the effect of antarctic sea ice on the southern hemisphere atmosphere during the southern summer this study examines the influence of antarctic sea ice distribution on the large scale circulation of the southern hemisphere using a fully coupled gcm where the sea ice submodel is replaced by a climatology of observed extremes in sea ice concentration three 150 year simulations were completed for maximum minimum and average sea ice concentrations and the results for the austral summer january march were compared using the surface temperatures forced by the sea ice distributions as a filter for creating the composite differences the results indicate that in the austral summer the polar cell expands contracts under minimum maximum sea ice conditions with corresponding shifts in the midlatitude ferrell cell we suggest that this response occurs because sea ice lies in the margin between the polar and midlatitude cells the polarity of the southern hemisphere annular sam mode is also influenced such that when sea ice is at a minimum maximum the polarity of the sam tends to be negative positive

alexander the great s tombolos at tyre and alexandria eastern mediterranean tyre and alexandria s coastlines are today characterised by wave dominated tombolos peculiar sand isthmuses that link former islands to the adjacent continent paradoxically despite a long history of inquiry into spit and barrier formation understanding of the dynamics and sedimentary history of tombolos over the holocene timescale is poor at tyre and alexandria we demonstrate that these rare coastal features are the heritage of a long history of natural morphodynamic forcing and human impacts in 332 bc following a protracted seven month siege of the city alexander the great s engineers cleverly exploited a shallow sublittoral sand bank to seize the island fortress tyre s causeway served as a prototype for alexandria s heptastadium built a few months later we report stratigraphic and geomorphological data from the two sand spits proposing a chronostratigraphic model of tombolo evolution

alaska landfast sea ice links with bathymetry and atmospheric circulation 1 using radarsat synthetic aperture radar sar imagery of northern alaska and northwestern canada we calculated a mean climatology of the annual landfast ice cycle for the period 1996 2004 we also present the monthly minimum mean and maximum landfast ice extents throughout the study area these data reveal where and when the landfast is most stable and which sections of the coast are susceptible to midseason breakout events stabilization of landfast ice is strongly related to the advance of the seaward landfast ice edge slie into waters around 18 m deep isobaths near this depth are a good approximation for midseason landfast ice extent comparison with work from the 1970s suggests a reduced presence of landfast ice in this region of the arctic due to later formation and earlier breakup this will likely lead to an increase in coastal erosion and may also have profound effects upon subsistence activities which are intimately linked to the timing of marine mammal migration patterns interannually landfast ice formation correlates with the incursion of pack ice into coastal waters suggesting that the later mean date of formation in recent years may be related to the increasingly northward location of the perennial sea ice edge the timing of breakup correlates well with onset of thawing air temperatures analysis of regional data shows a multidecadal trend toward earlier thaw onset which suggests that the observed change in breakup dates may be part of a longer term trend

seasonal relationships between large scale climate variability and antarctic sea ice concentration abstractthe observed relationships between anomalous antarctic sea ice concentration sic and the leading patterns of southern hemisphere sh large scale climate variability are examined as a function of season over 1980 2008 particular emphasis is placed on 1 the interactions between sic the southern annular mode sam and el nino southern oscillation enso and 2 the contribution of these two leading modes to the 29 yr trends in sea ice regression composite and principal component analyses highlight a seasonality in sh sea ice atmosphere interactions whereby antarctic sea ice variability exhibits the strongest linkages to the sam and enso during the austral cold season months as noted in previous work a dipole in sic anomalies emerges in relation to the sam characterized by centers of action located near the bellingshausen weddell and amundsen eastern ross seas the structure and magnitude of this sic dipole is found to vary considerably as a function of season consistent with the season

the miller range 090340 and 090206 meteorites identification of new brachinite like achondrites with implications for the diversity and petrogenesis of the brachinite clan miller range mil 090340 and mil 090206 are olivine rich achondrites originally classified as ureilites we investigate their petrography mineral compositions olivine cr valences equilibration temperatures and for mil 090340 oxygen isotope compositions and compare them with ureilites and other olivine rich achondrites we conclude that they are brachinite like achondrites that provide new insights into the petrogenesis of brachinite clan meteorites mil 090340 6 has a granoblastic texture and consists of 97 modal by area olivine fo molar mg mg fe 71 3 0 6 it also contains minor to trace augite chromite chlorapatite orthopyroxene metal troilite and terrestrial fe oxides approximately 80 by area of mil 090206 5 has a granoblastic texture of olivine fo 72 3 0 1 plus minor augite and chromite similar to mil 090340 but also containing minor plagioclase the rest of the section consists of a single crystal of orthopyroxene 11 3 mm poikilitically enclosing rounded grains of olivine fo 76 1 0 6 augite chromite metal and sulfide equilibration temperatures for mil 090340 and mil 090206 calculated from olivine spinel olivine augite and two pyroxene thermometry range from 800 to 930 c in both samples symplectic intergrowths of ca poor orthopyroxene opaque phases fe oxides sulfide metal occur as rims on and veins patches within olivine before terrestrial weathering the opaques were probably mostly sulfide with minor metal all petrologic properties of mil 090340 and mil 090206 are consistent with those of brachinite clan meteorites and largely distinct from those of ureilites oxygen isotope compositions of olivine in mil 090340 18o 5 08 0 30 17o 2 44 0 21 and 17o 0 20 0 12 are also within the range of brachinite clan meteorites and well distinguished from ureilites olivine cr valences in mil 090340 and the granoblastic area of mil 090206 are 2 57 0 06 and 2 59 0 07 respectively similar to those of three brachinites also analyzed here brachina hughes 026 nova 003 they are higher than those of olivine in ureilites even those containing chromite the valence systematics of mil 090340 mil 090206 and the three analyzed brachinites lower fo more oxidized cr are consistent with previous evidence that brachinite like parent bodies were inherently more oxidized than the ureilite parent body the symplectic orthopyroxene sulfide metal assemblages in mil 090340 mil 090206 and many brachinite clan meteorites have superficial similarities to characteristic reduction rims in ureilites however they differ significantly in detail they likely formed by reaction of olivine with s rich fluids with only minor reduction mil 090340 and the granoblastic area of mil 090206 are similar in modal mineralogy and texture to most brachinites but have higher fo values typical of brachinite like achondrites the poikilitic pyroxene area of mil 090206 is more typical of brachinite like achondrites the majority of their properties suggest that mil 090340 and mil 090206 are residues of low degree partial melting the poikilitic area of mil 090206 could be a result of limited melt migration with trapping and recrystallization of a small volume of melt in the residual matrix these two samples are so similar in mineral compositions cr valence and cosmic ray exposure ages that they could be derived from the same lithologic unit on a common parent body

multidisciplinary study of holocene archaeological soils in an upland mediterranean site natural versus anthropogenic environmental changes at cecita lake calabria italy abstract this paper highlights results of a multidisciplinary and multi analytical study of holocene archaeological soils around cecita lake sila massif calabria southern italy which represents a typical upland mediterranean environment it is focused on assessment of climatic and environmental changes that took place since late neolithic to roman times trying to discriminate natural from anthropogenic signals based on an integration of archaeological geomorphological stratigraphic pedological volcanological and soil charcoal pedoanthracological data the following paleoclimatic environmental reconstruction is proposed a warm and humid seasonally contrasted climate with an overall geomorphological stability suited for soil development characterized the late prehistoric environment holocene climatic optimum dominated by a widespread oak forest the main pedogenetic processes consisted in organic matter accumulation clay illuviation phyllosilicate and short range order mineral neogenesis from weathering of granite and volcanic ash sourced from late pleistocene holocene eruptions of the aeolian islands one or more mid holocene episodes of climate deterioration towards drier conditions indicated by a decrease of clay translocation processes and possible irreversible dehydration of poorly crystalline aluminosilicates into phyllosilicate clay minerals promoted intense land degradation this was in turn enhanced by increasing human activities for settlement and resource exploitation among which deforestation and ploughing for agriculture which led to a shift of the vegetation cover towards a dominant pine forest between 3 ka bp and the roman epoch humid and possibly cooler climatic conditions during the late holocene are indicated by the decrease of clay illuviation coupled with short range order components prevailing over phyllosilicate clays during roman soil formation

recent climate and ice sheet changes in west antarctica compared with the past 2 000 years west antarctic temperature and pressure observations begin onlyin 1957 and reliable satellite observations of antarctic sea icedate to 1979 comprehensive observations of glacier dynamicsin the most rapidly changing areas were initiated in the 1990s borehole temperature data from the wais although confirmingthe recent rapid rise in temperature do not resolve decadal scalevariability in the past

climate links and recent extremes in antarctic sea ice high latitude cyclones southern annular mode and enso in this article we study the climate link between the southern annular mode sam and the southern sea ice extent sie and discuss the possible role of stationary waves and synoptic eddies in establishing this link in doing so we have used a combination of techniques involving spatial correlations of sie eddy streamfunction and wind anomalies and statistics of high latitude cyclone strength it is suggested that stationary waves may be amplified by eddy anomalies associated with high latitude cyclones resulting in more sea ice when the sam is in its positive phase for most but not all longitudes a similar association is observed during enso la nina years although this synergy in the sam enso response may partially reflect preferential areas for wave amplification around antarctica the short extent of the climate records does not allow for a definite causality connection to be established with sie stronger polar cyclones are observed over the areas where the stationary waves are amplified these deeper cyclones will break up and export ice equatorward more efficiently but the near coastal regions are cold enough to allow for a rapid re freeze of the resulting ice break up we speculate that if global warming continues this same effect could help reverse the current positive antarctic sie trends once the ice gets thinner similarly to what has been observed in the northern hemisphere

sediment dispersal along northern israel coast during the early holocene geological and archaeological evidence abstract combined geological and archaeological study of finds at atlit yam a pre pottery neolithic settlement submerged off the carmel coast of northern israel provides new information on sediment provenance and dispersal in the southern levant clay mineral analyses of mud rich samples collected in a water well ca 8100 7550 yrs b p at this site are useful for determining the early holocene circulation pattern along this margin analyses record the predominance of fluvial sediment from proximal carmel highland sources to the east as indicated by illite and of marine sediment from the north and northeast as indicated by kaolinite this north to south coastal transport is in marked contrast to the present south to north dispersal pattern where smectite rich nile material is derived from distal sources and carried hundreds of kilometers to the carmel margin the interpreted coastal circulation pattern indicates that although the modern nile delta major source of sediment in the eastern mediterranean had begun to form about 8000 7500 yrs ago it had not yet begun to supply substantial amounts of sediment to as far north as the carmel coast by the time the water well was abandoned the atlit yam site serves as a unique geochronologic gauge valuable for interpreting climatic oceanographic and sedimentologic conditions in the se mediterranean which as recently as 7500 yrs ago were markedly different than those prevailing at present

benthic foraminiferal assemblages of the imperial harbor of claudius rome further paleoenvironmental and geoarcheological evidences this paper presents a paleoenvironmental reconstruction of historical development in the area of the ancient harbor of claudius based on micropaleontological and sedimentological data benthic foraminifera are reliable tools for this kind of research because they are sensitive to short time environmental changes induced by both natural and anthropogenic events by studying eight sediment cores collected from different sections of the harbor it was possible to reconstruct a comprehensive picture of the harbor complex qualitative and quantitative analysis of foraminiferal associations and sedimentological data along with radiocarbon dating were useful to identify three key intervals in the history of the coastal area where the harbor developed the first interval located at the bottom of all cores is characterized by a brackish water environment corresponding to the formation of the first deltaic cusp of the tiber river the second interval is characterized by the harbor activities that developed aft

benthic foraminiferal evidence and paleoenvironmental evolution of holocene coastal plains in the aegean sea greece abstract benthic foraminiferal composition of sedimentary successions during the last 7500 years was investigated from boreholes drilled in three rather tectonically stable coastal areas of the aegean sea alykes kitros lafrouda thrace and vravron attica the quantitative analysis of foraminiferal fauna enabled separation into two different groups that are supported by the analysis of modern benthic foraminiferal communities in the studied sites group a consists of ammonia tepida and haynesina germanica closed lagoon assemblage whereas the most common species of group b open lagoon assemblage are aubignyna perlucida miliolids elphidium spp and ammonia spp the foraminiferal composition integrated with radiometric dating provides information on holocene paleoenvironmental changes in the studied coastal plains related to sea land interaction alykes kitros and lafrouda thrace boreholes show a similar trend with an open lagoonal fauna in the lower part transitional upwards to closed lagoonal conditions this environmental change has taken place after 6500 cal bp in alykes kitros and around 3000 cal bp at lafrouda thrace the benthic communities of vravron attica borehole sediments seem to represent continuously an open lagoon shallow marine environment from 4700 to 400 cal bp

variability of sea ice in the northern weddell sea during the 20th century the record of winter fast ice in the south orkney islands northern weddell sea antarctica is over a century long and provides the longest observational record of sea ice variability in the southern hemisphere here we present analyses of the series of fast ice formation and breakout dates from 1903 to 2008 we show that over the satellite era post 1979 the timing of both final autumn formation and complete spring breakout of fast ice is representative of the regional sea ice concentrations sic in the northern weddell sea and associated with atmospheric conditions in the amundsen sea region to the west of the antarctic peninsula variation in the fast ice breakout date is influenced by the intensity of the westerly north westerly winds associated with the southern annular mode sam in contrast the date of ice formation displays correlations with regional oceanic and sea ice conditions over the previous 18 months which indicate a preconditioning during the previous summer and winter and exhibits variability associated with variation in tropical pacific sea surface temperature i e the el nino sothern oscillation enso a reduction in fast ice duration at the south orkney islands around the 1950s was associated with both later formation and earlier breakout however there were marked changes in variability with periodicities of 3 5 year 7 9 year and 20 year in each of the series and in their relationships with enso and sam indicating the need for caution in interpreting changes in ice conditions based on shorter term satellite series

molluscan faunas and paleobathymetry of holocene sequences in the northeastern nile delta egypt abstract the fossil molluscan component serves as a valuable indicator of the paleobathymetric variations which occurred in the nile delta egypt during the past 7500 years paleobiocoenoses have been identified on the basis of molluscan faunas in three radiocarbon dated cores as part of a long term study to help interpret the holocene evolution of the northeastern delta one of these smithsonian boring s 21 near port said has been selected as a type core because it includes a near complete holocene coarsening upward sequence of distinct open marine to coastal lithofacies typical of this depocenter the fossil molluscan faunas comprising 59 species all of which are presently living in the mediterranean serve to determine approximate changes in paleodepth at this site with time in particular the recognized paleocommunities show a good correspondence with several infralittoral biocoenoses of unconsolidated mud and sand rich substrates of the present mediterranean terrigenous mud fine well sorted sands fine sands in very shallow water and superficial muddy sands in sheltered areas the methodology was applied to two other cores of near comparable age in this region smithsonian core s 31 and boring fadda 1 earlier studied by others these two were also selected because they are characterized by a holocene sequence of marine to coastal lithologies similar to core s 21 the approach used serves to determine temporal and spatial differences in paleobathymetry at the three sites this investigation shows that analysis of the faunas in subsurface sections serves to refine paleoenvironmental interpretations of the nile delta moreover the molluscan paleobiocoenoses are best evaluated in conjunction with the lithofacies in which they occur

can molluscan assemblages give insights into holocene environmental changes other than sea level rise a case study from a macrotidal bay marennes oleron france during the late holocene the rate of sea level rise decreased and climate changes hydrodynamic processes or anthropogenic impacts became predominant parameters governing the sedimentary infill of estuarine environments the aim of this study is to describe the response of past benthic mollusc communities to these forcing factors mollusc skeletal remains were sampled from three 8000 5500 and 2600 year long sedimentary records in the marennes oleron bay atlantic coast france where environmental changes have previously been identified thanks to a combination of very high resolution seismic profiles and sedimentological data molluscan assemblages successfully record environmental changes even at the smallest temporal scale they provide relevant information regarding bathymetry salinity hydrodynamics oxygen content and sediment supply in the 8000 year long record the transition from an upper to a lower intertidal mudflat community provides evidence of a transgressive phase that occurred between 8000 and 7600 years bp in the 5500 year long record an oyster bank developed on the slopes of a tidal channel has been recovered the composition of the fossil community and the careful examination of skeletal remains suggest that the channel was hydraulically inefficient in response to the sediment infilling of its drainage area in the 2600 year long record a soft bottom shallow water subtidal mollusc community similar to that found nowadays in the marennes oleron bay has been recovered from both lower mixed sand mud and upper muddy units separated by a major regional unconformity dated to about 1000 years bp this sharp transition is recorded by a few rare species and was responsible for the local extinction of the bivalve lepton squamosum however the abundance of the most common species and the quantity of fragmented shells remain stable which may indicate that mud drape deposition was related to an increase in mud supply rather than a decrease in water energy the level of detail of the palaeoenvironmental reconstructions varies depending on the ecological requirements of the species stenotypic indicator species provide accurate quantitative information whereas eurytypic species add undesired variability to the assemblages since fossil molluscs are easy to collect and to identify and provide long term smoothed records of environment variations this study suggests that they can be used prior to any other biological proxy as a first step into reconstructions of holocene coastal environments

environmental evolution of the paliouras coastal lagoon in the eastern thermaikos gulf greece during holocene the integration of lithology determination micropaleontological and molluscan analyses scanning electron microscopy magnetic susceptibility measurement and radiocarbon dating contributed to the interpretation of a sedimentary succession recovered from a 870 cm long borehole drilled at the paliouras coastal lagoon in the eastern thermaikos gulf greece in this way the reconstruction of the creation and evolution of the lagoon during the last 8000 years was accomplished four main evolutionary phases are identified 1 initially the pre holocene basement of the study area was inundated during the early holocene marine transgression 2 since 8000 7900 cal yr bp an inner lagoon had been formed in the paliouras coastal plain within a rather restricted environment characterized by a haynesina germanica cerastoderma glaucum and hydrobia sp assemblage relatively high sediment magnetic susceptibility and an intense presence of abnormal foraminiferal tests and lenticular gypsum crystals 3 during 7600 6900 cal yr bp the inner lagoon presented a transition to an open system clearly connected to the sea and characterized by an ammonia beccarii aubignyna perlucida and miliolids assemblage more diversified molluscan fauna minimum sediment magnetic susceptibility and the occurrence of lenticular gypsum aggregates and finally 4 since 5900 cal yr bp to the present time the lagoon water body appears isolated from the marine environment except of occasional seawater intrusions the proposed evolutionary scenario for the paliouras coastal lagoon is in accordance with the existing models of the sea level rise in the aegean coastal areas concerning the time span before 4000 yr bp and the mid late holocene climate events

molluscan palaeoecology and sedimentological features an integrated approach from the miocene meduna section northern italy molluscs were studied to reconstruct the palaeoenvironmental conditions of the miocene sequence of the torrente meduna area friuli northern italy and to compare palaeobiological results with those of an earlier sedimentological analysis the study identifies six fossil communities and relevant individual assemblages and ascribes them to palaeobiocoenoses comparable to modern mediterranean ones introduced by french marine ecologists 1 chlamys praescabriuscula community 2 pecten burdigalensis community 3 loripes dentatus assemblage 4 protoma rotifera community 5 benus ancilla assemblage and 6 venus conus community the palaeobiological analysis demonstrates that the entire miocene sequence up to the late tortonian or very early messinian was deposited within the infralittoral zone at shallow to very shallow depths onto wave influenced bottoms the greatest water depth occurred during early tortonian and was of approximately 25 m palaeobiological and sedimentological methods provide different sets of information which complement each other efficiently general environmental conditions in this case a delta influenced environment can best be reconstructed on the basis of sedimentological data however specific aspects of the environment primarily palaeobathymetry may only be interpreted by means of through palaeobiological analysis

human impact on holocene sediment dynamics in the eastern mediterranean the example of the roman harbour of ephesus during the past millennia many erosion and accumulation processes have been modified by anthropogenic impact this holds especially true for the environs of ancient settlements and their harbours along the mediterranean coasts our multi proxy investigations in the roman harbour and the harbour canal of ephesus western turkey reveals that humans have significantly triggered soil erosion during the last three millennia since the eighth century bc and especially since the hellenistic period a high sed imentation rate indicates fast alluviation and delta progradation of the kucuk menderes deforestation agriculture especially ploughing and grazing especially goats were the main reasons for erosion of the river catchment area one consequence was significant siltation of the hellenistic roman harbour basin this sediment trap archives the human impact which was strongly enhanced from hellenistic roman to byzantine times second first centuries bc to the sixth seventh centuries ad evidenced by high sedimentation rates raised values of heavy metal contaminations lead pb copper cu the occurrence of fruit tree pollen and of intestinal parasites from the middle to the end of the first millennium ad the influence of ephesus declined which resulted in a decrease of human impact studies of several ancient settlements around the mediterranean sea tell a comparable story they also confirm that during their most flourishing periods the human impact totally overprinted the climatic one to detect the latter geo bio archives of relatively pristine areas have to be investigated in detail

ice core evidence for antarctic sea ice decline since the 1950s the instrumental record of antarctic sea ice in recent decades does not reveal a clear signature of warming despite observational evidence from coastal antarctica here we report a significant correlation p

an analysis of the atmospheric processes driving the large scale winter sea ice variability in the southern ocean the response of the sea ice in the southern ocean to the variability of the atmosphere on the period 1979 2004 is investigated using both model and observational data on the one hand our results show that in line with previous investigations the classical modes of atmospheric variability do not explain a large part of the winter sea ice extent variability integrated over the entire southern ocean on the other hand the regression between the ice extent and the atmospheric pressure displays a pattern with low pressure areas over the south atlantic over the indian ocean and on the southwestern part of the pacific ocean and a high pressure area over the antarctic region extending toward both the southeastern pacific and the region south of australia this pattern which does not correlate significantly with any of the known modes of atmospheric variability induces changes in the sea ice extent by influencing the air temperature the ice production and both the meridional and the zonal ice velocity however there is no clear link between the different centers of action of this pattern furthermore the correlation of the sea ice extent between the different sectors is generally low as a conclusion we must consider that the sea ice extent in the southern ocean over the last 30 years does not behave as a single entity its variability is the result of the combination of regional sea ice changes each sector should thus be examined separately

recent holocene paleo environmental evolution and coastline changes of kition larnaca cyprus mediterranean sea abstract sedimentological paleontological analysis and 14c dating of 17 cores obtained in the vicinity of the phoenician military harbor viii iv bc of kition bamboula cyprus provide new paleo environmental information for the reconstruction of shoreline changes for kition and larnaca bay over the last 4000 years we propose that a communication existed between the inner harbor of bamboula presently 400 m inland and the northern district of lichines which was a marine embayment our core data led us to revisit the previous hypothesis of a direct east west channel between the harbor and the open sea nicolaou k 1976 the historical topography of kition studies in mediterranean archaeology goteborg vol 153 pp 1 373 gifford j a 1978 paleogeography of archaelogical sites of the larnaca lowlands southeastern cyprus phd thesis university of minnesota pp 1 192 we propose instead that a spit of coarse material isolated the lagoon from the open sea from 2600 to 1600 years bp

interpretation of recent southern hemisphere climate change climate variability in the high latitude southern hemisphere sh is dominated by the sh annular mode a large scale pattern of variability characterized by fluctuations in the strength of the circumpolar vortex we present evidence that recent trends in the sh tropospheric circulation can be interpreted as a bias toward the high index polarity of this pattern with stronger westerly flow encircling the polar cap it is argued that the largest and most significant tropospheric trends can be traced to recent trends in the lower stratospheric polar vortex which are due largely to photochemical ozone losses during the summer fall season the trend toward stronger circumpolar flow has contributed substantially to the observed warming over the antarctic peninsula and patagonia and to the cooling over eastern antarctica and the antarctic plateau

an antarctic circumpolar wave in surface pressure wind temperature and sea ice extent the southern ocean is the only oceanic domain encircling the globe it contains the strong eastward flow of the antarctic circumpolar current and is the unifying link for exchanges of water masses at all depths between the world s major ocean basins1 as these exchanges are an important control on mean global climate the southern ocean is expected to play an important role in transmitting climate anomalies around the globe interannual variability has been often observed at high southern latitudes and observations of sea ice extent suggest that such features propagate eastwards around the southern ocean2 3 here we use data from a variety of observational techniques to identify significant interannual variations in the atmospheric pressure at sea level wind stress sea surface temperature and sea ice extent over the southern ocean these anomalies propagate eastward with the circumpolar flow with a period of 4 5 years and taking 8 10 years to encircle the pole this system of coupled anomalies which we call the antarctic circumpolar wave is likely to play an important role in climate regulation and dynamics both within and beyond the southern ocean

examining the interaction between multi year landfast sea ice and the mertz glacier tongue east antarctica another factor in ice sheet stability the mertz glacier tongue mgt east antarctica has a large area of multi year fast sea ice myfi attached to its eastern edge we use various satellite data sets to study the extent age and thickness of the myfi and how it interacts with the mgt we estimate its age to be at least 25 years and its thickness to be 10 55 m this is an order of magnitude thicker than the average regional sea ice thickness and too thick to be formed through sea ice growth alone we speculate that the most plausible process for its growth after initial formation is marine frazil ice accretion the satellite data provide two types of evidence for strong mechanical coupling between the two types of ice the myfi moves with the mgt and persistent rifts that originate in the mgt continue to propagate for large distances into the myfi the area of myfi decreased by 50 following the departure of two large tabular icebergs that acted as pinning points and protective barriers future myfi extent will be affected by subsequent icebergs from the ninnis glacier and the imminent calving of the mgt fast ice is vulnerable to changing atmospheric and oceanic conditions and its disappearance may have an influence on ice tongue ice shelf stability understanding the influence of thick myfi on floating ice tongues ice shelves may be significant to understanding the processes that control their evolution and how these respond to climate change and thus to predicting the future of the antarctic ice sheet

ice core records as sea ice proxies an evaluation from the weddell sea region of antarctica 1 ice core records of methanesulfonic acid msa from three sites around the weddell sea are investigated for their potential as sea ice proxies it is found that the amount of msa reaching the ice core sites decreases following years of increased winter sea ice in the weddell sea opposite to the expected relationship if msa is to be used as a sea ice proxy it is also shown that this negative msa sea ice relationship cannot be explained by the influence that the extensive summer ice pack in the weddell sea has on msa production area and transport distance a historical record of sea ice from the northern weddell sea shows that the negative relationship between msa and winter sea ice exists over interannual 7 year period and multidecadal 20 year period timescales national centers for environmental prediction national center for atmospheric research ncep ncar reanalysis data suggest that this negative relationship is most likely due to variations in the strength of cold offshore wind anomalies traveling across the weddell sea which act to synergistically increase sea ice extent sie while decreasing msa delivery to the ice core sites hence our findings show that in some locations atmospheric transport strength rather than sea ice conditions is the dominant factor that determines the msa signal preserved in near coastal ice cores a cautious approach is thus required in using ice core msa for reconstructing past sea ice conditions including the need for networks of ice core records and multiproxy studies to assess the significance of past msa changes at different locations around antarctica

surface sediments and macrofaunas of the crati submarine fan ionian sea italy abstract five dredge samples 8 grab samples and 18 light gravity cores from the fan delta fed crati submarine fan indicate that the surface cover of the fan is mud dominated comprising muddy turbidites thin bedded silty sandy turbidites and prodelta muds this high mud content does not reflect an abandonment phase of the fan but is the product both of the composition of the sediment load discharged by the crati river and of the littoral processes affecting the constline of the crati fan delta a predominantly northward longshore drift catches most of the coarse bed load and redistributes it along the actively prograding beaches of the fan delta the whole mud reaches the submarine basin via turbidity currents and surficial turbid plumes the biogenic fraction represented by mollusca and benthic foraminifera is scarce because of the high terrigenous input in situ mollusc assemblages which occur only outside the channellized areas vary significantly in composition between the different depositional environments of the fan there is a much higher proportion of filter feeding species in depositional areas more affected by the flow of turbidity currents lobes levees

reconstruction of holocene environmental changes in two archaeological sites of calabria southern italy using an integrated pedological and anthracological approach this paper focuses on the reconstruction of holocene climatic and environmental changes in two archaeological sites of southwestern and north central calabria southern italy it is based on a comparison of geoarchaeological pedological and pedoanthracological data from soil profiles in the coastal hilly and inland mountainous surroundings of palmi and cecita lake respectively at the palmi site the representative soil profile includes settlements and artefacts ranging from late neolithic to late early bronze age and undifferentiated historical epochs the archaeological record of soils at cecita spans from late neolithic early eneolithic to roman ages at both sites surface a horizons are affected by repeated plough marks all soils display some andisol like features related to some volcanic input during soil formation originating from late pleistocene to holocene explosive eruptions of the aeolian islands the occurrence of clay coatings their relict nature and overall dominant phyllosilicate clay minerals in the neolithic soil horizons of both sites suggest warm climate conditions with high moisture availability and some seasonal contrast during the late early middle holocene climatic optimum the post neolithic soils show comparable or more abundant amounts of short range order minerals than phyllosilicates and no to scarce clay coatings these features indicate a transition towards probably cooler prolonged humid conditions intercalated by one or more drought episodes severe land degradation is recorded between these major climatic phases indicated by human impact deforestation and agriculture and soil erosion soil charcoal analysis from cecita soils provide evidence of these anthropogenic environmental changes as indicated by the dominance of deciduous oak forest in neolithic soils followed by a transition to a mountain pine forest recorded in the roman soils a deciduous oak forest characterizes the vegetation at palmi from the neolithic onward

a review of sea ice proxy information from polar ice cores sea ice plays an important role in earth s climate system the lack of direct indications of past sea ice coverage however means that there is limited knowledge of the sensitivity and rate at which sea ice dynamics are involved in amplifying climate changes as such there is a need to develop new proxy records for reconstructing past sea ice conditions here we review the advances that have been made in using chemical tracers preserved in ice cores to determine past changes in sea ice cover around antarctica ice core records of sea salt concentration show promise for revealing patterns of sea ice extent particularly over glacial interglacial time scales in the coldest climates however the sea salt signal appears to lose sensitivity and further work is required to determine how this proxy can be developed into a quantitative sea ice indicator methane sulphonic acid msa in near coastal ice cores has been used to reconstruct quantified changes and interannual variability in sea ice extent over shorter time scales spanning the last 160 years and has potential to be extended to produce records of antarctic sea ice changes throughout the holocene however the msa ice core proxy also requires careful site assessment and interpretation alongside other palaeoclimate indicators to ensure reconstructions are not biased by non sea ice factors and we summarise some recommended strategies for the further development of sea ice histories from ice core msa for both proxies the limited information about the production and transfer of chemical markers from the sea ice zone to the antarctic ice sheets remains an issue that requires further multidisciplinary study despite some exploratory and statistical work the application of either proxy as an indicator of sea ice change in the arctic also remains largely unknown as information about these new ice core proxies builds so too does the potential to develop a more comprehensive understanding of past changes in sea ice and its role in both long and short term climate changes

tropical pacific high latitude south atlantic teleconnections as seen in δ18o variability in antarctic coastal ice cores 1 we use a network of eight ice cores from coastal dronning maud land dml antarctica to examine the role of the tropical enso el nino southern oscillation in the temporal variability of 18o in annual accumulation the longest record from the s100 ice core covering the period 1737 1999 is used to analyze the teleconnections between the tropical pacific and coastal dml on decadal scales and longer a shorter stacked coastal dml 18o series spanning 1955 1999 is constructed to assess the variability of enso teleconnection on interannual scales results suggest that on typical enso timescales of 2 6 years the strength of the teleconnection varies in time being stronger for years with generally negative phase of the southern annular mode sam on the timescales of approximately two decades bidecadal positive isotope anomalies are associated with oceanic warming and a westward sea surface temperature sst gradient in the equatorial pacific bidecadal variability in sam forced by the tropical pacific is proposed as a critical element in the teleconnection our analysis suggests that a multidecadal positive trend in the annual mean 18o values from the analyzed cores can be indicative of the atmospheric warming that begun in this part of the dml already in the 1910s the trend in 18o quantified in terms of long term surface air temperature sat changes is consistent with the instrumental data yet we speculate that the accurate estimation of sat trends requires an assessment of the potential role of secular sam and sea ice extent changes in shaping the isotopic signal

observed evidence of an impact of the antarctic sea ice dipole on the antarctic oscillation abstracta lagged maximum covariance analysis mca is applied to investigate the linear covariability between monthly sea ice concentration sic and 500 mb geopotential height z500 in the southern hemisphere sh the dominant signal is the atmospheric forcing of sic anomalies throughout the year but statistically significant covariances are also found between austral springtime z500 and prior sic anomalies up to four months earlier the mca pattern is characterized by an antarctic dipole adp like pattern in sic and a positively polarized antarctic oscillation aao in z500 such long lead time covariance suggests the forcing of the aao by persistent adp like sic anomalies the leading time of sic anomalies provides an implication for skillful predictability of springtime atmospheric variability

on the interannual variability of ocean temperatures around south georgia southern ocean forcing by el nino southern oscillation and the southern annular mode abstract the ocean around south georgia in the southwest atlantic sector of the southern ocean is highly productive with large stocks of antarctic krill supporting extensive colonies of marine and land based predators the operation of this ecosystem is strongly influenced by physical forcings and the role of the el nino southern oscillation enso phenomenon has been highlighted previously here we examine in detail the transmission of enso signals to south georgia and investigate other sources of interannual variability enso variability generates anomalies in sea surface temperature sst across the south pacific via atmospheric teleconnections these anomalies are advected toward south georgia within the antarctic circumpolar current acc and previous studies have focussed on long period advection order of 2 3 years from the southwest pacific we observe here however that the region close to the antarctic peninsula in the southeast pacific is especially susceptible to enso forcing via anomalous meridional winds this induces sst anomalies that are advected to south georgia on a much more rapid timescale order 5 6 months the phasing of these teleconnections is such that anomalies that reach the southeast pacific from farther west tend to be reinforced here by air sea ice interaction we also find an important role for the southern annular mode sam in determining sst variability at south georgia this is a circumpolar mode of climate variability and thus can readily influence local sst at south georgia directly the sam is however not perfectly zonally symmetric and like enso has a particular impact on meridional winds in the southeast pacific the average timescale for sam influence on south georgia sst is shorter than that of enso since it includes a stronger component of direct local forcing the south georgia ecosystem is not self sustaining with import of krill from breeding and nursery grounds upstream in the acc being important we speculate here that these varying meridional winds close to the antarctic peninsula play a direct role in promoting restricting the injection of shelf waters and the krill therein into the acc following which anomalies in krill density would be advected toward south georgia this offers a dynamical mechanism that might contribute to interannual changes in biological communities at south georgia in addition to existing theories both sam and enso have shown long period changes in recent decades with enso exhibiting a higher preponderance of el nino events compared with la nina events and the sam showing a marked trend toward a higher index state such long period behaviour is likely to induce changes in the south georgia ecosystem via their impacts on advection and sst for which an understanding of the physical mechanisms elucidated here will be key to unravelling

understanding the sam influence on the south pacific enso teleconnection the relationship between the el nino southern oscillation enso and the southern hemisphere annular mode sam is examined with the goal of understanding how various strong sam events modulate the enso teleconnection to the south pacific 45 70 s 150 70 w the focus is on multi month multi event variations during the last 50 years a significant p 0 10 relationship is observed most marked during the austral summer and in the 1970s and 1990s in most cases the significant relationship is brought about by la nina el nino events occurring with positive negative phases of the sam more often than expected by chance the south pacific teleconnection magnitude is found to be strongly dependent on the sam phase only when enso events occur with a weak sam or when a la nina el nino occurs with a positive negative sam phase are significant south pacific teleconnections found this modulation in the south pacific enso teleconnection is directly tied to the interaction of the anomalous enso and sam transient eddy momentum fluxes during la nina sam and el nino sam combinations the anomalous transient momentum fluxes in the pacific act to reinforce the circulation anomalies in the midlatitudes altering the circulation in such a way to maintain the enso teleconnections in la nina sam and el nino sam cases the anomalous transient eddies oppose each other in the midlatitudes overall acting to reduce the magnitude of the high latitude enso teleconnection

destruction of herod the great s harbor at caesarea maritima israel geoarchaeological evidence geoarchaeological analysis of ancient harbor deposits has answered questions regarding the timing and extent of the destruction of the harbor at caesarea maritima built by herod the great on israel s mediterranean coast by using stratigraphic micropaleontological foraminifera and geochemical sr isotopes analyses of the ancient harbor deposits we can establish a late first to early second century a d date for the destruction of the harbor this destruction occurred earlier was more rapid and widespread than previously proposed and was probably caused by seismic activity the new excavations also indicate that during the fourth to early sixth centuries a d geomorphological processes and siltation within the inner harbor allowed this area to be used in a limited capacity as a harbor

southern hemisphere synoptic behavior in extreme phases of sam enso sea ice extent and southern australia rainfall abstract the association between southern hemisphere cyclones and anticyclones and the el nino southern oscillation enso southern annular mode sam antarctic sea ice extent sie and rainfall in perth and melbourne is explored those cities are respectively located in the southwestern and southeastern corners of australia where substantial decreasing rainfall trends have been observed over the last decades the need for a more unified understanding of large scale anomalies in storm indicators associated with the climate features itemized above has motivated this study the main aim is to identify cyclone anomalous areas that are potentially important in characterizing continental rainfall anomalies from a hemispheric perspective focusing on midlatitude australia the study covers the satellite era from 1979 to 2003 and was conducted for the southern winter when midlatitude rainfall is predominantly baroclinic the results indicate a well organized hemispheric cyclone pattern associated with en

benthic biofacies to interpret holocene environmental changes and human impact in alexandria s eastern harbour egypt holocene molluscan and foraminiferal faunas sensitive ecological markers are statistically treated to define their temporal and spatial distributions in radiocarbon dated cores in alexandria s eastern harbour up core variations of these benthic biofacies record the evolution of depositional environments during the past 8000 years in this long occupied eastern mediterranean port the most important change occurred in the mid holocene between 6300 and 4300 yr ago a time of lower sea level and minimal human activity this faunal change indicating a transition from a somewhat protected to a more open and higher energy marine environment resulted primarily from rise of sea level lowering of the harbour floor and diminished shielding by pleistocene coastal ridges and reefs near the bay mouth and within the harbour since that time faunal assemblages have remained generally constant except during the period from 2100 to 1800 yr ago when greeks and romans built the heptastadion that connected alexandria to pharos island this construction effectively separated the eastern from the western harbour absence of a well marked faunal change during the past 18 centuries is unexpected particularly in light of the much increased population and associated human effects the harbour s overall large size rise in relative sea level and continued exchange of marine water between the open shelf and port have maintained an active circulation pattern the strong current regime and reworking of bottom sediments have generally masked short term human effects and altered the harbour s late holocene sediment stratigraphy these factors help explain why benthic biofacies primarily record influences of natural processes that prevailed in this relatively unconfined high energy marine setting rather than those of a more constricted and anthropogenically impacted port

coastal landfast sea ice decay and breakup in northern alaska key processes and seasonal prediction 1 seasonal breakup of landfast sea ice consists of movement and irreversible ice detachment in response to winds or oceanic forces in the late stages of ice decay the breakup process of landfast sea ice in the chukchi sea at barrow alaska was analyzed for the years 2000 through 2010 on the basis of local observations of snow and ice conditions weather records image sequences obtained from cameras coastal x band marine radar and satellite imagery we investigated the relation of breakup to winds tides and nearshore current measurements from a moored acoustic doppler current profiler two breakup modes are distinguished at barrow on the basis of the degree of ice decay mechanical breakup due to wind and oceanic forces follows ablation and weakening of the ice thermal breakup is the result of ice disintegration under melt ponds requiring little force to induce dispersion grounded pressure ridges are pivotal in determining the breakup mode the timing of thermal breakup of the nearshore ice cover was found to correlate with the measured downwelling solar radiation in june and july this linkage allows for the development of an operational forecast of landfast ice breakup results from forecasts during 2 years demonstrate that thermal breakup can be predicted to within a couple of days 2 weeks in advance the cumulative shortwave energy absorbed by the ice cover provides for a measure of the state of ice decay and potential for disintegration discriminating between the two modes of breakup bears the potential to greatly increase forecasting skill