the effect of bottom topography on the seasonality of the stability of the iceland faeroe front abstractwe investigate the effects of bottom topography on the instability eddy driven heat flux and overturning of a front that sits atop a ridge by varying the initial location of an idealized

near surface circulation of the nordic seas as measured by lagrangian drifters in the period june 1991 to august 1993 107 argos tracked drifters drogued to 15 m depth were released in the nordic seas or greenland iceland and norwegian seas the drifter movements revealed the strong and spatially confined current systems along the surface salinity fronts of the iceland faroe frontal zone and of the norwegian coast and along the continental margins and their extensions to the barents sea and spitsbergen the norwegian atlantic current is composed of three distinct streams two continental margin and one coastal branches which join into one single swift mean current west of the lofoten and vesteralen islands where the strongest measured currents are in excess of 110 cm s 1 in addition to the general cyclonic gyre circulation in the nordic seas the drifters indicate smaller cyclonic circulation patterns in all the major subbasins i e the iceland plateau the norwegian the lofoten and the greenland basins no surface signature of the east icelandic current is disclosed by the drifters interpolated and low pass filtered position data were used to construct maps of 15 m depth ensemble mean velocity velocity variability and residence time vigorous eddy fields are dominant in the strong currents and in the lofoten basin eulerian correlations indicate that they tend to propagate to the west in contrast the iceland plateau appears quiescent both in the mean and eddy velocities single particle diffusivities are computed and are found to be in the range 1 7 107 cm2 s 1 the corresponding lagrangian timescale and space scale are 1 3 days and 10 40 km respectively these lagrangian drifter measurements compose the first basin scale accurate near surface velocity data set of the nordic seas

stable climatic conditions in central germany during the last interglacial stable isotopic data from the high resolution limnic sequence in the opencast mine at grobern central germany confirm the relatively stable climate of the last interglacial deduced from pollen analyses after significant warming during the transition from the saalian to the eemian stable warm climatic conditions set in once the climatic optimum was reached in the course of biozones e4 to e5 from the middle of biozone e6b a gradual temperature decrease can be observed reaching a minimum at the start of biozone e7 the division of the early weichselian glacial in central germany into two stadials herning rederstall and two interstadials brorup odderade is also documented by the findings copyright 2000 john wiley sons ltd

the δ18o record along the greenland ice core project deep ice core and the problem of possible eemian climatic instability over 70 000 samples from the 3029 m long greenland ice core project grip ice core drilled on the top of the greenland ice sheet summit have been analyzed for 8o a highly detailed and continuous 8o profile has thus been obtained and is discussed in terms of past temperatures in greenland we also discuss a three core stacked annual 8o profile for the past 917 years the short term 50 years variability of the annual 8o signal is found to be 1 in the holocene and estimates for the coldest parts of the last glacial are 3 or higher these data also provide insights into possible disturbances of the stratigraphic layering in the core which seems to be sound down to the onset of the eemian spectral analysis of highly detailed sequences of the profile helps determine the smoothing of the 8o signal which for the holocene ice is found to be considerably stronger than expected we suggest this is due to a process involving diffusion of water molecules along crystal boundaries in the recrystallizing ice matrix deconvolution techniques were employed for restoring with great confidence the highly attenuated annual 8o signal in the holocene we confirm earlier findings of dramatic temperature changes in greenland during the last glacial cycle abrupt and strong climatic shifts are also found within the eem sangamon interglaciation which is normally recorded as a period of warm and stable climate in lower latitudes the stratigraphic continuity of the eemian layers is consequently discussed in section 3 of this paper in terms of all pertinent data which we are not able to reconcile

synoptic sections of the denmark strait overflow we report on a rapid high resolution survey of the denmark strait overflow dso as it crosses the sill the first such program to incorporate full water column velocity profiles in addition to conventional hydrographic measurements seven transects with expendable profilers over the course of one week are used to estimate volume transport as a function of density our observations reveal the presence of a strongly barotropic flow associated with the nearly vertical front dividing the arctic and atlantic waters the seven section mean transport of water denser than 27 8 is 2 7 0 6sv while the mean transport of water colder than 2 0 c is 3 8 0 8 sv although this is larger than the 2 9 sv of 2 c water measured by a 1973 current meter array we find that a sampling of our sections equivalent to the extent of that array also measures 2 9sv of cold water both the structure and magnitude of the measured flow are reproduced well by a high resolution numerical model of buoyancy driven exchange with realistic topography

a chronology for the long pollen record from lake wangoom western victoria australia as derived from uranium thorium disequilibrium dating the chronology of a long pollen record from lake wangoom one of the few long palaeoenvironmental records from southeastern australia is discussed in light of the acquisition of new uranium thorium disequilibrium utd dates of crucial importance has been the estimation of ages for two major pre holocene phases of forest expansion recorded in the sequence with implications for the timing of periods of high effective precipitation in the region the new utd ages indicate that the oldest forest phase falls within the penultimate interglacial whereas the later phase corresponds with the last interglacial this is older than indicated by previously reported utd and radiocarbon dates but confirms a chronology based on direct correlation with the pollen record from marine core e55 6 the new chronology of the lake wangoom sequence provides evidence that phases of sustained forest development in southeast australia relate to interglacial periods in comparison interstadial periods appear to be characterised by only minor arboreal development marked differences in the pattern of vegetation development evident in each of the interglacials are thought to reflect varying climatic and anthropogenic influences copyright 2002 john wiley sons ltd

evolution of palaeolake environment in poland during the eemian interglacial based on oxygen and carbon isotope data from lacustrine carbonates abstract the results of oxygen and carbon stable isotope investigations of eight eemian lacustrine sediments from poland are presented the values of 18o changed from ca 11 to 1 and 13c values oscillated between 3 5 and 7 0 the isotopic record correlated well with pollen cladoceran and diatom data the evolution of the palaeolakes in poland was reconstructed the palaeolakes originated during the final phase of the wartanian late saalian glaciation the 18o and 13c values of that time reflect the input of detrital carbonates into the basins the boundary between the glaciation and the interglacial period is expressed by a significant decrease in 18o and 13c values during the early eemian a positive trend in 18o values confirms the gradual climatic changes the eemian optimum is characterized by constant 18o and 13c values during the early vistulian weichselian glaciation the palaeolake declined the varying 18o values likely reflect frequent changes in water balance between precipitation and evaporation associated with an influence of marine circulation the fluctuations of the isotopic curves in the upper parts of the successions the post optimum were caused by a shallowing of the basin by infilling with sediments the observed shifts in the isotopic curves are due to the proximity of the baltic sea and earlier strong oceanic influences

periodic lake peatland shifts under the eemian and early weichselian climate changes in central europe on the basis of multi proxy studies abstract long term palaeoecological sequences dated to the eemian interglacial and weichselian glaciation are crucial for understanding cyclic climate changes and ecosystem responses this article presents a multi proxy palaeobotanical zoological and geochemical study considering variable aspects of the eemian early weichselian lake mire succession in central poland the investigated sequence collected from a former small kettle hole revealed many ecosystem alterations i e warm stages led to the terrestrialisation of the lake whereas stadial coolings to its reappearance hence we examined whether i the eemian warming influenced the ecological succession of the lake ii lakes which reappeared during the herning and rederstall stadial coolings developed alike and iii the beginning of peatland functioning interglacial or interstadial had an impact on further plant succession the results show that thermal amelioration during the eemian interglacial supported domination of tetraedron minimum and pediastrum boryanum var boryanum which contributed to the sedimentation of bituminous shales the expansion of salvinia natans in the final stage of lake existence middle eemian was probably a result of the mild climate characterised by the lack of late spring frosts algae in contrast to cladocera revealed bipartition of the herning and rederstall stadials older sections were colder younger warmer however geochemical and isotopic data point to the very low productivity of the lakes during those stadials the lake that existed during the herning stadial revealed very low taxonomical diversity of cladocera whereas that during the rederstall was characterised by relatively high diversity of this group during the late eemian and brorup interstadial rich fens with some oligotrophic patches with sphagnum sp developed this study revealed that small water bodies due to their very local character and often uniqueness of palaeo records may be a very valuable source of information about climate and palaeoecology of different groups of organisms during the eemian interglacial and the weichselian glaciation

the terrestrial eemian to late weichselian sediment record at beckentin ne germany first results from lithostratigraphic palynological and geochronological analyses abstract over recent decades a growing number of well documented records from terrestrial last interglacial sites across central europe have substantially improved our understanding of eemian climate and landscape dynamics despite this progress there are also large areas from which little information is available thus constituting significant paleo geographic gaps in the last interglacial record among the regions with still inadequate paleo environmental information is the maritime influenced area of ne germany at the southern margin of the eemian baltic sea here we present first results from a geological investigation of a new last interglacial site recently discovered during archaeological excavations near beckentin sw mecklenburg the study area is located approximately 25 km to the south of the maximum mis 2 ice limit of the scandinavian ice sheet in ne germany and thus lies outside the weichselian belt of glaciation based on lithostratigraphic and sedimentological logging complemented by geochemical xrf and palynological investigations we divide the local succession into three sections 1 a basal facies comprising saalian till and associated glaciofluvial sand overlain by section 2 consisting of a fen peat which grades into laminated organic to minerogenic mud the organic deposits of section 2 preserve a near complete eemian pollen inventory encompassing pollen zones pz i to vi menke and tynni 1984 above this rest poorly sorted periglacial sands section 3 with ventifacts and evidence for cryogenic deformation geochronological results from 230th u dating of the buried organic rich deposits at beckentin show that these units accumulated in a former dead ice depression between 118 7 6 ka and 114 6 5 ka during the eemian interglacial high resolution optically stimulated luminescence osl profiling undertaken with a portable luminescence reader reveals a significant hiatus between the lacustrine fines and overlying periglacial cover sand five osl ages obtained from these cover sediments and the sand filling of an ice wedge cast show that these strata formed between during the last glacial interglacial transition

vivaldi 1991 a study of the formation circulation and ventilation of eastern north atlantic central water abstract a synoptic hydrographic data set comprising 32 full depth ctd casts and 2500 ctd seasoar profiles to 500 m is used to describe the s properties and circulation of central water east of the mid atlantic ridge and between 39 n and 54 n eastward transport of 20 10 6 m 3 s 1 in the north atlantic current turns entirely northwards to the west of 54 n 20 w this transport consists in the upper layers of western north atlantic water freshened at temperatures below 10 c by mixing with subarctic intermediate water northern and southern branches of the north atlantic current are well defined and both turn northwards west of 20 w a further 10 10 6 m 3 s 1 of eastern north atlantic water forms and recirculates anticyclonically to the west of spain south of the north atlantic current and north of 40 n eastern north atlantic water is most weakly stratified east of 20 w and there is clear correlation between weakly stratified pycnostads and positive salinity anomalies relative to western north atlantic water thus eastern north atlantic water is a winter mode water in which strong winter cooling has increased the density and hence also the salinity anomaly at a given temperature near the southern entrance to the rockall trough there is evidence that salinities are also increased by mediterranean water influence circulation south of the north atlantic current is complex there is no evidence for direct ventilation southwards across 40 n where water properties s potential vorticity and cfc 113 and historical data all indicate westward ventilation east of 24 w with weak southward ventilation occurring further west in the vicinity of the azores the circulation pattern suggested is remarkably similar to that proposed by helland hansen and nansen in 1926 the eastern north atlantic geophysiske publicajoner 4 1 76 with anticyclonic circulation of colder eastern north atlantic water north of 40 n meeting warmer water from south of 40 n circulating cyclonically north of the azores current the distribution of pycnostads and s properties between 20 w and 35 w north of the azores indicates alternate bands of western and eastern north atlantic water moving eastward and westward respectively including evidence for westward motion immediately south of the southern branch of the north atlantic current possibly by westward propagation of anticyclonic eddies containing deep pycnostads

the cone penetration test in sands part ii general inference of state the state parameter concept provides a new method of characterizing sand behaviour but the utility of the concept relies on the ability to measure the state parameter in situ part i of this paper demonstrated a relationship between normalized cone resistance and state parameter for monterey sand in this paper the state parameter approach is applied to data from calibration chamber tests on several sands it is shown that this approach leads to a common relationship for all the data that includes the effects of material type quantified by the slope of the steady state line the state parameter for a sand can therefore be determined in situ with a reasonable precision using a general framework of interpretation which applies to all uncemented sands la notion de parametre d etat fournit une nouvelle methode pour caracteriser le comportement des sables mais son utilite depend de la possibilite de mesurer le parametre d etat in situ la premiere partie de cet article demontre une relation entre la resist

observed variability of the north atlantic current in the rockall trough from 4 years of mooring measurements the rockall trough is one of the main conduits for warm atlantic water to the nordic seas ocean heat anomalies originating from the eastern subpolar gyre are known to influence arctic sea ice ex

stable isotope composition of the holsteinian mis 11 freshwater snail valvata piscinalis o f muller 1774 from eastern poland and its palaeoenvironmental implications stable oxygen and carbon isotope investigations were conducted on shells of the freshwater gastropod valvata piscinalis from palaeolake deposits of holsteinian age marine isotope stage 11 from eastern poland the isotope record of this species was used for the first time as an archive of environmental conditions for selected lakes between the protocratic stage and the post optimum period of the interglacial the lowest 18o and 13c values of 8 1 and 12 1 respectively were recorded in the picea alnus zone at ortel krolewski palaeolake the sparse vegetation and low productivity of that time are reflected in the relatively low 13c values the first significant increase of temperature was recorded in the taxus zone i e an increase in 18o the higher temperature influenced the expansion of macrophytes which stimulated enhanced photosynthesis similar mean 18o values in the taxus and pinus larix zones imply no distinct temperature change v piscinalis populations from ossowka hrud and roskosz palaeolakes record variations in lake productivity during the climatic optimum of the interglacial carpinus abies zone the 18o values of that time are relatively high up to 4 5 and reveal no significant differences between the lakes decreases of the oxygen isotope values in the szymanowo lake reflect post optimum cooling

faroe bank channel overflow 1995 2005 abstract the faroe bank channel fbc is the deepest passage across the greenland scotland ridge and there is continuous overflow of dense water through the channel which provides a substantial contribution to the global thermohaline circulation since november 1995 acoustic doppler current profilers adcps have been moored at the sill of the channel continuously except for short annual servicing periods in addition to this ctd sections have regularly been occupied across the channel and instruments recording temperature and salinity have been moored for short periods these observations demonstrate that the channel due to its small width can be monitored fairly well with only one adcp mooring and they allow the generation of a time series of overflow volume flux for the 1995 2005 period the kinematic overflow flux defined solely from the velocity field was found to have an average value of 2 1 0 2 sv with a seasonal and with inter annual variations of approximately 10 amplitude but with no discernible trend for the whole period the average flux of water with potential density exceeding 27 8 kg m 3 was found to be 1 9 0 3 sv with average properties 0 25 c s 34 93 28 01 kg m 3 for this period no evidence was found for a weakening overflow flux but the salinity of the fbc overflow especially the warmer parts has increased substantially during the period which implies an increased average density on the order of 0 01 kg m 3 previous observations of a helical cross channel circulation are confirmed and may explain the thin pycnocline layer but shear instability induces intensive mixing that puts a lower limit on the layer thickness critical control at one point of the sill cross section rather than friction seems to govern the overflow dynamics and simple layered models can explain much of the observed features as well as the seasonal variation but potential vorticity as defined for a single overflow layer is not conserved a previously suggested 1950 2000 weakening of the fbc overflow which was partly based on a subset of the data presented here is not supported by the full dataset

timing and progression of the last interglacial derived from a high alpine stalagmite 1 u th dating and oxygen isotope analysis of a stalagmite from spannagel cave in the austrian alps provides information about the timing and progression of the last interglacial climate we determined two distinct growth intervals warm climate from 130 7 thousand years ka before the present to 130 0 ka and from 125 7 ka to 118 2 ka the latter containing two periods of ceased stalagmite growth colder climate at around 123 8 ka and 120 5 ka high resolution 18o analysis of stalagmite spa 50 reveals a clear regular cyclic pattern with periods of 197 109 and 21 years which are likely to be related to the suess gleissberg and hale cycles respectively indicating that eemian climate in the alps was forced by the sun

diatom responses to limnological and climatic changes at ribains maar french massif central during the eemian and early wurm abstract high resolution diatom analysis was carried out to assess the limnological and climatic changes that took place at ribains maar french massif central during the late pleistocene 131 105 ka bp with a focus on the eemian interglacial in particular numerical analyses were used to show that most of the variability in the fossil diatom assemblages was due to climate independently from the changes in the lake catchment vegetation as represented by pollen data diatom based quantitative reconstructions of the past limnological conditions as well as a comprehensive literature review on the auto ecological requirements for the principal diatom taxa were used to interpret the record an absolute time scale for the sequence was derived by matching the major pollen shifts with the radiometrically dated changes in oxygen isotopes observed in italian stalagmites this study shows that at ribains maar the transition from the riss saalian glacial to the eemian interglacial was marked by a gradual increase in the contribution of spring blooming diatom species indicating a longer growing season and milder winter spring conditions at that time a short cooling event interrupts this trend and may correspond to a stadial at the start of the eemian a peak in benthic taxa and the suppression of spring blooming flora probably reflects the effects of deglaciation on the catchment during the eemian interglacial itself three main phases were distinguished within the diatom record the first phase 8000 years in duration was dominated by stephanodiscus minutulus which suggests that intense mixing in the water column took place during spring the pollen record was simultaneously dominated by quercus and corylus that typify this phase as the climatic optimum of the eemian the second phase almost equal in duration to the first phase 7000 years is generally dominated by cyclotella taxa and suggests a less productive lake and much reduced period of spring mixing compared with the first phase in the pollen diagram this corresponds to an interval dominated by carpinus picea abies that indicates a cooler and wetter climate the third and last phase of the eemian 2000 year long saw the return to stephanodiscus dominated assemblages indicating a warming that may correspond to the dansgaard oeschger event 25 identified in the greenland ice core record in the early stage of the wurm glacial weichselian assemblages in the melisey i stadial 3000 year long were dominated by either aulacoseira subarctica or asterionella formosa which suggest colder spring conditions than during the late eemian but not as cold as the ones indicated by the pollen record stephanodiscus spp again dominate during the saint germain ia interstadial 5000 year long suggesting a return to the conditions that prevailed before the melisey stadial in agreement with the pollen record the record ends with the montaigu cold event which is characterised by a pinus peak in the pollen record and corresponds to a large abundance of a subarctica in the diatom sequence throughout the eemian the abundance of stephanodiscus spp which is thought to be driven by winter conditions show cyclic fluctuations that most likely match the cooling events identified in a pollen record from germany variation in insolation throughout the eemian may have been the driving factor behind the species succession observed in the diatom sequence while this study demonstrates that diatom analysis of lake sediment can provide very detailed information on long term climate change a review of the few other diatom investigations published on european eemian deposits shows that this technique has been so far seldom used to its full potential in this context in central and southern europe

the northern north atlantic ocean mean circulation in the early 21st century the decadal mean circulation in the northern north atlantic was assessed for the early 21st century from repeated ship based measurements along the greenland portugal ovide line from satellite altimetry and from earlier reported transports across 59 5 n and at the greenland scotland sills the remarkable quantitative agreement between all data sets allowed us to draw circulation pathways with a high level of confidence the north atlantic current nac system is composed of three main branches referred to as the northern central and southern branches which were traced from the mid atlantic ridge mar to the irminger sea the greenland scotland ridge and the subtropical gyre at ovide the northern and central branches of the nac fill the whole water column and their top to bottom integrated transports were estimated at 11 0 3 sv and 14 2 6 4 sv 1 sv 106 m3 s 1 respectively those two branches feed the cyclonic circulation in the iceland basin and the flow over the reykjanes ridge into the irminger sea this cross ridge flow was estimated at 11 3 4 2 sv westward north of 58 5 n the southern nac branch is strongly surface intensified and most of its top to bottom integrated transport estimated at 16 6 2 sv is found in the upper layer it is composed of two parts the northern part contributes to the flow over the rockall plateau and through the rockall trough towards the iceland scotland ridge the southern part feeds the anticyclonic circulation towards the subtropical gyre summing over the three nac branches the top to bottom transport of the nac across ovide was estimated at 41 8 3 7 sv because of the surface intensification of the southern nac branch the intermediate water is transported to the northeast atlantic mostly by the northern and central branches of the nac 11 9 1 8 sv eastward this water circulates cyclonically in the iceland basin and anticyclonically in the west european basin with similar transport intensities

recirculating components to the deep boundary current of the northern north atlantic abstract the meridional overturning system of the north atlantic is conventionally thought of as transporting warm water 4 c to high latitudes and covd water to low latitudes the northern cold water sources for this system are dense overflow from the nordic seas and less dense water from the labrador sea lsw the overflow components are carried westward by a deep northern boundary current dnbc that is shown here actually to begin southeast of the overflow regions the dnbc lies along the southern side of a system of islands and submarine ridges that divides the nordic seas from the subpolar basins the overflows act to increase the transport of the dnbc and this transport is further increased through the entrainment of warm waters once inside the labrador sea the dnbc is joined by lsw before continuing south to low latitudes as a cold deep western boundary current dwbc however published transport estimates are larger than can be explained by warm water entrainment alone thus indicating entrainment also of recirculating cold components the subject of this paper their sources are shown to be the lsw and cold abyssal waters originating from the southern hemisphere the lsw is entrained downward into the denser part of the dnbc and laterally into the upper part of the dwbc whereas the cold abyssal waters are supplied by an eastern intensified northward flow in the eastern atlantic that serves as the initial source of the dnbc and by a similar northward flow in the western atlantic the meridional overturning system described includes recirculations and poleward transport of cold water in addition tothe components described by the conventional system the cold abyssal waters in both the eastern and western basins have relatively low levels of oxygen and high concentrations of silicate reflecting their southern origin but their influence in the northwestern atlantic is somewhat obscurred by strong recirculating cyclonic gyres in the newfoundland and labrador basins this influence is detected by a deep silicate maximum extending poleward from the mid latitude western atlantic through the two gyres with eastern concentration and recirculating back diluted toward the south in the dwbc within the respective basins such a maximum also extends northward through the irminger basin into the dnbc but there is an ambiguity as to whether this is a direct extension of the signal from the south in the western basin or if it comes from the mid latitude eastern basin by way of westward flow through the charlie gibbs fracture zone it is perhaps consequence of both estimates of the volume transports of the various recirculating cold components indicate that they supply about as much water to the deep boundary currents as do the combined cold water sources in the north

on the spatial structure and temporal variability of poleward transport between scotland and greenland 1 the flow north of warm subtropical water though the northeastern atlantic is known to have many pathways that vary over time here we use a combination of upper ocean current measurements betwe

the great salinity anomaly in the northern north atlantic 1968 1982 the widespread freshening of the upper 500 800m layer of the northern north atlantic which this paper describes represents one of the most persistent and extreme variations in global ocean climate yet observed in this century though a range of explanations have been advanced to explain this event including in situ changes in the surface moisture flux this paper describes the great salinity anomaly as largely though not entirely an advective event traceable around the atlantic subpolar gyre for over 14 years from its origins north of iceland in the mid to late 1960s until its return to the greenland sea in 1981 1982 the overall propagation speed around this subpolar gyre is estimated at about 3cm s 1 of the total salt deficit associated with the anomaly as it passed south along the labrador coast in 1971 1973 about 72 109 tonnes a deficit equivalent to about two thirds of this figure 47 109 tonnes ultimately passed through the faroe shetland channel to the barents sea arctic ocean and greenland sea during the mid 1970s possible effects on deep water formation and on the representativeness of historical section data are discussed

direct measurement of volume flux in the faroe shetland channel and over the iceland faroe ridge 1 determining the exchange of water across the iceland faroe scotland ridge is of fundamental interest because it measures the rate of transformation of north atlantic water into dense water and thus the strength of the meridional overturning circulation moc here we study this exchange by monitoring all water flowing through the area east of iceland to near the bottom or 600 m depth using a 75 khz acoustic doppler current profiler adcp mounted on the high seas ferry m f norrona starting in march 2008 currents have been measured in the faroe shetland channel fsc and along the iceland faroe ridge ifr on the ferry s weekly round trips between iceland and denmark the detided average transports to the north across the two sections are 4 1 0 1 sv 106 m2s 1 through the fsc and 4 4 0 25 sv across the ifr this excludes 1 6 sv circulating around the faroes the norrona program is ongoing

convection in the greenland sea 1982 1993 convection in the greenland sea is studied using chlorofluorocarbons cfcs components f11 f12 and hydrographic distributions taken in spring 1993 a comparison with cfc data in the greenland sea deep water taken in 1989 shows that the cfc concentrations increased ony slightly that is the deep convection activity below 2200 m depth remained on the very low level of the previous years 1982 1989 a simple convection model shows that in the depth range 550 2250 m the mean annual convection rate ceased significantly in the period from 1989 to 1993 compared to the previous years 1982 1989 for the upper 500 m the modeled tracer concentrations deviate from the observations most likely due to horizontal advection neglected in the model

eemian climate fluctuations observed in a european pollen record recent ice core data from greenland1 2 suggest that the climate during the last interglacial period the eemian was more unstable than that of the holocene about 10 000 years ago to the present being characterized in particular by a series of cold episodes each lasting about 70 to 750 years subsequent analysis of a second greenland ice core3 4 however failed to corroborate the details of these eemian climate fluctuations a result that may be attributable to the effects of ice flow4 to resolve this discrepancy it is imperative to seek alternative sources of information about the eemian climate here we present climate reconstructions from pollen data from the annually laminated eemian lake sediment record at bispingen5 and from the eemian and holocene peat records at la grande pile6 the former record indicates that an initially warm period of 2 900 yr was followed by cooling and a series of colder episodes one of which had winter temperatures comparable to those at the end of the preceding cold stage the latter records show greater climate instability during the eemian than the holocene these results are in broad agreement with those from the grip ice core but contrast both with the gisp2 core3 4 and with recent high resolution marine records from the north atlantic7 8

state dependant dilatancy in critical state constitutive modelling of sand a bounding surface hypoplasticity model is modified to incorporate the basic premises of critical state soil mechanics and cover both dense and loose sand behavior the modification consists of ren

analysis of flow at the gate of taiwan strait 1 a field survey with ship borne acoustic doppler current profiler was carried out across the penghu channel the gate of taiwan strait from 17 to 20 of may 1999 a new method of least squares interpolation is used to separate the mean flow from tidal currents the technique uses gaussian interpolation functions with local support which also take into consideration the anisotropic nature of the flow structure optimal solution is obtained by determining the tradeoff between the misfit and the model order the analysis indicates that the currents in the penghu channel are essentially barotropic and characterized by strong semidiurnal tides and mean flow the along channel averaged tidal velocity amplitudes are 1 2 m s 1 and 0 32 m s 1 for semidiurnal and diurnal tides respectively the mean current is uniform with an average northward velocity of 0 73 m s 1 the total transport is about 1 6 sv which represents a significant mass and material flux into the east china sea

decadal variability in the outflow from the nordic seas to the deep atlantic ocean the global thermohaline circulation is the oceanic overturning mode which is manifested in the north atlantic ocean as northward flowing surface waters which sink in the nordic greenland iceland and norwegian seas and return southwards after overflowing the greenland scotland ridge as deep water this process has been termed the conveyor belt and is believed to keep europe 5 8 c warmer than it would be if the conveyor were to shut down the variability of today s conveyor belt is therefore an important component of climate regulation the nordic seas are the only northern hemisphere source of deep water and a previous study has revealed no long term variability in the outflow of deep water from the nordic seas to the atlantic ocean here i use flows derived from hydrographic data to show that this outflow has approximately doubled and then returned to previous values over the past four decades i present evidence which suggests that this variability is forced by variability in polar air temperature which in turn may be connected to the recently reported arctic warming

evidence for an abrupt climatic reversal during the last interglacial on the northeast qinghai tibetan plateau climatic change over qinghai tibetan plateau is controlled by alternation of the plateau summer and winter monsoon circulation which is triggered by thermodynamic and kinetic effects of the high plateau morphology loess paleosol sequences in northeast qinghai tibetan plateau are investigated to reconstruct variations of the plateau monsoon changes during the last glacial interglacial cycle on the basis of grain size data from two loess paleosol sequences that can be used as a proxy indicator of the plateau monsoon climate changes we find a short climatic reversal during transition from the most warm humid period of the last interglacial period corresponding with marine oxygen isotope stage 5e mis 5e to the subsequent relatively cold dry period corresponding with mis 5d in contrast to the younger dryas event this climatic event shifted toward more humid conditions reflects an episode of reduced strength of the plateau winter monsoon and increased influence of the plateau summer monsoon the age of this paleoclimatic event is estimated at 111 113 ka bp this climatic reversal expresses instability of the plateau monsoon system during transformation from a wet warm to a dry cold climate it may have been caused by the high topography that amplified climatic change in the northern hemisphere during the transition from mis 5e to mis 5d c 2006 elsevier ltd and inqua all rights reserved climatic change over qinghai tibetan plateau is controlled by alternation of the plateau summer and winter monsoon circulation which is triggered by thermodynamic and kinetic effects of the high plateau morphology loess paleosol sequences in northeast qinghai tibetan plateau are investigated to reconstruct variations of the plateau monsoon changes during the last glacial interglacial cycle on the basis of grain size data from two loess paleosol sequences that can be used as a proxy indicator of the plateau monsoon climate changes we find a short climatic reversal during transition from the most warm humid period of the last interglacial period corresponding with marine oxygen isotope stage 5e mis 5e to the subsequent relatively cold dry period corresponding with mis 5d in contrast to the younger dryas event this climatic event shifted toward more humid conditions reflects an episode of reduced strength of the plateau winter monsoon and increased influence of the plateau summer monsoon the age of this paleoclimatic event is estimated at 111 113 ka bp this climatic reversal expresses instability of the plateau monsoon system during transformation from a wet warm to a dry cold climate it may have been caused by the high topography that amplified climatic change in the northern hemisphere during the transition from mis 5e to mis 5d c 2006 elsevier ltd and inqua all rights reserved

quantitative reconstruction of climate variability during the eemian merkinė and weichselian nemunas in lithuania abstract little is known concerning climate changes in the eastern baltic region during the last interglacial glacial cycle and in particular climate changes during the weichselian in this study a quantitative reconstruction of the mean january and july temperature for the medininkai 117 site in lithuania is presented the reconstruction is based on pollen and plant macrofossils from this site which reveal that the vegetation was characteristic of many northern europe sites during the eemian and early weichselian gradual evolution of the vegetation suggests that relatively uniform climate conditions existed during the eemian our reconstructions support the view of a relatively stable eemian with short cooling phases of low amplitude a strong increase in temperature was apparent during the beginning of the interglacial and decrease during the transition to the weichselian reconstructed july temperatures of the eemian interglacial were approximately 2 c higher than today 18 5 c today 16 2 c and were similar to today for january 5 2 c today 5 1 c july temperatures during the early weichselian were only 2 c lower than during the eemian whereas the january temperatures gradually decreased winter temperatures were relatively high above 10 c during the early weichselian

hydrography and through flow in the north eastern north atlantic ocean the nansen project abstract the circulation and hydrography of the north eastern north atlantic has been studied with an emphasis on the upper layers and the deep water types which take part in the thermohaline overturning of the oceanic conveyor belt over 900 hydrographic stations were used for this study mainly from the 1987 1991 period the hydrographic properties of subpolar mode water in the upper layer which is transported towards the norwegian sea showed large regional variation the deep water mass was dominated by the cold inflow of deep water from the norwegian sea and by a cyclonic recirculation of lower deep water with a high antarctic bottom water content at intermediate levels the dominating water type was labrador sea water with only minor influence of mediterranean sea water in the permanent pycnocline traces of antarctic intermediate water were found geostrophic transports have been estimated and these agreed in order of magnitude with the local heat budget with current measurements with data from surface drifters and with the observed water mass modification a total of 23 sv of surface water entered the region of which 20 sv originated from the north atlantic current while 3 sv entered via an eastern boundary current of this total 13 sv of surface water left the area across the reykjanes ridge and 7 sv entered the norwegian sea while 3 sv was entrained by the cold overflow across the iceland scotland ridge approximately 1 4 sv of norwegian sea deep water was involved in the overflow into the iceland basin which with about 1 1 sv of entrained water and 1 1 sv recirculating lower deep water formed a deep northern boundary current in the iceland basin at intermediate depths where labrador sea water formed the dominant water type about 2 sv of entrained surface water contributed to a saline water mass which was transported westwards along the south icelandic slope