surface and subsurface data integration and geological modelling from the little ice age to the present in the ravenna coastal plain northwest adriatic sea emilia romagna italy abstract new geological analysis of the ravenna coastal plain has allowed a major update of the geological coastal model with anthropogenic overprints removed from an area heavily affected by human actions in the last four centuries a period in which the little ice age lia has had a large influence on the coastal dynamics the geological build up of the coastal plain is a natural occurrence that is important for understanding the present day coastal buildup however coastal zone anthropization has defined the actual coastal morphology canceling out most of surface expression needed to create an accurate coastal evolution model as the beach ridges morphology in the study area as the lack of surface expression due to the anthropogenic actions has changed the coastal zone under study it is not possible to only use geomorphological analysis to construct a local coastal evolution model because of this building a new model and understanding how coastal evolution would proceed without human influence would allow us to understand the interaction between natural forces and anthropogenic influence which has acted to shape the actual morphology of the study area from the lia period to the present days we therefore propose an integration of data using the following actual data from the surface such as the high resolution digital surface model dsm and the digital terrain model dtm the actual database from the emilia romagna region geological survey including the shapefile with the regional soil chart and the geological elements present in the study area knowledge from previous work carried out in the area and the subsurface data from ground penetrating radar gpr which would make the study the first to use a gpr survey of the coastal plain of the northwest adriatic in addition the work will follows a successful case study done in the southern brazilian coastal plain that integrated previous works done in the coastal plain with new methods such as gpr data acquisition the gpr data allows for corroboration of the interpretation of the coastal model constructed using the surface data finally the surface geological model proposed in this work may aid by providing the following i a new means for local coastal geology research ii a methodology to apply to other barrier lagoon systems around the world in order to update our knowledge about these systems and iii powerful information to support coastal managers and decision makers in constructing a long term master plan for effective integrated coastal zone management

stable isotope records of late quaternary climate and hydrology from mediterranean lakes the isomed synthesis lake isotope records can be used to assess the spatial coherency of late quaternary climate change across the circum mediterranean region we place modern and palaeo data within a simple conceptual lake response model to show that the isotope hydrology of most mediterranean lakes has been influenced strongly by water balance even in those systems that are chemically dilute i e freshwater 18o data on biogenic and endogenic carbonates from 24 lake basins are used to reconstruct multi millennial scale trends since the lgm while it is difficult to make direct comparisons between lake records in terms of single climatic parameters coherent regional isotopic trends can be identified during glacial times mediterranean lakes deposited carbonates isotopically heavier in 18o compared to the holocene partly due to source area effects isotopic enrichment was most marked during intervals corresponding to the h1 and younger dryas events confirming that late pleistocene cold stages in the north atlantic region were marked by aridity around much of the mediterranean almost all mediterranean lake records shifted to more depleted isotopic values during the last glacial interglacial transition lgit this shift is the reverse of the trend which characterised the same transition in lakes from northern and central europe and suggests that temperature changes were not an important direct driver of mediterranean lake isotopic records over glacial interglacial timescales in the early holocene many lakes in the eastern part of the region were more depleted isotopically than in recent millennia this corresponds with marine sapropel formation both chronologically and geographically and implies that increases in local rainfall contributed significantly to the creation of a freshwater lid and anoxia in the east mediterranean sea in contrast no such pattern is currently apparent from lake isotope records from the west mediterranean suggesting a possible nw se contrast in climate history during the holocene

multivariate hierarchical analyses of miocene mollusk assemblages of europe paleogeographic paleoecological and biostratigraphic implications mollusk dominated fossil assemblages from the marine miocene bioprovinces of europe the boreal province and the paratethys were analyzed by using bulk samples collected hierarchically across several spatiotemporal scales the study explores quantitative patterns recorded by benthic mollusk assemblages including implications for paleogeographic biostratigraphic and paleoenvironmental patterns and the relationship between spatiotemporal scale of analysis and levels of variability in paleontological data a total of 8455 specimens from 23 samples were collected from siliciclastic sediments clay and sand at 12 localities from france belgium the netherlands germany poland austria and hungary with the exception of one sample of serravallian age from the southeastern north atlantic all samples came from burdigalian and langhian deposits of the paratethys and the boreal province all specimens were identified to species level 297 species total classified in terms of ecology and analyzed by using multivariate and computer intensive methods the analyses focused on 1 bivalve gastropod ratios 2 diversity levels 3 multivariate taxonomic and ecological patterns and 4 multivariate euclidean distances between samples compared at five different scales within sites within localities within facies among facies among provinces the bivalve gastropod ratio is a highly volatile parameter thus its informative value is highly limited the estimates of alpha diversity sample species richness standardized by rarefaction indicate that fossil assemblages of the boreal province display higher diversity levels than those of the paratethys this result is consistent with the general tendency of isolated epicontinental basins to display impoverished fauna and may be due to geographic barriers limiting larval dispersal and to environmental instabilities inherent to marginal environments of epicontinental seaways rarefactions of pooled data indicate that for both provinces the taxonomic turnover among sites beta diversity accounts for 30 40 of species diversity multivariate analyses indicate that biogeographic variation between the provinces is the most important factor controlling differences among samples whereas facies type and stratigraphic position of samples play a secondary role the strong biogeographic signature is consistent with recent paleogeographic reconstructions that suggest a lack of a direct marine connection between the two provinces at that time the relatively poorer discrimination of mollusk assemblages across facies and biostratigraphic stages reflects the overriding role of the middle miocene biogeography in controlling the composition of mollusk assemblages the hierarchical multivariate analysis shows that with the increase in the scale of observation within sites within localities within facies among facies among provinces the average multivariate distance between samples increases continuously new heterogeneities that add notable amounts of new variation exist at each scale of observation the highest increase is observed for the among provinces comparison level again indicating the major role of geographic sources of variation in the data the hierarchical approach provides a rigorous way to quantify the effects of scale dependent sources of variability on paleontological patterns

hydrological changes in the mediterranean sea over the last 30 000 years sea surface temperatures were reconstructed over the last 30 000 years from alkenone paleothermometry sst alk and planktonic foraminifera assemblages using the modern analog technique mat sst foram along two cores of the mediterranean sea md84 632 levantine basin and md04 2797 siculo tunisian strait oxygen isotope of planktonic foraminifera g bulloides for core md04 2797 and g ruber for core md84 632 were also determined sst alk in the levantine basin indicate colder values at the last glacial maximum lgm 14 c than earlier established from mat and a cooling amplitude of 6 7 c comparable to the central mediterranean sea climatic events such as the younger dryas yd and heinrich events 1 and 2 h1 and h2 were times of significant cooling in the two cores in the eastern basin values of local seawater oxygen isotope w indicate relatively saltier waters during the lgm and deglaciation than today with increasing w values higher salinity in the eastern basin and decreasing ones lower salinity in the central mediterranean sea during cold stadials the observed alterations of surface water properties t and w in the central and eastern mediterranean at the lgm are consistent with model experiments showing slightly lower evaporation in the mediterranean than today except for the eastern basin

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

the arid humid transition in the sahara and the sahel during the last deglaciation at the time of the last glacial maximum the sahara and sahel regions of north africa were extremely dry new records of rainfall show that during the subsequent deglaciation the transition from arid to humid conditions in these regions occurred synchronously in two main steps comparison with other records of palaeoclimate in europe and the north atlantic ocean shows that certain common factors controlled changes in ocean and atmosphere dynamics during the deglaciation

observational evidence of salt lens formation in the iberian basin the quasi synoptic picture of the mesoscale eddy field off portugal is presented on the basis of recent hydrographic measurements the dynamic topography and the salinity field at middepths 900 1300 m is shown to be dominated by several isolated meddy structures superimposed on a general east west gradient deduced from the actual dynamical situation there is evidence for meddy generation in this region numerical process studies demonstrate the possibility of vortex formation by baroclinic instability of a northward middepth jet of mediterranean water and by fragmentation of larger scale mediterranean water blobs

el nino as a mediator of the solar influence on climate 1 using a climate model of intermediate complexity we simulate the response of the el nino southern oscillation enso system to solar and orbital forcing over the holocene solar forcing is reconstructed from radiocarbon production rate data using various scaling factors to account for the conflicting estimates of solar irradiance variability as estimates of the difference since the maunder minimum range from 0 05 to 0 5 of the solar constant we consider these two extreme scenarios along with the intermediate case of 0 2 we show that for large or moderate forcings the low pass filtered east west sea surface temperature gradient along the equator responds almost linearly to irradiance forcing with a short phase lag about a decade wavelet analysis shows a statistically significant enhancement of the century to millennial scale enso variability for even a moderate irradiance forcing in contrast the 0 05 case displays no such enhancement orbitally driven insolation forcing is found to produce a long term increase of enso variability from the early holocene onward in accordance with previous findings when both forcings are combined the superposition is approximately linear in the strong scaling case overall the sea surface temperature response is of the magnitude required and is persistent enough to induce important climatic perturbations worldwide the results suggest that enso may plausibly have acted as a mediator between the sun and the earth s climate a comparison to key holocene climate records from the northern hemisphere subtropics and midlatitudes shows support for this hypothesis

characteristics of surface signatures of mediterranean water eddies in this work we obtain new results on the manifestation of meddies or of other deep eddies at the sea surface further developing the results by bashmachnikov and carton 2012 the quasi geostrophic equations are used to describe a near axisymmetric vortex in the upper ocean forced at its lower boundary by the isopycnal elevation of a moving meddy the solution thus obtained provides a better approximation of the characteristics of meddy surface signals the results show that in subtropics large meddies with dynamic radius rm 30 km are always seen at the sea surface with aviso altimetry that medium size meddies with rm 20 km may be seen at the sea surface only if they are sufficiently shallow and strong while small meddies with rm 10 km generally cannot be detected with the present accuracy of altimetry data the intensity of meddy surface signals decreases to the south with the decrease of the f n ratio the seasonal variation in intensity of the surface signal for northern meddies 45 n is on the order of 2 3 cm but for subtropical meddies 35 n it can be on the order of 5 10 cm the radii of meddy surface signals range from 1 to 2 times the radii of the corresponding meddies for most of the observed subtropical meddies the upper limit should be used numerical experiments show that surface signals of meddies translated with drift are efficiently dispersed by the radiation of rossby waves at the same time for meddies translated by a background current the surface signal does not show strong dissipation

the use of faunal gradient analysis for intraregional correlation and assessment of changes in sea floor topography in the type cincinnatian abstract in paleobiology and stratigraphy there is a growing need to develop high resolution chronostratigraphic frameworks at regional scales which would permit unprecedented assessments of spatiotemporal variation in preserved biotas here we present an intraregional correlation for the kope and lower fairview formations of the type cincinnatian on the basis of detrended correspondence analysis dca of faunal census data we believe that the method also holds promise as a tool of correlation in other fossiliferous venues the data were collected directly in the field at closely spaced stratigraphic intervals but with relatively coarse taxonomic and quantitative data resolution this approach is independent of lithologic assessments and does not require the delineation of sequence stratigraphic architecture in the study area faunal curves were constructed for each locality on the basis of stratigraphic changes in sample scores for dca axis 1 the curves were smoothed to reveal a long term signal of

interaction of mediterranean water eddies with sedlo and seine seamounts subtropical northeast atlantic abstract during years 2003 and 2004 both sedlo and seine seamounts lying in the area of influence of the mediterranean water outflow in the northeast atlantic were investigated in the framework of the eu funded project oasis analysis of ctd data shows that the levels of major variability in temperature and salinity were confined to the upper ocean layer which is subject to seasonal air sea heat exchange and to the mediterranean water mw level in this paper we concentrate on the latter case and show that the variability observed resulted from mediterranean water eddies meddies colliding with the seamounts combined data from ctd surveys current meter moorings ship mounted adcp and satellite altimetry suggest that during the period of observations there was only one meddy interacting with each of the seamounts on sedlo seamount intensive interaction resulted in the loss by the meddy of about 25 of the salt around the seamount whereas on seine the meddy or portion of it escaped the seamount after performing several rotations around the summit without any significant interaction

merging and migration of two meddies in this study a scenario is developed of two adjacent mediterranean water eddies meddies as they were observed merging and drifting through the iberian basin observations are based on four rafos floats at 850 1050 dbar two hydrographic surveys centered roughly at 38 n 24 w and trajectories of surface drifters drogued at 100 m in april 1991 the meddy a was identified and labeled by surface drifters during the revisit one month later two meddies were encountered b1 and b2 in the vicinity of the former meddy a the coalescence of b1 subsequently identified as a one month older and b2 is inferred from a simple kinematic model describing the observed movement of the rafos floats for up to three months after the second ctd survey the deduced vorticity front radius 15 km within b1 was of insufficient strength to keep the core waters of b1 isolated and prevent the absorption of b1 by b2 the resulting meddy b1 b2 showed a clear near surface dynamical signal its deep root 1800 m could explain the expulsion from the meddy of the remaining rafos float and surface drifter at the time of the meddy s collision with the josephine seamount for the first time a set of lagrangian and hydrographic observations give direct evidence that neighboring meddies can merge as predicted by theoretical considerations

geographical variability of the first baroclinic rossby radius of deformation global 1 83 18 climatologies of the first baroclinic gravity wave phase speed c1 and the rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles these new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the northern hemisphere and the south atlantic and with a 1 83 18 fine resolution map of c1 for the tropical pacific it is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5 15 owing to seemingly minor computational errors geographical variations in the new high resolution maps of c1 and l1 are discussed in terms of a wkb approximation that elucidates the effects of earth rotation stratification and water depth on these quantities it is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the world ocean this is rationalized from consideration of the wkb approximation

on the southward motion of mediterranean salt lenses abstract a new mechanism is proposed to account for the southward motion of salt lenses in the canary basin it relies on the active mixing that is observed at the periphery of such eddies between the warm salty mediterranean waters of the core and the surrounding fresher and cooler atlantic waters intrusions driven by this thermohaline contrast feed on the eddy potential energy and drain off the eddy volume anomaly submitted to the continuous entrainment of its own fluid by the frontal turbulence the salt lens suffers a velocity divergence at its periphery induced by a geostrophic adjustment process this causes in turn a squashing of the density surfaces and the salt lens must then move southward to conserve its potential vorticity a possibility offered by the spherical nature of the earth it appears that mixing may load to the coherent latitudinal displacement of an ensemble of fluid parcels on a plant while at the same time dissipating the energy of the structure itself

global sea level control on local parasequence architecture from the holocene record of the po plain italy abstract holocene deposits exhibit distinct predictable and chronologically constrained facies patterns that are quite useful as appropriate modern analogs for interpreting the ancient record in this study we examined the sedimentary response of the po plain coastal system to short term millennial scale relative fluctuations of sea level through high resolution sequence stratigraphic analysis of the holocene succession meters thick parasequences form the building blocks of stratigraphic architecture above the younger dryas paleosol a prominent stratigraphic marker that demarcates the transgressive surface early holocene parasequences s 1 3 record alternating periods of rapid flooding and gradual shoaling and are stacked in a retrogradational pattern that mostly reflects stepped post glacial eustatic rise conversely middle to late holocene parasequences s 4 8 record a complex pattern of coastal progradation and delta upbuilding that took place following sea level stabilization at highstand starting at about 7 cal ky bp the prominent transgressive surface at the base of parasequence 1 correlates with the period of rapid global sea level rise at the onset of the holocene mwp 1b whereas flooding surfaces associated with parasequences 2 and 3 apparently reflect minor early holocene eustatic jumps reported in the literature changes in shoreline trajectory parasequence architecture and lithofacies distribution during the following eustatic highstand had instead an overwhelming autogenic component mostly driven by river avulsions delta lobe switching local subsidence and sediment compaction we document a 1000 year delayed response of the coastal depositional system to marine incursion farther inland from the maximum landward position of the shoreline a dramatic reduction in sediment flux due to fluvial avulsion resulted in marine inundation in back barrier position whereas coastal progradation was simultaneously taking place basinwards we demonstrate that the landward equivalents of marine flooding surfaces parasequence boundaries may be defined by brackish and freshwater fossil assemblages and traced for tens of kilometers into the non marine realm this makes millennial scale parasequences whether auto or allogenic in origin much more powerful than systems tracts for mapping detailed extents and volumes of sediment bodies the holocene parasequences of the po coastal plain with strong age control and a detailed understanding of sea level variation may provide insight into the driving mechanisms and predictability of successions characterized by similar depositional styles but with poor age constraint resulting in more robust interpretations of the ancient record

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

magnetostratigraphic dating of an intensification of glacial activity in the southern italian alps during marine isotope stage 22 abstract we applied magnetostratigraphy and mammal biostratigraphy to date climate sensitive pollen cycles and lithostratigraphic units of the pliocene pleistocene leffe sedimentary succession from the southern alps italy the leffe section was correlated to additional sections casnigo fornaci di ranica and pianengo to construct a stratigraphic network along a common fluviatile system the serio river sourced in the southern alps and flowing southward into the po river basin we obtained a coherent scenario of climate variability for the last 2 myr at leffe lacustrine deposition commenced during the olduvai normal subchron 1 94 1 78 ma and lasted up to a chronologic level compatible with marine isotope stage mis 22 0 87 ma pollen analysis revealed that climate varied cyclically from warm temperate to cool during this time interval but never as cold as during glacial intervals at around mis 22 climate cooled globally gravels attributed to high energy braided river systems fed locally by alluvial fans prograded from the serio river catchment area over the leffe basin and toward the po plain in response to a generalized event of vegetation withdrawal and enhanced physical erosion at this time alpine valley glaciers reached their first maximum southward expansion with glacier fronts located at only 5 km upstream from leffe

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

a meddy off cape st vincent part i description abstract a meddy an eddy formed from mediterranean source water was surveyed in detail with two types of expendable profilers and a ctd instrument the muddy comprised two distinct vertically aligned tenses with a combined thickness of 650 m both lenses were stratification minima the upper lens was warmer fresher 12 25 c 36 5 psu and more circular the lower lens was cooler more saline 12 1 c 36 65 psu and more elliptical oriented alone a northeast by southwest line the upper lens homogeneous out to a radius of 6 km had a radius of maximum velocity of 9 km its relative vorticity was 0 85 f and its ertel potential vorticity 4 10 12 m s 1 was 17 times below ambient levels due to the combined effects of negative relative vorticity and vortex stretching the meddy contained more kinetic energy than available potential energy energy burger number of 2 5 compared with historical meddies it had a larger burger number and a more negative vorticity rossby number

accounting for kinetic isotope effects in soreq cave israel speleothems abstract there is growing evidence that speleothem calcite grows out of isotopic equilibrium with cave drip water with clumped isotope analysis providing a sensitive indicator for disequilibrium this disequilibrium is primarily the result of co2 degassing from a thin film of water leading to irreversible 13c enrichment and reversible 18o enrichment and 47 depletion here we examine isotopic disequilibrium in soreq cave israel using multiple modern day and late holocene speleothems the variability observed in 47 is small within the analytical uncertainty but the 47 derived temperature is offset from the modern cave temperature by 4 c reflecting degassing related disequilibrium that is fairly constant spatially 18o is more heterogeneous reflecting short term variability in drip water 18ow combined with variability in the speleothem growth rates and related fractionation between dissolved carbonate species and the growing calcite mineral this complexity however is markedly reduced by spatial or temporal averaging enabling an interpretation of the cave paleoclimate record we examine the soreq cave speleothems through a comparison with 2 types of thermometers one is based on caco3 precipitation from a bulk solution and is typically used for calibration of the 47 and 18o thermometers a second that is based on caco3 precipitating at the surface of the solution thus focusing and amplifying the thin film characteristics of speleothem formation soreq cave speleothems are intermediate between these thermometers providing a cave specific thermometer calibration

a census of meddies tracked by floats recent subsurface float measurements in 27 mediterranean water eddies meddies in the atlantic are grouped together to reveal new information about the pathways of these energetic eddies and how they are often modified and possibly destroyed by collisions with seamounts twenty meddies were tracked in the iberian basin west of portugal seven in the canary basin during february 1994 14 meddies were simultaneously observed 11 of them in the iberian basin most 69 of the newly formed meddies in the iberian basin translated southwestward into the vicinity of the horseshoe seamounts and probably collided with them some meddies 31 passed around the northern side of the seamounts and translated southwestward at a typical velocity of 2 0 cm s into the canary basin some meddies observed there were estimated to be up to 5 yr old four meddies in the canary basin collided with the great meteor seamounts and three meddies were inferred to have been destroyed by the collision overall an estimated 90 of meddies collided with major seamounts the mean time from meddy formation to a collision with a major seamount was estimated to be around 1 7 yr combined with the estimated meddy formation rate of 17 meddies yr from previous work this suggests that around 29 meddies co exist in the north atlantic therefore during february 1994 we observed about half of the population of meddies

sampling of oceanic rings by satellite radar altimeter in the present paper the probability for a mesoscale oceanic rings to be seen by a perfect satellite altimeter is investigated first the motion of a ring center is determined using a stochastic differential equation the problem of radar altimeter sampling is then investigated first in the one dimensional case then for two dimensions the probability of a ring to be seen by a satellite is then computed and is shown to depend on the satellite period and fundamental interval the mean and standard deviation of the ring speed and the distance between the ring center and the nearest track when the ring appears the maximum of this probability and the time at which the maximum arises give an estimate of the satellite ability to sense the rings the observation of gulf stream gs warm and cold core rings wcr ccr by the topex poseidon and geosat altimeters are then presented as examples for both satellites and ring events the probability for the ring center to lie on a satellite track i e the entire ring signal is seen is very low less than 5 however more than 90 of the gs wcrs and 65 of the gs ccrs are seen at least once i e the distance between the ring center and a satellite track is less than the ring radius with a probability over 80 the mean probability for the satellite to see a significant part of the ring signal the distance between the ring center and a satellite track is less than half the ring radius drops to about 50 aliasing between ring motion and satellite sampling should be taken into account during the definition of altimetric data assimilation methods for numerical models on the other hand the probability of view is high enough to indicate that altimetric data could improve climatological and statistical studies of mesoscale eddies

impacts of abrupt climate changes in the levant from last glacial dead sea levels abstract a new detailed lake level curve for lake lisan the last glacial dead sea reveals a high frequency of abrupt fluctuations during marine isotope stage 3 mis3 compared to the relatively high stand characterizing mis2 and the significantly lower holocene lake the lake level fluctuations reflect the hydrological conditions in the large watershed of the lake which in turn reflects the hydro climatic conditions in the central levant region the new curve shows that the fluctuations coincide on millennial timescales with temperature variations recorded in greenland four patterns of correlation are observed through the last ice age 1 maximum lake elevations were reached during mis2 the coldest interval 2 abrupt lake level drops to the lowest elevations coincided with the occurrence of heinrich h events 3 the lake returned to higher stand conditions along with warming in greenland that followed h events 4 significant lake level fluctuations coincided with virtually every greenland stadial interstadial cycle over glacial interglacial time scales northern hemisphere glacial cooling induces extreme wetness in the levant with high lake levels reaching 160 m below mean sea level mbmsl approximately 240 m above typical holocene levels of 400 mbmsl these orbital time scale shifts are driven by expansions of the european ice sheet which deflect westerly storm tracks southward to the eastern mediterranean resulting in increased sea air temperature gradients that invoke increased cyclogenesis and enhanced moisture delivery to the levant the millennial scale lake level drops associated with greenland stadials are most extreme during heinrich stadials and reflect abrupt cooling of the eastern mediterranean atmosphere and sea surface which weaken the cyclogenic rain engine and cause extreme levant droughts during the recovery from the effect of heinrich stadials the regional climate configuration resumed typical glacial conditions with enhanced levant precipitation and a rise in lake lisan levels similar cyclicity in the transfer of moisture to the levant affected lake levels during all of the non heinrich stadial interstadial cycles

modern shallow to deep water bivalve death assemblages in the red sea ecology and biogeography abstract this study provides quantitative comparisons of modern bivalve death assemblages between shallow marine deep shelf and bathyal settings cluster and discriminant analyses of the bivalve fauna distinguish four sample groups which are primarily separated by water depth shallow marine vs deeper shelf vs bathyal and sedimentological features fine grained shallow marine vs coarse grained shallow marine the four groups consist of taxonomically and or ecologically distinct faunal associations association 1 from fine grained shallow marine environments 6 40 m is characterized by the infaunal chemoautotrophic lucinoidea and suspension feeding corbulidae and veneroidea association 2 from coarse grained shallow marine environments 1 19 m is dominated by the infaunal suspension feeding cardioidea glycymerididae and deposit feeding tellinoidea but the importance of epifaunal cemented and byssate suspension feeding ostreoidea chamoidea arcoidea spondylidae and mytiloidea increases association 3 from deeper shelf mainly 50 100 m is strongly characterized by suspension feeding epifauna diverse pteriomorpha mainly limopsidae spondylidae and mytiloidea and association 4 from bathyal settings mainly 300 1900 m consists mainly of infaunal carnivorous cuspidariidae suspension feeding limopsidae and deposit feeding nuculanidae the two shallow water associations and the association from the deep shelf show considerable overlaps in taxonomic composition they also show a south to north alteration in their faunal composition which probably reflects their common post pleistocene immigration from refuge areas in the gulf of aden or gulf of oman the bathyal fauna in contrast is very distinct and homogeneous in all investigated respects throughout the red sea basin the dominance of endemic faunas the presence of bivalves with clearly tethyan origin and significant differences to deep sea faunas from the mediterranean basin and the gulf of aden indicate that in some deep water parts of the red sea pliocene faunas have survived during the pleistocene

a multidisciplinary study of ecosystem evolution through early pleistocene climate change from the marine arda river section italy the arda river marine succession italy is an excellent site to apply an integrated approach to paleoenvironmental reconstructions combining the results of sedimentology body fossil paleontology and ichnology to unravel the sedimentary evolution of a complex marine setting in the frame of early pleistocene climate change and tectonic activity the succession represents a subaqueous extension of a fluvial system originated during phases of advance of fan deltas affected by high density flows triggered by river floods and overlain by continental conglomerates indicating a relative sea level fall and the establishment of a continental environment an overall regressive trend is observed through the section from prodelta to delta front and intertidal settings the hydrodynamic energy and the sedimentation rate are not constant through the section but they are influenced by hyperpycnal flows whose sediments were mainly supplied by an increase in apennine uplift and erosion especially after 1 80 ma the arda section documents the same evolutionary history of coeval successions in the paleo adriatic region as well as the climatic changes of the early pleistocene the different approaches used complement quite well one another giving strength and robustness to the obtained results

facies phosphate and fossil preservation potential across a lower cambrian carbonate shelf arrowie basin south australia abstract the effects of sedimentological depositional and taphonomic processes on preservation potential of cambrian small shelly fossils ssf have important implications for their utility in biostratigraphy and high resolution correlation to investigate the effects of these processes on fossil occurrence detailed microfacies analysis biostratigraphic data and multivariate analyses are integrated from an exemplar stratigraphic section intersecting a suite of lower cambrian carbonate palaeoenvironments in the northern flinders ranges south australia the succession deepens upsection across a low gradient shallow marine shelf six depositional facies sequences are identified ranging from protected fs1 and open fs2 shelf lagoonal systems high energy inner ramp shoal complex fs3 mid shelf fs4 mid to outer shelf fs5 and outer shelf fs6 environments non metric multi dimensional scaling ordination and two way cluster analysis reveal an underlying bathymetric gradient as the main control on the distribution of ssfs unlike groups that produced primary organophosphatic biominerals taxa that built calcareous skeletons are more taphonomically controlled which is further exacerbated by sampling and processing biases a strong facies association with condensed and reworked horizons suggests the stratigraphic occurrence of calcareous groups reflects conditions conducive to preservation phosphogenesis and phosphatization rather than true stratigraphic ranges consequently organophosphatic taxa should take precedence in the erection of biostratigraphic zones for subdivision of lower cambrian successions

microendolithic structures from the fort payne formation lower mississippian kentucky and tennessee implications for the paleoenvironment of carbonate mud mounds abstract resin cast embedment and naturally occurring internal molds have revealed an assemblage of microendoliths from the lower mississippian fort payne formation microendoliths produced by the heterotrophs orthogonum lineare orthogonum giganteum and saccomorpha clava dominate this unit as well as the phototroph produced traces ichnoreticulina elegans and fascichnus dactylus a chlorophyte ostreobium quekettii and cyanobacterium hyella caespitosa respectively they were found within a variety of fossil substrates including solitary corals bryozoans brachiopods and gastropods with a notable absence in all trilobites and echinoderms the fort payne from the lake cumberland dale hollow region of southern kentucky northern tennessee contains a suite of fossiliferous green shale deposits with isolated locations of enigmatic carbonate mud mounds the latter commonly referred to as waulsortian mounds in other geographical areas have been the center of much speculation in the past few decades and the paleoenvironmental parameters behind their formation remain controversial using the aforementioned microendoliths a sense of the light availability within the illinois basin can be determined the assemblage of ichnotaxa uncovered is representative of light conditions spanning from dysphotic to aphotic using previously constrained depth parameters that indicate a depth of no more than 100 m a dysphotic environment suggests that the water column was eutrophic presumably due to high productivity within the illinois basin this would seem to corroborate several other inferences about the early mississippian including the growing number of suspension feeding echinoderms the restructuring of phytoplanktonic communities and increased nutrient flux from a developing terrigenous floral weathering regime in the early mississippian

diatom based tidal level transfer functions as an aid in reconstructing quaternary history of sea level movements in the uk this research analyses the diatom asssemblages recorded from six uk coastal sites and relates these diatom assemblages to tidal levels the relationship between diatom assemblages and tidal levels is examined statistically in order to develop a diatom based tidal level transfer function the results suggest that there is highly significant correlation between the diatom assemblages and water levels from mean high water of neap tides to highest astronomical tide p 0 01 99 random permutations a weighted average wa transfer function is thus established and the predictive ability of this transfer function is highly satisfactory finally this transfer function is applied successfully to estimate palaeotidal levels from fossil diatom data recorded in late holocene coastal sequences copyright 1999 john wiley sons ltd

a numerical study on the successive formation of meddy like lenses 1 we present a process study on the sustaining mechanism of lens formation using a series of numerical experiments of a density current over a sloping bottom with a cape along the coastline water parcels in the bottom density current are shed into the offshore region leading to periodic formation of anticyclonic lenses as part of baroclinic dipolar vortices the cyclonic partner is more prominent at the surface and the coupled vortices are carried by the mean current established in the offshore region parameter dependence of dipole generation is examined which suggests that the background current is necessary for the detached eddies to be coherent in the downstream direction and for shedding events to repeat nof and pichevin 1996 it is also shown that the density mixing of the bottom current provides criteria for cyclogenesis at the sea surface a detailed analysis is given by a five layer model forced by a water mass source sink which reproduces the baroclinic dipolar vortices similar to those observed in the preceding z coordinate model we find that the dipole generation is due to the finite amplitude divergence convergence of the baroclinic current passing the cape stern and chassignet 2000 the overall analyses suggest three necessary conditions for successive eddy formation 1 a localized variation in the coastline causing the finite amplitude disturbance 2 mixing of mediterranean water with the surrounding fluids leading to anticyclonic rotation of meddies as well as cyclogenesis at the surface and 3 background currents that advect the detached vortices out of the source region index terms 4255 oceanography general numerical modeling 4219 oceanography general continental shelf processes 4520 oceanography physical eddies and mesoscale processes 4528 oceanography physical fronts and jets keywords eddy shedding dense water plume numerical simulation

late quaternary palaeoenvironmental evolution of the adriatic coastal plain and the onset of po river delta abstract despite abundant geologic literature about the po coastal plain stratigraphic architecture beneath modern po river delta is virtually unknown in this paper combined sedimentological micropalaeontological and geochemical investigations of three continuous cores cores 1 to 3 about 40 m thick enable for the first time the detailed reconstruction of subsurface stratigraphy in the po river delta area along with its late quaternary palaeoenvironmental evolution lowstand deposits formed during the last glacial maximum are expressed as a fining upward succession of fluvial channel and related overbank deposits capped by a stiff overconsolidated horizon above this unconformable surface the lower post glacial succession transgressive systems tract or tst is less than 7 m thick and includes a deepening upward succession of back barrier shoreface and inner shelf deposits on the other hand the overlying highstand systems tract is considerably thicker up to 27 m and comprises the bulk of recent delta progradation i e vertically stacked prodelta delta front and delta plain deposits stratigraphic correlations within early transgressive back barrier deposits show vertically stacked thin shallowing upward successions reflecting an internal subdivision of tst into small scale parasequences the homogeneous shallow marine clay that accumulated at the turnaround from transgressive to highstand conditions can be palaeontologically differentiated into two packages miliolidae dominated and ammonia cribroelphidium dominated reflecting open marine and river influenced conditions respectively timing of maximum marine ingression maximum flooding surface mfs is recorded within the open marine clays at about 5500 calibrated yr bp by minor changes in microfauna geochemical characterization of core 1 testifies that distinct changes in sediment provenance accompanied the palaeoenvironmental evolution of the study area under changing relative sea level conditions at lowstand times the study area was an alluvial plain under the influence of adige river as suggested by comparatively high ba al values within pre holocene fluvial deposits increasing upward values of cr al 2 o 3 and ni mg within tst suggest an increasing sediment provenance from the po river during early stages of transgression via the longshore drift the onset of modern age po delta in the study area is precisely identified in core 1 at 25 10 m depth and has a distinctive double signature in terms of microfaunal assemblages po river sediments are clearly marked by the development of a characteristic foraminiferal association dominated by the opportunistic species nonionella turgida a taxon typically abundant in the marginal zone of present northern adriatic sea mud belt po river deposits are also fingerprinted by a peculiar geochemical composition corresponding to maximum cr and ni concentrations

d h ratios of fluid inclusions of soreq cave israel speleothems as a guide to the eastern mediterranean meteoric line relationships in the last 120 ky abstract d h studies of fluid inclusions of speleothems of the soreq cave israel are made using the method of vacuum thermal extraction d h measurements of present day carbonate pool margins and waters show that the value of the vacuum thermal extraction fractionation ex d extracted water d cave water is 30 0 1 4 for the soreq cave deposits d h analyses of fluid inclusions of two fossil speleothems formed during periods equivalent to glacial times suggest that their isotopic compositions follow the global meteoric water line mwl d 18 o relationship compared to present day waters which follow the mediterranean meteoric water line mmwl trend two samples from interglacial periods show isotopic trends between these lines these differences are presumed to reflect cooler less evaporative conditions in the eastern mediterranean sea during glacial times

long term ecosystem stability in an early miocene estuary the question of ecosystem stability is central to ecology and paleoecology and is of particular importance for estuaries which are environmentally highly variable considered as geologically short lived and among the most degraded modern ecosystems of our planet understanding their ecological dynamics over geological time scales requires paleontological data in a sequence stratigraphic framework which allows evaluation of paleocommunity dynamics in an environmental context a 445 m thick estuarine succession in a satellite basin of the vienna basin austria shows continuous sedimentation over 700 k y and can be divided into two transgressive systems tracts and a highstand systems tract in contrast to expectations no major physical disturbances of the ecosystem involving abrupt changes in diversity and biofacies composition occurred at fl surfaces and at the sequence boundary accommodation space remained remarkably constant over the depositional history of the basin and all changes between depositional environments were therefore more or less gradational biotic change along the studied succession can be described as a gradual faunal replacement in response to habitat tracking a process also reported for some normal marine shelf environments benthic assemblages in the estuarine succession were strongly dominated by a few taxa and developed along two indirect gradients water depth and hydrodynamic energy these gradients show subtle long term trends corresponding to the sequence stratigraphic architecture tectonics affected the sequence architecture in this particular marginal marine setting it controlled accommodation space and sedimentary input and provided stable boundary conditions over hundreds of thousands of years our study demonstrates for the fi rst time that estuaries which are under great environmental pressure today are resilient to natural environmental perturbations and can persist over geological time scales

comparison of high resolution sub annual records of trace elements in a modern 1911 1992 speleothem with instrumental climate data from southwest australia high spatial resolution measurements of mg p u sr ba and na using 193 nm excimer laser ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern australia the age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew 1911 1992 this chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content eleven laser ablation transects across a 0 5 mm wide section of the speleothem growth axis were measured cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record p and u positively and mg inversely mimic the sudden 20 decrease in annual rainfall experienced by this region since 1965 we argue that p from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil owing to the low p retention capacity of southwest australian soils both vegetation activity and the transport of vegetation derived hpo42 are sensitive to rainfall groundwater p concentration may also influence the transport of u through the strong affinity between phosphate and uranyl ions mg appears to be sensitive to groundwater residence time as this affects drip water mg ca composition by preferential loss of ca during drier episodes when calcite precipitates before reaching the stalagmite the effects of groundwater residence time may also be important for sr on inter annual scales however the behaviour of sr on the annual cycle is opposite to mg but compatible with ba and na which are shown to depend on speleothem growth rate

meddy dynamics and interaction with neighboring eddies southwest of portugal observations and modeling 1 during the semane 2000 experiment southwest of portugal two meddies were found in near contact these meddies had hydrological radii of about 20 and 30 km thickness of 900 m maximum temperatures of 12 45 c and 13 45 c and maximum salinities of 36 52 and 36 78 the smaller meddy with more pronounced thermohaline anomalies was clearly double cored at 750 and 1300 m depths while the wider one was more diffuse and more homogeneous the associated geostrophic velocities referenced at 2000 m locally reached 0 5 m s in the smaller meddy and 0 2 m s in the wider one three rafos floats and two deep drogued surface drifters seeded in the two meddies rapidly gathered in the more intense meddy this meddy trajectory revealed by the float motion was first eastward then southward maps of sea level anomaly indicate that this motion did not correspond to the long term evolution of the initial positive sea level anomaly signature of the meddies and that neighboring cyclones must have played a role in the meddy evolution to determine the role of each eddy in the observed evolution several scenarios were studied with a three layer quasi geostrophic numerical model the interaction of two meddies in isolation did not result in the observed meddy trajectories on the long term the interaction of these two meddies with successive neighboring cyclones provided a more realistic trajectory of the meddy containing the floats

the climate variability in northern levant over the past 20 000 years the levant constitutes an important region for assessing linkages between climate and societal changes throughout the course of human history however large uncertainties remain in our understanding of the region s hydroclimate variability under varying boundary conditions here we present a new high resolution precisely dated speleothem oxygen carbon isotope and sr ca records spanning the last 20 ka from jeita cave northern levant our record reveals a higher lower precipitation evaporation p e balance during the last glacial maximum and bolling interstadial heinrich stadial 1 the early middle holocene is characterized by a trend toward higher p e state culminating between similar to 7 and 6 ka the middle late holocene is characterized by two millennial length drier periods during 5 3 4 2 and 2 8 1 4 ka on submillennial time scale the northern levant climate variability is dominated by 500 year periodicity comparisons with the regional proxy records suggest persistent out of phase climate variability between the northern and southern levant on a wide range of timescales

rapid coupling between ice volume and polar temperature over the past 150 000 years a new approach to dating a continuous sea level record using speleothem u th ages shows that past variations in global ice volume occurred within centuries of polar climate change with rates of sea level rise reaching at least 1 metre per century

a low seasonality scenario in the mediterranean sea during the calabrian early pleistocene inferred from fossil arctica islandica shells understanding past seasonal temperature variability in the ocean is essential to evaluate the effects of future climate change on marine ecosystems here we estimate seasonal water temperature amplitudes from stable oxygen isotope 18oshell values of fossil shells of arctica islandica assuming 18owater 0 9 0 1 v smow specimens were collected from three pleistocene successions emilian and sicilian substages of the calabrian in central and southern italy i e rome lecce and sicily biostratigraphic analyses from rome quarry deposits indicate an age between 1 6 and 1 2 ma whereas sicily and lecce successions are slightly more recent between 1 1 and 0 62 ma prior to carbonate geochemical analysis we checked the shells for potential diagenetic alterations e g from aragonite to calcite using confocal raman microscopy 18oshell transects indicate an annual temperature amplitude of about 3 c during the early pleistocene this is in sharp contrast to reconstructions based on faunal assemblages according to which the simultaneous occurrence of boreal and warm water species in the calabrian mediterranean sea suggests a much higher seasonality ca 10 c the low seasonality and the relatively cold water 9 10 c indicate the outcrops represent colder climatic conditions compared to modern times and suggest the occurrence of a maximum glacial phase

can meddies be detected by satellite altimetry geosat exact repeat mission altimeter data have been used to estimate the sea surface height anomaly relative to a 2 year mean reference surface in the eastern north atlantic ocean horizontal maps of the sea surface height anomaly for various periods were constructed by means of an objective analysis procedure the mean sea level was approximated by the dynamic topography from climatological hydrographic data results were compared to the dynamic topography calculated from hydrographic ground truth data sampled during march 1988 on an eddy resolving station network in the iberian basin despite the low signal to noise ratio of the altimeter data in this part of the ocean the agreement of the altimeter signal with hydrographic measurements is found to be significant individual cyclonic and anticyclonic eddies in the mediterranean outflow are identified in the altimetric maps the information visible in the sea surface height is significantly correlated with the dynamic topography of the layer 500 3000 dbar containing the core of the mediterranean outflow and maximum velocities of the baroclinic eddies the successive development of the identified eddies as studied from a sequence of sea surface height maps indicates a slight westward drift of the most pronounced feature with approximately 1 9 cm s propagation velocity the inferred path of that feature is consistent with additional information from moored current meter data

an analysis of the evolution of meddies in the north atlantic using floats and multisensor satellite data previous studies focusing on the remote detection of mediterranean eddies meddies have reported that the isopycnal surface changes derived from satellite multisensor measurements at the approximate depth of 400 m can be used to sense the presence of underlying meddies while the isopycnal surface near that depth does indeed reveal the locations of meddies an analysis of isopycnal surface changes in response to the evolution of meddies has yet to be made accordingly this research focuses on analyzing the relationship between isopycnal surface changes and the evolution of meddies the vertical isopycnal surface variability of meddies which is directly related to contributions from rotational velocity interior thermal variation and vertical displacement of meddies is observed and studied using float observations from a mediterranean undercurrent seeding experiment amuse the contributions of each of the three aforementioned parameters are estimated enabling us to understand their relative role in changing the isopycnal surface above meddies furthermore in order to further understand meddies evolution and their associated forcing the dominant frequencies of their horizontal and vertical displacements as well as the sea surface height variability above the meddy are analyzed using the hilbert huang transform finally the horizontal and the vertical eddy viscosity dissipation of meddies is computed and compared with a theoretical model the empirical horizontal and the vertical eddy viscosities are found to be 7 106 cm2 s 1 and 200 cm2 s 1 respectively this study will therefore contribute to understanding how the isopycnal surface is related to the presence of meddies what frequencies dominate its variability and the values of eddy viscosity which can be used for a numerical model

controlling factors on a paleo lake oxygen isotope record yammouneh lebanon since the last glacial maximum abstract late quaternary paleoclimatic changes in the levant are difficult to extract from carbonate oxygen isotope records partly because the factors controlling the terrestrial 18 o signals are not fully understood in this region characterized by sharp climatic gradients here we address this purpose by presenting the first 14 c dated isotope record from the northern levant the record is based on oxygen isotopes from ostracod shells from lacustrine palustrine deposits accumulated in a small karstic hydrologically open basin yammouneh located on the eastern flank of mount lebanon we have first constructed a composite isotopic record obtained from three different ostracod taxa this yields an oxygen isotope record of ostracods ost related to the most widespread species ilyocypris inermis and converted to 18 o values coeval with calcite precipitated in equilibrium c with the lake water l as with other records from the mediterranean region the yammouneh profile shows maximum and minimum c values during the lgm and the early holocene respectively and a slight late holocene increase in order to discuss the potential causes of the observed 18 o values fluctuations e g changes in the isotopic composition of the moisture source temperature precipitation minus evaporation p e balance or atmospheric circulation we tentatively reconstruct the lake water isotope composition by correcting the c values for lake water temperature using regional paleotemperature estimates inferred l values were then corrected for the isotopic composition of the eastern mediterranean sea surface water the moisture source derived from planktonic foraminifera 18 o values corrected for alkenone based sea surface temperature our study suggests that holocene l fluctuations are primarily linked to changes in the sea surface water composition source effect amplified by enhanced inland rainfall during the early holocene during the lgm low l values at yammouneh are likely due to the ground temperature effect on the rainfall isotope composition possibly associated with a steeper altitudinal thermal gradient inland and with changes in air mass trajectories over the mediterranean sea

in situ and remote sensing signature of meddies east of the mid atlantic ridge 1 mediterranean water eddies meddies are thought to play an important climatic role nevertheless their dynamics are not sufficiently known because of difficulties encountered in their observation though propagating below the main thermocline a number of pieces of evidence of sea surface manifestation of meddies are collected the present work is based on joint in situ and altimetry data analyses to prove that the meddies can be followed with remote sensing data for long periods of time the in situ observations are based on data from an oceanographic cruise which crossed three meddies and reanalysis of historical data sets including rafos floats paths suggested methodology permitted us to obtain uninterrupted tracks for several meddies for a period from several months to more than 2 years it was found that the dynamically calm region to the north of the azores current presents favorable conditions for meddy tracking the meddy surface signal may become shattered and difficult to follow during interaction with a strong dynamic structures the azores current surface vortexes or peaking topography theoretical considerations support the observations and lead to the conclusion that the dynamic signature of meddies at the sea surface is an intrinsic property of meddy dynamics

dynamics and evolution of a northern meddy abstract a meddy was discovered in april 1997 off the northwestern corner of spain near 45 n 11 30 w it was tracked during 18 months with lagrangian floats and deep drogued buoys and several cruises were set to collect further hydrological and lowered adcp measurements on it the meddy named ulla was a one core lens with maximum values of temperature and salinity of 11 5 c and 36 17 psu near 1000 m depth yielding anomalies above 2 5 c and 0 5 psu compared to its environment its rotation frequency was close to 1 loop every 5 days the maximum azimuthal velocities of 15 20 cm s 1 were reached near a 15 km radius the meddy had a wide remote influence notably up to the surface and was associated with a total azimuthal volume transport of around 10 sv sv 106 m3 s 1 of which around 2 sv was trapped in the core a widening of the radial structure with decreasing depth was notable in august 1997 meddy ulla was significantly elliptic for most of the time and depending on the periods the main el

physical boundaries of intrathermocline ulleung eddies in the east japan sea abstract a new eddy detection algorithm is developed based on the particle tracking experiment pte to determine the spatial extent of the intrathermocline ulleung eddies iue in the east japan sea ejs the new eddy detection method enables us to identify three regions of interests the iue transitional regions between the iue and mean currents and mean current regions around iue the estimated spatial boundary of the iue is expressed as least square fitted elliptic characteristics from february to september 2015 accordingly we could obtain three main results after analyzing the iue 1 the center and the highest sea level height of the iue are not co located suggesting that the iue is sustained by potential vorticity through the relative vorticity in response to bathymetry changes 2 the highest sea level is always anchored around ulleung island which is associated with the relatively high chlorophyll concentration chl around the edge of the iue and 3 the shape of the iue is strongly influenced by the current systems in the ulleung basin furthermore the semi major and semi minor axes and its ratios are determined as well as the mean areas and the highest sea surface height of the iue to understand the spatio temporal characteristics of the iue and the dominant frequencies on it

onshore to offshore anatomy of a late quaternary source to sink system po plain adriatic sea italy abstract in understanding the evolution of siliciclastic systems late quaternary analogs may enable reliable predictive models of facies tract architecture the po plain adriatic sea system where a wealth of research has been conducted during the last 20 years represents one of the most intensively investigated late quaternary successions with the aid of a chronologically well constrained stratigraphy paleoenvironmental evolution is tracked for the first time from fluvial to deep marine realms over 1000 km in length vertical stacking trends onshore and stratal terminations offshore are the key observations that allow identification of surfaces with sequence stratigraphic significance systems tract boundaries in the distinct segments of the system recurring motifs in stratigraphic architecture showing tight coupling of sedimentary responses among source area catchment basin and coastal and marine depocenters reveal a cyclicity driven by glacio eustatic fluctuations in the milankovitch band due to high rates of subsidence middle pleistocene forced regressive systems tracts are exceptionally expanded and the mis5e mis2 interval late pleistocene preserves a nearly continuous record of fourth order 100 kyr stepwise sea level fall the stratigraphic architecture of last glacial maximum deposits highlights the genetic relations between channel belt development pedogenesis and sediment delivery to the lowstand delta through narrow incised valley conduits the late glacial holocene succession records the last episode of sea level rise and stabilization through well developed patterns of shoreline transgression regression tst hst that can be readily traced updip from offshore to onshore locations architectural styles across the whole system reflect a dominance of allogenic forcing in the tst as opposed to a predominantly autogenic control on stratigraphic development in the hst external drivers of facies architecture were also effective on millennial timescales the younger dryas cold reversal which marks the transgressive surface on land records a short lived episode of subaqueous progradation that is correlative onshore with widespread immature paleosol development and small sized channel belt formation quantitative assessment of sediment budgets over different time intervals requires precise positioning of the key bounding surfaces based on this approach we outline for the first time over the entire po adriatic basin an estimate of the sediment volumes stored in each systems tract

the influence of an upper thermocline current on intrathermocline eddies abstract in this study the effect of an upper layer current on the propagation of intermediate vortices such as mediterranean water eddies is investigated the author discusses the advection mechanism proposed by hogg and stommel and shows how the vertical shear of the mean current can also modify the dynamics of an eddy acting as a gradient source of background potential vorticity

evidence for holocene changes in australian indonesian monsoon rainfall from stalagmite trace element and stable isotope ratios abstract trace element and stable isotope ratios from an active stalagmite lr06 b1 recovered from liang luar cave on the island of flores eastern indonesia are used to reconstruct the position of the austral summer inter tropical convergence zone and australian indonesian summer monsoon variability during the holocene uranium series dating of the stalagmite shows that it commenced growth 12 640 years ago with hiatuses spanning 8 560 to 6 420 and 3 670 to 2 780 years ago stalagmite mg ca and sr ca ratios correlate significantly with one another and with 18 o and 13 c throughout the record this suggests that the mg ca and sr ca ratios are dominated by prior calcite precipitation a process whereby degassing in the vadose zone during periods of low recharge causes deposition of calcite and disproportionate loss of ca 2 ions relative to mg 2 and sr 2 upstream of the stalagmite the degree of initial 234 u 238 u disequilibrium also appears to have been controlled by recharge to the overlying aquifer together with the mg ca sr ca and 18 o values the initial uranium isotope activity ratios 234 u 238 u i imply a generally drier early holocene coincident with a lower sea level and lower southern hemisphere summer insolation comparison of speleothem 18 o time series from flores and borneo shows that they vary in unison for much of the holocene however there is a significant decrease in the borneo 18 o record 6 000 to 4 000 years ago that does not occur in the flores record this anomaly may be related to a change in the australian indonesian summer monsoon circulation in response to a protracted positive phase of the indian ocean dipole under this scenario stronger upwelling off of western indonesia would based on present day effects result in reduced summer convective activity over flores and a subsequent northward shift of the intertropical convergence zone

properties and pathways of mediterranean water eddies in the atlantic abstract data from ship vertical casts nodc data set argo profiling floats coriolis data set and rafos type neutral density floats woce data set are used to study characteristics of meddies in the northeast atlantic in total 241 mediterranean water eddies meddies and 236 parts of float trajectories within meddies are selected for detailed analysis the results suggest that the meddy generation rate at the southern and southwestern iberian peninsula portimao canyon cap st vincent estremadura promontory gorringe bank is 3 times that at the northwestern iberian peninsula porto aveiro canyons cape finisterre and galicia bank meddies generated south of estremadura promontory the southern meddies as compared to those generated north of it the northern meddies have smaller radii smaller vertical extension higher aspect ratio higher rossby number and higher stability stronger potential vorticity anomaly these latter properties result from the southern meddies higher relative vorticity and stronger buoyancy frequency anomaly away from the generation regions meddy drift concentrates along four main paths three quasi zonal paths northern central southern and a path following the african coast coastal the quasi zonal paths are aligned to the isolines of the ambient potential vorticity field several cross path exchanges identified in this work are aligned to topographic rises northward translation of the northern meddies within the north atlantic current to the subpolar gyre is detected within the first 600 km from the coast meddy merger is proved to be a common event this explains the observed difference in radii between the newly generated meddies and those away from the iberian margin the decay of the southern meddies proceeds mainly via the loss of their skirts and does not affect meddy cores until the latest stages the decay of the northern meddies goes in parallel with the decay of their cores in average meddy decay is achieved within 1 2 years although may take over 3 years collisions with the mid atlantic ridge and seamounts sensibly decrease meddy lifetimes meddy decay also speeds up when meddies meet the azores current or the north atlantic current a rapid drop in the number of meddies south of the azores current proves that it represents a dynamic barrier for weak meddies

horizontal dispersion within an anticyclonic mesoscale eddy abstract ship mounted adcp and buoy data are used to fit an azimuthal velocity profile to a n e atlantic mesoscale eddy chosen as a site for a lagrangian biogeochemical survey the cruise forming part of the uk plankton reactivity in the marine environment prime initiative together with the buoy derived locus of the eddy centre the adcp derived velocity field allows observations of a sulphur hexafluoride sf6 tracer release within the eddy to be put into a non translating non rotating frame analysis of the transformed data suggests that the patch of tracer though spreading remained coherent throughout the nine day survey a linear regression on the square of the radial patch width versus time gives an estimate for the effective horizontal diffusion coefficient of 22 10 m 2 s 1 this is consistent with previous estimates of diffusion rates at the o 10 km lengthscale of the patch theory predicts a corresponding along streamline spreading time of 14 days this implies that the tracer patch mixed little with the surrounding waters during the first five days of the survey suggesting that biogeochemical processes were little affected by lateral mixing during this period the theory is inapplicable at later times because the area was struck by a storm at the start of the sixth day which resulted in the halving of sf6 concentrations using a model of a circular eddy with the calculated velocity profile the dispersion of the initial patch of tracer is simulated for different diffusivities the results confirming the estimate of along streamline mixing time and demonstrating the enhancement of azimuthal diffusion by the radial shear of the flow

kinematics and dynamics of a mediterranean salt lens abstract two surveys of the absolute velocity field of an eddy of mediterranean water meddy in the eastern north atlantic were conducted one year apart in 1984 and 1985 two velocity regimes were revealed within the radius of maximum velocity the meddy rotated anticyclonically as a solid body with a depth dependent rotation period near 6 days at its mid depth 1000 m one year later the radius of the core had decreased by one third the rotation rate of the lens also decreased except at its mid depth where there was a small but perceptible increase there was a sharp 5 km or less transition between the core and the outer region where the velocity decayed exponentially with radius a strong potential vorticity front due to the abrupt change in sign of horizontal shear kept the core isolated from the outer region potential vorticity was nearly constant within the upper confines of the core over the study period whereas there was a notable increase in potential vorticity in the lower portion of

eddy generation in the mediterranean undercurrent abstract in the framework of the european union mast iii project canary islands gibraltar azores observations 24 rafos floats were deployed in the mediterranean water mw undercurrent off south portugal between september 1997 and september 1998 a preliminary analysis of this lagrangian approach complemented with xbt and current meter data show some of the major aspects of the flow associated with the undercurrent as well as associated eddy activity floats that stayed in the undercurrent featured a downstream deceleration and a steering by bottom topography three meddy formations at cape st vincent could be isolated from the float data the dynamical coupling of meddies and cyclones was observed for a considerable period of time the generation of two dipolar structures in the portimao canyon region also was observed with the float data a major bathymetric relief gorringe bank was not only an important constraint to the eddy trajectories and of the flow at the mw levels but also a site for meddy formation

westward motion of mesoscale eddies abstract since the pioneering work of nof the determination of the westward drift of mesoscale eddies under the planetary beta effect has been a recurrent theme in mesoscale oceanography and several different formulae have been proposed in the literature here recpatiulation is sought and within the confines of a single layer model a generalized formula is derived although it is similar to nof s the present formula is established from a modified definition and with fewer assumptions it also recaptiulates all other formulae for the one layer model and applies to a wide variety of situations including cases when the vortex develops a wake of rossby waves or undergoes axismmetrization following the derivation of the formula a physical interpretation clarifies the migration mechanism which can be divided between a self induced propulsion and a reaction from the displaced ambient fluid numerical simulations with primitive and geostrophic equations validate the formula for a variety of length sc

an index to distinguish surface and subsurface intensified vortices from surface observations in this study the authors first show that it is difficult to reconstruct the vertical structure of vortices using only surface observations in particular they show that the recent surface quasigeostrophy sqg and interior and surface quasigeostrophy isqg methods systematically lead to surface intensified vortices and those subsurface intensified vortices are thus not correctly modeled the authors then investigate the possibility of distinguishing between surface and subsurface intensified eddies from surface data only using the sea surface height and the sea surface temperature available from satellite observations a simple index based on the ratio of the sea surface temperature anomaly and the sea level anomaly is proposed while the index is expected to give perfect results for isolated vortices the authors show that in a complex environment errors can be expected in particular when strong currents exist in the vicinity of the vortex the validity of the index is then analyzed using results from a realistic regional circulation model of the peru chile upwelling system where both surface and subsurface eddies coexist the authors find that errors are mostly associated with double core eddies aligned surface and subsurface cores and that the index can be useful to determine the nature of mesoscale eddies surface or subsurface intensified from surface satellite observations however the errors reach 24 and some possible improvements of the index calculations are discussed

stratigraphic paleoecology bathymetric signatures and sequence overprint of mollusk associations from upper quaternary sequences of the po plain italy upper quaternary sequences of the po plain italy were used to assess the informative strength and sequence stratigraphic overprint of quantitative paleoecological patterns three densely sampled cores 89 samples 98 genera 23 280 specimens dominated by extant mollusk species with known environmental distributions were analyzed with detrended correspondence analysis dca the dca scores calibrated using extant genera provided outstanding estimates of bathymetry 3 m and related environmental parameters depth related successions of mollusk associations delineated by using dca were consistent with independent sequence stratigraphic interpretations and yielded insights inaccessible via routine techniques e g depth estimates for maximum flooding surfaces the dca ordination demonstrates the severity of the sequence stratigraphic overprint samples are highly uniform taxonomically during late transgressive systems tracts and highly variable during the following highstand systems tracts when analyzed across comparable systems tracts similar species associations repeat during the last and current interglacial cycles suggesting that po plain mollusk associations have remained remarkably stable over the past 125 k y the results are consistent with the bathymetric interpretation of the dc axis 1 postulated previously for the paleozoic fossil record demonstrate the sequence stratigraphic overprint of paleoecological patterns predicted by computer modeling and illustrate the utility of quantitative paleoecological patterns in augmenting sequence stratigraphic interpretations

erosion of a surface vortex by a seamount abstract numerical experiments are carried out on the f plane using a shallow water isopycnal model to analyze the behavior of a surface intensified anticyclonic vortex when it encounters an isolated seamount the advection by the vortex of deep fluid parcels across the isobaths is known to generate deep anticyclonic and cyclonic circulations above and near the bathymetry respectively these circulations are shown to exert a strong shear on the upper layers which causes an erosion of the initial vortex by filamentation the erosion often results in a subdivision of the eddy while the eroded original structure forms a dipole with the deep cyclone and is advected away the filaments torn off from the original core aggregate into a new eddy above the seamount splitting in more than two structures is sometimes observed the erosion process is quantified by the bulk volume integral of the eddy potential vorticity anomaly a sensitivity study to different parameters of the configuration distance between

the history and decay of a mediterranean salt lens subsurface coherent vortices called meddies1 are formed by the outflow of salty water from the mediterranean sea1 2 into the north atlantic in october 1984 we began a study to observe the life history and large scale changes of a meddy by identifying a specific meddy and carefully mapping it and seeding it with sofar floats3 these neutrally buoyant floats are tracked acoustically and can be located aboard ship as this meddy moved southward across the madeira abyssal plain it was resurveyed three more times during a span of two years being able to find this same lens 100km in diameter on successive surveys was itself a unique achievement that allowed us to observe the meddy evolution and to gain new insight into the importance of different mixing mechanisms that cause meddy decay we find evidence of mixing by at least three processes 1 lateral mixing by the exchange of layers of water thermohaline intrusions 4 5 2 vertical mixing at the underside of the lens by salt fingers6 and 3 mixing by turbulence together these cause the net heat and salt anomalies to decay with an e folding time of about one year despite the mixing the relative vorticity at the core remained constant for the first year and the meddy retained its coherent shape over a two year period

hydrography and mollusc faunas of the baltic and the white sea north sea seaway in the eemian abstract palynologically dated mollusc and cirriped faunas from a region extending from the north sea through the baltic and karelia to the arkhangelsk region show that the hydrography of the baltic was very different from the holocene for 2 2 5 ka in the early eemian a seaway existed from the barents to the north sea through karelia until it was severed at the present continental watershed to the north of lake onega after this the ladoga onega trough remained an arm of the baltic for several millennia the benthic faunas are comparable to the holocene but their boundaries were displaced much further into the baltic notable differences from the holocene are the absence or rarity of the macoma balthica biocoenosis and the presence of cold portlandia dominated biocoenoses in karelia in the belt sea and western baltic winter sea surface temperatures and salinity were higher than now by ca 6 c and 15 and the distinctly brackish top layer was missing at the same time cold bottom water 2 5 c with a tendency to anoxia characterised the karelian arm of the baltic water exchange through this area was inhibited by the constriction to the north of lake onega and the basin and threshold bathymetry water transport through the white sea baltic seaway was too sparse to play an active role in the north atlantic surface circulation or climatic change in the region the high salinity and temperature in the belt sea and western baltic persisted throughout the eemian and are explained by wider and deeper passage from the north sea to kattegat wider straits through denmark higher salinity in the north sea higher evaporation as well as more dispersed fresh water supply the advection of oceanic water into the baltic culminated in the early eemian before the carpinus zone and probably resulted in an oceanic climate in the baltic region while at the same time cold winters produced cold bottom water in the karelian arm

stratigraphic paleoecology of the valle di manche section crotone basin italy a candidate gssp of the middle pleistocene abstract macro benthic assemblages from the lower to middle pleistocene of the valle di manche vdm section crotone basin southern italy were used to assess the value of merging paleoecological quantitative patterns into a sequence stratigraphic framework two way cluster and detrended correspondence dca analyses were applied to the macrofossil data matrix comprising 22 samples 157 species and 5761 specimens specifically two way cluster analysis allowed for the characterization of five shelf related biofacies and four sub biofacies along section biofacies change along the vdm generally supported previous sequence stratigraphic interpretations and suggests that faunal turnover is the result of habitat tracking dca stratigraphic curves dc1 sample scores calibrated to the depth preferences of extant species provided quantitative estimates of bathymetry and the assessment of related parameters e g grain size sedimentation turbidity when plotted stratigraphically calibrated dc1 scores highlight the magnitude of relative sea level fluctuations at the scale of the section as well as individual sequences and systems tracts additionally dca derived paleobathymetric trends track the oscillations of the 18 o record indicative of global sea level change based on this comparison it is held that macro benthic assemblages once supported by a robust statistical interpretation can be employed successfully as a proxy for 18 o depicting the variability in local water depths the potential of this approach is especially high for studies in shallow water depositional settings where dependable 18 o data are typically difficult to obtain

observed mean and mesoscale upper ocean circulation in the midlatitude northeast atlantic 1 lagrangian instruments and altimetry data are used to investigate the upper 0 to 500 m mean and mesoscale circulations in a region of the midlatitude northeast atlantic 36 47 n 13 23 w a formation and subduction area of subpolar mode water lagrangian data were collected between september 2000 and september 2001 with isobaric subsurface floats totaling 34 0 float years and surface drifting buoys totaling 27 9 buoy years the near surface 0 100 m mean circulation is dominated by two weak 5 cm s eastward currents which veer southward in the domain in the 100 to 500 m deep layer these eastward mean currents retroflect westward and form two anticyclonic circulation cells opened to the west and separated by a cyclonic cell eddy kinetic energy is decreasing from the northwest to the southeast of the area from 100 200 cm s 2 to 20 30 cm s 2 long lived anticyclones and cyclones display mean coherent displacements both to the southwest westward eddy propagation speeds close to that of long rossby waves increase southward and are consistent with a superposition of beta effect and advection by mean currents southward eddy displacements are coherent with the observed mean currents in the north anticyclones are seen to consist of central and subpolar mode water eddies most of them likely originating from the eastern boundary whereas in the south most anticyclonic features result from the influence of mediterranean water eddies meddies on the upper layers cyclonic activity is concentrated in cyclonic zones which are seen to exchange floats and water properties

sequence stratigraphy and the resolution of the fossil record sequence stratigraphy a major theoretical achievement of earth sciences integrates facies associations and stratal architecture within a chronological framework of the geological record the sequence stratigraphic model implies that sediment supply to the basin preservation potential of individual horizons and the resolution of paleontological data co vary with base level fluctuations especially for siliciclastic depositional systems using holocene transgressive regressive successions of the po plain italy we assessed the model s hypotheses by analyzing 249 marine mollusk shells dated individually using 14 c calibrated amino acid racemization methods as postulated by the model the temporal resolution of the fossil record frequency of depositional events and net accumulation rates decreased upward concomitantly through the transgressive systems tract reaching minima in the condensed section maximum flooding zone the reverse trend with increasingly frequent thicker and less time averaged beds was observed throughout the overlying highstand systems tract the results quantify the postulated sequence stratigraphic asymmetry in temporal resolution of the fossil and sedimentary records

facies architecture and latest pleistocene holocene depositional history of the po delta comacchio area italy abstract integrated sedimentological and micropaleontological study of 16 cores and 137 piezocone penetration tests approximately 40 m deep in the comacchio area enables the documentation of the depositional history of southeastern po plain in the last 30 ka in response to fluctuating sea level sedimentation within an alluvial plain was the dominant feature across the entire study area during the pronounced sea level fall that culminated in the last glacial maximum thin lowstand fluvial sediments form the lower part of a shallow incised valley above the last glacial maximum unconformity whereas a characteristic paleosol separates the last glacial alluvial plain deposits from the overlying postglacial deposits in the interfluves transgressive and highstand deposits show a well developed stacking pattern of retrogradational coastal plain and estuarine and progradational deltaic facies detailed reconstruction of transgressive paleogeography shows evolutionary features that can be useful for refin

tracking three meddies with sofar floats abstract three meddies were tracked for up to two years in the canary basin using neutrally buoyant sofar floats these meddies have cores of warm salty mediterranean water and are approximately 100 km in diameter 800 m thick and are centered at a depth of 1100 m meddy 1 was tracked for two years 1984 86 with five floats as it drifted 1090 km southward with a mean velocity of 1 8 cm s 1 four shipboard surveys made during these two years revealed the nearly total decay of meddy 1 by gradual mixing processes meddy 2 drifted 530 km southwestward over 8 5 months with a mean velocity of 2 3 cm s 1 until it collided with hyeres seamount near 31 n 29 w the floats trapped in this meddy then stopped looping abruptly implying a major disruption of this meddy meddy 3 drifted 500 km southwestward for a year and a half with a mean translation velocity of 1 1 cm s 1 a comparison of the velocity of meddies to the velocity of nearby floats at 1100 m depth outside of the meddies shows clearly that all three m

the evolution and propagation of quasigeostrophic ocean eddies abstractthe long term evolution of initially gaussian eddies is studied in a reduced gravity shallow water model using both linear and nonlinear quasigeostrophic theory in an attempt to understand westward propagating mesoscale eddies observed and tracked by satellite altimetry by examining both isolated eddies and a large basin seeded with eddies with statistical characteristics consistent with those of observed eddies it is shown that long term eddy coherence and the zonal wavenumber frequency power spectral density are best matched by the nonlinear model individual characteristics of the eddies including amplitude decay horizontal length scale decay and zonal and meridional propagation speed of a previously unrecognized quasi stable state are examined the results show that the meridional deflections from purely westward flow poleward for cyclones and equatorward for anticyclones are consistent with satellite observations examination of the fluid transport properties of the eddies shows that an

constraints on hydrological and paleotemperature variations in the eastern mediterranean region in the last 140 ka given by the δd values of speleothem fluid inclusions abstract speleothem fluid inclusions potentially provide vital data on the paleohydrological conditions in glacial and interglacial periods we show here that d analyses of fluid inclusions from speleothems in three caves in the eastern mediterranean region israel provide a basis for understanding hydrological and temperature variations in the last 140 ka using measured d fluid inclusion values and temperature ranges constrained by the present day mediterranean meteoric water line mmwl and the global mwl we show a strong compatibility between the land and marine temperature records with the highest land temperatures occurring at 120 130 ka 17 22 c and the present 18 c and the lowest temperatures during the lgm about 10 c lower than present interglacial waters are constrained to follow the mmwl and most glacial waters also plot close to the mmwl with a slight shift towards the mwl however during two remarkable brief periods at the termination of the lgm the waters plot on the mwl suggesting that both sharp cooling and an increase in relative humidity above the em sea reduced d excess values to those of the global system

quantitative bathymetric models for late quaternary transgressive regressive cycles of the po plain italy abstractin marine settings quantitative bathymetric models can be developed using various water depth proxies including epibiont distribution sedimentologic features and the distribution of benthic taxa in time and space here the late quaternary bathymetric history of the po coastal plain italy has been reconstructed using mollusk samples from a network of 16 cores multiple analytical approaches have been applied in a comparative fashion a direct ordination approach was used to estimate sample bathymetry using weighted averaging of genera with known preferred depth weighted averaging carries an advantage of analytical simplicity and produces direct ordination models expressed in environmentally meaningful units indirect ordination methods based on depth estimates developed using posteriori calibrated ordination strategies correspondence and detrended correspondence analysis calibrated against present day bathymetric data yielded results consistent with weighted averaging regardless of the

glacio eustatic control of continental shallow marine cyclicity from late quaternary deposits of the southeastern po plain northern italy abstract integrated sedimentological and micropaleontological foraminifera ostracods pollens investigations of a 173 m long continuous core in the subsurface of the se po plain reveal a cyclic facies distribution of continental to shallow marine deposits radiometric and pollen data enable an age attribution of the study units to the late middle pleistocene holocene glacioeustasy appears to have exerted a major control on facies development as documented by the close relationships between cyclic lithofacies patterns and the curves of eustatic fluctuation particularly relative sea level falls and lowstand phases were characterized by the development of alluvial sedimentation whereas major transgressive pulses and subsequent highstands are reflected by abrupt shifts to paralic and shallow marine deposits this facies architecture is paralleled by a distinctive pollen distribution reflecting the alternation of a glacial type of vegetation dominated by pinus and nonarboreal pollen types with interglacial mixed deciduous broad leaved forests

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

dynamics of benthic marine communities across the early middle pleistocene boundary in the mediterranean region valle di manche southern italy biotic and stratigraphic implications abstract the valle di manche vdm section calabria southern italy offers the opportunity to investigate the ostracod turnover along a continuous shelf succession straddling the early middle pleistocene boundary and compare it against other paleoenvironmental i e mollusks and paleoclimatic uvigerina peregrina 18o records high resolution ca 1 sample m ostracod fauna quantitative data coupled with gradient analysis detrended correspondence analysis and non metric multi dimensional scaling document a strong relationship between changes in faunal composition and lithofacies vertical stacking patterns the comparison between the mollusk and ostracod derived ordination data demonstrates that the meio and macro faunal turnover is guided by a common complex gradient bathymetry the integrated ostracod mollusk gradient analysis also provides a trend in water depths along the section highlighting to what extent such multivariate approach can improve the paleoenvironmental and sequence stratigraphic interpretation of ancient shallow marine successions when plotted stratigraphically ordination major axis sample scores reveal two increasing decreasing patterns in water depth that fit well with the t r cycles previously identified paleobathymetric estimates combined with the vertical distribution of key ostracod groups i e epiphytic taxa on sandy substrates vs deep sea mud related taxa allow refining depositional trends stratal stacking patterns and position of previously not well resolved sequence stratigraphic surfaces within each t r cycle e g transgressive surface ts indeed two rapid increases in water depth values mark the tss that separate shallowing upward progradational rst from deepening upward retrogradational tst stratal stacking patterns of shelf deposits the tss which underline fine grained successions dominated by deep sea mud lover taxa are invariably constrained to the inception of interglacials marine isotope stages mis 21 and 19 identified within the vdm section by benthic foraminifera 18o values within both the vdm t r cycles the deepest conditions ca 140 m of water depth are invariably identified within the neopycnodonte unit slightly above the lightest 18o intervals the overlying decreasing bathymetric trend coupled with shifts in ostracod ecological groups allows to identify in the bryozoans lithofacies the stillstand falling of the relative sea level also tracked by a progressively heavier 18o record more stable paleobathymetric conditions around 40 45 m of water depth characterize the overlying silt sand deposits dominated by epiphytic species and showing the heaviest 18o values

hydrological and dynamical characterization of meddies in the azores region a paradigm for baroclinic vortex dynamics the structure des echanges mer atmosphere proprietes des heterogeneites oceaniques recherche experimentale semaphore oceanographic experiment surveyed a 500 500 km2 domain south of the azores from june to november 1993 and collected hydrological data float trajectories and current meter recordings this data exhibited three intrathermocline eddies of mediterranean water meddies two of them being repeatedly sampled their hydrological and dynamical properties are quantified here by an isopycnic analysis for the three meddies intense temperature and salinity anomalies up to 4 c and 1 1 practical salinity units psu are observed extending vertically over up to 1000 m and centered around 1000 m horizontally these anomalies spread out to radii of 50 60 km while the maximum azimuthal velocities 30 cm s 1 as computed by geostrophy lie only at 35 40 km from the central axis these meddies followed curved trajectories with drift velocities up to 7 5 cm s 1 under the influence of the neighboring mesoscale features cyclonic vortices or azores current meanders the three dimensional structure of potential vorticity in and around these features evidences their complex interactions northwest of the domain a meddy was coupled to a subsurface anticyclone forming an aligned vortex it later interacted with the azores current creating a large amplitude northward meander by vertical alignment of vorticity in the southeastern part of the domain another meddy was vertically aligned with an anticyclonic meander of the azores current and horizontally coupled with a cyclone of large vertical extent these two features as well as a small warm and salty fragment in their vicinity seem to result from the southward crossing of the meddy under the azores current these observations illustrate previous theoretical studies of baroclinic vortex dynamics

evolution of a mediterranean salt lens scalar properties abstract the evolution of a mediterranean salt lens meddy over a two year period is examined several nondimensional numbers can be used to describe the overall decay in the structure of the moddy two rossby numbers one using the central relative vorticity and another using the radius and velocity of the azimuthal velocity maximum did not change over the two year period however the burger number n2h2 f2l2 increased as the meddy decayed another burger number the ratio of total kinetic energy to total available potential energy decreased from 1 1 to 0 6 over a one year period the rates at which the meddy lost salt and heat are consistent with estimates of horizontal fluxes by intrusions a horizontal diffusivity of o 5 m2 s 1 is needed if this flux by intrusions is parameterized by an eddy coefficient simple models of the evolution of an isolated eddy by horizontal and vertical mixing of mass and momentum are examined these simple attempts to explain the evolution of the meddy suggest more c

sea land correlation of pollen records in the eastern mediterranean for the glacial interglacial transition biostratigraphy versus radiometric time scale abstract pollen diagrams based on marine cores from the eastern mediterranean and arabian seas and land cores from greece turkey the levant and western iran during the last deglaciation reveal a similar succession of conspicuous pollen abundance maxima an early phase with chenopodiaceae signaling the highest aridity a late phase with pistacia and gramineae in the mediterranean domain and tropical humid taxa in the arabian sea domain indicating conditions of mildest winter and wettest summer between these two phases the record for deciduous oak in the mediterranean and near east shows a continuous increase that points to rising moisture the chronology of this succession and its exact relationship with the marine isotopic record of global climate are established using marine cores the marine records dated by the ams 14 c method show that the chenopodiaceae phase correlates with the younger dryas chronozone globally dated 11 000 to 10 000 bp during which the climate reversed to quasi glacial conditions at least in the northern hemisphere they also show that the pistacia phase during which the mediterranean climate reached its seasonal optimum occurred from 9000 to 6000 14 c years bp boreal and early atlantic chronozones defined in nw europe in the first half of the holocene the oak pollen abundance increases rapidly from 10 000 to 9000 bp preboreal chronozone thus in terms of climate the younger dryas chronozone is regionally expressed by wide spread desert conditions as a cold and arid period during the pistacia phase the climate was most favourable both for plants that require frost free winters such as the mediterranean pistacia and those that need spring summer moisture such as gramineae at low annual moisture level seasonally 300 mm and deciduous oak at higher levels 600 mm all year without summer drought during the brief intermediary phase the climate changed drastically through an increase of winter temperature and of spring summer moisture the chronologies of the land cores however based on few 14 c dates show significant discrepancies with the marine based time frame these discrepancies imply a lack of coherence in the climate history of this mediterranean irano turanian region we propose using the chronology derived from the marine records for the entire region the local 14 c dates generally appear too old perhaps because of geological contamination of the material by older carbon

lagrangian observations of meddy formation during a mediterranean undercurrent seeding experiment mediterranean eddies meddies play an important role in maintaining the temperature and salinity distributions in the north atlantic but relatively little is known about their early life histories including where how often and by what mechanism they form a major field program called a mediterranean undercurrent seeding experiment has been carried out to directly observe meddy formation and the spreading pathways of mediterranean water into the north atlantic between may 1993 and march 1994 49 rafos floats were deployed sequentially in the mediterranean undercurrent south of portugal and tracked acoustically for up to 11 months the float deployments were accompanied by high resolution xbt sections across the undercurrent nine meddy formation events were observed in the float trajectories six near cape st vincent at the southwestern corner of the iberian peninsula and three near the estremadura promontory along the western portuguese continental slope meddy formation thus occurs where the continental slope turns sharply to the right when facing in the downstream direction of the undercurrent after conditionally sampling the float dataset to identify floats that were well seeded in the undercurrent the authors have estimated a meddy formation rate of 15 20 meddies per year the timescale for meddy formation at cape st vincent was found to be 3 7 days shorter than previous estimates based on the volume of larger meddies meddies were observed to form most frequently when the speed of the mediterranean undercurrent was relatively fast the meddy formation process at cape st vincent resembles the conceptual model of e a d asaro whereby anticyclonically rotating eddies are formed by separation of a frictional boundary layer with negative relative vorticity at a sharp corner comparison of the relative vorticity in the anticyclonic shear zone of the undercurrent and that of the newly formed meddies shows that much of the anticyclonic relative vorticity in meddies can be accounted for by the horizontal shear in the undercurrent this confirms earlier work suggesting that the classical mechanism for the generation of submesoscale coherent vortices by collapse and geostrophic adjustment of a weakly stratified fluid injected into a stratified ocean may not be the principle mechanism at work in the formation of meddies at cape st vincent

systematic vertical and lateral changes in quality and time resolution of the macrofossil record insights from holocene transgressive deposits po coastal plain italy abstract in siliciclastic marine settings skeletal concentrations are a characteristic feature of transgressive intervals that provide insights into biological and sequence stratigraphic processes to investigate taphonomic signatures of transgressive intervals we analysed three cores along a depositional profile from the high resolution chrono and stratigraphic framework of the holocene po coastal plain in northern italy coupled multivariate taphonomic and bathymetric trends delineated spatial and temporal gradients in sediment starvation bypassing suggesting that quality and resolution of the fossil record vary predictably along the studied depositional profile moreover integration of taphonomic bathymetric and fossil density trends across the study area reveals distinctive signatures useful in characterizing facies associations and determining surfaces and intervals of sequence stratigraphic significance within the southern po plain succession taphonomic degradation of macroskeletal remains increases from proximal nearshore to distal offshore locations this trend is discernible for both biologically driven bioerosion and physically driven e g dissolution abrasion shell alterations compared to the up dip most proximal core the down dip core is distinguished by shell rich lithosomes affected by ecological condensation co occurrence of environmentally non overlapping taxa and by higher taphonomic alteration the onshore offshore taphonomic trend likely reflects variation in sediment accumulation along the depositional profile of the holocene northern adriatic shelf with surface near surface residence time of macroskeletal remains increasing down dip due to lower accumulation rates these results indicate that during transgressive phases changes in sea level base level are likely to produce down dip taphonomic gradients across shelves where the quality and resolution of the fossil record both deteriorate distally radiocarbon calibrated amino acid racemisation dates on individual bivalve specimens and the chronostratigraphic framework for this profile suggest jointly that the high levels of taphonomic degradation observed distally developed over millennial time scales 8ky whereas in proximal setting overall low taphonomic degradation and geochronologic constrains point to centennial scale time averaging during the late transgression phase patterns documented in the holocene transgressive and lowermost regressive deposits of the southern po plain may be characteristic of siliciclastic dominated depositional systems that experience high frequency base level fluctuations

precise dating of dansgaard oeschger climate oscillations in western europe from stalagmite data the signature of dansgaard oeschger events millennial scale abrupt climate oscillations during the last glacial period is well established in ice cores and marine records but the effects of such events in continental settings are not as clear and their absolute chronology is uncertain beyond the limit of 14 c dating and annual layer counting for marine records and ice cores respectively here we present carbon and oxygen isotope records from a stalagmite collected in southwest france which have been precisely dated using 234u 230th ratios we find rapid climate oscillations coincident with the established dansgaard oeschger events between 83 000 and 32 000 years ago in both isotope records the oxygen isotope signature is similar to a record from soreq cave israel and deep sea records indicating the large spatial scale of the climate oscillations the signal in the carbon isotopes gives evidence of drastic and rapid vegetation changes in western europe an important site in human cultural evolution we also find evidence for a long phase of extremely cold climate in southwest france between 61 2 0 6 and 67 4 0 9 kyr ago

paleoclimate and vegetation of the last glacial cycles in jerusalem from a speleothem record a speleothem isotopic record taken from jerusalem is used to reconstruct regional climate over the last 170 000 years glacial periods in jerusalem were generally cooler and wetter than the present climate stage 5e in the desert margin of jerusalem was extremely unstable dry and warm and instability persisted throughout the transition to glacial conditions the climate after stage 5e became gradually cooler and wetter over a 20 000 year interval and did not recover to interglacial conditions in stages 5c and 5a the 13 c varied by up to 12 from glacial stages 6 4 3 2 values of 10 to 12 that reflect dense c 3 vegetation above the studied cave and up to 0 in early stage 5 when there was probably complete loss of vegetation the climatic instability during interglacial periods is much larger than during glacial periods and glacial interglacial transitions do not behave the same in each climatic cycle in this region

meddy trajectories in the canary basin measured during the semaphore experiment 1993 1995 as part of the structures des echanges mer atmosphere proprietes des heterogeneites oceaniques recherche experimentale semaphore experiment four mediterranean water eddies meddies were identified in the canary basin and tracked with freely drifting rafos floats one large and energetic meddy discovered 1700 km west of cape saint vincent portugal set a distance and speed record as it translated another 1700 km southwestward at 3 9 cm s during 1 5 years this meddy traveled 57 of the distance from cape saint vincent toward the spot mcdowell and rossby 1978 found a possible meddy north of the dominican republic two meddies were observed to interact with the azores current as they passed underneath or through it three meddies collided with tall seamounts which seemed to disrupt the normal swirl velocity perhaps fatally in two cases one meddy appeared to bifurcate when it collided with seamounts