structure of large amplitude internal solitary waves the horizontal and vertical structure of large amplitude internal solitary waves propagating in stratified waters on a continental shelf is investigated by analyzing the results of numerical simulations and in situ measurements numerical simulations aimed at obtaining stationary solitary wave solutions of different amplitudes were carried out using a nonstationary model based on the incompressible two dimensional euler equations in the frame of the boussinesq approximation the numerical solutions which refer to different density stratifications typical for midlatitude continental shelves were obtained by letting an initial disturbance evolve according to the numerical model several intriguing characteristics of the structure of the simulated large amplitude internal solitary waves like for example wavelength amplitude and phase speed amplitude relationship as well as form of the locus of zero horizontal velocity emerge consistent with those obtained previously using stationary euler models the authors approach which tends to exclude unstable oceanic internal solitary waves as they are filtered out during the evolution process was also employed to perform a detailed comparison between model results and characteristics of large amplitude internal solitary waves found in high resolution in situ data acquired north and south of the strait of messina in the mediterranean sea from this comparison the importance of using higher order theoretical models for a detailed description of large amplitude internal solitary waves observed in the real ocean emerge implications of the results showing the complexity related to a possible inversion of sea surface manifestations of oceanic internal solitary waves into characteristics of the interior ocean dynamics are finally discussed

typhoon induced highly nonlinear internal solitary waves off the east coast of korea 1 highly nonlinear internal solitary waves isws propagating both onshore and offshore were detected in a sar image taken approximately 19 hours after typhoon maemi s passage across the east coast of korea analysis of ocean buoy data suggests that the isws were generated by near inertial waves in response to typhoon wind the near inertial waves can propagate seaward due to a downwelling coastal jet positive relative vorticity offshore of the jet and interact with sharply varying topography producing the isws the area of sharply varying topography approximately 28 km off the coast is suggested as a source region for the isws simple calculations of wave speed based on the two layered korteweg devries kdv equation with upper layer thickness and densities at both layers fixed indicate that the isws were generated 6 hours prior to the time of the acquisition of the sar image approximately 13 hours after the typhoon passage consistent with simultaneous buoy measurements

airborne synthetic aperture radar tracking of internal waves in the strait of gibraltar abstract as part of the international gibraltar experiment we realized on june 22 and 24 1986 two surveys of the strait of gibraltar on board an aircraft equipped with a synthetic aperture radar our objective was to observe at spring tides and during two twelve hour tidal cycles at 24 h interval the generation of internal wave trains linked to the hydraulic jump formed west of the sill during the westward phase of the tidal current and their eastward propagation in the strait the speed of propagation of these waves and the effect of the diurnal component of the tide on their generation and propagation could then be determined our results suggest that two solitary waves of equal amplitude propagated eastwards in the strait on june 22 the tidal coefficient being equal to 92 with a speed relative to the ground of 2 1 to 2 6 m s 1 24 h later during the second survey on june 24 tidal coefficient 90 we observed the propagation of a train of non linear waves the speed of the leading wave of which being about 1 9 ms 1 our data show that other waves pass over the camarinal sill after the release of the bore and secondary internal wave trains are shown to propagate eastwards from there although our sar data show the appearance of waves west of the northern sill at about 4 h after high water hw the mechanism leading to their generation is not clear these waves could propagate eastwards all along the strait and or northwestwards along the western spanish coast they could be responsible for the solitary type events observed at the eastern entrance of the strait at about 7 h after hw by ziegenbein 1969 1970 these events are noticeable in the hydrological parameters time series of armi and farmer 1988 and in the high rate current data 2 min apart from their april 1986 cruise besides these alongstrait waves our sar data show the existence of cross strait waves and give an idea of their wavelength and speed of propagation their presence leads to perturbations in the current revealed by simultaneous current data at the camarinal sill and north of cape cires

advanced remote sensing of internal waves by spaceborne along track insar a demonstration with terrasar x since the seasat mission in 1978 satellite based synthetic aperture radar sar images have been used to study oceanic internal waves internal waves become visible in sar images because their orbital currents modulate the surface roughness while this leads to an accurate spatial representation of internal wave patterns the complexity of the imaging mechanism makes it difficult to derive actual currents and internal wave amplitudes from sar signatures we demonstrate in this paper how a more robust parameter retrieval is possible with along track interferometric sar insar data that resolve amplitudes and temporal phase changes of the backscattered signal together the latter of which are directly related to the scatterers line of sight velocities our example data set which was acquired by terrasar x in dual receive antenna mode at dongsha south china sea exhibits strong signatures of internal waves in the interferogram amplitude and phase we use a simple internal soliton parameterization and a numerical radar imaging model to find a plausible combination of internal wave parameters which leads to good agreement between simulated and observed signatures testing the sensitivity of radar amplitude and phase signatures to various parameters we show that along track insar data should generally permit more accurate and less ambiguous internal wave parameter retrievals than conventional sar images

el nino evolution during the holocene revealed by a biomarker rain gauge in the galapagos islands abstract the el nino southern oscillation enso represents the largest perturbation to the climate system on an inter annual time scale but its evolution since the end of the last ice age remains debated due to the lack of unambiguous enso records lasting longer than a few centuries changes in the concentration and hydrogen isotope ratio of lipids produced by the green alga botryococcus braunii which blooms during el nino rains in the galapagos islands indicate that the early holocene 9200 5600 yr bp was characterized by alternating extremes in the intensity and or frequency of el nino events that lasted a century or more our data from the core of the enso region thus calls into question earlier studies that reported a lack of el nino activity in the early holocene in agreement with other proxy evidence from the tropical pacific the mid holocene 5600 3500 yr bp was a time of consistently weak el nino activity as were the early middle ages 1000 1500 yr bp el nino activity was moderate to high during the remainder of the last 3500 years periods of strong or frequent el nino tended to occur during peaks in solar activity and during extended droughts in the united states great plains linked to la nina these changing modes of enso activity at millennial and multi centennial timescales may have been caused by variations in the seasonal receipts of solar radiation associated with the precession of the equinoxes and or changes in solar activity respectively

three dimensional to two dimensional cross strata transition in the lower pleistocene catanzaro tidal strait transgressive succession southern italy sandstone tidal cross strata are the predominant sedimentary feature of strait fill stratigraphic successions however although widely described in numerous studies tidal strait fill two dimensional and three dimensional cross strata have rarely been reported to occur in discrete intervals which are laterally adjacent or vertically stacked and the meaning of this stratigraphic architecture has not yet been fully investigated understanding of the processes responsible for changes in the internal features of modern and ancient tidal bedforms is essential in order to predict lateral and vertical heterogeneities in analogous reservoir strata this facies based study aims to interpret the three dimensional to two dimensional cross strata transition observed in the lower pleistocene mixed siliciclastic bioclastic sandstone filling the catanzaro strait in southern italy during a continuous phase of tectonically driven marine transgression tidal cross strata disappear in the uppermost interval of the studied succession where mudstone strata prevail this stratigraphic trend is interpreted as the evidence of an important change in the tidal strait hydrodynamics due to a phase of relative sea level rise at the beginning of the transgression three dimensional tidal dunes migrated throughout the ca 3 to 4 km wide and ca 30 km long wnw ese oriented catanzaro strait due to strong tidal currents amplified through the seaway and flowing in semi diurnal phase opposition as the intermediate phase of transgression enlarged the seaway width the tidal current strength decreased as tidal water exchange occurred over a larger cross sectional area the progressive reduction of the bed shear stress modified three dimensional tidal dunes into an extensive two dimensional bedform field at the end of the transgression the further widening of the catanzaro strait into a ca 10 to 12 km wide marine passageway changed the tidally dominated strait into a non tidal open shelf the results of this research suggest the presence of a critical cross sectional area in the narrowest strait centre zone which controls the activation and deactivation of tidal current amplification along a marine seaway

holocene climate variability and change a data based review the holocene thermal maximum with peak temperatures prior to 7 ka bp is mostly accentuated in the northern hemisphere still visible in the southern hemisphere and possibly did not exist in the tropics between this period and the modern warming a remarkable negative temperature trend occurred in the northern hemisphere which was probably the effect of a decreasing orbital induced insolation during the boreal summer on average the northern hemisphere humidity precipitation records do not show any significant trend a mechanistic explanation for the multi decadal to century scale holocene cold relapses which mainly occurred in the atlantic european regions exists for only the early holocene cooling events which are probably the result of a collapse of the meridional overturning circulation owing to freshwater outbursts from the laurentide ice sheet possibly the late holocene cold events after c 4 ka bp are influenced by the covarying influence of major tropical volcanic eruptions and grand solar minima

diagenesis and geochemistry of porites corals from papua new guinea implications for paleoclimate reconstruction coral proxy records of sea surface temperature sst and hydrological balance have become important tools in the field of tropical paleoclimatology however coral aragonite is subject to post depositional diagenetic alteration in both the marine and vadose environments to understand the impact of diagenesis on coral climate proxies two mid holocene porites corals from raised reefs on muschu island papua new guinea were analysed for sr ca 18 o and 13 c along transects from 100 aragonite to 100 calcite thin section analysis showed a characteristic vadose zone diagenetic sequence beginning with leaching of primary aragonite and fine calcite overgrowths transitional to calcite void filling and neomorphic fabric selective replacement of the coral skeleton average calcite sr ca and 18 o values were lower than those for coral aragonite decreasing from 0 0088 to 0 0021 and 5 2 to 8 1 respectively the relatively low sr ca of the secondary calcite reflects the sr ca of dissolving phases and the large difference between aragonite and calcite sr ca partition coefficients the decrease in 18 o of calcite relative to coral aragonite is a function of the 18 o of precipitation carbon isotope ratios in secondary calcite are variable though generally lower relative to aragonite ranging from 2 5 to 10 4 the variability of 13 c in secondary calcite reflects the amount of soil co 2 contributing 13 c depleted carbon to the precipitating fluids diagenesis has a greater impact on sr ca than on 18 o the calcite compositions reported here convert to sst anomalies of 115 c and 14 c respectively based on calcite sr ca compositions in this study and in the literature the sensitivity of coral sr ca sst to vadose zone calcite diagenesis is 1 1 to 1 5 c per percent calcite in contrast the rate of change in coral 18 o sst is relatively small 0 2 to 0 2 c per percent calcite we show that large shifts in 18 o reported for mid holocene and last interglacial corals with warmer than present sr ca ssts cannot be caused by calcite diagenesis low level calcite diagenesis can be detected through x ray diffraction techniques thin section analysis and high spatial resolution sampling of the coral skeleton and thus should not impede the production of accurate coral paleoclimate reconstructions copyright 2003 elsevier science ltd

a review of holocene solar linked climatic variation on centennial to millennial timescales physical processes interpretative frameworks and a new multiple cross wavelet transform algorithm article i nfo wereportontheexistenceandnature of holocene solar andclimaticvariationson centennialto millennial time scales we introduce a new solar activity proxy based on nitrate no3 concentration from the talos dome ice core east antarctica we also use a new algorithm for computing multiple cross wavelet spectra in time fre quency space that is generalized for multiple time series beyond two our results provide a new interpretive framework for relating holocene solaractivity variations on centennial to millennial timescales to co varying cli mate proxies drawn from a widespread area around the globe climatic proxies used represent variation in the north atlantic ocean western pacific warm pool southern ocean and the east asian monsoon regions our wavelet analysis identifies fundamental solar modes at 2300 yr hallstattzeit 1000 yr eddy and 500 yr unnamed periodicities leaves open the possibility that the 1500 1800 yr cycle may either be fundamental or derived and identifies intermediary derived cycles at 700 yr and 300 yr that may mark rectified responses of the atlantic thermohaline circulation to external solar modulation and pacing dating uncertainties suggest that the 1500 yr and 1800 yr cycles described in the literature may represent either the same or two separate cycles but in either case and irrespective too of whether it is a fundamental or derived mode in the sense of dima and lohmann 2009 the 1500 1800 yr periodicity is widely represented in a large number of paleoclimate proxy records it is obviously premature to reject possible links between changing solar activity at these multiple scales and the variations that are commonly observed in paleoclimatic records

theory of radar imaging of internal waves radar images taken over ocean areas in particular those obtained by the synthetic aperture radar sar onboard the american seasat satellite in 19781 2 sometimes show features that seem to be surface manifestations of oceanic internal waves3 11 here i present a theory explaining the large radar signatures of internal waves in which the imaging is attributed to variations in the short scale surface roughness induced by current variations associated with internal waves

computation of t phase seismograms using stairsteps to model seafloor bathymetry changes stair step boundaries are employed to represent range dependent seafloor bathymetry in many types of numerical modeling methods however if an overly coarse discretization is used to simulate smoothly varying bathymetry the acoustic solution is degraded in a way that simulates scattering geometrical optics approximations can be used to derive discretization criteria for simulating a smoothly sloping interface for the case of a source embedded in either an acoustic or an elastic seafloor and applied to modeling t phases a finite difference time domain modeling approach is used to synthesize t phases for both smoothly sloping and rough seafloor boundaries it is shown that scattering at a rough seafloor boundary yields ocean borne acoustic phases with velocities near those of observed t phase while smooth seafloor models yield t phases with slower horizontal velocities the long duration of the computed t phases for both the rough acoustic and elastic models is consistent with energy being scattered into the sound channel both as it transits the ocean crust boundary as well as at several subsequent seafloor reflections however comparison between the elastic and acoustic modeling solutions indicates that the t phase wavetrain duration decreases with decreasing impedance contrast between the ocean and seafloor

fluorescent bands in massive corals result from terrestrial fulvic acid inputs to nearshore zone the discovery of yellow green fluorescent bands in the skeletons of massive corals from inshore waters of the great barrier reef and the temporal and spatial correlations of these bands with adjacent river flow1 prompted an investigation into the substances responsible for the phenomenon we have determined that all regions of the coral skeleton contain fulvic acids2 3 which impart a blue background fluorescence the yellow green fluorescent bands found only in inshore coral appear to result from enhanced concentrations of low relative molecular mass 10 000 fulvic acids from adjacent river input these compounds are ubiquitous and the yellow green banding phenomenon can be expected to occur in massive corals located near to significant river systems in the widely distributed genus porites4 the great age of the largest colonies1 means that extremely long highly resolvable records of coastal runoff exist throughout tropical nearshore seas

interdecadal decadal climate variability from multicoral oxygen isotope records in the south pacific convergence zone region since 1650 a d 1 in the south pacific interdecadal decadal oceanic and atmospheric variability referred to as the interdecadal pacific oscillation ipo is most pronounced in the south pacific convergence zone spcz salinity front region here we have used annual average oxygen isotope 18o time series from five coral cores collected from fiji and tonga in this region to construct a fiji tonga interdecadal decadal pacific oscillation f t idpo index of low frequency 9 and 55 years climate variability back to 1650 a d we first demonstrate the consistency between this f t idpo index and a mean sea level msl pressure based spcz position index spi 1891 2000 thus verifying the ability of coral 18o to record past interdecadal decadal climatic variations in this region back to 1891 the f t idpo index is then shown to be synchronous with the ipo index 1856 2000 suggesting that this coral based index effectively represents the interdecadal decadal scale climate variance back to 1650 the regularity of the f t idpo index indicates that interdecadal decadal variability in the spcz region has been relatively constant over the past 350 years with a mean frequency of 20 years variance peaks near 11 and 35 years there is a consistent antiphase correlation of the f t idpo index and the interdecadal decadal components in equatorial pacific coral 18o series from maiana and palmyra this observation indicates that the eastward expansion westward contraction of the eastern salinity front of the western pacific warm pool wpwp occurs simultaneously 1 year with the westward eastward shift of the spcz salinity front during positive ipo negative ipo phases this is the same relationship observed during the phases of the el nino southern oscillation

warm season temperatures since 1600 bc reconstructed from tasmanian tree rings and their relationship to large scale sea surface temperature anomalies we describe an improved tree ring reconstruction of mean warm season november april temperatures for tasmania from huon pine this record extends back to 1600 bc and is based on a tree ring chronology that was processed to retain as much low frequency variance as possible the resulting reconstruction explains 46 6 of the variance and verifies significantly when compared to withheld instrumental data cross spectral analysis of actual and estimated temperatures over the 1886 1991 common period indicates that most of the unexplained variance is at periods 12 years the squared coherency ranges between 0 6 0 8 and the cross spectral gain indicates that the amplitude of the reconstruction is a nearly unbiased estimate of the true temperature amplitude therefore this reconstruction should be especially useful for studying multi decadal temperature variability in the tasmanian sector of the southern hemisphere over the past 3592 years to this end we examined the time evolution of low frequency temperature amplitude fluctuations and found evidence for a 35 amplitude reduction after ad 100 that persisted until about ad 1900 since that time the low frequency temperature amplitude has systematically increased we also show how this reconstruction is related to large scale sea surface temperatures sst in the indian ocean and eastward to the dateline pointwise correlations between the tasmanian record and ssts reveal a relationship that extends across the southern indian ocean and towards the arabian sea this pattern is largely determined by inter decadal temperature variability with correlations in this 10 year bandwidth commonly exceeding 0 6 over most of the southern indian and southwestern pacific sectors a rotated empirical orthogonal function analysis reveals that the pattern of pointwise correlations found between the temperature reconstruction and ssts is largely explained by the linear combination of three orthogonal modes of sst variability

chronological control of coral records using luminescent lines and evidence for non stationary enso teleconnections in northeast australia eight multicentury porites coral cores were used to develop a 373 year chronology by cross dating techniques adapted from dendrochronology characteristic patterns of distinct luminescent lines within the coral skeletons were matched between coral cores from inshore and mid shelf reefs in the central great barrier reef australia skeleton plots of luminescent banding were produced for each core and combined into a master chronology back to ad 1615 in addition to improving dating control the luminescence master chronology provides a proxy for burdekin river runoff and queensland summer rainfall variations in the magnitude of the correlation between the luminescence master and the mann et al 2000 nino3 sea surface temperature reconstruction provides insights into the long term stability of el nino southern oscillation enso telecon nections burdekin river runoff was significantly inversely related to enso variability for much of the period from the ad 1650s to 1800 suggesting that enso related te

the lifecycle of nonlinear internal waves in the northwestern south china sea abstractthe life cycle of nonlinear internal waves niws to the southeast of hainan island in the northwestern south china sea is investigated using synergistic satellite observations in situ mea

tropical river flow and rainfall reconstructions from coral luminescence great barrier reef australia 1 rainfall and river flow in northeast queensland australia are highly seasonal and show high interannual and decadal variability that is modulated by el nino southern oscillation enso events and the pacific decadal oscillation pdo reconstructions of october september freshwater input to the great barrier reef lagoon and october september queensland rainfall are developed from visual assessment of the occurrence and intensity of luminescent lines in massive porites from up to 25 coral cores from 15 nearshore reefs regularly influenced by river flood plumes separate reconstructions are developed for four rivers herbert burdekin pioneer and fitzroy and these are used to reconstruct total annual freshwater flow into the great barrier reef 69 74 variance calibrated and an index of queensland rainfall 53 57 variance calibrated the reconstructions extend back to 1631 but are most reliable from 1661 and capture significant decadal variability the reconstructions provide insights into long term tropical rainfall and river flow variability and the behavior of enso and the pdo over several centuries significant though weak relationships are found between these reconstructions and an independent reconstruction of enso the reconstructions highlight that observations from the instrumental records of high interannual and decadal rainfall and river flow variability in northeast australia also characterize the past few centuries although there appears to be no overall trend toward wetter or drier conditions the reconstructions suggest that the variability of rainfall and river flow has increased during the twentieth century with more very wet and very dry extremes than in earlier centuries as projected for the region as a consequence of global warming

oceanic internal waves in the sulu celebes sea under sunglint and moonglint moonglint and sunglint satellite imagery acquired from moderate resolution imaging spectroradiometer modis and visible infrared imaging radiometer suite viirs satellite sensors were used to study the characteristics of internal waves iws and their relationship to tides and stratification in the sulu celebes sea tidally generated iws propagate northwestward and southeastward into the sulu and celebes seas showing a spring neap tidal cycle behavior with larger smaller iws occurring under spring neap tides respectively the length of iw crests their wavelength and phase speed derived from the sunglint moonglint image pairs were observed to decrease from spring to neap tides iws in the sulu celebes sea which are correlated with oceanic stratification display seasonal and regional fluctuations in the celebes sea iws were less frequently observed but propagated with faster phase speeds and larger scales compared to those in the sulu sea comparisons of stratification and barotropic tidal transport among the iws generation sites indicate that the shallowing maximum brunt vaisala frequency and strongest tidal transport around pearl bank are major factors contributing to greater iw activity compared to other generation sites iws generated near pangutaran island and pearl bank further merge into one dynamical system creating longer wave crests of 200 km that travel at faster phase speed sim 2 5 text m cdot text s 1 in the sulu sea this paper demonstrates a new application using a combination of sunglint moonglint imagery in tracking an important oceanic phenomenon

internal waves in the strait of messina studied by a numerical model and synthetic aperture radar images from the ers 1 2 satellites a new numerical two layer model is presented which describes the generation of internal tidal bores and their disintegration into internal solitary waves in the strait of messina this model is used to explain observations made by the synthetic aperture radar sar from the european remote sensing satellites ers 1 and ers 2 the analysis of available ers 1 2 sar data of the strait of messina and adjacent sea areas show that 1 northward as well as southward propagating internal waves are generated in the strait of messina 2 southward propagating internal waves are observed more frequently than northward propagating internal waves 3 sea surface manifestations of southward as well as northward propagating internal waves are stronger during periods where a strong seasonal thermocline is known to be present 4 southward propagating internal bores are released from the sill between 1 and 5 hours after maximum northward tidal flow and northward propagating internal bores are released between 2 and 6 hours after maximum southward tidal flow and 5 the spatial separation between the first two internal solitary waves of southward propagating wave trains is smaller in the period from july to september than in the period from october to june the numerical two layer model is a composite of two models consisting of 1 a hydrostatic generation model which describes the dynamics of the water masses in the region close to the strait s sill where internal bores are generated and 2 a weakly nonhydrostatic propagation model which describes the dynamics of the water masses outside of the sill region where internal bores may disintegrate into internal solitary waves due to a technique for movable lateral boundaries the generation model is capable of simulating the dynamics of a lower layer that may intersect the bottom topography the proposed generation propagation model depends on one space variable only but it retains several features of a fully three dimensional model by including a realistic channel depth and a realistic channel width it is driven by semidiurnal tidal oscillations of the sea level at the two open boundaries of the model domain numerical simulations elucidate several observed characteristics of the internal wave field in the strait of messina such as north south asymmetry times of release of the internal bores from the strait s sill propagation speeds and spatial separations between the first two solitary waves of internal wave trains

on the dynamics of internal waves in a nonlinear weakly nonhydrostatic three layer ocean aspects of the dynamics of internal solitary waves evolving in a three layer ocean are investigated using a new numerical multilayer model that solves the nonlinear weakly nonhydrostatic boussinesq equations and uses high resolution in situ data the model applications refer to two different phenomena frequently observed in the real ocean which can be described using a three layer model rather than a two layer model in the first application the influence of the strength of a shallow seasonal thermocline superimposed on a two layer permanent stratification on the structure of internal solitary waves is studied it is found that while for small to medium wave amplitudes a decrease in the strength of the thermocline yields an increase in the simulated wavelengths for large wave amplitudes this dependence is no longer monotonic in particular in the limiting case of a vanishing thermocline first mode internal solitary wave solutions of the three layer numerical model tend to the analytical internal solitary wave solutions of the miyata equations a two layer model in which the full nonlinearity of the shallow water theory up to first order phase dispersion is retained in the second application that refers particularly to high resolution observations made north and south of the strait of messina in the eurafrican mediterranean basin the generation of internal solitary waves by the evolution of surface and subsurface water jets is investigated the analysis of the in situ data shows in fact that from very energetic surface and subsurface jet like disturbances subject to strong turbulent mixing internal solitary waves emerge as robust quasi nondissipative oceanic features idealized flow conditions aimed at approximating possible initial stages of the observed water jets are imposed to force our numerical model in general good agreement is found between characteristics of observed and simulated wave fields our investigation identifies the observed water jets as peculiar features of the complex ocean dynamics and suggests that layered numerical models can represent helpful tools in understanding fundamental processes inherent in their intricate dynamics

late holocene sea level fall and turn off of reef flat carbonate production rethinking bucket fill and coral reef growth models relative sea level rise has been a major factor driving the evolution of reef systems during the holocene most models of reef evolution suggest that reefs preferentially grow vertically during rising sea level then laterally from windward to leeward once the reef flat reaches sea level continuous lagoonal sedimentation bucket fill and sand apron progradation eventually lead to reef systems with totally filled lagoons lagoonal infilling of one tree reef southern great barrier reef through sand apron accretion was examined in the context of late holocene relative sea level change this analysis was conducted using sedimentological and digital terrain data supported by 50 radiocarbon ages from fossil microatolls buried patch reefs foraminifera and shells in sediment cores and recalibrated previously published radiocarbon ages this data set challenges the conceptual model of geologically continuous sediment infill during the holocene through sand apron accretion rapid sand apron accretion occurred between 6000 and 3000 calibrated yr before present b p cal yr b p followed by only small amounts of sedimentation between 3000 cal yr b p and present with no significant sand apron accretion in the past 2 k y this hiatus in sediment infill coincides with a sea level fall of 1 1 3 m during the late holocene ca 2000 cal yr b p which would have caused the turn off of highly productive live coral growth on the reef flats currently dominated by less productive rubble and algal flats resulting in a reduced sediment input to backreef environments and the cessation in sand apron accretion given that relative sea level variations of 1 m were common throughout the holocene we suggest that this mode of sand apron development and carbonate production is applicable to most reef systems

a nonlinear model of the shoaling and refraction of interfacial solitary waves in the ocean part i development of the model and investigations of the shoaling effect abstract oceanic internal waves are frequently observed to be of large amplitude and to exhibit significant wave front curvature as seen in synthetic aperture radar images the aim of this paper is to present a refraction model in two horizontal dimensions including moderate amplitude effects to model these common properties of internal waves the model incorporates second order nonlinearity and uses a ray method to allow arbitrary refraction for these preliminary investigations with the model a two layer ocean is assumed with an upper layer thickness of 50 m and a density difference across the layers of 0 5 kg m 3 an important aspect affecting the refraction of nonlinear waves is shoaling as the phase speed of a nonlinear wave depends on its amplitude in part i of this paper the development of the model is described and the shoaling phenomenon is investigated in detail the shoaling of interfacial internal solitary waves over both slowly varying and rapidly varying bathymetry is studied a wedg

images of diagenetic textures in porites corals from papua new guinea and indonesia diagenesis is now recognized as a potentially major source of error in paleoclimatic reconstructions from fossil and modern coral geochemical records key to avoiding spurious results caused by diagenesis is thorough screening of coral material prior to geochemical analysis in this data brief we present color images from thin sections of fossil and modern porites corals and demonstrate the effectiveness of thin sections in detecting low levels of diagenesis the images presented here cover a range of coral preservation levels from pristine aragonite to 100 calcite we particularly focus on samples containing around 1 diagenetic material a level known to create artifacts in key climate parameters such as sea surface temperature and close to the detection limits of other screening methods such as x ray diffraction xrd a qualitative scheme is also presented to rate the degree of diagenesis in a coral where xrd results are not available or where secondary aragonite is present overall this collection of images is designed as a starting point in combination with other techniques to assist in identifying and screening corals for diagenesis

solitary internal waves in the celtic sea abstract an examination is made of tidally generated high frequency internal wave trains propagating from the shelf break of the celtic sea and armorican shelf the waves propagate on shelf after maximum off shelf tidal streaming at speeds of about 70 cm s 1 giving a wavelength between successive tidal disturbances of 30 km as the waves travel on shelf they are advected by the barotropic tide and can take on a solitary wave form

a model for the alboran sea internal solitary waves abstract the propagation into the alboran sea of the interface depression generated at the strait of gibraltar by the interaction of the semidiurnal tidal current with the main camarinal sill is studied numerically by using a unidirectional model with two horizontal space dimensions an initial waveform within the strait is determined whose evolution corresponds with the train of internal solitary waves detected in the alboran sea by means of current measurements at different depths as described by kinder the agreement is good for two points located at about 45 km east of the strait the first aligned with the strait axis and the second 20 km to the north moreover the shape and amplitude of this initial condition are in agreement with a typical interface depression generated in the strait by the interaction of the tidal current with the sill a series of numerical experiments with different initial conditions is also performed to study the sensitivity of the model results to changes in the initial i

on the discrimination of radar signatures of atmospheric gravity waves and oceanic internal waves on synthetic aperture radar images of the sea surface synthetic aperture radar sar images acquired over the ocean frequently show sea wave like patterns that have wavelengths well above those of ocean surface waves and that are sea surface signatures of oceanic internal waves oiws or of atmospheric gravity waves agws however it is often difficult to decide whether they result from the first or the second kind of waves which has led many investigators to misinterpret sar images of the sea surface based on solitary wave and radar imaging theories of agws and oiws we present criteria that help distinguish between them however there are cases where these criteria which are based solely on the shape and structure of the features visible on the sar images yield ambiguous results in these cases one must resort to additional information on the generation of agws and oiws which are listed in this paper

internal waves in the gulf of california observations from a spaceborne radar pronounced signatures of internal waves were detected repeatedly in the gulf of california by the seasat synthetic aperture radar sar a series of nine images with exactly repeating ground coverage was used to study the temporal variability of the internal wave field in the area it was found that the number of observed wave groups was highly correlated with the strength of the local tides the maximum number occurred during spring tides and the minimum number occurred during neap tides indicating that the internal waves were tidally forced most of the wave activity was found to the north of 28 n where the tides were the strongest in the gulf the application of a simple nonlinear internal wave model to the observations indicated that the peak to peak amplitude of the observed waves was about 50 m with an uncertainty of a factor of 2 the estimated upper bound for the rate of the loss of tidal energy to internal waves was about 5 1015 erg s representing only 10 of the rate of the dissipation of the dominant m2 tide in the gulf

scylla and charybdis observed from space scylla and charybdis are in greek mythology two immortal and irresistible monsters who beset the narrow waters separating the italian peninsula from sicily they give poetic expressions to exceptional oceanographic features encountered in the strait of messina recently the seasat satellite has added new information on the oceanography of this strait for the first time experimental evidence is presented that internal waves are generated in the strait of messina the generation mechanism is linked to tidal currents washing over the shallow sill within the strait the experimental data originate from a synthetic aperture radar sar image obtained from the seasat satellite on sept 15 1978 and from subsequent in situ measurements carried out from the italian research vessel bannock in nov 1980 the circular wave pattern visible on the seasat sar image is interpreted in terms of internal solitons furthermore the seasat sar image also reveals tagli special types of tidal bores encountered in the strait of messina

great barrier reef coral luminescence reveals rainfall variability over northeastern australia since the 17th century 1 northeast tropical queensland rainfall is concentrated in the summer half year and characterized by high interannual variability partly related to el nino southern oscillation enso events this results in highly variable river flows affecting nearshore coral reefs of the great barrier reef australia freshwater flood events are recorded in long lived annually banded massive coral skeletons as luminescent lines quantitative measurements of luminescence intensity were made for 20 porites coral cores from nearshore reef sites between 11 s and 23 s seventeen of the coral luminescence series were significantly correlated with an instrumental record of northeast queensland summer rainfall and were used to develop seven significantly calibrated and verified rainfall reconstructions based on between 17 starting 1891 and 1 starting 1639 coral series the longest reconstruction based on more than one coral provides insights into northeast queensland rainfall variability from the late 17th century comparisons with various independent climate proxies are equivocal the magnitude and significance of relationships with for example a proxy enso index vary through time an extended drier period reconstructed from approximately the 1760s to the 1850s is associated with lower interannual rainfall variability since the late 19th century average rainfall and its variability have significantly increased with wet and dry extremes becoming more frequent than in earlier centuries this suggests that a warming global climate maybe associated with more variable tropical queensland rainfall

long internal waves and columnar disturbances in the strait of messina during a pilot cruise in the strait of messina we observed the interface time evolution between atlantic and levantine water layers due to semidiurnal tides our data are in fairly good agreement with the models computed by del ricco 1982 and by hopkins et al 1984 as regards long lasting 1 hour or more water movements quick transient perturbations of columnar shape probably eddies which we have called bignami columns were also observed and analyzed using both a koden fish finder and moored temperature sensors

analysis of nonlinear internal waves observed by landsat thematic mapper in this work we test the compatibility between the theoretical parameters of a nonlinear wave model and the quantitative information that one can deduce from satellite derive0 data the theoretical parameters are obtained by applying an inverse problem to the solution of the cauchy problem for the korteweg de vries equation our results are applied to the case of internal wave patterns elaborated from two different satellite sensors at the south of messina the thematic mapper and at the north of messina the synthetic aperture radar

modeling the oceanic circulation in the area of the strait of sicily the remotely forced dynamics in order to describe aspects of the baroclinic dynamics in the region of the strait of sicily a high resolution multilayer numerical model has been implemented in a central mediterranean region including the tyrrhenian and the ionian seas three layers have been considered representing water of atlantic origin maw the levantine intermediate water liw and deep water of the mediterranean quasi stationary circulations representing the local manifestation of the large scale mediterranean conveyor belt are obtained after an adjustment time of o 2 months by imposing steady fluxes along the remote open boundaries in the absence of meteorological forcings these circulations can be interpreted as possible dynamic scenarios of the seasonal variability in the strait of sicily in the numerical simulations an inflow of maw and an outflow of liw through the strait of sardinia an outflow of maw and an inflow of liw through the ionian boundary and an outflow of maw through the corsica channel are imposed resulting in a vanishing total net transport in each layer for realistic values of these transports the model captures the main features of the observed circulation such as i the separation of the algerian current into two branches one directed toward the tyrrhenian sea and the other entering the strait ii a secondary bifurcation of maw within the strait giving rise to a southward moving current that follows the tunisian continental slope and to a current that flows southeastward along the southern sicilian coast and then northward along the southern italian coasts the so called atlantic ionian stream iii a bifurcation of liw at the strait level leading to a main current directed toward the strait of sardinia and to a weaker current that after having crossed the strait bends eastward and enters the tyrrhenian sea sensitivity experiments carried out by imposing different boundary fluxes have shed light on the functioning of the maw and liw bifurcations first of all for a given net transport of maw and liw through the strait imposed indirectly by the boundary fluxes the ratio rmaw between the transport of maw entering the tyrrhenian sea and that entering the strait is found to be virtually independent of the boundary imposed algerian current transport it is on the contrary determined by a local dynamic control which selects the value rmaw 0 43 for a net maw liw strait transport of 61 sv in excellent agreement with observations second for decreasing baroclinic transports the ratio rmaw is found to decrease up to the limiting value rmaw 0 2 corresponding to the linear regime for transports o 0 1 sv finally rmaw is found to be very sensitive to the barotropic transport t through the strait whereas the corresponding ratio for the liw rliw is virtually independent of t for t 5 20 5 sv rmaw 1 1 while for t 51 0 5 sv rmaw decreases by one order of magnitude rmaw 0 1 in other words a weakening of the liw or a strengthening of the maw net transport through the strait reduces the relative intensity of the tyrrhenian branch of maw and vice versa on the other hand for values of t within the same range one always findsrliw 20 3 it thus appears that the local control exerted by the topography through the liw potential vorticity budget forces the transport of the tyrrhenian branch of liw to be always 1 3 of that directed toward the strait of sardinia

evidence of short internal waves trailing strong internal solitary waves in the northern south china sea from synthetic aperture radar observations abstract sea surface signatures of short internal waves trailing strong internal solitary waves isws have been detected on several synthetic aperture radar sar images acquired by the advanced synthetic aperture radar asar onboard the european envisat satellite over the northern south china sea scs such configurations were found recently by vlasenko et al 2010 in numerical simulations carried out with the mit general circulation model mitgcm they showed that the short internal waves which have wavelengths of 1 5 km and amplitudes of 20 m ride on second mode isws the existence of these short internal waves which follow a first mode isw can be explained in terms of the taylor goldstein equation that includes a shear in the background current associated with a second mode isw the simulations predict that the short internal waves occur in two distinct areas one close to the luzon strait ls and the other further west in the first area they are generated by the disintegration of a baroclinic bore which is generated by the interaction of the tidal current with the steep two ridged topography in the ls in the second area they are generated when the faster first mode isw overtakes the second mode isw of the previous tidal cycle we have screened the asar archive of the european space agency esa and found many sar images acquired over the northern scs showing sea surface signatures of such short internal waves trailing a much longer first mode strong isw the detailed analysis of six of these sar images shows good correlation between modeled and observed internal wave fields

analysis of nonlinear internal waves in the new york bight this paper presents the results on internal wave analysis of the current meter mooring data in the new york bight from the sar internal wave signature experiment sarsex selective sets of current and temperature measurements are analyzed for a parametric study of internal wave characteristics and shear effects on wave parameters are studied based on the limited data from moorings the solitary wave theory has been extended for the wave evolution on a continental shelf by including dissipation and shoaling effects a series of numerical simulations are performed to demonstrate the relative importance of dissipation and shoaling effects from an observed initial wave packet at the upstream mooring the numerical evolution simulation compares reasonably well with the measurements at the distant mooring for the leading two large solitons

experimental reconstruction of monsoon drought variability for australasia using tree rings and corals 1 an experimental reconstruction uses three well dated annually resolved proxies from australasia 0 40 s 95 155 e to provide large scale information on sep jan australasian monsoon variability based on the palmer drought severity index pdsi for 1787 2002 the proxies are 1 a ring width chronology of callitris intratropica for northern australia 1847 2006 2 a tree ring and coral based reconstruction of the oct nov pdsi 1787 2003 for java indonesia and 3 a rainfall reconstruction for northeastern australia 1631 2002 based on great barrier reef coral luminescence all three proxies show considerable explanatory value for reconstructing monsoon rainfall variability over much of australia and environs which will improve as additional records become available the success of this proof of concept experiment largely reflects the highly significant spatially coherent correlations between austral spring and summer pdsi australasian climate and enso

a study of internal wave propagation in the strait of gibraltar using shore based marine radar images abstract an x band marine radar on windmill hill gibraltar was used to monitor the propagation of internal waves in the strait of gibraltar during march april and june 1986 surface roughness features of the waves were observed out to a range of 15 km from photographic images of the radar screen the positions of image features were measured manually using a digitizing table and these data were then computer processed to give wave arrival times and phase speeds during most tidal cycles an internal undular bore generated at camarinal sill was observed to pass eastward a waves these occurred throughout the experiments although less frequently near neap tides the time of travel to gibraltar varied significantly so that the bore arrived between four and nine hours after high water arrival times were found to be closely related to the amplitude of the upper layer tidal current this current had a strong diurnal component which was manifested as an inequality between the arrival times of success

remote imaging of internal solitons in the coastal ocean abstract during a combined in situ and airborne remote sensing exercise off oceanside ca a compact airborne spectrographic imager casi observed alongshore lineations which were associated with an internal soliton packet accompanying a tidally generated internal solitary wave solibore the soliton packets were most evident in the images at green wavelengths which penetrate the deepest into the water column and only weakly evident at optical wavelengths with shallower penetration we believe that this is the first observation of internal soliton packets determined from remotely sensed upwelled radiance we hypothesize that the lineations were produced by changes in the upwelling radiance from the interior of the water column not by changes in surface reflectance using a simulation it is demonstrated that such lineations can be produced by vertical modulation of the inherent optical properties iops during the passage of the internal soliton packet since surface manifestations are not always present this opens the potential for broadly based inventories of internal solitons in coastal waters

palaeohydrological variation in a tropical river catchment a reconstruction using fluorescent bands in corals of the great barrier reef australia massive long lived corals in inshore waters of the great barrier reef contain yellow green fluorescent bands these bands are due to terrestrial humic and fulvic compounds incorporated into the coral skeleton during high river flow events fluorescence measurements are presented for two colonies of porites spp from locations in the path of the burdekin river floodwaters the major river in north queensland draining into the coral sea the records extend from ad 1737 to 1980 and 1644 to 1986 respectively the two independent coral records show a high degree of similarity the two series are combined and used to reconstruct burdekin river runoff for the period ad 1644 to 1980 the regression model accounts for 83 of the annual water year variability of burdekin river flow and is verified over independent data the 337 year reconstruction thus increases by threefold the length of record for considering interannual to decadal climate variations in northeast australia instrumental and reconstructed burde

re evaluating mid holocene reef turn off on the inshore southern great barrier reef abstract in the face of changing global climate the future of corals reefs is uncertain high latitude reefs may offer potential refugia for corals under projected increasing sea surface temperatures ssts to understand the reef growth potential of modern high latitude reefs it is first necessary to understand past reef growth and response to climatic and environmental changes the history of the great barrier reef gbr has been shown to be punctuated by a multi millennial mid holocene reef turn off or initiation hiatus in the northern and southern gbr 5500 2500 years before present yr bp here we present the results of chronologically constrained reef matrix cores from five continental island fringing reefs and coral communities in the keppel islands to revaluate the timing extent and possible drivers of the mid holocene hiatus in the southern gbr earliest initiation occurred at wedge and halfway islands at 7773 19 yr bp and 7455 20 yr bp respectively following initiation vertical reef accretion at halfway was comparable to previously reported rates for the gbr of 3 4 mm yr 1 increasing to 8 0 mm yr 1 between 6100 and 5500 yr bp conversely the coral community at wedge island located closer to mainland terrestrial influence accreted

mid holocene sea level and coral reef demise u th dating of subfossil corals in moreton bay australia it is increasingly apparent that sea level data e g microfossil transfer functions dated coral microatolls and direct observations from satellite and tidal gauges vary temporally and spatially at regional to local scales thus limiting our ability to model future sea level rise for many regions understanding sealevel response at far field locations at regional scales is fundamental for formulating more relevant sea level rise susceptibility models within these regions under future global change projections fossil corals and reefs in particular are valuable tools for reconstructing past sea levels and possible environmental phase shifts beyond the temporal constraints of instrumental records this study used abundant surface geochronological data based on in situ subfossil corals and precise elevation surveys to determine previous sea level in moreton bay eastern australia a far field site a total of 64 u th dates show that relative sea level was at least 1 1 m above modern lowest astronomical tide lat from at least 6600 cal yr bp furthermore a rapid synchronous demise in coral reef growth occurred in moreton bay 5800 cal yr bp coinciding with reported reef hiatus periods in other areas around the indo pacific region evaluating past reef growth patterns and phases allows for a better interpretation of anthropogenic forcing versus natural environmental climatic cycles that effect reef formation and demise at all scales and may allow better prediction of reef response to future global change

oceanographic processes and morphosedimentary products along the iberian margins a new multidisciplinary approach abstract our understanding of bottom currents and associated oceanographic processes e g overflows barotropic tidal currents including intermittent processes e g vertical eddies deep sea storms horizontal vortices internal waves and tsunamis is rapidly evolving many deep water processes remain poorly understood due to limited direct observations but can generate significant depositional and erosional features on both short and long term time scales this paper represents a review work which describes for the first time these oceanographic processes and examines their potential role in the sedimentary features along the iberian continental margins this review explores the implications of the studied processes given their secondary role relative to other factors such as mass transport and turbiditic processes and highlights three major results a contourite depositional and erosional features are ubiquitous along the margins indicating that bottom currents and associated oceanographic processes control the physiography and sedimentation b the position of interfaces between major water masses and their vertical and spatial variation in time specifically appears to exert primary control in determining major morphologic changes along the slope gradient including the contourite terraces development and c contourites deposits exhibit greater variation than the established facies model suggests therefore a consistent facies model however faces substantial challenges in terms of the wide range of oceanographic processes that can influence in their development an integrated interpretation of these oceanographic processes requires an understanding of contourites seafloor features their spatial and temporal evolution and the near bottom flows that form them this approach will synthesize oceanographic data seafloor morphology sediments and seismic images to improve our knowledge of permanent and intermittent processes around iberia and evaluate their conceptual and regional role in the margin s sedimentary evolution given their complexes three dimensional and temporally variable nature integration of these processes into sedimentary oceanographic and climatological frameworks will require a multidisciplinary approach that includes geology physical oceanography paleoceanography and benthic biology

high resolution palaeoclimatology of the last millennium a review of current status and future prospects this review of late holocene palaeoclimatology represents the results from a pages clivar intersection panel meeting that took place in june 2006 the review is in three parts the principal high resolution proxy disciplines trees corals ice cores and documentary evidence emphasizing current issues in their use for climate reconstruction the various approaches that have been adopted to combine multiple climate proxy records to provide estimates of past annual to decadal timescale northern hemisphere surface temperatures and other climate variables such as large scale circulation indices and the forcing histories used in climate model simulations of the past millennium we discuss the need to develop a framework through which current and new approaches to interpreting these proxy data may be rigorously assessed using pseudo proxies derived from climate model runs where the answer is known the article concludes with a list of recommendations first more raw proxy data are required from the diverse disciplines and from more locations as well as replication for all proxy sources of the basic raw measurements to improve absolute dating and to better distinguish the proxy climate signal from noise second more effort is required to improve the understanding of what individual proxies respond to supported by more site measurements and process studies these activities should also be mindful of the correlation structure of instrumental data indicating which adjacent proxy records ought to be in agreement and which not third large scale climate reconstructions should be attempted using a wide variety of techniques emphasizing those for which quantified errors can be estimated at specified timescales fourth a greater use of climate model simulations is needed to guide the choice of reconstruction techniques the pseudo proxy concept and possibly help determine where given limited resources future sampling should be concentrated

sea surface temperature and salinity reconstruction from coral geochemical tracers massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers corals present several advantages for palaeoclimate research they grow continuously and can live up to 1000 years they are easy to date and they can be sampled at high resolution weekly to monthly resolution both live and fossil corals can be collected in the field in the past two decades significant efforts have been made to identify robust tracers of sea surface temperature sst and salinity sss in corals to date sr ca and 18o are considered to be the most reliable sst tracers although changes in seawater 18o can significantly alter sst reconstructed from coralline 18o because these variations in seawater 18o can be linked to sss changes this initial problem can in fact be turned into an advantage and provide us with an sss tracer the sst component in the coral 18o signal can either be evaluated through sr ca measurements or in some case simply filtered out however there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton the effects of growth rate light intensity feeding habits ph and water chemistry are still poorly documented a review of the strength and weaknesses of sr ca and 18o is presented together with some examples of sst and sss reconstructions other potential sst tracers are also reviewed it is expected that the ability to grow corals in aquarium under controlled conditions and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite

generation mechanism of internal waves by tidal flow over a sill the generation mechanism of internal waves by relatively strong tidal flow over a sill is clarified analytically special attention is directed to the role of the tidal advection effect which is examined by use of characteristics an internal wave which propagates upstream is gradually formed over the sill through the interference among infinitesimal amplitude internal waves elementary waves emanated from the sill at each instant of time in the accelerating decelerating stage of tidal flow the effective amplification of an internal wave takes place as the froude number exceeds falls below unity because during this period the internal wave slowly travels downstream upstream crossing over the sill where elementary waves are efficiently superimposed when the strength of the tidal advection effect is appropriate the internal wave formed in the accelerating stage ac wave and that formed in the decelerating stage dc wave overlap so that the resultant wave height becomes very large since the relative position of ac and dc waves varies depending on the strength of the tidal advection effect the resultant internal wave form is strongly affected by it when the tidal advection effect is strong the ac wave is carried too far downstream to interfere with the dc wave and hence the resultant wave form consists of two crests and two troughs when the tidal advection effect is moderate the optimum interference between ac and dc waves occurs and the resultant wave form consists of one crest and one trough with its horizontal scale approaching that of the sill when the tidal advection effect is weak the internal wave height becomes very small since elementary waves propagate almost freely in the tidal flow without coming close together and the resultant wave form approaches a sinusoidal wave of tidal frequency

abrupt changes in the asian southwest monsoon during the holocene and their links to the north atlantic ocean during the last ice age the indian ocean southwest monsoon exhibited abrupt changes that were closely correlated with millennial scale climate events in the north atlantic region1 2 3 suggesting a mechanistic link in the holocene epoch which had a more stable climate the amplitude of abrupt changes in north atlantic climate was much smaller and it has been unclear whether these changes are related to monsoon variability here we present a continuous record of centennial scale monsoon variability throughout the holocene from rapidly accumulating and minimally bioturbated sediments in the anoxic arabian sea our monsoon proxy record reveals several intervals of weak summer monsoon that coincide with cold periods documented in the north atlantic region4 including the most recent climate changes from the medieval warm period to the little ice age and then to the present we therefore suggest that the link between north atlantic climate and the asian monsoon is a persistent aspect of global climate

application of a transient reduced gravity plume model to the denmark strait overflow a hydrostatic reduced gravity two dimensional primitive equation numerical model for the simulation of transient bottom arrested gravity plumes was developed by adopting an algorithm from a wadden sea model a model that simulates the wetting and drying of mud flats sand banks etc with a movable lateral boundary the vertically integrated nonlinear rotational model accounts for the dissipation of momentum due to bottom friction and for the entrainment of water mass properties from a spatially structured but stagnant ambient water body it predicts the temporal and spatial evolution of the flow field and the water mass modification within a gravity plume that descends on an arbitrary topography previous model investigations considered a laterally integrated streamtube whereas our model resolves the plume horizontally in the streamtube approach it was assumed that the plume descends in a stationary almost geostrophic balance modified only by bottom drag and entrainment the results of this model demonstrate that this balance may be disturbed whenever the plume encounters topographic disturbances which for the initial intruding phase in particular accounts for its highly transient character the model results are in good agreement with theoretical and laboratory investigations and with observations as is demonstrated by some basic test experiments an application to the overflow of dense water through the denmark strait is presented

a multiproxy index of the el nino southern oscillation a d 1525 1982 1 an understanding of past variability in the el nino southern oscillation enso on interannual interdecadal and longer time scales would be useful in assessing recent observed changes to enso and in determining the realism of climate model simulations using tree ring coral and ice core data we reconstruct a proxy based enso index between a d 1525 and 1982 unlike most previous studies which have drawn climate proxies from limited geographic regions our network is pacific basin wide using enso sensitive proxies from the western equatorial pacific new zealand the central pacific and subtropical north america by considering multiple teleconnection regions this network provides a more robust proxy enso signal the common signal recorded in the multiproxy network has a high correlation with the southern oscillation index soi nino 3 4 sea surface temperature nino3 4 sst and a combined ocean atmosphere enso index cei the proportion of instrumental variance explained is 47 for the soi 48 for nino3 4 sst and 52 for the cei the proxy enso index also displays skill in reproducing warm and cold extremes of the soi the proxy enso index over the last 450 years shows considerable amplitude and frequency modulation in the 3 10 year band on multidecadal time scales there is a relative reduction in the amplitude of high frequency variability during the sixteenth early seventeenth and mid eighteenth centuries in contrast high frequency enso variability has increased over the last 200 years variability during the first half of the twentieth century is similar to that evident in the nineteenth century

tidal forcing of the water mass interface in the strait of messina the tidal currents of the strait of messina and their effect on the displacement of the water mass interface are discussed utilizing the historical velocity data of francesco vercelli taken from 100 anchor stations during 1922 and 1923 the data show a complex strongly tidal behavior in which speeds of 200 300 cm s are attained over the sill messina is an amphidromic point for the tides of the two main basins of the mediterranean sea and two distinct water masses flow through the strait at different stages of the tide the subsurface levantine intermediate water flowing north alternating with surface tyrrhenian water flowing south the time evolution of the interface between the two marine water layers at the semidiurnal periodicity is computed from the observed distribution of acceleration term for the baroclinic component this interface shows large vertical oscillations with amplitudes of 100 m intersecting both the surface and bottom the results are in reasonable agreement with recent satellite data and other recent field observations and numerical experiments an estimate of the mean position of the interface is made by assuming that the potential energy required to uplift the interface from the equilibrium depth of 150 m to the observed 30 m depth over the sill is derived from the time independent contribution of the nonlinear field acceleration term the results are in reasonable agreement with observations

discerning the timing and cause of historical mortality events in modern porites from the great barrier reef the life history strategies of massive porites corals make them a valuable resource not only as key providers of reef structure but also as recorders of past environmental change yet recent documented evidence of an unprecedented increase in the frequency of mortality in porites warrants investigation into the history of mortality and associated drivers to achieve this both an accurate chronology and an understanding of the life history strategies of porites are necessary sixty two individual uranium thorium u th dates from 50 dead massive porites colonies from the central inshore region of the great barrier reef gbr revealed the timing of mortality to have occurred predominantly over two main periods from 1989 2 4 1 to 2001 4 4 1 and from 2006 4 1 8 to 2008 4 2 2 a d with a small number of colonies dating earlier overall the peak ages of mortality are significantly correlated with maximum sea surface temperature anomalies despite potential sampling bias the frequency of mortality increased dramatically post 1980 these observations are similar to the results reported for the southern south china sea high resolution measurements of sr ca and mg ca obtained from a well preserved sample that died in 1994 6 2 3 revealed that the time of death occurred at the peak of sea surface temperatures sst during the austral summer in contrast sr ca and mg ca analysis in two colonies dated to 2006 9 3 0 and 2008 3 2 0 suggest that both died after the austral winter an increase in sr ca ratios and the presence of low mg calcite cements as determined by sem and elemental ratio analysis in one of the colonies was attributed to stressful conditions that may have persisted for some time prior to mortality for both colonies however the timing of mortality coincides with the 4th and 6th largest flood events reported for the burdekin river in the past 60 years implying that factors associated with terrestrial runoff may have been responsible for mortality our results show that a combination of u th and elemental ratio geochemistry can potentially be used to precisely and accurately determine the timing and season of mortality in modern massive porites corals for reefs where long term monitoring data are absent the ability to reconstruct historical events in coral communities may prove useful to reef managers by providing some baseline knowledge on disturbance history and associated drivers 2014 elsevier ltd all rights reserved

evidence of reduced mid holocene enso variance on the great barrier reef australia this study was funded by the national environmental research programme nerp tropical ecosystems hub project 1 3 characterising the cumulative impacts of global regional and local stressors on the present and past bio diversity of the gbr to j xz jmp sgs trc y xf and others and australian research council lief grant le0989067 for the purchase and installation of the mc icp ms essential for this study to jxz jmp y xf and others as well as an australian postgraduate award apa to ndl we are grateful to eric matson from the australian institute of marine science aims for technical assistance in obtaining the fossil coral cores and to hard rock earth works rod morelli and associates in townsville for allowing access to the corals we also thank st vincent s private hospital brisbane for ct scans and queensland diagnostic imaging indooroopilly for x rays we thank an anonymous reviewer for helpful comments on an earlier manuscript the data used in this study are available through the cited references figures and tables as well as in the supporting information to this manuscript

yellow sea ocean acoustic solitary wave modeling studies 1 this study is in an area south of the shandong peninsula near the region where zhou et al 1991 observed anomalous drops in acoustical intensity solitary wave generation and propagation simulations are performed using the lamb 1994 nonhydrostatic model the model simulations show that for summer conditions the existing semi diurnal tidal flow over the topographic variations formed internal bores and solitary waves for the shandong area we analyzed summer observations from synthetic aperture radar sar that tracked solitary wave trains from their surface roughness signatures the images contained seven events consisting of internal bores and solitary waves that traveled in a well defined direction for 2 5 days the origin of the trains appeared at a well defined point along a steep topographic drop the sar observations guided and tuned the model simulations by comparing spectra of observed and modeled wavelengths the tuned model yields wavelengths within factors of 2 or less of those derived from sar data wavelength and amplitude dispersion analysis showed two dispersion regimes modeled phase speeds were at the lower limit of phase speeds deduced from sar data from about 0 8 to 1 0 m s acoustical intensity calculations in the presence of solitary wave trains will be undertaken in a subsequent paper using a parabolic equation acoustical model along the path of solitary wave train propagation

evidence for suppressed mid holocene northeastern australian monsoon variability from coral luminescence summer monsoon rainfall in northeastern ne australia exhibits substantial interannual variability resulting in highly variable river flows the occurrence and magnitude of these seasonal river flows are reliably recorded in modern inshore corals as luminescent lines here we present reconstructed annual river flows for two 120 year mid holocene windows based on luminescence measurements from five cores obtained from three separate coral colonies we were able to cross date the luminescence signatures in four cores from two of the colonies providing confidence in the derived reconstruction present day ne australian rainfall and river flow are sensitive to el nino southern oscillation enso variability with la nina el nino events typically associated with wetter drier monsoon seasons thus our replicated and annually resolved coral records provide valuable insights into the northern australian summer monsoon and enso variability at a key period 6 ka when greenhouse gas levels and ice sheet cover were comparable to the preindustrial period but orbital forcing was different average modern and mid holocene growth characteristics were very similar suggesting that sea surface temperatures off ne australia at 6 kyr were also close to present values the reconstructed river flow record suggests however that the mid holocene australian summer monsoon was weaker less variable from year to year possibly indicative of reduced enso variability and characterized by more within season flood pulses than present in contrast to today the delivery of moisture appears to have been dominated by eastward propagating convective coupled waves associated with the madden julian oscillation

comment on internal waves an under explored source of turbulence events in the sedimentary record by l pomar m morsilli p hallock and b badenas earth science reviews 111 2012 56 81 this discussion is an attempt to alert the sedimentologic community that there is an immediate need to carry out fundamental research on process sedimentology of internal waves and internal tides in modern oceans despite the exhaustive theoretical experimental observational and numerical analyses of modern internal waves and internal tides by oceanographers with their focus on ocean mixing and modeling there are absolutely no core based studies by sedimentologists on the origin of primary sedimentary structures formed by baroclinic currents associated with internal waves and internal tides in modern marine environments as a consequence there are no objective sedimentological criteria for distinguishing internal wave deposits amid this knowledge vacuum the temptation to interpret ancient rock record as internal wave deposits must be tempered

evidence from wavelet analysis for a mid holocene transition in global climate forcing a strong mid holocene transition has been identified by wavelet analyses in several sea ice cover records from the circum antarctic area ice core records taylor dome byrd and tropical marine records the results are compared with those previously published in a synthesis of north atlantic records and with 4 new records from the norwegian and icelandic seas and from a coastal site in ireland these new records confirm the previous pattern for the north atlantic area extend this pattern nearly to the arctic circle and include a continental record we further tested the possibility of extending this scheme using continental records from south america the holocene pattern proposed here confirms the importance of external forcing during the early holocene solar activity 1000 years cyclicity and 2500 years during the entire holocene even if the signal is disturbed by meltwater fluxes the second part of the holocene is then marked by the gradual appearance of internal forcing thermohaline circulation around 1500 years associated with a stabilisation of the signal coupling between ocean and atmosphere seems to play a fundamental role in the observed frequencies which vary accordingly in the atlantic circum antarctic and pacific areas the north atlantic area seems to be the instigator of thermohaline circulation as shown by its sensitivity to meltwater discharges during the early holocene even though each sector is independent with regards to its frequency content around 1600 years for atlantic area around 1250 years for antarctica the holocene methane pattern still under debate ruddiman w f 2003a orbital insolation ice volume and greenhouse gases quaternary science review 22 1597 1629 ruddiman w f 2003b the anthropogenic greenhouse era began thousands of years ago climatic change 61 261 293 could be explained by a more efficient thermohaline circulation around the mid holocene with an anthropogenic effect initiated at not vert similar2500 bp as shown by the inter hemispheric gradient

mid holocene sea surface conditions and riverine influence on the inshore great barrier reef we present measurements of sr ca 18o and spectral luminescence ratios g b from a mid holocene porites sp microatoll recovered from the nearshore great barrier reef gbr these records were used as proxies to reconstruct sea surface temperature sst the 18o of surrounding seawater 18osw and riverine influence respectively and compared with records from a modern porites sp microatoll growing in the same environment strong riverine influence in the mid holocene record is indicated by 1 an increased annual 18osw range in the mid holocene record 2 negative peaks in 18o characteristic of flood events and 3 a higher g b luminescence ratio seasonal cycles in g b suggest that humic acid inputs were elevated for a longer portion of the year during the mid holocene the seasonal cycle of 18osw peaked earlier in the year in the mid holocene record relative to the modern while mean 18osw values from the mid holocene record were similar to modern values these records provide an insight into the oceanographic conditions the nearshore gbr experienced during mid holocene climatic shifts and are consistent with a strong australian indonesian summer monsoon aism system at 4700 cal yr bp

fluorescent bands in massive corals record centuries of coastal rainfall massive coral colonies on the great barrier reef grow outwards at 5 25 mm yr 1 ref 1 skeletal density varies seasonally in all massive corals from the great barrier reef and an exact temporal record of growth can be obtained by x radiography of appropriately cut sections of the colony2 3 environmental influences on coral growth have been described from such analyses4 6 this is the first report from the skeletons of massive corals of yellow green fluorescent bands which appear under long wave uv light such fluorescence is confined to corals growing within 20 km of the shore and is not present in massive corals from mid and outer shelf reefs of the central great barrier reef region the timing width and intensity of the fluorescent bands correlate strongly with summer monsoonal rainfall and coastal runoff large colonies several centuries old can provide long records of the strength and periodicity of terrestrial runoff to the tropical nearshore environment such records are potentially important to climatology meteorology agriculture civil engineering and management of the great barrier reef

study of the generation and propagation of internal waves in the strait of gibraltar using a numerical model and synthetic aperture radar images of the european ers 1 satellite a weakly nonhydrostatic two layer numerical model based on the boussinesq equations is presented which is capable of describing among others the generation and propagation of nonlinear weakly dispersive internal waves in the strait of gibraltar the model depends on one space coordinate only but it retains several features of a fully three dimensional model by including a realistic bottom profile a variable channel width and a trapezoidal channel cross section the nonlinear primitive boussinesq equations include horizontal diffusion bottom friction and friction between the two water layers the model is driven by a height difference of the mean interface depth between the atlantic and the mediterranean boundaries and by semidiurnal tidal oscillations of the barotropic transport the model presented in this paper describes 1 the mean and tidal flow in the strait of gibraltar 2 the variation of the depth of the interface during a tidal cycle 3 the generation of strong depressions of the interface at the western sides of the spartel sill and the camarinal sill 4 the generation of strong eastward propagating internal bores and 5 their disintegration into trains of internal solitary waves the surface convergence patterns associated with depressions of the interface at the camarinal sill internal bores and internal solitary waves are calculated and compared with roughness patterns visible on synthetic aperture radar sar images of the first european remote sensing satellite ers 1 in total 155 ers 1 sar scenes from 94 satellite overflights over the strait of gibraltar which were acquired in the period from january 1992 to march 1995 have been analyzed it is shown that the proposed model is capable of explaining the observed temporal and spatial evolution of surface roughness patterns associated with eastward propagating internal waves inside the strait of gibraltar as well as the observed east west asymmetry of the internal wave field

indices of el nino evolution abstract to characterize the nature of el nino southern oscillation enso sea surface temperature sst anomalies in different regions of the pacific have been used an optimal characterization of both the distinct character and the evolution of each el nino or la nina event is suggested that requires at least two indices i sst anomalies in the nino 3 4 region referred to as n3 4 and ii a new index termed here the trans nino index tni which is given by the difference in normalized anomalies of sst between nino 1 2 and nino 4 regions the first index can be thought of as the mean sst throughout the equatorial pacific east of the date line and the second index is the gradient in sst across the same region consequently they are approximately orthogonal tni leads n3 4 by 3 to 12 months prior to the climate shift in 1976 77 and also follows n3 4 but with opposite sign 3 to 12 months later however after 1976 77 the sign of the tni leads and lags are reversed

modeling of hydraulically controlled exchange flow in the bosphorus strait abstract recent hydrographic observations obtained in the bosphorus strait illustrate several features of the flow that may be related with the internal hydraulics a two layer numerical model indicates that the two way exchange flow may indeed be subject to a series of internal hydraulic adjustments along the strait due to morphological features such as sills a contraction and abrupt expansion of the width of the strait the model identifies three distinct regions of the supercritical flow the lower layer flow of the marmara sea origin is directed to the north towards the black sea in a progressively thinning layer and is controlled by the sill located near the black sea entrance of the strait the upper layer water of the black sea origin flows in the opposite direction and is controlled upon reaching the constricted region located about 10 12 km away from the marmara end of the strait the upper layer flow is then matched to the subsequent subcritical conditions by undergoing an internal hydraulic ju

mid to late holocene climate change an overview the last 6000 years are of particular interest to the understanding of the earth system because the boundary conditions of the climate system did not change dramatically in comparison to larger glacial interglacial changes and because abundant detailed regional palaeoclimatic proxy records cover this period we use selected proxy based reconstructions of different climate variables together with state of the art time series of natural forcings orbital variations solar activity variations large tropical volcanic eruptions land cover and greenhouse gases underpinned by results from general circulation models gcms and earth system models of intermediate complexity emics to establish a comprehensive explanatory framework for climate changes from the mid holocene mh to pre industrial time the redistribution of solar energy due to orbital forcing on a millennial timescale was the cause of a progressive southward shift of the northern hemisphere nh summer position of the intertropical convergence zone itcz this was accompanied by a pronounced weakening of the monsoon systems in africa and asia and increasing dryness and desertification on both continents the associated summertime cooling of the nh combined with changing temperature gradients in the world oceans likely led to an increasing amplitude of the el nin o southern oscillation enso and possibly increasingly negative north atlantic oscillation nao indices up to the beginning of the last millennium on decadal to multi century timescales a worldwide coincidence between solar irradiance minima tropical volcanic eruptions and decadal to multi century scale cooling events was not found however reconstructions show that widespread decadal to multi century scale cooling events accompanied by advances of mountain glaciers occurred in the nh e g in scandinavia and the european alps this occurred namely during the little ice age lia between ad w1350 and 1850 when the lower summer insolation in the nh due to orbital forcing coincided with solar activity minima and several strong tropical volcanic eruptions the role of orbital forcing in the nh cooling the southward itcz shift and the desertifi cation of the sahara are supported by numerous model simulations other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics but there is also evidence that changes in the ocean heat transport took place during the lia at high northern latitudes with possible additional implications for climates of the southern hemisphere sh

regional pn body wave magnitude scale mb pn for earthquakes along the northern mid atlantic ridge we obtained a robust regional body wave magnitude scale mb pn for earthquakes along the northern mid atlantic ridge by using pn wave recorded at continental stations the new magnitude scale is mb pn log10 a nm 1 86 log10 100 km c 1 62 where a is the zero to peak amplitude of pn wave on the simulated vertical wood anderson seismogram in nanometers is the epicentral distance in kilometers 1 86 represents amplitude attenuation c is the station correction and 1 62 anchors the mb pn to the moment magnitude mw plus amplitude loss in the two crustal legs by using moment magnitude as reference we obtained the event magnitude adjustments ema which represent the difference between the known long period mw and the short period mb pn emas correlate with the source property where ridge events show strong long period waves but poor high frequency signals which lead to mb pn mw and negative adjustment of 0 20 0 24 m u almost all normal faulting events are along spreading ridges whereas strike slip events are along the fracture zones and transform faults hence we developed source specific magnitude adjustments ssma which range from 0 27 m u for earthquakes along the ridges to 0 26 m u for earthquakes along the transform faults using ssma we obtained a regional pn magnitude that is consistent with mw and mb p the regression relationship is mw 0 91 mb pn ssma 0 46 with a standard deviation of 0 15 m u

holocene changes in eastern tropical pacific climate inferred from a galapagos lake sediment record abstract paleoclimate records from the tropical pacific suggest the early to mid holocene was a period of reduced el nino southern oscillation enso variability with a transition to modern increased enso frequency occurring some time in the last few thousand years however the nature and timing of this shift remains uncertain due to the discontinuous nature and or coarse resolution of many enso proxies as well as a lack of agreement between previously published records a new continuous climate record from el junco crater lake in the galapagos islands reveals several abrupt changes in lake level and precipitation through the holocene hydroclimatic model simulations suggest that el junco lake level responds sensitively to increases in precipitation associated with el nino events rising during wet el nino events and falling during the intervening dry periods grain size data from el junco sediment cores indicate past lake level variability likely associated with changing seasonal precipitation and enso frequency the grain size data suggest increased precipitation intensity prior to 9000 120 cal years bp and after 4200 130 cal years bp as well as a two step increase in precipitation at 3200 160 and 2000 100 cal years bp maximum holocene precipitation and inferred enso variability occurred between 2000 100 and 1500 70 cal years bp during the same period that six other independent proxy records suggest higher enso frequency and longer stronger el nino events decreasing sediment carbon nitrogen c n ratios in el junco sediments indicate rising lake levels from the early holocene to present corroborating the grain size data the inferred increase in precipitation at 4200 130 cal years bp and at 2000 100 cal years bp coincides with decreasing southwest asian and east asian monsoon intensity suggesting tropical pacific climate and the asian monsoon were interconnected systems at centennial to millennial timescales during the holocene a weakening trend in the asian monsoon and the trend toward wetter conditions at el junco also coincide with a trend toward cooler and drier conditions inferred from cariaco basin sediment proxies from the mid holocene to present suggesting the migration of the intertropical convergence zone itcz likely influenced hydrological changes in both the eastern tropical pacific and the asian monsoon region during the holocene

the role of internal waves in the late quaternary evolution of the israeli continental slope abstract internal waves are widely present in world s oceans propagating in stratified ocean layers such as the seasonal pycnocline at continental shelves and slopes breaking of internal waves may create turbulence of sufficient energy to erode and transport sediments in this study we investigate the late pleistocene to recent impact of internal waves on the morphology of the israeli mediterranean continental slope based on mooring data we show that the internal wave spectrum on the upper slope contains significant energy at near inertial and semidiurnal tidal frequencies sediment subbottom profiler data show two fields of nearly contour parallel sediment waves located in water depths of 80 m 130 m and 190 m 350 m respectively a zone of flat seafloor morphology and remarkably constant slope inclination of 1 0 1 2 separates both sediment wave fields the entire stretch of seafloor between 80 m and 350 m corresponds to depths of major ocean density stratification supporting the propagation of internal waves in addition this area is critically inclined with respect to semidiurnal internal tides and supercritically inclined with respect to near inertial waves two scenarios previously related to internal wave breaking we propose that breaking internal waves control the inclination of the israeli continental slope and contribute to sediment starvation within the zone of flat seafloor morphology the formation of sediment waves is attributed to high frequency trailing internal waves of similar wavelengths as sediment waves observed within a seismic image of the water column we correlate subbottom profiler data to a radiocarbon dated sediment core no sediment waves formed from 16 cal ka 8 cal ka indicating that the seafloor impact of internal waves ceased during a time of rapid sea level rise and fresh water input in the eastern mediterranean realm the end of this period coincides with the formation of sapropel s1

a shifting river of sand the profound response of australia s warrego river to holocene hydroclimatic change abstract in dryland river catchments palaeochannels provide some of the key records for understanding the changes in river character and behaviour that can occur in response to different extrinsic and intrinsic controls here we combine modern hydroclimatic datasets satellite imagery field surveys and optically stimulated luminescence osl dating of palaeochannels to investigate the response of the 850 km long warrego river located in central eastern australia to holocene hydroclimatic change the modern warrego is an intermittent to ephemeral low energy river unit stream power 4 w m 2 and is characterised by low sinuosity straight narrow

on the determination of characteristics of the interior ocean dynamics from radar signatures of internal solitary waves in this paper we discuss two different methods of inferring characteristics of the interior ocean dynamics from radar signatures of internal solitary waves visible on synthetic aperture radar sar images the first one consists in the recognition and the interpretation of sea surface patterns of internal solitary waves the second one consists in the analysis of the modulation depth of the normalized radar backscattering cross section nrcs associated with internal solitary waves for this purpose we consider a data set composed of sar and in situ measurements carried out from 1991 to 1997 in the region of the strait of messina the recognition and the interpretation of sea surface patterns of internal solitary waves in the strait of messina can be used to study characteristics of the density distribution in the area the internal wave field varies with seasonal variations in the vertical density stratification and with remotely induced variations i e variations induced by the larger scale circulation in the horizontal density distribution in order to inquire into the possibility of inferring parameters of the interior ocean dynamics by analyzing the modulation of the nrcs associated with internal solitary waves several numerical simulations are carried out using a radar imaging model these simulations are performed by assuming different wind conditions and internal wave parameters it is shown that an accurate knowledge of wind conditions is crucial for deriving internal wave parameters and hence parameters of the interior ocean dynamics from the modulation of measured nrcs associated with internal solitary waves

the sulu sea internal soliton experiment abstract we present the results of a comprehensive study of large amplitude internal solitons generated in the sulu sea in the philippines by intense tidal flow over a sharp bathymetric feature surface signatures of these waves have been observed in images from the dmsp landsat and nimbus 7 satellites and the space shuttle sir a synthetic aperture radar a two week experiment was conducted in the sulu sea in may 1980 from r v oceanograher during which a three mooring phased array of current meters and thermistors was implanted near the wave source and at 82 km and 200 km from the source seventeen soliton packets were observed whose properties underwent significant change as they propagated across the sea vertical profiles of density temperature and acoustic backscatter as well as radar and photographic surface signatures were obtained from the ship data from satellites moorings and the ship give unprecedented information on the spatial and temporal characteristics of solitary waves which ha

pharmacokinetic modelling of multi decadal luminescence time series in coral skeletons abstract as corals grow they incorporate chemical indicators of seawater conditions into their aragonite skeleton after they have traversed an outer living tissue layer long lived massive coral skeletons can record decade and century long time series of seawater status one such environmental clue is luminescence intensity which can correspond to river flow patterns and has been attributed to humic acid incorporation seawater humic acid levels are linked to river flow as rainfall extracts them from catchment soils to then flow into rivers and coastal seas however discrepancies exist when validating coral luminescence records against river flow data with intense luminescence sometimes occurring in the absence of increased flows this contributes to uncertainty when reconstructing pre instrumental river flows and rainfall from coral luminescence here we demonstrate that a major portion of coral core luminescence time series can be explained using a single compartment pharmacokinetic model that incorporates river flow measurements as the equivalent of drug dose the model was robust for luminescence series in corals from near shore reefs regularly influenced by river flow the model implies that after floods a proportion of subsequent luminescence peaks can be derived from the initial flood this explains why some luminescence peaks after floods often do not correspond to additional significant river flows this provides the first mechanism based explanation for temporal changes in coral skeleton luminescence that incorporates a mathematical link between two independent time series making this proxy even more robust for reconstructing river flow and rainfall

evidence for the influence of atlantic ionian stream fluctuations on the tidally induced internal dynamics in the strait of messina abstract on 24 and 25 october 1995 high resolution oceanographic measurements were carried out in the strait of messina by using a towed conductivity temperature depth chain and a vessel mounted acoustic doppler current profiler during the period of investigation the surface water of the tyrrhenian sea north of the strait sill was heavier than the surface water of the ionian sea south of the strait sill as a consequence during northward tidal flow surface water of the ionian sea spread as a surface jet into the tyrrhenian sea whereas during southward tidal flow heavier surface water of the tyrrhenian sea spread after having sunk to a depth of about 100 m as a subsurface jet into the ionian sea both jets had the form of an internal bore which finally developed into trains of internal solitary waves whose amplitudes were larger north than south of the strait sill these measurements represent a detailed picture of the tidally induced internal dynamics in the strait of messina during the period of i