the role of the barents sea in the arctic climate system present global warming is amplified in the arctic and accompanied by unprecedented sea ice decline located along the main pathway of atlantic water entering the arctic the barents sea is the site of coupled feedback processes that are important for creating variability in the entire arctic air ice ocean system as warm atlantic water flows through the barents sea it loses heat to the arctic atmosphere warm periods like today are associated with high northward heat transport reduced arctic sea ice cover and high surface air temperatures the cooling of the atlantic inflow creates dense water sinking to great depths in the arctic basins and 60 of the arctic ocean carbon uptake is removed from the carbon saturated surface this way recently anomalously large ocean heat transport has reduced sea ice formation in the barents sea during winter the missing barents sea winter ice makes up a large part of observed winter arctic sea ice loss and in 2050 the barents sea is projected to be largely ice free throughout the year with 4 c summer warming in the formerly ice covered areas the heating of the barents atmosphere plays an important role both in arctic amplification and the arctic heat budget the heating also perturbs the large scale circulation through expansion of the siberian high northward with a possible link to recent continental wintertime cooling large air ice ocean variability is evident in proxy records of past climate conditions suggesting that the barents sea has had an important role in northern hemisphere climate for at least the last 2500 years

a 2000 year record of atlantic water temperature variability from the malangen fjord northeastern north atlantic a high resolution sedimentary record from the subarctic malangen fjord in northern norway northeastern north atlantic has been investigated in order to reconstruct variations in influx of atlantic water for the last 2000 years the fjord provides a regional oceanographic climatic signal reflecting changes in the north atlantic heat flux at this latitude because of its deep sill and the relatively narrow adjoining continental shelf the reconstructions are based on oxygen and carbon isotopic studies of benthic foraminifera from a high accumulation basin in the malangen fjord providing subdecadal time resolution a comparison between instrumental measurements of bottom water temperatures at the core location and the reconstructed temperatures from benthic foraminiferal 18o for the same time period demonstrates that the stable isotope values reflect the bottom water temperatures very well the reconstructed temperature record shows an overall decline in temperature of c 1 c from c 40 bc to ad 1350 this

climate and oceanographic variability in the sw barents sea during the holocene the holocene section of the marine sediment core psh 5159n located in the sw barents sea has been studied at high resolution with a multiproxy approach a well stratified water column occurred at the site 11 9 8 ka bp the stratification was probably a result of a winter sea ice cover and or fresh warm surface waters during summer stratification and resultant reduction in air sea interaction allowed for warmer bottom water temperatures the general situation 11 9 8 ka bp could have been associated with an anomalous high pressure system over the nordic seas and the arctic ocean during the 11 10 5 ka bp interval the polar front was located close to the barents sea margin the polar front moved towards the site from 10 5 ka bp and from 9 8 to 7 5 ka bp it was probably located close to the site at 7 5 ka bp the polar front retreated eastwards as the present day oceanographic pattern established the mid holocene was in general characterized by rather stable conditions in contrast highly variable cond

tide induced head fluctuations in a confined aquifer with sediment covering its outlet at the sea floor 1 a confined coastal aquifer usually extends under the sea for some distance with its submarine outlet covered by a thin layer of sediment with properties dissimilar from the aquifer previous theoretical studies neglected this outlet capping in this paper an analytical solution is derived for a confined aquifer subject to tidal fluctuations with a leaky boundary condition at the outlet capping for the cases that offshore length of the aquifer and or the leakance of the outlet capping are either zero or infinity existing solutions in literature are obtained it is shown that our analytical solution can also be used to describe the tidal wave propagation in a confined aquifer extending infinitely under a tidal river the full solution agreed well with the observations in a piezometer in the jahe river basin in china 200 m inland from the coastline where the tide induced head fluctuations without delay were observed but cannot be explained using previous analytical and numerical solutions ignoring the effect of the outlet capping the sensitivity analysis showed that the combined actions of the tidal loading and outlet capping lead to complex dependency of the head fluctuation on the outlet capping s leakance when the offshore confined aquifer is short the inland head fluctuation increases with the outlet capping s leakance in this case significant negative phase shift occurs if the leakance is small for offshore aquifer length greater than a threshold value the inland head fluctuations are independent of this length and the outlet capping s leakance

variability of the north atlantic current during the last 2000 years based on shelf bottom water and sea surface temperatures along an open ocean shallow marine transect in western europe marine localities on the west european shelf have been studied to reconstruct the nearshore palaeoceanography of the last two millennia the sites form a transect from the iberian margin northeastward via scotland to western norway and iceland proxies used for palaeoclimatic reconstructions include stable isotopes benthic and planktonic foraminfera diatoms dinoflagellates as well as geochemical and sedimentological parameters major changes as well as long term trends in oceanographic conditions are observed in the records including a general cooling trend through much of the last millennium there is a clear linkage between the atmospheric processes and the oceanic circulation and the ocean temperature variability in the records can be correlated with the so called mediaeval warm period and little ice age these oscillations are however by no means unique within the last two millennia as an example sea surface temperatures to the north of iceland and on the iberian margin were higher in the roman warm period than at any time during the mediaeval warm period however the palaeoceanographic record generally supports a distinct cooling at the transition between the mediaeval warm period and the little ice age while a number of records indicate a warming of coastal and shelf waters during the last 200 years the twentieth century does not appear to be unusual when the proxy records spanning the last two millennia are examined

seafloor geomorphology of the sw barents sea and its glaci dynamic implications abstract three dimensional 3d reflection seismic imaging techniques provide a unique means of identifying large scale submarine geomorphic features produced by former ice sheets we have used such techniques to image the geomorphology of the sw barents sea but using a dense grid of 2d seismic covering a 240 000 2 km large study area supplemented with 3d seismic from selected areas the study area is located at the convergence of ice flow from the former fennoscandian barents sea and svalbard ice sheets the morphology of the major cross shelf troughs is characterized by elongated ridge groove features interpreted to be glacial bedforms produced by fast flowing grounded glaciers mega scale glacial lineations have been grouped into distinct flow sets related to three specific ice flow events these events document the last glacial maximum lgm and two readvances during deglaciation of specific interest is a detailed and well preserved set of seafloor imprints in the bjornoyrenna trough which acted as the main pathway for ice streams draining the surrounding ice sheets the geomorphic features indicate that bjornoyrenna hosted six separate ice stream lobes that diverged fan like at their margins but were not all active simultaneously an end moraine zone 68 km wide up to 85 m high and 300 km long filled the whole width of this major glacial trough as a result of high sediment flux within sub ice stream deformable beds the imprint of this ice stream system can be followed on our seabed images for 500 km however detailed geomorphologic elements demonstrate that these imprints reflect time transgressive behaviour and do not indicate the length or width of single ice streams the seismic derived seafloor geomorphology demonstrates that the barents sea ice behaved in a much more dynamic way during the last glaciation than previously assumed with major shifts between ice originating from the fennoscandian spitsbergen and barents sea ice sheets

wave set up wave run up and beach water table interaction between surf zone hydraulics and groundwater hydraulics the relationship between wave set up wave run up and beach water table is reviewed starting from the work and ideas of nielsen and using laboratory observations of wave set up and beach water table in beaches formed from various beach materials under similar wave conditions a new more extensive analysis of wave set up on impermeable fixed plane beaches has been made using all available experimental data scaling parameters for set up and water depth based upon both deep water and breaking wave conditions and incorporating appropriate forms of the surf similarity parameter are developed the dimensionless set up parameters are of the form n long right leg n long right leg b h0 0 n where 0 3 n 0 5 for deep water wave parameters and n long right leg n long right leg b hb tan ib n where n 0 4 for breaking wave conditions 0 tan ho lo and ib hb 1 2 g 1 2 t tan

holocene climate variability of the norwegian atlantic current during high and low solar insolation forcing 1 a high resolution sediment core from the voring plateau has been studied to document the centennial to millennial variability of the surface water conditions during the holocene climate optimum hco and the late holocene period lhp in order to evaluate the effects of solar insolation on surface ocean climatology quantitative august summer sea surface temperatures sssts with a time resolution of 2 40 years are reconstructed by using three different diatom transfer function methods spectral and scale space methods are applied to the records to explore the variability present in the time series at different time scales the ssst development in core md95 2011 shows a delayed response to northern hemisphere maximum summer insolation at 11 000 years b p the record shows the maximum ssst of the hco to be from 7 3 to 8 9 kyr b p which implies that the site was located in the regional warm water pool removed from the oceanic fronts and arctic waters superimposed on the general cooling trend are higher frequency variabilities at time scales of 80 120 210 320 320 640 and 640 1280 years the climate variations at the time scale of 320 640 years are documented both for periods of high and low solar orbital insolation we found evidence that the submillennial scale mode of variability 640 900 years in ssst evident during the lhp is directly associated with varying solar forcing at the shorter scale of 260 450 years the ssst during the lhp displays a lagged response to solar forcing with a phase locked behavior indicating the existence of a feedback mechanism in the climate system triggered by variations in the solar constant as well as the role of the thermal inertia of the ocean the abruptness of the cooling events in the lhp especially pronounced during the onsets of the holocene cold period i approximately 2300 years b p and the little ice age approximately 550 years b p can be explained by a shutdown of deep convection in the nordic seas in response to negative solar insolation anomalies these cooling events are on the order of 1 5 c

hydraulic head response of a confined aquifer influenced by river stage fluctuations and mechanical loading summary the response to river stage fluctuation of a drilled well penetrating a confined aquifer was simulated using a stream aquifer interaction algorithm because the confined aquifer is overlaid by a water table aquifer the algorithm was coupled with formulae used to correct the heads for mechanical loading the coupling of stream aquifer interaction and mechanical loading models was tried for the first time in this study the test site was a drilled well installed on the montalto uffugo aquifer located at the calabria university groundwater test field calabria region south of italy this aquifer comprises a 44 m thick sand bank bounded on bottom and top by clay layers and covered by a 7 m thick sandy conglomerate being adjacent to the mavigliano river overall the head changes caused by a river stage raise represented a contribution of 49 3 57 8 to the total head while mechanical loading accounted for the remaining 50 7 32 2 the loading was triggered by a sequence of short spaced rainfall events lasting for a total of 167 days which caused recharge to the unconfined aquifer thickening the water column by some 3 1 m

wave setup and runup an integrated approach abstract by extending and sharpening the usual definitions of water depth and mean water level throughout the swash zone it is shown that the elevation of the shore line on an impermeable beach is logically at the runup limit not at the average water line level thus the runup limit becomes a point on the setup profile and this leads to a significant expansion of the experimental information on setup which can be extracted from the existing literature from the experimental data base thus extended a first approximation to a universal description of setup profiles is derived i e the most appropriate vertical and horizontal scaling parameters are suggested for the shape of the mean water surface in the inner surf zone existing setup data show that traditional simplistic setup models are inadequate for modelling the shape of the most landward part of the mean water surface and hence for predicting the shoreline setup instead it is suggested to base estimates of the shoreline setup on the relation between this quantity and the maximum runup height together with well proven runup formulae the validity of this approach needs to be established quantitatively however through simultaneous measurements of runup and mean water surface on in natural beaches

historical variability of sea ice edge position in the nordic seas 1 historical ice observations in the nordic seas from april through august are used to construct time series of ice edge position anomalies spanning the period 1750 2002 while analysis showed that interannual variability remained almost constant throughout this period evidence was found of oscillations in ice cover with periods of about 60 to 80 years and 20 to 30 years superimposed on a continuous negative trend the lower frequency oscillations are more prominent in the greenland sea while higher frequency oscillations are dominant in the barents the analysis suggests that the recent well documented retreat of ice cover can partly be attributed to a manifestation of the positive phase of the 60 80 year variability associated with the warming of the subpolar north atlantic and the arctic the continuous retreat of ice edge position observed since the second half of the 19th century may be a recovery after significant cooling in the study area that occurred as early as the second half of the 18th century

structural analysis of fault populations along the oblique ultra slow spreading knipovich ridge north atlantic ocean 74 30 n 77 50 n abstract the knipovich ridge 73 30 78 40 n is an extreme end member of the mid ocean ridge spreading system both in terms of spreading rate fault population characteristics conform to observational and experimental analyses of oblique rifting and spreading systems for the ridge as a whole faults in the axial region are short straight isolated not linked into complex fault zones and exhibit length scaling relationships characteristic of young and active fault systems faults are generally oblique to both the ridge axis and the spreading direction and orientations vary systematically with angle between ridge and spreading direction along axis analysis reveals the influence of axial segmentation on fault population characteristics segment centers are dominated by faults perpendicular and sub perpendicular to plate motion with longer characteristic length and generally lower fracture density conversely segment ends are dominated by faults striking oblique to plate motion with shorter characteristic length and generally higher fracture density we infer that faulting in segment centers is strongly influenced by the mechanical effects of dike intrusion perpendicular to plate motion while faulting in segment ends is controlled by the mechanics of oblique rifting non transform discontinuities and or accommodation zones the contrasts between these distinct structural and mechanical settings along the ridge axis are accentuated by the high obliquity and ultra slow spreading rate of this spreading system

tidal influence on self potential measurements long term surface and borehole self potential sp monitoring was conducted in the uk chalk aquifer at two sites the coastal site is c 1 7 km from the coast and the inland site is c 80 km from the coast at both sites power spectral density analysis revealed that sp data contain the main ocean tidal periodic components however the principal lunar component m2 the dominant ocean tidal component was most significant at the coastal site the m2 signal in surface referenced sp data at the inland site was partly due to telluric currents caused by the geomagnetic ocean dynamo earth and or atmospheric tides also contributed as the sp power spectrum was not typical of a telluric electric field the m2 component in borehole referenced data at the inland site was below the significance level of the analysis method and was two orders of magnitude smaller than the m2 signal in borehole referenced sp data at the coastal site the tidal response of the sp data in the coastal borehole is therefore primarily driven by ocean tides these cause changes in fluid pressure and chemical concentration gradients within the coastal aquifer leading to time varying electrokinetic and exclusion diffusion potentials borehole referenced sp measurements could be used to characterize and monitor tidal processes in coastal aquifers such as the intrusion of seawater

the role of the north atlantic drift in the millennial timescale glacial climate fluctuations abstract the greenland ice core records show that the overall cold climate of the last glacial period was repeatedly interrupted by short rapid warmings the events known as dansgaard oeschger d o events are strongly imprinted in the north atlantic marine records suggesting that they were linked to north atlantic circulation changes however the causes of the d o events are poorly understood and they represent one of the most intriguing puzzles of the last glacial period in order to investigate a possible mechanism we have studied variations in the distribution of benthic and planktonic foraminifera oxygen isotopes and ice rafted debris during the last glacial period in eight cores from the north atlantic and the nordic seas taken at mid depth from 853 to 1760 m the parameters indicate in agreement with previous studies that the circulation system during the interstadials resembled the present system atlantic surface water flowed north into the nordic seas where most of it sank through convection and as cold deep water flowed back into the north atlantic during the stadials a halocline was established in the nordic seas and in the northernmost part of the north atlantic and the outflow from the nordic seas stopped however below the cold light surface layer the relatively warm water of the north atlantic drift continued to flow across the north atlantic and into the nordic seas here warming up the deep water masses we suggest that the warm water gradually made the water column unstable the pivotal abrupt climate warmings were caused by sudden upwelling of the deep warm water masses causing overturning of the entire water column and onset of convection

structural characterization of an island aquifer via tidal methods 1 a set of water level time series collected along a transect through a sedimentary island aquifer was used to test the utility of various simple models of ocean tidal propagation in bounded one dimensional aquifers fourier spectra were calculated for the ocean tidal modes and compared with spectra measured in wells along the island transect other sources of fluctuation could be neglected an observed spatial bias in the well responses attenuations and lags could not be modeled by a homogeneous aquifer theory a theory involving composite heterogeneity accounted well for the spatial bias yielding estimates of aquifer transmissivities and storage coefficients indicating a fivefold difference in hydraulic diffusivity along the transect a lack of well locations toward one end of the transect reduced the statistical significance of this result with correlations between regression parameters evident at the same time a second bias was seen involving the ratio of signal amplitude and lag with penetration distance into the aquifer as observed in prior tidal studies a brief set of numerical experiments showed that horizontal layering in aquifer properties was the most probable cause of this propagation bias application of these results to the island data set supported a conceptual stratigraphic model of a highly conductive sloping stratum underlying a less conductive superficial sand layer this model is inconsistent with well logs along the island transect but is supported by additional off transect well logs it was concluded that one dimensional tidal propagation models may be useful in inverse characterization of aquifers with macroscale hydrogeological structures and that the analysis of measured propagation bias has the potential to yield extra information on aquifer properties in the vertical direction

a process study of mesoscale meanders and eddies in the norwegian coastal current abstract a series of noaa satellite images shows that the norwegian coastal current ncc over the norwegian trench was disturbed by mesoscale meanders with 60 100 km wavelengths in the first several days the meanders grew and propagated northward some meanders were pinched off seaward forming anticyclonic eddies the flow pattern became very chaotic around 23 february and then on 25 27 february it changed into a systematic pattern again with three cyclonic vortices developing on the offshore side of the ncc axis accompanied by seaward meanders or separated anticyclonic eddies on their northern sides acoustic doppler current profiler measurement showed these vortices to have significant barotropic components and to move northward at 5 km day 1 a quasi geostrophic two layer model is employed first to show the basic behavior of the system model sensitivity is examined with various vertical profiles of the initial jet and various bottom topography baroclinic instability is an essential mechanism t

natural variability of benthic foraminiferal assemblages and metal concentrations during the last 150 years in the ingoydjupet trough sw barents sea abstract while today the sw barents sea is a relatively un impacted and uncontaminated area industrial activities related to the petroleum industry are projected to increase in the coming decades this makes the area a valuable natural laboratory to establish pre impacted baselines as a precursor for future seabed monitoring programs here we present benthic foraminiferal assemblages and metal concentrations in four sediment cores from the ingoydjupet trough sw barents sea covering approximately the last 150 years this information supports the application of foraminiferal assemblages as a bio monitoring tool applicable in high latitudes at all stations metal concentrations in the sediment correspond to no effect concentrations the downcore metal concentrations are mainly attributed to natural variability of the clay fraction and total organic content of the sediments agglutinated foraminifera are poorly preserved down core patterns in the calcareous foraminiferal assemblages suggest an enhanced food supply as a result of increased atlantic water inflow through the region during the last 150 years at near shore stations the norwegian coastal current additionally influences assemblages decadal scale climatic oscillations are indicated by increased calcareous fluxes and are attributed to variability in the food rich atlantic water this study serves as an important baseline data set prior to increasing industrial activities in the sw barents sea and thereby contributes to a better understanding of natural environmental variability

environmental changes off north iceland during the deglaciation and the holocene foraminifera diatoms and stable isotopes abstract a combined study of foraminifera diatoms and stable isotopes in marine sediments off north iceland records major changes in sea surface conditions since about 15 800 cal years yr bp results are presented from two gravity cores obtained at about 400 m water depth from two separate sedimentary basins on each side of the submarine kolbeinsey ridge the chronology of the sedimentary record is based partly on ams 14c dates partly on the vedde and the saksunarvatn tephra markers as well as the historical hekla ad 1104 tephra during the regional deglaciation the planktonic foraminiferal assemblages are characterised by consistently high percentages of sinistrally coiled neogloboquadrina pachyderma however major environmental variability is reflected by changes in stable isotope values and diatom assemblages low 18o values indicate a strong freshwater peak as well as possible brine formation by sea ice freezing during a pre bolling interval greenland stadial 2 corresponding to the heinrich 1 event the foraminifera suggest a strong concurrent influence of relatively warm and saline atlantic water and both the foraminifera and the diatoms suggest mixing of cold and warm water masses similar but weaker environmental signals are observed during the younger dryas greenland stadial 1 around the level of the vedde ash each freshwater peak is succeeded by an interval of severe cooling both at the beginning of the bolling allerod interstadial complex greenland interstadial 1 and during the preboreal presumably associated with the onset of intense deep water formatiom in the nordic seas the holocene thermal optimum between 10 200 and about 7000 cal years yr bp is interrupted by a marked cooling of the surface waters around 8200 cal yr bp this cold event is clearly expressed by a pronounced increase in the percentages of sinistrally coiled n pachyderma corresponding to a temperature decrease of about 3 c a general cooling in the area is indicated after 7000 6000 cal yr bp both by the diatom data and by the planktonic foraminiferal data after a severe cooling around 6000 cal yr bp the planktonic foraminiferal assemblages suggest a warmer interval between 5500 and 4500 cal yr bp minor temperature fluctuations are reflected both in the foraminiferal and in the diatom data in the upper part of the record but the time resolution of the present data is not high enough to pick up details in environmental changes through the late holocene

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

reconstructions of surface ocean conditions from the northeast atlantic and nordic seas during the last millennium we undertake the first comprehensive effort to integrate north atlantic marine climate records for the last millennium highlighting some key components common within this system at a range of temporal and spatial scales in such an approach careful consideration needs to be given to the complexities inherent to the marine system composites therefore need to be hydrographically constrained and sensitive to both surface water mass variability and three dimensional ocean dynamics this study focuses on the northeast ne north atlantic ocean particularly sites influenced by the north atlantic current a composite plus regression approach is used to create an inter regional ne north atlantic reconstruction of sea surface temperature sst for the last 1000 years we highlight the loss of spatial information associated with large scale composite reconstructions of the marine environment regional reconstructions of ssts off the norwegian and icelandic margins are presented along with a larger scale reconstruction spanning the ne north atlantic the latter indicates that the medieval climate anomaly warming was most pronounced before ad 1200 with a long term cooling trend apparent after ad 1250 this trend persisted until the early 20th century while in recent decades temperatures have been similar to those inferred for the medieval climate anomaly the reconstructions are consistent with other independent records of sea surface and surface air temperatures from the region indicating that they are adequately capturing the climate dynamics of the last millennium consequently this method could potentially be used to develop large scale reconstructions of ssts for other hydrographically constrained regions

factors influencing the distribution patterns of recent deep sea benthic foraminifera east of new zealand southwest pacific ocean abstract this study investigates which combination of environmental factors most strongly influences the distribution patterns of benthic foraminferal tests 0 63 m in a region bisected by the subtropical front east of new zealand seafloor sample sites extend from outer shelf 90 m to abyssal 4700 m depths across substrates ranging from biogenic terrigenous gravelly sand to hemipelagic mud and occur under the influence of antarctic intermediate water aaiw and circumpolar deep waters as well as receiving detritus from both subtropical and subantarctic surface water masses elevated values of the planktic foraminiferal fragmentation index and reworked small paleogene planktic foraminifera at outer shelf and bathyal depths coincide with areas of strong bottom currents q mode cluster analysis on the census counts of 398 benthic species clusters the 66 samples into three large groups shallow bathyal abyssal and at a lower level 10 mappable associations are recognised a combination of canonical correspondence analysis and a correlation coefficient matrix was used to relate the faunal data to a set of measured environmental proxies these analyses show that factors that have a relationship with depth are the most significant in determining foraminiferal distribution the principal environmental factors which appear to most strongly influence this benthic foraminiferal distribution are dissolved oxygen content in bottom waters sustainability of organic carbon flux rates seasonality of food supply lateral advection of water masses bottom water carbonate corrosiveness energetic state at the benthic boundary layer grain size composition of substrate salinity and temperature of the bottom waters shallow water associations 90 1250 m dominated by cassidulina carinata and trifarina angulosa occur within coarse substrates under well oxygenated high energy regimes and sustained food input the occurrence of the bathyal associations 230 2840 m dominated by c carinata alabaminella weddellensis and abditodentrix pseudothalmanni closely mirrors the distribution of aaiw within a region of variable food supply the sustainability of food supply combined with bottom water type and associated ventilation and dissolution strongly influence the composition of abyssal associations 1200 4700 m mostly dominated by epistominella exigua and a weddellensis

wave set up on coral reefs 2 set up on reefs with various profiles abstract all available laboratory data for wave set up on two dimensional reef profiles of various shapes have been compared with data from an idealised horizontal reef with a steep reef face gourlay 1996 the data is generally well represented by a relationship between the relative set up parameter gh r t o and the submergence parameter g h r h r h o and the relative set up on reef profiles of natural form is found to be less than that observed on the idealised horizontal reef the important influences of reef rim slope and variable water depths on the reef top have been investigated and some methods for allowing for them are suggested comparison of data for irregular waves with that for regular waves has led to the development of a simple method for estimating the effects of wave groups upon the magnitude of the steady state mean wave set up gh r the results of the analyses are applied to the determination of wave set up and its effects at three specific coral reef sites

the distribution of living benthic foraminifera on the continental slope and rise off southwest norway abstract surface sediment samples taken by corer from 45 stations on the norwegian continental margin and in the norway basin have been investigated for their benthic foraminiferal content unlike previous studies the living benthic foraminiferal fauna was differentiated from empty tests comprising the foraminiferal death assemblage factor analysis of both the living and dead faunal data reveals six living species assemblages and five corresponding dead assemblages the additional living assemblage is characterized by the arenaceous speciescribrostomoides subglobosum that dominates between 1400 and 2000 m water depth but is rare in the dead faunal data trifarina angulosa and to a lesser extent cibicides lobatulus characterize the shallowest foraminiferal assemblage from 200 to 600 m water depth where it is associated with strong bottom currents and warm saline atlantic water of the north atlantic drift on the slope between 600 and 1200 m water depth themelonis zaandami species assemblage dominates particularly in areas characterized today by rapid sedimentation of terrigeneous material between 1000 and 1400 m depth where the slope is covered by fine grained organic rich terrigeneous mud the living foraminiferal assemblage is characterized bycassidulina teretis andpullenia bulloides below 1400 m three foraminiferal assemblages are found c subglobosum is found from 1400 to 2000 m cibicidoides wuellerstorfi andepistominella exigua predominantly live from 2000 to 3000 m water depth and below 3000 m oridorsalis umbonatus andtriloculina frigida dominate the fauna all of theelphidium excavatum tests found in this study and thecassidulina reniforme tests found above 500 m water depth were found to be reworked analysis of the sediment grain size distribution and the organic carbon content in surface samples from the deepest stations suggest that the abundance ofc wuellerstorfi ande exigua is positively correlated to relatively coarse caused by planktic foraminifera and organic rich sediments whereas high frequencies ofo umbonatus andt frigida coincide with low organic carbon content we suggest thatc wuellerstorfi is adapted to deep sea environments with relatively high food supply tolerating relatively low interstitial water oxygen content whereaso umbonatus may tolerate lower food supply prefering well oxygenated interstitial waters

wave generated flow on coral reefs an analysis for two dimensional horizontal reef tops with steep faces waves breaking on the seaward rim of a coral reef generate a flow of water from the exposed side of the reef to the sheltered side and or to either channels through the reef rim or lower sections of the latter this wave generated flow is driven by the water surface gradient resulting from the wave set up created by the breaking waves this paper reviews previous approaches to modelling wave generated flows across coral reefs and discusses the influence of reef morphology and roughness upon these flows laboratory measurements upon a two dimensional horizontal reef platform with a steep reef face provide the basis for extending a previous theoretical analysis for wave set up on a reef in the absence of a flow gourlay m r 1996b wave set up on coral reefs 2 set up on reefs with various profiles coastal engineering 28 1755 to include the interaction between a unidirectional flow and the wave set up the laboratory model results are then used to demonstrate that there are two basic reef top flow regimes reef top control and reef rim control using open channel flow theory analytical relationships are derived for the reef top current velocity in terms of the offreef wave conditions the reef top water depth and the physical characteristics of the reef top topography the wave set up and wave generated flow relationships are found to predict experimental values with reasonable accuracy in most cases the analytical relationships are used to investigate wave generated flows into a boat harbour channel on heron reef in the southern great barrier reef c 2005 elsevier b v all rights reserved

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

correlation between textural characteristics of marine sediments and benthic foraminifera in highly anthropogenically altered coastal areas abstract the coastal zone is the most variable area in the marine system in terms of environmental parameters and it is characterised by the highest granulometric variability considering that the distribution of benthic foraminifera is controlled by several biotic and abiotic factors including sediment texture this may be considered one of the main factors influencing foraminiferal assemblage composition the role of sediment grain size on foraminiferal species distribution has been recognised by several studies but only in a few cases it has been considered from a quantitative viewpoint on this rationale 137 sediment samples collected in three different italian national relevance sites bagnoli baia and augusta affected by different type and degree of pollution were analysed for grain size and benthic foraminifera although the influence of pollution on foraminifera distribution in these areas had been recognised in earlier studies the present research applied statistical analysis pearson correlation and co inertia analysis in order to highlight the correlation between sediment fractions and foraminiferal species the correlation found in all sites between the most abundant species and specific sediment fractions indicated that sediment grain size is a primary factor controlling species distribution the effect of sediment type conditions the distribution of previously recognised pollution tolerant species which show preference for silty and or clayey sediments because muddy sediments favour contaminant accumulation such species are more exposed to polluted habitats and consequently their tolerance to anthropogenically altered conditions may be considered an adaptive strategy

bottom currents interpreted from iceberg ploughmarks revealed by multibeam data at tromsoflaket barents sea abstract multibeam data have been acquired on eastern tromsoflaket a bank in the southwestern barents sea comprising a plateau detailed examination of the multibeam backscatter data however reveals a high variability of sediments especially in and around iceberg ploughmarks we observe coarser sediments on the levees either side of the ploughmarks than inside the furrows moreover we frequently note asymmetries in the distribution of fine sediments across these ploughmark features drawing inspiration from previous studies of bottom currents which use the distribution of sediments across bedforms e g sand waves we have interpreted the direction of bottom currents on tromsoflaket by examining the local distribution of fine sediments across iceberg ploughmarks which are the most prominent bedform in this area further integration of our results with existing grain size current speed models have allowed estimates of the bottom current speeds to be obtained such interpretations are particularly valuable in this area where availability of bottom current measurements sparse our approach makes valuable and novel use of multibeam data and results show good agreement with the limited set of available current data and models we can identify near bottom pathways for the norwegian atlantic current and norwegian coastal current the two major current systems in this region and the patterns of circulation help to explain the sedimentation regime and identify recent erosion and deposition areas

wave set up on a natural beach wave set up the superelevation of mean water level owing to the presence of breaking incident waves was measured at the shoreline of a natural beach offshore pressure sensors monitored incident wave conditions the set up of the shoreline was found to be about 0 17hs where hs is the significant wave height in deep water

recent benthic foraminiferal associations and ecology of the scotia sea and argentine basin abstract we investigated 88 surface sediment samples taken with a multiple corer from the southwestern south atlantic ocean for their live rose bengal stained and dead benthic foraminiferal content using q mode principal component analysis six live and six dead associations are differentiated live and dead association distributions correspond fairly well differences are mainly caused by downslope transport and selective test destruction in addition four potential fossil associations are calculated from the dead data set after removal of non fossilizable species these potential fossil associations are expected to be useful for paleoceanographic reconstructions environments are described in detail for the live and potential fossil associations and for selected species along the upper argentine continental slope strong bottom currents control the occurrence of live dead and potential fossil angulogerina angulosa associations here particles of a high organic carbon flux rate remain suspended below this high energy environment live dead and potential fossil uvigerina peregrina dominated associations correlate with enhanced sediment organic carbon content and still high organic carbon flux rates the live a angulosa and u peregrina associations correlate with high standing crops furthermore live and dead epistominella exigua nuttallides umbonifer associations were separated dominance of a nuttallides umbonifer potential fossil association relates to coverage by antarctic bottom water aabw and lower circumpolar deep water lcdw above the calcite compensation depth ccd three associations of mainly agglutinated foraminifera occur in sediments bathed mainly by aabw or cdw a reophax difflugiformis association was found in mud rich and diatomaceous sediments below the ccd a psammosphaera fusca association occurs in coarse sediments poor in organic carbon while a cribrostomoides subglobosus ammobaculites agglutinans association covers a more variable environmental range with mud contents exceeding 30 one single eggerella bradyi martinottiella communis association poor in both species and individuals remains from the agglutinated associations below the ccd if only preservable species are considered for calculation

estimating hydraulic properties of coastal aquifers using wave setup summary wave setup is the elevated mean water table at the coast associated with the momentum transfer of wave breaking which occurs generally over several days groundwater responses to wave setup were observed as far as 5 km inland in central maui hawaii the analysis showed that at times of energetic swell events wave driven water table overheights dominate low frequency groundwater fluctuations associated with barometric pressure effects matching peak frequencies at 1 7 10 6 hz and 3 7 10 6 hz were identified in setup and observed head using spectral decomposition similar to tides the setup propagation through the aquifer shows exponentially decreasing amplitudes and linearly increasing time lags due to the longer periods of setup oscillations the signal propagates deeper into the aquifer 10 km in central maui than diurnal tides 5 km and can therefore provide information on greater length scales hydraulic diffusivity was estimated based on the setup propagation an effective diffusivity of 2 3 107 m2 d is consistent with aquifer parameters based on aquifer tests and tides a one dimensional numerical model supports the results of the analytical solution and strengthens the suitability to estimate hydraulic parameters from setup propagation the methodology is expected to be beneficial to high permeability coastal environments such as on volcanic islands and atolls

beach water table fluctuations due to wave run up capillarity effects high frequency beach water table fluctuations due to wave run up and run down have been observed in the field waddell 1976 such fluctuations affect the infiltration exfiltration process across the beach face and the interstitial oxygenation process in the beach ecosystem accurate representation of high frequency watertable fluctuations is of importance in the modeling of 1 the interaction between seawater and groundwater more important the effects on swash sediment transport and 2 the biological activities in the beach ecosystem capillarity effects provide a mechanism for high frequency water table fluctuations previous modeling approaches adopted the assumption of saturated flow only and failed to predict the propagation of high frequency fluctuations in the aquifer in this paper we develop a modified kinematic boundary condition kbc for the water table which incorporates capillarity effects the application of this kbc in a boundary element model enables the simulation of high frequency water table fluctuations due to wave run up numerical tests were carried out for a rectangular domain with small amplitude oscillations the behavior of water table responses was found to be similar to that predicted by an analytical solution based on the one dimensional boussinesq equation the model was also applied to simulate the water table response to wave run up on a sloping beach the results showed similar features of water table fluctuations observed in the field in particular these fluctuations are standing wave like with the amplitude becoming increasingly damped inland we conclude that the modified kbc presented here is a reasonable approximation of capillarity effects on beach water table fluctuations however further model validation is necessary before the model can confidently be used to simulate high frequency water table fluctuations due to wave run up

benthic foraminiferal assemblages from the eastern weddell sea between 68 and 73 s distribution ecology and fossilization potential surface sediment samples taken with a vented box corer from the eastern weddell sea on four profiles perpendicular to the continental margin have been investigated for their benthic foraminiferal content the live fauna was differentiated from empty tests comprising the foraminiferal death assemblage based on the dead assemblages potential fossil assemblages were calculated to facilitate the analogy with late neogene core material five distinct live assemblages inhabit the continental margin today six dead assemblages and five potential fossil assemblages respectively correspond to these biocoenoses a predominantly calcareous live fauna dominated by trifarina angulosa is correlated with strong bottom currents and sandy sediments at the shelf break and on the uppermost continental slope below this on the upper slope down to 2000 m water depth the predominantly calcareous bulimina aculeata assemblage coincides with the core of warm 0 c weddell deep water and with fine and more organic rich sediments these calcareous live assemblages completely change composition during early diagenesis because of calcite dissolution within the uppermost sediment which depends largely on the grain size distribution of the sediment and the fluxes of organic matter therefore a still calcareous t angulosa dominated fossil assemblage indicates the sandy substrates on the shelf break and the upper slope whereas the deeper slope with hemipelagic calm sedimentation and with high fluxes of organic matter is indicated by martinottiella nodulosa the characteristic arenaceous fossil remnant of the former predominantly calcareous live b aculeata fauna on a continental terrace between 2500 and 3500 m water depth cribrostomoides subglobosus dominates the live fauna but because of rapid disintegration of the empty tests of this agglutinated species a predominantly calcareous fauna characterized by oridorsalis umbonatus and epistominella exigua comprises the dead assemblage and the potential fossil assemblage respectively on the lower continental slope between the carbonate lysocline 3500 m and the carbonate compensation depth 4000 m tests of nuttallides umbonifer are the characteristic dead and potential fossil remnants of a former predominantly arenaceous live fauna which is associated with the lower part of the antarctic bottom water aabw this corroborates earlier investigations suggesting a relationship between the carbonate corrosiveness of water masses and the distribution of n umbonifer this is important for inferring paleo routes and estimates of paleo production rates of aabw during the neogene

analysis of tide and offshore storm induced water table fluctuations for structural characterization of a coastal island aquifer analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean this study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal as well as offshore storm pulse signals through a coastal aquifer offshore storms produce high wave activity but are not necessarily linked to significant onshore precipitation in this study we focused on offshore storm events during which no onshore precipitation occurred extensive groundwater level data collected on a sand barrier island sable island ns canada show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone two dimensional groundwater flow simulations were conducted to test the leaky confined unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined unconfined coastal aquifers this study illustrates that analysis of offshore storm signal propagation in addition to tidal signal propagation provides a valuable and low resource approach for large scale characterization of permeable heterogeneous coastal aquifers such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate

setup and swash on a natural beach wave setup and swash statistics were calculated from 154 runup time series measured on a moderately steep beach under incident waves varying from 0 4 to 4 0 m significant wave height when scaled by the incident wave height setup swash height and total runup the sum of setup and half the swash height were found to vary linearly with the surf zone similarity parameter 0 h0 l0 1 2 the foreshore slope appeared the appropriate value for the calculation of 0 although the setup data showed some influence of an offshore bar at low tide for low irribaren numbers the swash height in the incident frequency band becomes saturated while for high irribaren numbers no such signs of saturations were seen thus the infragravity band appears to become dominant in the swash below some value of 0 for these data that value is approximately 1 75 although there is considerable scatter associated with that estimate

late glacial holocene clay minerals elucidating glacial history in the sw barents sea abstract detailed investigations of the distribution of clay minerals of late glacial holocene sediments from the sw barents sea provide important new information about the provenance and transport paths of the sediments this information leads to better understanding of the onset of the last deglaciation and subsequent advances retreats of the barents sea and fennoscandian ice sheets the results show interaction and changes in the fennoscandian ice sheet and bjornoyrenna ice stream during the last deglaciation high illite content and maximum kaolinite content 18 700 cal yr b p indicate glacial erosion from both the fennoscandian ice sheet and bjornoyrenna ice stream lgm ii the occurrence of a c reniforme dominated benthic foraminiferal assemblage 18 700 cal yr b p indicates that the northern most cores site in ingoydjupet had already been deglaciated and was probably situated in a glacier distal environment in addition smectite content reaching its highest level concurrent with the presence of neogloboquadrina pachyderma sin dominated planktic foraminifera can be related to the strengthening of the atlantic current the inflow of the atlantic water may have triggered deglaciation of the fennoscandian ice sheet bolling interstadial a rapid increase in illite content reflecting strong melting of the fennoscandian ice sheet 15 000 cal yr b p indicates the onset of deglaciation in a core closer to the continent decrease of illite and ird content together with the deposition of laminated sediments during the older dryas stadial 15 000 14 000 cal yr b p indicates colder conditions and formation of at least seasonal sea ice in addition increased kaolinite content indicates increased glacial erosion of the bjornoyrenna ice stream the highest values of illite content and increased ird content 14 000 13 000 cal yr b p can be related to strong melting of the fennoscandian ice sheet a slight indication of the younger dryas cold period is given by the decrease in illite and ird contents all clay contents are more stable during holocene compared to lgm and the last deglaciation

sortable silt and fine sediment size composition slicing parameters for palaeocurrent speed and palaeoceanography fine sediment size 63 ixm is best measured by a sedimentation technique which records the whole size distribution repeated size measurement with intermediate steps of removal of components by dissolution allows inference of the size distribution of the removed component as well as the residue in this way the size of the biogenic and lithogenic noncarbonate fractions can be determined observations of many size distributions suggest a minimum in grain size frequency curves at 8 to 10 ixm the dynamics of sediment erosion deposition and aggregate breakup suggest that fine sediment behavior is dominantly cohesive below 10 1xm grain size and noncohesive above that size thus silt coarser than 10 ixm displays size sorting in response to hydrodynamlc processes and its properties may be used to infer current speed silt that is f mer than 10 ixm behaves in the same way as clay 2 xm useful parameters of the distribution are the 10 63 ixm mean size and the percentage 10 63 ixm in the fine fraction we cannot use size distributions to distinguish the nature of the currents therefore to infer water mass advection speeds i e the mean kinetic energy of the flow ku regions of high eddy kinetic energy ke must be avoided at the present such abyssal regions lie under the high surface k e of major current systems gulf stream kuroshio agulhas antarctic circmpolar current and brazil falldand currents in the argenthe basin this is probably a satisfactory guide for the pleistocene with regard to the carbonate subfraction of the size spectrum size modes due to both cocco iths and foramlnlferal fragments can be recognized and analyzed with the boundary between them again at about 10 lm the flux of less than 10 lm carbonate at pelagic sites above the lysocline is another candidate for a productivity indicator

applicability of analytical solutions to tidal propagation in circular islands abstract the propagation of tides into coastal aquifers is an important phenomenon in the migration of coastal contaminants for the representation of shoreline boundary conditions in regional scale groundwater models and for the estimation of aquifer properties based on tidal amplitude attenuation and or phase increase in this study an analytical solution to the propagation of tidal fluctuations in a radial flow field applicable to circular islands is compared to the existing straight coastline ferris solution the analytical solution is compared to numerical simulation using seawat of a simple harmonic ocean tide and its propagation within a circular island this represents the first attempt to combine a previous correction that allows seawat to simulate axisymmetric flow and a modification to seawat to create tidal boundary conditions bench testing the analytical solution against the numerical model confirms the numerical approach the circular island solution is compared to the ferris solution in terms of tidal amplitude decay and phase shift whereas amplitude decay from the ferris solution is valid only for near shore locations within circular islands the ferris solution produces reasonable phase lag estimates for typical aquifer diffusivities and for most locations within circular islands by comparing the ferris and circular island solutions we propose a correction factor to the ferris solution that allows it to be applied in circular boundary settings this extends the application of the widely applied ferris solution to a broader range of situations

swash aquifer interaction in the vicinity of the water table exit point on a sandy beach the coupling of sandy beach aquifers with the swash zone in the vicinity of the water table exit point is investigated through simultaneous measurements of the instantaneous shoreline swash front location pore pressures and the water table exit point the field observations reveal new insights into swash aquifer coupling not previously gleaned from measurements of pore pressure only in particular for the case where the exit point is seaward of the observation point the pore pressure response is correlated with the distance between the exit point and the shoreline in that when the distance is large the rate of pressure drop is fast and when the distance is small the rate decreases the observations expose limitations in a simple model describing exit point dynamics which is based only on the force balance on a particle of water at the sand surface and neglects subsurface pressures a new modified form of the model is shown to significantly improve the model data comparison through a parameterization of the effects of capillarity into the aquifer storage coefficient the model enables sufficiently accurate predictions of the exit point to determine when the swash uprush propagates over a saturated or a partially saturated sand surface potentially an important factor in the morphological evolution of the beach face observations of the shoreward propagation of the swash induced pore pressure waves ahead of the runup limit shows that the magnitude of the pressure fluctuation decays exponentially and that there is a linear increase in time lags behavior similar to that of tidally induced water table waves the location of the exit point and the intermittency of wave runup events is also shown to be significant in terms of the shore normal energy distribution seaward of the mean exit point location peak energies are small because of the saturated sand surface within the seepage face acting as a rigid lid and limiting pressure fluctuations landward of the mean exit point the peak energies grow before decreasing landward of the maximum shoreline position

tidal wave propagation in a coastal aquifer effects of leakages through its submarine outlet capping and offshore roof summary this paper considers a leaky aquifer system comprising an unconfined aquifer a confined aquifer and a confining layer the aquifer s roof the unconfined aquifer terminates at the coastline the confined aquifer and its roof extend under the sea for a certain distance the aquifer s submarine outlet is covered by a thin layer of sediment referred to as the outlet capping hereafter with properties dissimilar to the aquifer previous studies either neglected the leakage through the aquifer s roof or the outlet capping this paper considers both effects and gives an analytical solution to describe the tide induced head fluctuation in the aquifer system for aquifers with zero or infinite offshore length or with impermeable roof or outlet capping or without the outlet capping existing solutions in the literature are obtained we defined the threshold value for the offshore aquifer length which was found to be less than 5 km for typical coastal aquifer systems for an aquifer with its offshore length greater than the threshold the inland head fluctuation becomes insensitive to variations of this length and the outlet capping s leakance the leakage through the offshore roof decreases the threshold value when the offshore confined aquifer is short the inland head fluctuation increases with the outletcapping s leakance in this case negative phase shift occurs near the coastline only for aquifers with small leakages through the offshore roof and the outlet capping in general