holocene palaeoclimates from peat stratigraphy macrofossil proxy climate records from three oceanic raised bogs in england and ireland quantified analyses of plant macrofossil remains have been made from three profiles of peat from raised bogs spanning a distance of 425 km from western ireland to northern england the reconstructed vegetation of each profile is related to changing bog surface wetness bsw and since the bogs are ombrotrophic these bsw changes are interpreted in terms of changing climate using age depth models based on a total of 49 radiocarbon dates a number of wetter and drier phases are identified and phase shifts to wetter and or cooler climates are defined prominent coincident changes to wetter conditions are dated in at least two of the profiles to ca 4400 4000 1750 1400 and 1000 cal bp and in all three profiles at 3200 2750 2350 2250 and around 700 cal bp these phases are related to proxy climate changes in other terrestrial data sets from northwest europe and a broad degree of synchroneity is demonstrated

compilation of non annually resolved holocene proxy climate records stacked holocene peatland palaeo water table reconstructions from northern britain abstract the number and range of holocene palaeoclimate reconstructions from various regions of the world have increased dramatically over the last decade the data density for many regions and proxies now offers the potential of robust regional scale reconstructions that avoid the problems of records from individual sites and improve communication between palaeoclimate subdisciplines and climate modellers however there are problems with chronological uncertainties and quantification of proxies which make compilation of multiple records difficult here we explore a stacking and tuning approach to the derivation of regional records from peatland climate proxies to test its applicability to non annually resolved terrestrial records twelve individual records from northern britain based on water table reconstructions from testate amoebae analysis were divided into four regions records were detrended normalised and compared within regions to identify clear correlative events the original chronologies of the records were tuned using both these events and independent age markers the stacked record for northern britain indicates pronounced changes to wet conditions at 3600 2760 and 1600 cal yr bp with more minor changes at 3060 2050 1260 860 550 and 260 cal yr bp the main wet phases are highly correlated with mid european lake highstands wider north atlantic climate change inferred from ocean and ice core records and solar variability tuning and stacking of non annual terrestrial palaeoclimate records is a new approach to the compilation and reconciliation of individual records within coherent climatic regions and provides a tool for upscaling of palaeoclimate records for climate model data comparisons

forest fires and insects palaeoentomological research from a subfossil burnt forest the role of fire within pinus mire ecosystems is explored by focusing on a palaeoentomological investigation of the extensive burnt fossil forest preserved within the basal deposits of the raised mires of thorne and hatfield moors humberhead levels eastern england remains of charred tree macrofossils roots stumps and trunks are widely distributed across both sites mainly comprising pinus and betula evidence from this research and elsewhere suggests fires were a common event on pinus mires and may indicate that such episodes played an important role in the development of raised bogs a fire loving pyrophilous insect fauna appears to have been attracted to the burnt areas and the decline and extirpation in britain of a number of pyrophilous species e g stagetus borealis isrealsson suggests the former importance of this type of habitat within british pinus mire systems the lack of consideration given to the role of natural fires within the british landscape is questioned and the interpretation of charcoal within mire deposits as a possible anthropogenic indicator is highlighted as an area that would benefit from some reconsideration

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

imaging of ocean waves by synthetic aperture radar a comparison of results from seasat and sir b experiments in the north atlantic new analyses of wave spectra extracted from seasat sar images of the jasin site in the northeast atlantic are presented as tests of wave imaging theory spectra extracted from orbit 757 during a high sea state are dominated by the effects of smearing but the rms image smear is less than half that expected from in situ measurements of surface motions in a low sea state on orbit 547 fair agreement can be achieved between sar and buoy spectra but this requires that the smearing length be greater than was observed on orbit 757 these findings are compared with results obtained from the shuttle imaging radar sir b mission in order to assess the quantitative understanding of wave imaging by sar

identifying changing fluvial conditions in low gradient alluvial archaeological landscapes can coleoptera provide insights into changing discharge rates and floodplain evolution using examples from dated alluvial deposits in the trent basin uk this paper suggests that the waterlogged remains of insects mainly beetles can be used to detect the occurrence of varying discharge and changing patterns of flood plain evolution in low gradient alluvial landscapes of holocene age this approach may provide invaluable data where the finer grained nature of sedimentation means that other types of information such as coarse boulder berms are lacking comparison of coleoptera assemblages from three high energy and two lower energy deposits indicates that a number of distinctive characteristics can be identified and criteria can be set for the distinction of these two contrasting depositional environments this approach is tested using coleoptera remains recovered from a palaeochannel fill at spalford meadows in the lower trent valley the application of this methodology could contribute to the reconstruction of river histories a key factor in understanding the distribution of valley floor archaeological settlement patterns

improved age modelling approaches as exemplified by the revised chronology for the central european varved lake soppensee abstract one of the key factors in understanding past climate change is the development of robust age models that have sufficient chronological precision for comparing different palaeoclimate archives while retaining accuracy recent developments in bayesian age modelling are applied here to the swiss varve lake soppensee we develop revised age models for this sequence using the available stratigraphic information to constrain the calibrated radiocarbon ages we begin by using stratigraphical order as the only constraint and then sequentially increase the information incorporated into the model using relative varve age sample depth and varying depositional models within this bayesian framework we develop internally robust models that significantly improve the dating precision and are applicable to both varved and non varved sequences we then compare the model output to wider chronological information such as the age of the laacher see tephra in order to test the model accuracy the results of this exercise suggest that these methods can be used to build very reliable improved age models in a variety of records

a deglacial middle holocene record of biogenic sedimentation and paleoproductivity changes from the northern norwegian continental shelf 1 the relative proportions of marine organic carbon and biogenic carbonate in a high resolution record from a glacial trough on the northern norwegian continental shelf were used to decipher changes in biogenic sedimentation and paleoproductivity from the last deglaciation to the middle holocene decadal scale to century scale oscillations in biogenic sedimentation and surface ocean productivity recorded in the andfjorden sediments are synchronous with abrupt climate changes in open oceanic and atmospheric regimes of the high northern latitudes following several fluctuations during the bolling allerod interstadial the most dramatic drop in marine organic carbon and biogenic carbonate proportions occurred during the younger dryas however many short term and low amplitude events during the preboreal and the holocene have also affected biogenic sedimentation in the outer andfjorden apparently these abrupt changes in biogenic sedimentation were caused by the suppression of a potential upwelling center in the outer andfjorden by variable atlantic water inflow over the past 14 000 years the adjustment of decadal high productivity coastal systems to freshwater forced multiple cooling events during the late glacial to middle holocene highlights the impact of global climate changes on the climate sensitive local ecosystems off coastal norway

consistently large marine reservoir ages in the norwegian sea during the last deglaciation with the exception of the gs 1 younger dryas coldperiodmarine reservoir ages for the last deglaciation in the north atlantic norwegian sea are generally assumed to have been around 400 500 radiocarbon years in magnitude earth planet sci lett 126 1994 275 radiocarbon 37 1995 53 quat res 52 1999 104 nature 412 2001 724 by comparing the climate records obtained from the grip ice core nature 359 1992 311 j quat sci 13 4 1998 283 andfrom north atlantic norwegian sea cores quat res 52 1999 104 geology 23 12 1995 1059 nature 356 1991 757 nature 356 1992 757 paleoceanography 3 1 1988 1 nature 343 1990 612 earth planet sci lett 126 1994 275 with radiocarbon dated european continental records we show that marine reservoir ages in the norwegian sea were of the order of 1000 14 c yr including large uncertainties this approach rests on the reasonable assumption that climate changes throughout the ne atlantic andeurope were more or less synchronous at the centennial scale fairly large variations in reservoir ages over time may have been causedby changing atmospheric 14 c content the results indicate that detailed land sea correlations for the north atlantic during the last deglaciation are not feasible using radiocarbon dating alone r 2003 elsevier science ltd all rights reserved

models for synthetic aperture radar imaging of the ocean a comparison theoretical comparisons are made of different models for synthetic aperture radar sar imaging of ocean waves the velocity bunching model distributed surface model lyzenga model canadian center for remote sensing radarsat ccrs radarsat model and the ocean research and engineering ore model are compared analytically with respect to their description of the sar imaging process and the radar backscatter process the study concentrates on the temporal description of the backscatter process and its impact on sar imaging of the ocean sample simulations are conducted so as to quantify some of the similarities and differences of the aforementioned models other sar imaging models are discussed as they pertain to the comparisons noted above the analytical and numerical simulations show that the lyzenga model the ccrs radarsat model and the ore model are similar for most commonly occurring sea states the velocity bunching model is similar to these models when the sar integration time is small but it tends to deviate for long integration times the distributed surface model is shown to describe the imaging process adequately when the radar backscatter is highly correlated in space and time

paludification and pollen representation the influence of wetland size on tilia representation in pollen diagrams the representation of taxa with poorly dispersed pollen grains in pollen diagrams is strongly influenced by basin size waterlogging and peat formation paludification can by leading to an expans

correlating archaeological and palaeoenvironmental records using a bayesian approach a case study from sutton common south yorkshire england this paper presents a case study aimed at correlating archaeological events obtained from radiocarbon measurements and dendrochronology from the site of sutton common with a radiocarbon dated pollen sequence obtained from a palaeochannel deposit adjacent to the area of the main archaeological activity it demonstrates the use of a bayesian approach to quantifying whether the timing of palynological events interpreted as reflecting anthropogenic impacts are likely to be associated with archaeological events the results suggest that bronze age activity in the form of a mortuary enclosure and associated cremation burials are probably not contemporary with the palynological evidence for disturbance to the oak hazel woodland in this period subsequent evidence for local woodland clearance and agriculture is estimated to precede the construction of the large iron age enclosure in 372 bc with increases in anthropogenic indicators following this event the construction of the site does not appear to have had a pronounced impact on the local vegetation with hazel the only woody taxon to show clear reductions despite the use of a substantial number of oak timbers in the enclosure palisade percentages of oak remain remarkably stable later farming activity on the site probably post dates the end of activity in the enclosures the value of the methodology is discussed in relation to quantifiable and robust correlations of archaeological and palaeoenvironmental narratives of landscape and human activity

a comparison of sir b directional ocean wave spectra with aircraft scanning radar spectra directional ocean wave spectra derived from shuttle imaging radar b sir b l band imagery collected off the coast of southern chile on 11 and 12 october 1984 were compared with independent spectral estimates from two airborne scanning radars in sea states with significant wave heights ranging from 3 to 5 meters the sir b derived spectra at 18 and 25 off nadir yielded reasonable estimates of wavelengths directions and spectral shapes for all wave systems encountered including a purely azimuth traveling system a sir b image intensity variance spectrum containing predominantly range traveling waves closely resembles an independent aircraft estimate of the slope variance spectrum the prediction of a u s navy global spectral ocean wave model on 11 october 1984 exhibited no significant bias in dominant wave number but contained a directional bias of about 30 espect to the mean of the aircraft and spacecraft estimates

centennial climate variability in the british isles during the mid late holocene abstract multi millennial climate changes were relatively minor over the mid late holocene in the british isles because orbitally forced insolation changes were smaller than those at higher latitudes centennial climate variability is thus likely to have exerted a greater influence on the environment and human society of the region proxy climate records from the british isles covering the last 4500 years are assembled and re evaluated with the aim of identifying centennial climate variability reflected by multi proxy indicators the proxies include bog oak populations peatland surface wetness flooding episodes from fluvial deposits speleothem annual band width and oxygen isotopes chironomids from lake sediments and sand and dune deposition most proxies reflect water balance rather than temperature alone and records predominantly reflect warm season climate a series of 12 key periods of enhanced precipitation evaporation p e are identified by their presence in two or more proxy records variability in p e is much greater than that shown by temperature proxies and there is no necessary association between warm cool and dry wet periods although the data for temperature are less robust than those for p e a series of key temperature changes are proposed based on speleothem 18o and chironomid inferred july temperature records relatively cool before c 3100 years bp warmer 3100 2000 years bp cool 2000 1250 cal years bp warm 1250 650 cal years bp and cool 650 cal years bp onwards some key increases in p e 2750 1650 550 cal years bp show a strong correspondence with bond cycles in ocean proxy records for increased ice rafted debris decreased summer sea surface temperatures and sometimes decreased north atlantic deep water circulation other higher frequency changes in p e are also strongly related to sst variability whilst some of the main changes to cooler ssts and increased p e are approximately coincident with reduced solar output most are not and thus must be the result of the internal dynamics of the ocean and atmosphere future work should concentrate on firmly establishing the pattern of temperature change improving chronological accuracy and precision in existing records and improving process based understanding of proxies

ocean wave imaging by synthetic aperture radar results from the sir b experiment in the n e atlantic waveheight spectra were extracted from synthetic aperture radar sar images close to a number of wave measuring buoys and the results of radar and in situ measurements were compared as a test of wave imaging theory sar and buoy spectra of waves traveling close to the radar range direction were in good quantitative agreement with any discrepancies probably attributable to the processing technique however sar estimates of the amplitude of azimuth traveling waves were very much lower than buoy derived values this cannot be accounted for by appealing to nonlinear imaging by the velocity bunching mechanism or by velocity smearing calculating the scene coherence time from the available buoy data rather the scene coherent time must be reduced by a factor of about two to within the range 0 022 0 027 s this result highlights a lack of knowledge of scatterer motions and lifetimes on the sea surface

a deterministic sea clutter space time model based on physical sea surface in the conventional space time signal model the statistical amplitude of the clutter is assumed to be a specific distribution for sea clutter a pulse to pulse correlation matrix is added to the temporal covariance matrix to describe the motion of the sea surface however such sea clutter model cannot reflect the property of the sea clutter in this paper a space time model for the sea clutter is presented based on the physical sea surface model in which the clutter amplitude is deterministic instead of statistic the reflectivity and the radial velocity of the sea clutter for any specific position and time are computed based on the physical sea surface both the aforementioned two factors vary with time which corresponds to the time variation of the sea surface moreover the spatial channel decorrelation is modeled which has an effect on the spatial covariance matrix of the sea clutter the simulated angle doppler spectra and the signal to clutter plus noise ratio loss show that the reflectivity of the sea clutter makes the space time adaptive processing performance degrade and the radial velocity of the sea clutter results in a more significant spread of the clutter power spectrum in sea state 4 than sea state 2 the doppler spectrum can be acquired by the space time model proposed in this paper instead of the experimental doppler model for sea clutter for a given sea state the low range resolution has a more prominent effect on the power spectrum because of severer spatial channel decorrelation

river response to rapid holocene environmental change evidence and explanation in british catchments macklin m g jones a f lewin j 2010 river response to rapid holocene environmental change evidence and explanation in british catchments quaternary science reviews 29 13 14 1555 1576 sponsorship welsh assembly government and the higher education funding council for wales for funding this study through its support of the centre for catchment and coastal research at aberystwyth university

estimating wave orbital velocity through the azimuth cutoff from space borne satellites it has been long accepted that ocean wave conditions recorded from synthetic aperture radar sar aboard satellites resolve large scale swells sars make use of its displacement to achieve fine resolution however the random surface motions can reduce its nominal azimuthal resolution accordingly the sar spectral azimuth response mirrors the probability distribution of the radial velocity component of the scatters this effect quantified in a measure called the azimuth cutoff is estimated by defining a scale based on the fitting of a gaussian function to the radar cross section azimuth spectrum the independent measure provides additional sea state information related to the root mean square surface orbital wave velocity we use data recorded from the european space agency s envisat advanced sar in the c band spanning its lifetime 2003 2012 our purpose is to first establish the validity of the azimuth cutoff using both colocated buoys and modeled wave data some systematic biases are corrected using other sar derived parameters improving the accuracy of the estimate despite our efforts errors exist in the presence of swell extreme wind waves and related to the wave direction under the majority of the sea states the parameter is well behaved as a final point applications using the wave orbital velocities are described in terms of diagnosing a spectral wave model and the wave climate as illustrated the returned radar signal provides useful sea state information that resolves wind speeds wave orbital velocities from the wind waves and swells

mire development pathways and palaeoclimatic records from a full holocene peat archive at walton moss cumbria england plant macrofossil data have been used to identify the successive mire communities occupying both central and marginal locations in the walton moss peatland complex during the last 10 500 years the reconstructed pathways of mire development indicate that early holocene fen and fen carr communities were succeeded by species indicative of deep mire water tables and oligotrophic conditions the character of the fen bog transition fbt is compared with similar records of peatland development from britain and scandinavia and with independent climate data for the early holocene the pseudohochmoor of central europe is suggested as an approximate modern analogue for the dry pioneer oligotrophic mire type and alternative explanations for its presence are explored the first major increase in ombrotrophic sphagna occurred at c 7800 cal bp overlying sphagnum peats provide a continuous record of climate change inferred from fluctuations in raised mire surface wetness the proxy palaeoclimate record reconstr

focusing of synthetic aperture radar ocean images with long integration times synthetic aperture radar sar images obtained in the sar and x band ocean nonlinearities chesapeake light tower saxon clt experiment are processed with long integration times 6 s and analyzed to study the effects of focusing two images with near azimuth traveling waves were chosen for the study the first image consists of relatively short wavelength wind waves traveling in the same general direction as the aircraft the second image consists of a long atlantic swell traveling in the opposite direction to the aircraft at these long integration times the image spectral intensities are found to be sensitive to the focus setting the spectral intensity at the optimum focus is 400 of that at zero focus for the first image and 167 for the second image the focusing curves for both images agree well with those predicted by a model developed by several groups and referred to here as the consensus model this model predicts an optimum focus setting that is equal to one half of the effective phase speed of the dominant wave in the azimuth direction the velocity bunching model underpredicts the optimum focus setting significantly the study concludes that in long integration time sar processing of surface waves such as the spotlight mode the image contrast is sensitively dependent on the focus setting and that the optimum focus setting is given by one half of the effective phase speed of the dominant surface wave

azimuth smearing in synthetic aperture radar ocean image spectra from the norwegian continental shelf experiment of 1988 along track resolution loss in synthetic aperture radar ocean images is investigated using airborne c band data collected at different altitudes a method is developed for qualifying and quantifying the amount of smearing the smearing can be described as a low pass filtering process acting on the image spectra even in a nonlinear region of imaging the dependency on the ratio of range to platform velocity and the radar incidence angle is presented an intrinsic value for the subresolution velocity spread i e the rms facet velocity is estimated to be in the region u 0 59 0 73 m s for the measurements available on march 11 1988 with significant wave height 4 m and wind speed 8 m s these values for u allow a conversion of the smearing to ers 1 geometry giving a spatial smearing x in the range 68 84 m which corresponds to a resolution varying between 300 and 370 m in the along track direction

the last 18 kyr fluctuations in norwegian sea surface conditions and implications for the magnitude of climatic change evidence from the north sea a combined record of three cores spanning the last 18 kyr from the northern north sea is investigated for content of benthic and planktonic foraminifera and stable oxygen isotopes the paleoenvironmental development through this time period shows an early deglaciation 18 14 4 ka and the younger dryas 12 7 11 5 ka characterized by arctic polar conditions and increased ice rafting in the norwegian channel during the bolling allerod period warm sea surface temperature 9 c conditions similar to present conditions are inferred while bottom waters stayed cold 0 1 c with normal salinity the bolling allerod period is interrupted twice at 13 9 13 6 ka older dryas and at 13 0 12 8 ka inter allerod cooling period by reductions in sea surface temperatures and increased sea ice cover the beginning of the holocene period is marked by increases in surface and bottom water temperature superimposed on the broad climatic changes through the holocene a series of short lived oscillations in the ocean circulation are recorded the amplitude of these holocene events appears larger in the early holocene prior to 8 ka than compared with the remaining part of the holocene this amplification can possibly be attributed to a general increased freshwater budget in the north atlantic at this time during the final stages of the deglaciation of the laurentide and scandinavian ice sheets

wind wave directions determined from synthetic aperture radar imagery and from a tower in lake michigan directional wave spectra calculated from digitized synthetic aperture radar sar images of waves on lake michigan are compared to a wave directional spectrum determined from measurements taken at a tower and to a one dimensional spectrum determined from a waverider buoy the comparison is within one frequency band for peak energy frequency and within 20 for direction but the sar image intensity spectrum does not have the same shape as a wave height spectrum wave refraction directions observed in the sar spectra are within 10 of classical wave refraction calculations

holocene sea level change and coastal evolution in the humber estuary eastern england an assessment of rapid coastal change new stratigraphic data collected from six sites in the humber estuary establish a record of holocene relative sea level rsl change and enable testing of four possible causes of rapid coastal change sea level rise changes in sedimentation storm surge history and human impact mean high water of spring tides mhwst in the humber rose from c 9 m od at 7500 cal yrs bp to 0 m od by 4000 cal yrs bp at an average long term rate of c 3 9 mm yr 1 after this the rate of rise gradually decreased to c 1 mm yr discrete episodes of rapid rsl rise are not identified although their absence may reflect limited data availability however we do observe two episodes of rapid coastal change in the humber estuary the first occurs between c 3200 and 1900 cal yrs bp as marine conditions expand to their holocene maximum and then contract this pattern of coastal development differs from that in the east anglian fenlands suggesting local processes control sedimentation at one or both of these sites the sec

a simulation for spaceborne sar imagery of a distributed moving scene a computer simulation that is designed to represent aspects of spaceborn synthetic aperture radar sar imagery of the ocean surface is presented the simulation is unique in that a scatterer density per resolution cell is explicitly included thus allowing the incorporation of various scattering natures from purely specular to purely diffuse the simulation may be applied to ocean surface wave imaging since velocity bunching and scene coherence times are also included certain assumptions inherent in the velocity bunching formulation limit the applicability of the simulation in its present form to spaceborn sar systems only two experiments based on this simulation are considered 1 the effect of varying the target density and 2 the effect of the mean scene coherence time in the imaging of a ocean swell system

holocene environmental change in the yorkshire ouse basin and its influence on river dynamics and sediment fluxes to the coastal zone geomorphological geochemical and geochronological investigations of holocene fluvial sedimentary sequences have been undertaken within a range of upland piedmont and lowland valley floor reaches in the yorkshire ouse catchment northern england the aims of these studies have been to a evaluate the effects of prehistoric and historic land use change on catchment erosion and sediment delivery to river channels and floodplains b establish the degree to which episodes of river erosion and sedimentation are controlled by climate related variations in flood regime and c assess the spatial heterogeneity of river response to environmental change and how this is likely to influence short and long term sediment storage as well as sediment transfer to the humber estuary similar discontinuities in the holocene alluvial record are evident at many sites in the yorkshire ouse catchment though local differences in river sensitivity to externally imposed change have resulted in a complicated and often unique relationship between river behaviour and environmental change the large proportion of particulate borne contaminant metals resulting predominantly from historical mining stored in the vale of york strongly indicates that sediment delivery from the ouse catchment to the humber estuary during the holocene may have been relatively low this suggests that the degree of connectivity between river estuarine and coastal transport systems as well as spatial and temporal variations in fluvial sediment storage are the key controls of long term land ocean sediment fluxes

can we characterise openness in the holocene palaeoenvironmental record modern analogue studies of insect faunas and pollen spectra from dunham massey deer park and epping forest england this paper examines the degree to which tree associated coleoptera beetles and pollen could be used to predict the degree of openness in woodland the results from two modern insect and pollen analogue studies from ponds at dunham massey cheshire and epping forest greater london are presented we explore the reliability of modern pollen rain and sub fossil beetle assemblages to represent varying degrees of canopy cover for up to 1000 m from a sampling site modern woodland canopy structure around the study sites has been assessed using gis based mapping at increasing radial distances as an independent check on the modern insect and pollen data sets these preliminary results suggest that it is possible to use tree associated coleoptera to assess the degree of local vegetation openness in addition it appears that insect remains may indicate the relative intensity of land use by grazing animals our results also suggest most insects are collected from within a 100 200 m radius of the sampling site

distribution of planktic foraminifera at the ice margin in the arctic fram strait planktic foraminifera were collected in net tows 63 m along two east west transects at 78 and 80 n in the fram strait northern nordic seas at five concurrent depth intervals in the upper 200 m of the water column in the ice free zone absolute abundances in the upper 200 m of the water column up to 500 individuals m3 were obtained along the ice margin the absolute abundances reached up to 1250 ind m3 while in the ice covered areas not more than 50 ind m3 have been found surprisingly these strong variations in abundance are not accompanied by significant changes in faunal assemblages between the ice free and the ice covered regions neogloboquadrina pachyderma is the dominant species in most samples making up to 60 of the total faunal assemblage globigerina quinqueloba contributes 38 and all other species combined make up only 2 of the total fauna both absolute and relative abundances of the collected foraminifera are strongly dependent on the mesh size used using smaller mesh sizes provides a wider species spectrum which is of special interest for paleoceanographic reconstructions in the nordic seas where fossil assemblages 150 m often consist of only one species the specific hydrographic conditions in the fram strait with warm atlantic waters underlying cold polar surface waters result in a rather atypical depth distribution of the planktic foraminifera all species seem to prefer the temperate atlantic waters between 50 m and 200 m thus the species composition as well as geochemical tracers do not reflect the surface ocean conditions which again has potentially interesting implications for paleoceanographic reconstructions

the preboreal oscillation around the nordic seas terrestrial and lacustrine responses the occurrence of an early preboreal climatic cooling oscillation pbo in lacustrine and glacial records from northwest europe iceland and greenland is reviewed and documented the often subtle response of the proxy records to this oscillation in combination with its short duration make it difficult to detect owing to its chronostratigraphic position between the 10 000 9900 and 9600 9500 14 c plateaux c 11 300 11 150 calendar yr bp it is also difficult to 14 c date with precision we find that the vegetation response to the pbo varies between sites and regions in contrast to the pioneer vegetation in iceland and southern sweden the expanding birch pine forest in germany denmark was more susceptible to deteriorating growing conditions the combined lacustrine tree ring and glacial records imply that the pbo was characterised by cool and humid conditions throughout northwestern and central europe this is documented by vegetation changes decreased aquatic production increased soil erosion increased 2 h and 13 c content in tree rings readvances or stillstands of the ice sheet in norway and finland and ingression of brackish water into the baltic icelandic proxy records from lake sediments and glacial moraines imply cooler conditions than during the previous preboreal period but not as extreme as during the younger dryas greenland records suggest that the early preboreal was characterised by ice readvances as an effect of cool climate and increased precipitation in relation to the younger dryas it was not until the end of the pbo that climate was warm enough to melt the land based ice sheet this preboreal oscillation found on both sides of the nordic seas is interpreted as an effect of increased freshwater forcing on the thermohaline circulation in the nordic seas which is implied by a simultaneous and distinct rise in the atmospheric 14 c 12 c ratio a slow down of the thermohaline circulation may tempor arily have pushed the polar front further south 1997 by john wiley sons ltd preboreal oscillation thermohaline circulation lacustrine records glacial records chronology

aircraft and satellite measurement of ocean wave directional spectra using scanning beam microwave radars a microwave radar technique for remotely measuring the vector wave number spectrum of the ocean surface is described the technique which employs short pulse noncoherent radars in a conical scan mode near vertical incidence is shown to be suitable for both aircraft and satellite application the technique has been validated at 10 km aircraft altitude where we have found excellent agreement between buoy and radar inferred absolute wave height spectra

paleoceanographic development in the sw barents sea during the late weichselian early holocene transition abstract the late weichselian early holocene variability of the north atlantic current has been studied with focus on the zonal component of this meridional transport during the transition from glacial to interglacial conditions the investigated sediment core is from 409 m water depth in the sw barents sea eight accelerator mass spectrometry ams 14c dates show that the core covers the last 20 000 cal yr b p with a centennial scale resolution during late weichselian early holocene planktic foraminiferal assemblages were analyzed using the 100 m size fraction and foraminiferal planktic and benthic 13c and 18o isotopes were measured furthermore a range of physical and chemical analyses has been carried out on the bulk sediment samples four time periods have been identified which represent the varying oceanographic conditions in ingoydjupet a glacial trough located off the north coast of norway in the sw barents sea 1 the late glacial before ca 15 000 cal yr b p influenced by the nearby ice sheets with high amounts of sea ice or iceberg transported detritus 2 the late oldest dryas stadial and the bolling allerod interstadial ca 15 000 12 700 cal yr b p with cold surface water conditions influenced by the collapse of the nearby ice sheets high amounts of sea ice or iceberg transported detritus and melt water and weak subsurface inflow of atlantic water 3 the younger dryas cold stadial 12 700 11 650 cal yr b p with low primary productivity and extensive sea ice cover and 4 the preboreal and early holocene 11 650 6800 cal yr b p cal yr b p with strong influx of atlantic water into the area near absence of ice rafted debris and generally ameliorated conditions in both surface and bottom water masses as seen from a high flux of foraminifera and increased marine primary production

real time observations of southern ocean wave fields from the shuttle imaging radar during the april and october 1994 flights of the space shuttle endeavour c band synthetic aperture radar sar signal was acquired and processed in real time into ocean wave images and two dimensional image spectra by an on board processor the image spectra were transmitted to the ground as they were acquired during 20 days of observations spanning the two missions over 100000 spectra were collected these data provide the first truly synoptic directional measurements of the southern ocean wave field with additional processing estimates of ocean wavelength and propagation direction were extracted from the spectra during the october mission daily comparisons of these estimates with wave model predictions were made available at a world wide web site the authors describe the computations performed by the processor and the real time data flow and ground processing in addition they summarize and interpret some gross characteristics of the processor observed real time wave field from the april and october missions

a sensitive high resolution record of late holocene climatic change from a raised bog in northern england proxy climatic data in the form of plant macrofossils have been analysed from a 5 m core from bolton fell moss cumbria uk detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years the record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog surface wetness for the latter half of the holocene as bog surface wetness is directly controlled by the prevailing climatic conditions this reconstruction can be viewed as a proxy climate record twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12 4 yr cm 1 the regular sampling intervals thus provide a time series of past bog surface wetness spectral analyses of this series indicates that wetness changes are cyclic with a ca 800 year periodicity

late holocene paleoecology and sedimentary history of a small lowland catchment in central england a variety of paleoecological and sedimentary techniques were used to investigate the storage of sediment within a small lowland catchment during the holocene radiocarbon dating of vertically accreted floodplain deposits allowed the calculation of inorganic accumulation rates these rates show a dramatic increase in sediment deposition during the late bronze age and early iron age 2900 2300 yr b p due to deforestation and cultivation of the catchment slopes and resultant soil erosion the soils within the catchment were susceptible to structural damage surface waterlogging and slope wash erosion from the calculated increases in sediment storage estimates of catchment erosion were made which vary from around 20 to 140 tons km 2 yr 1 the study of alluvial chronology at this scale can provide unique information on the source areas of holocene floodplain sediments and provide long term erosion rates

comparison of shuttle imaging radar b ocean wave image spectra with linear model predictions based on aircraft measurements during october 1984 coincident shuttle imaging radar b synthetic aperture radar sar imagery and wave measurements from airborne instrumentation were acquired the two dimensional wave spectrum was measured by both a radar ocean wave spectrometer and a surface contour radar aboard the aircraft in this paper we compare two dimensional sar image intensity variance spectra with these independent measures of ocean wave spectra to verify previously proposed models of the relationship between such sar image spectra and ocean wave spectra the results illustrate both the functional relationship between sar image spectra and ocean wave spectra and the limitations imposed on the imaging of short wavelength azimuth traveling waves

archaeological and environmental investigations of a lateglacial and holocene river sedimentary sequence on the river soar at croft leicestershire uk the sediments stratigraphy and archaeology of several sections through lateglacial and holocene deposits associated with the past course of the thurlston brook at croft leicestershire uk are outlined the results of pollen plant macrofossil and insect analyses from these deposits are presented and this information is used to provide a detailed reconstruction of changing river conditions and human land use at this location during the holocene despite the presence of hiatuses in the record seen at croft and other sites of this scale with accurate work and clear dating controls it is possible to stitch together continuous detailed sequences the general pattern of holocene landscape and fluvial change appears to echo that seen in the trent valley region and nationally it is suggested that small headwater catchments such as at croft have the potential to provide detailed and sensitive records of holocene events comparable with those from standard sediment sequences

on the estimation of wave slope and height varnance spectra from sar imagery a procedure is described for using synthetic aperture radar sar imagery to estimate two dimensional ocean wave slope and height variance spectra the logic underpinning the procedure is based both on the results of the numerical simulation of sar wave imagery and analytic descriptions of the sar imaging process the procedure when applied to sar imagery of waves acquired during the recent shuttle imaging radar mission sir b is shown to produce spectra that agree with independent measures of both the two dimensional slope and height variance spectra the implications of these results for future sar missions aimed at measuring ocean waves are considered

slicks waves and fronts observed in a sea coastal area by an x band airborne synthetic aperture radar abstract this article reports observations made in a sea coastal zone by an airborne x band sar this zone includes a basin connected to the sea and the vicinity of the rhone river estuary we present the experiment and the data processing procedures including in particular a method for removing speckle effects from image spectra of waves observations of slick patterns in the basin are reported and used to relate their spatial distribution to features of the circulation as predicted by modelling then we present the wave phenomena observed at sea off shore the observations are found to be consistent with actual wind conditions differences in wave visibility between the images are discussed using the ocean wave sar imaging theory the significant wave height is calculated from the image presenting the best geometry for wave detection along the coast the wave transformations observed are discussed on the basis of the results of a simple wave model initialized by the main wave parameters measured off shore the complicated refraction effects predicted by the model can only be partially detected on the radar images because of the geometry of the observations finally a frontal event is detected and interpreted as the signature of the boundary of the river plume the wave current model of skop and leipold 1988 explains the brightness of the radar signature of the front among other results the conclusion emphasizes the good adequation of airborne sar systems for remote sensing of the coastal environment

theory of synthetic aperture radar ocean imaging a marsen view this paper reviews basic synthetic aperture radar sar theory of ocean wave imaging mechanisms using both known work and recent experimental and theoretical results from the marine remote sensing marsen experiment several viewpoints that have contributed to the field are drawn together in a general analysis of the backscatter statistics of a moving sea surface a common focus for different scattering models is provided by the mean image impulse response function which is shown to be identical to the spatially varying frequency variance spectrum of the local complex reflectivity coefficient from the analysis has emerged a more complete view of the sar imaging phenomenon than has been previously available a new generalized imaging model is proposed

changes in the flow of atlantic water into the arctic ocean since the last deglaciation evidence from the northern svalbard continental margin 80 n 1 the svalbard archipelago is located in the high arctic 76 80 n within the northernmost reach of the west spitsbergen current which is the continuation of the north atlantic current in this specific setting close to the polar front even small variations in the current system are expected to give large and distinct signals in paleoceanographic parameters thus the svalbard area is ideal for monitoring the past history of the inflow of atlantic water to the arctic ocean we have studied sediment core np94 51 taken outside the mouth of the hinlopen strait on the northern svalbard shelf the paleoceanographic development of the last deglaciation and the holocene has been reconstructed using benthic and planktonic foraminifera oxygen isotopes and ice rafted detritus the results show that the first strong subsurface inflow of atlantic water to the arctic ocean after the last glacial maximum commenced at 12 6 14c kyr b p circa 15 000 calendar cal years b p during the bolling allerod interstadial during the younger dryas polar conditions prevailed at the surface with extensive sea ice cover and the inflow of atlantic derived water was generally diminished the inflow of more saline but still cold atlantic water was relatively strong during the early holocene and caused intensified seasonal biological productivity the atlantic water inflow declined gradually during the mid holocene between 4500 and 1100 cal years b p the inflow was very weak and the bottom waters over the northern svalbard margin were cold and of lower salinity during the last 1000 years climatic conditions improved such that the subsurface inflow of atlantic derived water increased however the surface waters were still cold

evidence from the high latitude north atlantic for variations in antarctic intermediate water flow during the last deglaciation we present evidence that the characteristic chemical signature based on coupled benthic foraminiferal cd ca and d13c of antarctic intermediate waters aaiw penetrated throughout the intermediate depths of the atlantic basin to the high latitude north atlantic during the abrupt cooling events of the last deglaciation heinrich 1 and the younger dryas aaiw may play the dynamic counterpart to the bipolar seesaw when near freezing salty bottom waters from the antarctic aabw sluggishly ventilate the deep ocean our data reinforce the concept that interglacial circulation is stabilized by salinity feedbacks between salty northern sourced deep waters nadw and fresh southern sourced waters aabw and aaiw further the glacial ocean may be susceptible to the more finely balanced relative densities of nadw and aaiw due to either freshwater input or a reversal of the salinity gradient such that the ocean is poised for nadw collapse via a negative salinity feedback the unstable climate of the glacial period and its termination may arise from the closer competition for ubiquity at intermediate depths between northern and southern sourced intermediate waters

fluvial responses to climate and sea level change a review and look forward summary fluvial landforms and deposits provide one of the most readily studied quaternary continental records and alluvial strata represent an important component in most ancient continental interior and continental margin successions moreover studies of the long term dynamics of fluvial systems and their responses to external or allogenic controls can play important roles in research concerning both global change and sequence stratigraphy as well as in studies of the dynamic interactions between tectonic activity and surface processes these themes were energized in the final decades of the twentieth century and may become increasingly important in the first decades of this millennium this review paper provides a historical perspective on the development of ideas in the fields of geomorphology quaternary geology vs sedimentary geology and then summarizes key processes that operate to produce alluvial stratigraphic records over time scales of 103 106 years of particular interest are changes in discharge regimes sediment supply and sediment storage en route from source terrains to sedimentary basins as well as changes in sea level and the concept of accommodation late quaternary stratigraphic records from the loire france mississippi usa colorado texas usa and rhine meuse the netherlands rivers are used to illustrate the influences of climate change on continental interior rivers as well as the influence of interacting climate and sea level change on continental margin systems the paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea level change at present empirical field based research on fluvial response to climate and sea level change lags behind a the global change community s understanding of the magnitude and frequency of climate and sea level change b the sequence stratigraphic community s desire to interpret climate and especially sea level change as forcing mechanisms and c the modelling community s ability to generate numerical and physical models of surface processes and their stratigraphic results a major challenge for the future is to catch up which will require the development of more detailed and sophisticated quaternary stratigraphic sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings there is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter 102 103 years and longer 104 106 years time scales than has commonly been the case to date as well as in larger river systems from source to sink studies of quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre quaternary rock record

advection of atlantic water to the western and northern svalbard shelf since 17 500 cal yr bp abstract the changes in flow and character of the warm atlantic water through the last 17 500 cal yr are reconstructed from the distribution of benthic foraminifera species planktonic and benthic foraminifera abundances stable oxygen isotopes and lithology in two cores from the western and northern shelf of svalbard the results show almost continuous presence of atlantic water at the shelf areas since 14 500 cal yr bp the bolling and allerod intervals stand out as periods of highest bottom waters temperatures the strong inflow of saline but chilled atlantic water during the early holocene was followed by cooling and freshening of the bottom waters during the mid and late holocene the two records reveal synchronous oceanographic changes that are closely tied to changes in the flow of atlantic water recorded further south in the nordic seas the early holocene warming was not just an effect of higher solar insolation but was also due to increased heat flux from the stronger atlantic water inflow driven by wind force and or thermohaline circulation

comparison of aircraft synthetic aperture radar and buoy spectra during the norwegian continental shelf experiment of 1988 aircraft synthetic aperture radar sar measurements from seven flight paths at two different altitudes were acquired over a trimodal ocean wave system off the coast of norway on march 11 1988 these three wave systems traveling in different directions were also measured by a directional buoy with the buoy spectra rotated into the radar coordinates for comparison with sar spectra fifteen subspectra were averaged to obtain the measured sar spectra and sixteen spectral bands were averaged to obtain the measured buoy spectra the seven flight paths in conjunction with the three wave systems resulted in a nearly uniform distribution of azimuth peak directions varying from 0 to 83 and r v varying from 28 to 110 the comparison of the sar and buoy derived peak wavelength and direction shows some scatter we consider the scatter to be due primarily to the statistical uncertainty in the spectral estimates the wave number resolution and differences in the temporal and spatial averaging scanning distortion is shown to cause significant bias in the sar and buoy comparison for slow flying aircraft imaging ocean wave swell correction of the sar spectra for this special radar ocean condition gives significant improvement in the sar buoy comparison we investigate the relative importance of the motion related mechanisms velocity bunching velocity smearing and scanning distortion and the tilt contributions using four nondimensional imaging parameters

numerical simulation of synthetic aperture radar image spectra for ocean waves a numerical model for predicting the synthetic aperture radar sar image of a moving ocean surface is described and results are presented for two sir b data sets collected off the coast of chile wave height spectra measured by the nasa radar ocean wave spectrometer rows were used as inputs to this model and results are compared with actual sir b image spectra from orbits 91 and 106 additional parametric variations are presented to illustrate the effects of nonlinearities in the imaging process

holocene floodplain palaeoecology of the humberhead levels implications for regional wetland development the acquisition of high quality well dated local site records is essential for progressing regional environmental reconstructions as part of a wider study designed to examine intra and extra site ecosystem responses to environmental change this paper presents new palaeoecological data from the floodplain of the river torne in the humberhead levels south yorkshire the sampling site lies adjacent to the lowland raised mire of hatfield moors a location with a long history of palaeoecological investigations the potential of using floodplain records to reconstruct local variations in ecosystem response to environmental change is also considered coleoptera and pollen are used to reconstruct floodplain ecosystem dynamics whilst chronologies are established using bayesian age depth modelling between 10 200 cal bp and 2300 cal bp the floodplain experienced multiple phases of ecological change at 10 200 9910 cal bp a cut off channel began to infill with peat while the surrounding floodplain remained relatively dry with pinus forest growing nearby between 9630 9500 cal bp and 7270 7020 cal bp a depositional hiatus occurred in the sedimentary record by the end of this period the local woodland had diversified and expanded to mixed deciduous tree cover a wet shift identified at 6870 6160 cal bp was shortly followed by a rise in alnus and tilia from 6410 6160 cal bp at this time widespread floodplain paludification had occurred in the humberhead levels which was largely controlled by relative sea level rsl rise and the associated rise in regional water tables floodplain expansion also resulted in the widespread occurrence of alnus dominated fen woodland the local torne floodplain experienced varying levels of wetness that influenced the decline and subsequent regeneration of the woodland from 5870 5640 cal bp at this time the ulmus decline is identified in the pollen stratigraphic record floodplain hydrology appears to have been controlled by a combination of water table fluctuations and changes in channel pattern flow both of which can be linked to rsl variations recorded in the humber estuary floodplain alluviation also linked to rising water tables is dated to 4360 4160 cal bp anthropogenic woodland clearance further upstream may have further compounded this event

a high resolution study of holocene paleoclimatic and paleoceanographic changes in the nordic seas 1 high resolution records from images core md95 2011 in the eastern norwegian sea provide evidence for relatively large and small scale high latitude climate variability throughout the holocene during the early and mid holocene a situation possibly driven by consistent stronger westerlies increased the eastward influence of arctic intermediate and near surface waters for the late holocene a relaxation of the atmospheric forcing resulted in increased influence of atlantic water the main changes in holocene climate show no obvious connection to changing solar irradiance and spectral analysis reveals no consistent signature for any periodic behavior of holocene climate at millennial or centennial timescales there are however indications of consistent multidecadal variability

azimuth falloff effects in two antenna sar measurements of ocean wave spectra estimates of ocean wave spectra obtained from conventional synthetic aperture radar sar images suffer from the azimuth falloff effect which limits the range of azimuth wavenumbers that can be observed by such systems this effect was earlier predicted to be modified by the use of a second receive antenna which is displaced from the first in the along track direction the authors present experimental evidence which is consistent with these theoretical predictions and suggests that the azimuth falloff limitations inherent in conventional sar systems can be overcome by the use of two or more appropriately spaced antennas

large and small scale spatial evolution of digitally processed ocean wave spectra from seasat synthetic aperture radar precision digitally processed and corrected synthetic aperture radar sar image spectra along a large portion of seasat orbit 1339 september 28 1978 have revealed a number of unique potentials but also some substantial limitations of spaceborne sar for global ocean wave monitoring sar appears to be capable of monitoring the spatially evolving ocean wave number spectrum with high statistical reliability the large scale few hundred kilometer spatial evolution of the spectrum is generally consistent with the location in time and space of wave generating sources even when multiple wave systems are present on a more local scale of just a few tens of kilometers the nearshore wave number spectrum responds to local depth changes but is too noisy to respond reliably to local current changes the seasat sar was severely restricted in its ability to sense azimuthtraveling along track waves in high sea states azimuth waves corresponding to ocean wavelengths shorter than about 200 m were either undetected or severely attenuated in the higher sea states hs 2 m azimuth waves shorter than 100 m are not detectable in even the lowest sea states moreover there is a tendency for attenuated wave systems to be shifted toward the range direction this effect will significantly impede studies of spatial evolution of seasat sar spectra without some additional correction strategy

ocean wave spectral distortion in airborne synthetic aperture radar imagery during the norwegian continental shelf experiment of 1988 c band radar images of ocean gravity waves off the norwegian coast were processed into one dimensional azimuth spectra these spectra were used to measure the azimuth spectral width cutoff on the basis of a least squares fit to a gaussian spectral shape the widths were calculated for a range of wave heights 2 5 m and wind speeds 2 18 m s during 3 days in march 1988 velocity smearing estimates were extracted independent of r v and incidence angle based on an imaging model and the measured azimuth cutoffs with values varying from 0 4 to 0 7 m s quantitative velocity smearing estimates are important as input to models describing the distortion in wave imagery we propose a first order model which neglects velocity bunching for ocean swell with peak wavelengths longer than about 250 m this model is offered as a first estimate of when ocean wave swell will be detected by the c band sar on board the ers 1 spacecraft the model predicts that this swell will be imaged under light winds of the order of 2 4 m s higher wind speeds cause larger smearing which may result in significant distortion of the imaged swell provided that the swell is traveling near the direction of the spacecraft ground track

mesolithic neolithic settlements minino 2 and zamostye 5 in their geo environmental setting upper volga lowland central russia abstract the local landscapes of early mesolithic neolithic settlements within the upper volga outwash plain are reconstructed based on the investigation of the multilayer archaeological sites minino 2 and zamostye 5 moscow district russian forest zone according to former descriptions by the authors vandenberghe et al 2010 regional environments in the different stages of the holocene beginning from the preboreal are considered using pollen data while local landscapes including relief soil vegetation and water regime are reconstructed on the base of sediments fossil soils and macrofossils as preserved in a series of burial pits of different age colonization of the area by hunters fishermen followed the local proglacial lake filling and shallowing at the end of the lateglacial postglacial period about cal 12 0 12 2 ka bp drying landscape inherited sharply undulating topography where elevated dry sites were populated up to a flooding episode between cal 2 5 and 2 8 ka bp or about 850 bc water receded between 1 7 and 1 9 cal ka bp while large scale peat accumulation and wetland expansion began about 650 700 bp during the holocene depressions had been gradually filled with organic deposits reflecting change of hydrological regimes the most significant wetting occurred about cal 5 3 5 4 ka bp soil evolution has proceeded from initial calcareous alkaline soils to leached acid soils and further to peaty soils

multiproxy surface wetness records from replicate cores on an ombrotrophic mire implications for holocene palaeoclimate records ombrotrophic mires can provide records of palaeoclimate over the mid to late holocene in several areas of the world their potential is currently partly limited by difficulties with scaling indices based on plant macrofossils and humification and the need to account for the internal variability of the mire system this paper explores the use of testate amoebae analysis as a third technique and assesses the minimum within site variability by comparing results from two closely spaced cores reconstruction of surface wetness changes was carried out on cores from the centre of an intermediate raised blanket mire coom rigg moss northumberland by analysis of testate amoebae plant macrofossils and humification surface wetness changes were expressed as mean annual water table changes inferred from testate amoebae assemblages two separate indices based on plant macrofossils and percentage transmission of humification extracts comparisons between the proxies suggest good agreement of general trends in sphagnum peats but some differences in monocot and ericaceous peats the magnitude of surface wetness changes also differs within sphagnum peats the records from the separate cores converge over time and replicability between cores is best in the last 1000 yr changes over this period are similar to those shown by estimates based on documentary sources good agreement is obtained between a normalised plant macrofossil index and normalised reconstructed water table values and it is suggested that this approach could form the basis for improved composite multiproxy records from peatlands copyright 1999 john wiley sons ltd

paleoceanographic reconstructions of surface ocean conditions in the greenland iceland and norwegian seas through the last 14 ka based on diatoms prior reconstructions of the last glacial maximum and the holocene did not include detailed paleoclimate data from the greenland iceland and norwegian gin seas which cover sensitive areas for oceanographic boundaries sea ice distribution and deep water formation in order to fill this gap we studied nine well dated sediment cores from this area and reconstructed the paleoceanographic conditions of the surface gin seas at 2000 year intervals since 13 400 bp based on the diatom record results show that a n s extending sea ice free corridor had opened along norway already at 13 400 bp indicating a northward flow of a branch of the north atlantic drift possibly caused by a change in the jet stream flow due to the decreased height of the north american ice sheet a major change of climatic conditions occurred over the gin seas as the insolation anomaly reached its maximum around 9000 bp when the sea ice cover and the oceanic fronts retreated to a northwesterly position along greenland and the ocean temperatures rose the first half of the holocene is recorded as the warmest period during the last 13 400 bp in the gin seas the duration of this climatic optimum decreased both toward the north and toward the margins of the area the second half of the holocene is characterized by a cooling trend in step with the decreasing insolation these results support the proposal of imbrie et al 1992 that the gin seas region acts as an initial responder to insolation changes

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research