the global mesoscale eddy available potential energy field in models and observations global maps of the mesoscale eddy available potential energy eape field at a depth of 500m are created using potential density anomalies in a high resolution 112 5 global ocean model maps made from both a free running simulation and a data assimilative reanalysis of the hybrid coordinate ocean model hycom are compared with maps made by other researchers from density anomalies in argo profiles the hycom and argo maps display similar features especially in the dominance of western boundary currents the reanalysis maps match the argo maps more closely demonstrating the added value of data assimilation global averages of the simulation reanalysis and argo eape all agree to within about 10 the model and argo eape fields are compared to eape computed from temperature anomalies in a dataset of moored historical observations mho in conjunction with buoyancy frequencies computed from a global climatology the mho dataset allows for an estimate of the eape in high frequency motions that is aliased into the argo eape values at mho locations 15 32 of the eape in the argo estimates is due to aliased motions having periods of 10 days or less spatial averages of eape in hycom argo and mho data agree to within 50 at mho locations with both model estimates lying within error bars observations analysis of the eape field in an idealized model in conjunction with published theory suggests that much of the scatter seen in comparisons of different eape estimates is to be expected given the chaotic unpredictable nature of mesoscale eddies

influence of stratification on residual tidal currents in the yellow sea the m 2 tide and residual current generation in the yellow sea are examined using the blumberg and mellor 1987 numerical coastal ocean circulation model with no stratification the model tide and tidal currents show good agreement with the observed tide and tidal currents coherent residual currents are predicted around the southwest of korea flowing northward as a strong jet with a maximum speed of 8cm s 1 and around yangtze bank flowing southeastward as a weak broad current with initial stratification tidal mixing occurs in the bottom boundary layer which leads to surface tidal fronts around yangtze bank and the southwest of korea and our model experiments reproduce successfully the basic water property structure in these regions the resulting stratified tidal rectification intensifies the residual currents at the front and at the top of the bottom boundary layer over the sloping bottom so that the vertical structure of the residual currents is modified the strong residual currents in the top of the bottom mixed layer around yangtze bank support the interpretation of kim et al 1991 for the southeastward movement of yellow sea bottom cold water in summer the residual currents in the surface layer reach 40 of the mean currents observed by beardsley et al 1992 using satellite tracked drifters deployed in the yellow sea in summer these results suggest that stratified tidal rectification is an important process in driving the summertime subtidal flow in the yellow sea

double averaging concept for rough bed open channel and overland flows theoretical background the goal of this paper is to discuss the spatial averaging concept in environmental hydraulics and develop it further by considering transport equations for fluid momentum passive substances and suspended sediments the averaging theorems the double averaged in time and in space fluid momentum equation and advection diffusion equations for a passive substance and suspended sediments are introduced and their limitations and applications for modeling rough bed flows experimental design and data interpretation are discussed the suggested equations differ from those considered in terrestrial canopy aerodynamics and porous media hydrodynamics by accounting for roughness mobility change in roughness density in space and time and particle settling effects for the case of suspended sediments we show that the form of the double averaged equations may depend on the type of decomposition of flow variables and that this difference may have important implications for modeling we also show that the suggested methodology offers better definitions for hydraulic characteristics variables and parameters such as flow uniformity flow two dimensionality and bed shear stress

marine incursions of the past 1500 years and evidence of tsunamis at suijin numa a coastal lake facing the japan trench sandy deposits of marine origin underlie the floor of suijin numa a coastal lake midway along the subduction zone marked by the japan trench the deposits form three units that are interbedded with lacustrine peat and mud above a foundation of marine probably littoral sand unlike the lacustrine deposits all three sandy units contain marine and brackish diatoms the middle unit b contains in addition graded beds sug gestive of multiple waves of long wavelength and period the uppermost unit c probably dates to a time in the area s written history when the lake was separated from the sea by a beach ridge plain at least 0 5 km wide and several metres high units a and b postdate ad 540 870 and unit c postdates ad 1030 1640 as judged from radiocarbon dating of leaves and seeds unit b pre dates ad 915 and unit c postdates that year as judged from a tephra within the peat that separates units b and c the age constraints permit correlation of unit b with a tsunami in ad 869 that reportedly devastated at least 100 km of coast approximately centred on sendai unit c may represent a later catastrophic tsunami in 1611 or perhaps a storm surge that inundated much of sendai the lake lacks obvious signs of tsunamis from the region s largest twentieth century earthquakes which were centred to the north in 1933 m 8 1 and directly offshore in 1936 m 7 5 and 1978 mw 7 6

reconstructing relative flooding intensities responsible for hurricane induced deposits from laguna playa grande vieques puerto rico extreme coastal flooding primarily during hurricane strikes has deposited sand rich layers in laguna playa grande a back barrier lagoon located on the island of vieques puerto rico silici clastic grain size distributions within these overwash deposits fine landward away from the barrier and toward the mainland a simple advective settling model can explain this pattern of lateral sorting and is used to constrain the relative magnitude of past flooding events a deposit associated with the a d 1928 san felipe hurricane is used as a modern analogue to test the technique which produces reasonable estimates for wave heights that exceed the barrier during the event a 5000 yr reconstruction of local flooding intensity is developed that provides a measure of the competence for each overwash event to transport coarser grained sediment a fixed distance into the lagoon this reconstruction indicates that although the laguna playa grande record exhibits large scale changes in hurricane frequency on centennial to millennial time scales the magnitude of these events has stayed relatively constant over the last 5000 yr no evidence exists for an anomalously large hurricane or tsunami event with a competence for sediment transport greater than historical hurricane events

controls on links between geomorphical and surface sedimentological variability aitutaki and maupiti atolls south pacific ocean abstract isolated carbonate platforms and atolls occur throughout the geologic record from archean to present although the roles of sea level change tectonics and sediment supply on large scale changes in stratigraphical architecture of these systems are relatively well understood the details of the nature and controls on sedimentological variability between and within individual geomorphic elements on platforms and atolls are less well constrained the purposes of this study are 1 to describe compare and contrast geomorphological and sedimentological characteristics of surficial holocene sediments from two south pacific atolls aitutaki and maupiti representing different physical and chemical oceanographic settings and 2 to explore possible causes for sedimentological heterogeneity by contrasting the patterns with those present on other platforms and regions both atolls include annular shelf edge reef systems with a red algal rim and reef flat flanked lagoonward by reef sand aprons up to 1 500 m wide these aprons consist of moderately sorted coarse sand and gravel with an abundance of halimeda coral and red algal fragments broadly sediments become finer and better rounded away from margins water depths increase abruptly inboard of these reef sand aprons into platform interiors with depths up to 25 m maupiti and 9 m aitutaki although patch reefs dot these lagoons sediment is commonly poorly sorted with bimodal and polymodal size distributions and includes a mix of whole and fragmented skeletal grains peloids and ooids mud and fine sand are abundant up to 80 on maupiti 85 on aitutaki the occurrence of peloids fine ooid sand and oolitically laminated skeletal grains on maupiti atoll as previously documented on aitutaki is consistent with interpretations of the impact of elevated regional ocean total alkalinity ta and ph levels in this part of the pacific on these wave dominated atolls open ocean waves impinging on the platform margins generate currents that transport sediment from the reef across the sand apron and towards the platform interior unlike the tide dominated platforms of the bahamas however weak tides preclude strong daily agitation and circulation so ooids do not grow large and mud and fine sand transported into the atoll interiors is sequestered there in the interiors both sediment produced in situ and fine allochthonous sediment are more influenced by biological processes than by physical transport processes so bioturbated muddy sand is most common collectively the comparative analysis provides actualistic process based conceptual models for the nature and controls on variability of shelf margin reef and reef apron systems and platform interiors within and among atolls

satellite observations of a western boundary current in the bay of bengal satellite infrared observations of the bay of bengal during the latter part of february 1985 reveal the existence of two bands of warm water that resemble western boundary currents along the east coasts of india and sri lanka a recently formed elliptical warm core eddy with a major axis of nearly 150 km appears at longitude 90 e and latitude 19 n at the end of the axis of the current color infrared images of sea surface temperature are used to illustrate the sea surface temperature patterns and to estimate their displacements with time

a mixing layer theory for flow resistance in shallow streams 1 a variety of surface roughness characterizations have emerged from nineteenth and twentieth century studies of channel hydraulics when the water depth h is much larger than the characteristic roughness height ks roughness formulations such as manning s n and the friction factor f can be explicitly related to the momentum roughness height zo in the log law formulation for turbulent boundary layers thereby unifying roughness definitions for a given surface however when h is comparable to or even smaller than ks the log law need not be valid using a newly proposed mixing layer analogy for the inflectional velocity profile within and just above the roughness layer a model for the flow resistance in shallow flows is developed the key model parameter is the characteristic length scale describing the depth of the kelvin helmholtz wave instability it is shown that the new theory originally developed for canopy turbulence recovers much of the earlier roughness results for flume experiments and shallow gravel streams this study is the first to provide such a unifying framework between canopy atmospheric turbulence and shallow gravel stream roughness characterization the broader implication of this study is to support the merger of a wealth of surface roughness characterizations independently developed in nineteenth and twentieth century hydraulics and atmospheric sciences and to establish a connection between roughness formulations across traditionally distinct boundary layer types

the roles of elevation and salinity as primary controls on living foraminiferal distributions cowpen marsh tees estuary uk abstract benthic foraminiferal assemblages in subrecent deposits are commonly used to reconstruct past sea level interpretations are generally made by comparison with either modern dead or total live plus dead assemblages in both cases there will have been post mortem changes that have differentially affected preservation it is therefore important to establish the primary ecological controls by analysis of the living assemblages we have determined the spatial and temporal variability of intertidal benthic foraminifera in the surface 0 1 cm sediments from a time series survey of 31 sampling stations at cowpen marsh for a period of 12 months we counted 112 067 live foraminifera assigned to 28 species the fauna was dominated by two agglutinated species jadammina macrescens and trochammina inflata on the high and middle marshes and three calcareous species elphidium williamsoni haynesina germanica and quinqueloculina spp on the low marsh and tidal flat the standing crop of the whole intertidal zone including the high middle low marsh and tidal flat habitats and the individual species varied both temporally and spatially the standing crop of the intertidal zone as a whole was greatest in the summer months and showed a positive correlation with elevation the standing crops of the high and middle marshes showed similar temporal variation with peaks in summer and autumn and a trough in winter the low marsh showed numerous peaks and troughs of standing crop during the year whereas the tidal flat showed a single peak in summer the standing crops of jadammina macrescens and trochammina inflata on the high and middle marshes peaked from april to may and august to october with troughs in winter these agglutinated species showed a strong correlation with elevation haynesina germanica peaked in may to august and november to january on the low marsh whereas on the tidal flat there was a single peak in july the standing crops of e williamsoni on the low marsh and tidal flat were relatively high in june and may and july respectively quinqueloculina spp peaked in may to july on the low marsh and july on the tidal flat the species was also found in the middle marsh from july to may and high marsh from september to november haynesina germanica showed a strong negative correlation with elevation whereas the other two dominant calcareous species demonstrated weak negative correlations with both elevation and salinity reconstructing former sea level depends primarily on the recognition of high and middle marsh assemblages and in this study these are shown to be strongly controlled by elevation rather than salinity caution may be needed in interpreting low marsh and tidal flat data as salinity plays a more important role here

hurricane records on the south carolina coast can they be detected in the sediment record abstract more than 40 short cores were collected from 10 localities in the myrtle beach to mcclellandville coastline of south carolina the localities were selected on the basis of whether or not they should have a well preserved record of recent hurricanes most notably hugo which occurred in september 1989 of the 40 cores collected results from two sites are presented here as examples price s inlet a non tidal intra beach ridge area which was directly in the path of the eyewall of hugo and sandpiper pond which is a coastal non tidal pond near murrells inlet about 50 75 km north of where the main landfall of hurricane hugo but still in the area of high storm surge these cores were analyzed for percentage organic carbon visual observations x rays and microfossils the microfossils were used to differentiate marine non marine sequences in the non tidal inlets and identify reworked sediments by means of displaced benthic foraminifera cores were dated using pb 210 techniques that provide resolution for the last 100 yr in price s inlet the hugo effect was most pronounced with an 8 cm thick sand layer containing many nearshore foraminifera showing transport from offshore in sandpiper pond we could see the trace of hugo from the offshore foraminifera contained in sediments sandwiched between the freshwater intervals both before and after hugo however there was little detectable trace in the x rays or sedimentology of this core to indicate a storm event hence we can recognize a range of responses for hurricanes in the form of different types of sediment layers and microfossil assemblages in these non tidal areas depending on where the impact point is on the coast here we are able to distinguish at least two types of signals from the same storm which has significant implications for detecting these events in the pre historic record and determining their paleo periodicity

assessing surficial foraminiferal distributions as an overwash indicator in sur lagoon sultanate of oman abstract the identification of tsunami and storm deposits in arid coastal environments can be problematic as overwash sediments may not show significant contrasting lithologic characters with lagoonal sediments in this study foraminifera were evaluated as an overwash indicator in a small 12 km2 intertidal lagoon located at sur in the sultanate of oman the lagoon is shallow

sediments deposited by the 2004 indian ocean tsunami along the malaysia thailand peninsula stratigraphy grain size distribution and foraminiferal assemblages of pre tsunami and tsunami sediment from the indian ocean tsunami at five sites along the malaysia thailand peninsula were analyzed to gain information on tsunami sediment source and deposition style between three and five stratigraphic units were identified at each site and contained between one and three fining upward sequences reflecting waning flow or pre backwash deposition coarser sand layers reflecting uprush high energy flow separated the fining upward sequences with the exception of one site sungai burong which contained a coarsening upward sequence all contacts between the pre tsunami and tsunami sediment were sharp or erosional medium and coarse sand dominated all of the tsunami sediment deposits and often contained shell fragments foraminiferal assemblages were able to differentiate pre tsunami sediment from tsunami sediment where no lithological or grain size distribution change was evident between two and four foraminiferal zones were identified at each of the five sites and provided estimates of sediment source and wave characteristics

source parameters for the 1952 kern county earthquake california a joint inversion of leveling and triangulation observations coseismic leveling and triangulation observations are used to determine the faulting geometry and slip distribution of the july 21 1952 mw 7 3 kern county earthquake on the white wolf fault a singular value decomposition inversion is used to assess the ability of the geodetic network to resolve slip along a multisegment fault and shows that the network is sufficient to resolve slip along the surface rupture to a depth of 10 km below 10 km the network can only resolve dip slip near the fault ends the preferred source model is a two segment right stepping fault with a strike of 51 and a dip of 75 sw the epicentral patch has deep 6 27 km left lateral oblique slip while the northeastern patch has shallow 1 12 5 km reverse slip there is nearly uniform reverse slip epicentral 1 6 m northeast 1 9 m with 3 6 m of left lateral strike slip limited to the epicentral patch the seismic moment is m0 9 2 0 5 1019 n m mw 7 2 the signal to noise ratio of the leveling and triangulation data is reduced by 96 and 49 respectively the slip distribution from the preferred model matches regional geomorphic features and may provide a driving mechanism for regional shortening across the comanche thrust and structural continuity with the scodie seismic lineament to the northeast

hurricane induced sediment deposition in a gulf coast marsh abstract rates of sediment accumulation in four coastal marsh communities in the mississippi river deltaic plain louisiana were studied using feldspar clay marker horizons the results indicate that normal riverine flooding contributes relatively little

the importance of symbiont bearing benthic foraminifera for west pacific carbonate beach environments abstract in the tropical central and west pacific as well as in the east indian ocean symbiont bearing benthic foraminifera often are the main producers of calcium carbonate grains deposited at beaches the proportion of foraminiferal tests in medium sized to coarse sand grains may range from 20 to 95 this depends on two factors productivity and transport because foraminifers do not live on or in the sandy bottom near the beaches but prefer firm substrate in high energy environments close to the front of coral reefs foraminiferal tests are produced in extreme numbers on the reef crest of sesoko island okinawa japan 0 6 kg m 2 year 1 which is covered by macroalgae or in the transition zone between the crest and the reef moat 1 3 kg m 2 year 1 empty tests released by reproduction or death are entrained at the reef crest by waves and transported by currents this transport depends on the direction and intensity of currents connecting the habitat reef crest and transition to moat with the deposition area central moat lagoon beach habitat destruction and or the interruption or diversion of water flow hinders the accumulation of foraminiferal tests at the beach where deepening the moat intensifies beach parallel currents supply to and deposition at the beach are reduced while the remaining sand is eroded by tropical cyclones understanding the ecology especially population dynamics of larger foraminifera in combination with factors influencing the transport of empty tests is essential to preserve the balance between deposition and removal of sand at carbonate beaches in the west pacific and east indian ocean

mg ca and sr ca as novel geochemical proxies for understanding sediment transport processes within coral reefs sediment transport is a key driver of reef zonation and biodiversity where an understanding of sediment dynamics gives insights into past reef processes and allows the prediction of geomorphic responses to changing environmental conditions however modal conditions within the back reef seldom promote sediment transport hence direct observation is inherently difficult large benthic foraminifera lbf have previously been employed as tracers to infer sediment transport pathways on coral reefs as their habitat is largely restricted to the algal flat and post mortem their calcium carbonate test is susceptible to sediment transport forces into the back reef foraminiferal test abundance and post depositional test alteration have been used as proxies for sediment transport although the resolution of these measures becomes limited by low test abundance and the lack of variation within test alteration here we propose the novel use of elemental ratios as a proxy for sediment transport two species baculogypsina sphaerulata and calcarina capricornia were analysed using a taphonomic index within one tree and lady musgrave reefs great barrier reef australia inductively coupled plasma atomic emission spectrometry icp aes was used to determine mg ca and sr ca and these ratios were compared with taphonomic data decreases in test mg ca accompany increases in sr ca in specimens from algal flat to lagoonal samples in both species mirroring trends indicated by taphonomic values therefore indicating a relationship with test alteration to delineate mechanisms driving changes in elemental ratios back scattered electron bse images elemental mapping and in situ quantitative spot analyses by electron microprobe microanalysis epma using wavelength dispersive x ray spectrometers wds were performed on un altered algal flat and heavily abraded tests for both species epma analyses reveal heterogeneity in mg ca between spines and the test wall implying the loss of appendages results in a decrease in mg ca bse imaging and wds elemental mapping provided evidence for cementation facilitated by microbial boring as the primary cause of increasing sr ca these novel proxies hold advantages over taphonomic measures and further provide a rapid method to infer sediment transport pathways within back reef environments

sedimentary facies of bora bora darwin s type barrier reef society islands south pacific the unexpected occurrence of non skeletal grains abstract barrier reefs when encircling small islands have been comparatively little noticed by voyagers but they well deserve attention in their structure they are little less marvelous than atolls and they give a singular and most picturesque character to the scenery of the islands they surround darwin 1842 p 2 sediment sampling revealed six modern sedimentary facies in the barrier reef system around the volcanic island of bora bora including mixed skeletal packstone peloidal packstone halimeda rich packstone to grainstone coralgal grainstone wackestone and mudstone whereas sediments rich in corals and coralline algae are abundant on reefs and carbonate shoals mud rich sediments with mollusks and foraminifera occur in deep lagoons 15 40 m carbonate mud is composed largely of aragonite needles probably derived from codiaceans like halimeda and coccoliths in moderate abundances despite the proximity to a volcanic island the content of siliciclastics in the sediments is low 10 on average which is a consequence of the absence of permanent water courses in addition to skeletal grains non skeletal grains cemented fecal pellets aggregates occur in high abundance 30 50 in shallow lagoons 5 m on the eastern side of bora bora this observation opposes the widely held concept that non skeletal carbonate grains are abundant on platforms from the atlantic ocean but virtually missing in recent indo pacific reefs and carbonate platforms in bora bora non skeletal grains and aggregates apparently form in warm shallow 5 m moderately agitated areas with relatively low sedimentation rates in addition early cementation is probably favored by elevated alkalinity and ph in surface waters in this part of the south pacific in the same area some 900 km to the southwest of the study area ooids and peloids have recently been discovered in the shallow lagoon of aitutaki cook islands more occurrences of abundant non skeletal grains probably exist in the indo pacific region however too few locations have been systematically studied a comparison of the new bora bora data with other modern reefs and platforms shows that sediment occurrence and distribution exhibits basic patterns in that marginal areas are dominated by coarse grained coralgal sediment whereas lagoons and platform interiors are characterized by mollusk foram halimeda and non skeletal grains and fines still grain abundances may vary significantly among locations and again suggest the need for more studies in order to fully understand the factors controlling occurrence and distribution of modern sediments

geochemistry and grain size distribution of surface sediments of a large semi enclosed lagoon connected to the western bay of bengal abstract batticaloa is a large 135 5 km2 semi enclosed micro tidal lagoon that formed by barrier deposits in eastern sri lanka and has a unique geographic position due to its tropical monsoonal climate and absence of tectonics the recent soft bottom sediments of batticaloa lagoon were studied on the basis of geochemistry and grain size distribution in order to interpret their characteristics and provenance poor to moderately sorted medium sands are the dominant sedimentary deposits for the lagoon therefore a medium energy condition is suggested for sediment deposition the average silt and clay fraction of the lagoon sediments is less than 3 indicating medium or high energy flows coarser deposits are restricted to channel and lagoon mouths the scatter plots of nb zr cr and sc vs th and cr v vs y ni show a felsic provenance for the sediments the normalized diagrams of major element oxides and trace elements for the regional rocks vijayan complex of sri lanka indicate high country rock influence for the sedimentation for the semi enclosed setting the enrichment and distribution of zr th nb cr and tio2 suggest the possibility of mineral sands that are fractionated with hydrodynamic setting of the lagoon

lake sediment record of late holocene hurricane activities from coastal alabama coastal lake sediments contain a stratigraphically and chronologically distinct record of major hurricane strikes during late holocene time frederic a category 3 hurricane that struck the alabama coast on the gulf of mexico in 1979 left a distinct sand layer in the nearshore sediments of lake shelby as a result of storm tide overwash of beaches and dunes sediment cores taken from the center of lake shelby contain multiple sand layers suggesting that major hurricanes of category 4 or 5 intensity directly struck the alabama coast at ca 3 2 3 0 2 6 2 2 1 4 and 0 8 ka 14 c yr with an average recurrence interval of 600 yr the alabama coast is likely to be struck by a category 4 or 5 hurricane within the next century

representative roughness height of submerged vegetation 1 roughness length scale is important in the evaluation of resistance caused by submerged vegetation in open channel flows by transforming the concept of hydraulic radius a representative roughness height is proposed in this study for quantifying effect of submerged vegetation on flow resistance in the surface layer the proposed roughness height is characterized by its proportionality to both stem diameter and vegetation concentration and performs better than other length scales in collapsing resistance data collected under a wide range of vegetation conditions an approach is then developed for estimate of the average flow velocity and thus resistance coefficients for both cases of rigid and flexible vegetation comparisons are also made between the present study and other four formulas available in the literature this study also shows that all the formulas if simplified for some simple conditions can be unified in a general form

tides in the bay of bengal the amplitudes and phases of the tidal constituents m2 s2 k1 and o1 in the bay of bengal are deduced from tide gauge records at 112 locations with the aid of numerical models based on the vertically integrated equations of motion and continuity tidal elevations along the southern open boundary of the bay were obtained by interpolation from observations the results are presented in the form of cotidal charts these show that the constituents examined have no amphidromic points in the bay of bengal apart from a degenerate amphidrome for m2 in the northwest part of the bay

prediction of mean turbulent flow velocity in a permeable walled pipe abstract determining the characteristics of pipe flow and the effect of friction resistance is relevant to a variety of applications in hydraulic and hydrological engineering such as flood control river restoration and ground runoff prediction in the nikuradse s experiments the relative roughness and the bulk reynolds number are used to scale the darcy friction factor thereby determining the mean velocity recent observations using permeable walled pipes however indicate that the friction factor can significantly deviate from the results obtained in nikuradse s approach here we propose a concise model to estimate the mean velocity of the pipe flow over permeable walls the model is formulated using a data driven approach based on the analytical solution of the mean velocity and the similarity analysis dimension conservation of the two extreme cases impermeable and porous pipe flow we show that the proposed approach can derive a physically meaningful formula for the mean velocity furthermore we propose a simple momentum transfer model which confirms the findings from the data driven approach the momentum transfer model indicates that the friction factor can be scaled with two different relative hydraulics radius scales which are intrinsically determined by two different eddy sizes lastly the present approach is examined by comparing it with another approximate formula and the limited experimental data in the literature

studies on settling traction and entrainment of larger benthic foraminiferal tests implications for accumulation in shallow marine sediments settling and traction velocities were measured on optimally preserved tests of larger foraminifera using a settling tube and flume tank within larger foraminifera with porcelaneous tests the peneroplids peneroplis antillarum p planatus p pertusus and dendritina cf d zhengae are distinguished by low test densities ca 1 2 that do not change with growth buoyancy is high because of low reynolds numbers and increases in large individuals because of the allometric change of test shape the fusiform alveolinella quoyi with test densities ca 1 6 is characterized by high reynolds numbers inducing the weakest buoyancy within porcelaneous larger foraminifera the highest buoyancy was recorded for the three soritids parasorites orbitolitoides sorites orbiculus and amphisorus hemprichii because of their low test densities ca 1 25 and the extremely flat biconcave plate like shape flat tests however reduce traction and entrainment from smooth surfaces within hyaline larger foraminiferat the amphisteginids show thick lenticular amphistegina lobifera a radiata to thin lenticular tests a bicirculata a papillosa influencing buoyancy here high test densities ca 1 8 decrease with growth in a lobifera a lessonii and a bicirculata and remain constant in a radiata and a papillosa minimum velocities required for entrainment are lower for thick lenticular tests and higher for thin lenticular tests test densities remain constant with growth in the calcarinid baculogypsina sphaerulata 1 78 and decrease slightly in calcarina gaudichaudii and neorotalia calcar starting at 1 85 all living under extreme hydrodynamic conditions density decreases the most in baculogypsinoides spinosus starting at 1 8 resulting in higher buoyancy through low reynolds numbers traction is promoted in spherical tests of baculogypsina and baculogypsinoides within nummulitids the thick lenticular palaeonummulites venosus test density decreasing with size starting at 1 78 is less buoyant expressed in high reynolds numbers but easily entrained thick lenticular juveniles and extremely flat adults distinguish operculinella cumingii heterostegina depressa and the giant cycloclypeus carpenteri test densities increase during growth starting from ca 1 6 and attaining a maximum of 1 8 buoyancy is low in small tests and high in large tests while entrainment velocities are reduced as the tests flatten high buoyancy is also a characteristic of the entirely flat tests in operculina ammonoides from deeper regions and planostegina operculinoides which is expressed in the lowest reynolds numbers within larger foraminifera

energetics of barotropic and baroclinic tides in the monterey bay area abstracta detailed energy analysis of the barotropic and baroclinic m2 tides in the monterey bay area is performed the authors first derive a theoretical framework for analyzing internal tide energetics based on the complete form of the barotropic and baroclinic energy equations which include the full nonlinear and nonhydrostatic energy flux contributions as well as an improved evaluation of the available potential energy this approach is implemented in the stanford unstructured nonhydrostatic terrain following adaptive navier stokes simulator suntans results from three dimensional high resolution suntans simulations are analyzed to estimate the tidal energy partitioning among generation radiation and dissipation a 200 km 230 km domain including all typical topographic features in this region is used to represent the monterey bay area of the 152 mw energy lost from the barotropic tide approximately 133 mw 88 is converted into baroclinic energy through internal tide generation and 42 56

tsunami sedimentary facies deposited by the storegga tsunami in shallow marine basins and coastal lakes western norway sedimentary successions in small coastal lakes situated from 0 to 11 m above the 7000 year bp shoreline along the western coast of norway contain a distinctive deposit very different from the sediments above and below the deposit is interpreted to be the result of a tsunami inundating the coastal lakes an erosional unconformity underlies the tsunami facies and is traced throughout the basins with most erosion found at the seaward portion of the lakes the lowermost tsunami facies is a graded or massive sand that locally contains marine fossils the sand thins and decreases in grain size in a landward direction above follows coarse organic detritus with rip up clasts here termed organic conglomerate and finer organic detritus the tsunami unit generally fines and thins upwards the higher basins 6 11 m above the 7000 year shoreline show one sand bed whereas basins closer to the sea level 7000 years ago may show several sand beds separated by organic detritus these alternations in the lower basins may reflect repeated waves of sea water entering the lakes in basins that were some few metres below sea level at 7000 years bp the tsunami deposit is more minerogenic and commonly present as graded sand beds but also in some of these shallow marine basins organic rich facies occur between the sand beds the total thickness of the tsunami deposit is 20 100 cm in most studied sites an erosional and depositional model of the tsunami facies is developed

influence of sediment transport dynamics and ocean floor morphology on benthic foraminifera offshore fraser island australia abstract the extensive longshore sediment transport system along the se margin of australia transports yearly 500 000 m 3 of sand from the gold coast of southern queensland north towards fraser island fraser island which consists of 203 km 3 of quartz sand is presently not increasing in size and north of the island quartz sand is replaced by carbonate sand recent multibeam sonar seafloor imagery and sediment analysis has established that the transported sand is being diverted by strong ebb tidal flow over the continental shelf edge onto the tasman abyssal plain through a series of active gullies that incised the continental slope foraminiferal distribution patterns on the shelf and slope are closely linked to the variable ocean floor morphology and associated physical processes in sample locations outside the continental slope gullies areas unaffected by downslope sediment transport foraminiferal assemblages gradually change in accordance with bathymetric zones and their prevailing ecological parameters species diversity evenness the proportion of infaunal species and the abundance of agglutinated taxa all increase with depth assemblages within gullies of the clastic sand transport route are significantly different estuarine and shelf species are transported over the shelf break and mix with typical slope species along the transport path resulting in continued high species diversities as the sediment and faunal load enters the abyssal plain a faunal portion continues to travel within the capricorn sea valley to over 4000 m depth the erosional nature of gullies results in reduction of agglutinated species subtle topographic features such as ridges or levees within the canyon and deep sea valley act as protection from the main erosional sand transport pathway and support the presence of fragile and erect suspension feeders foraminiferal distribution patterns would have received an entirely different biofacies interpretation without linking them to ocean floor processes as revealed through multibeam sonar imagery

diatoms as an aid in identifying late holocene tsunami deposits diatoms bacillariophyta help identify the onshore deposits of tsunamis from earthquakes on the cascadia subduction zone along the pacific coast of oregon washington and british columbia and on faults high in the north american plate in the puget sound area of washington at the copalis river washington diatom analyses suggest that a tsunami deposit about 300 calendric years old 300 yr bp originated from sandy shoals of the lower estuary rather than nearby beaches or coastal dunes at cultus bay and west point washington well preserved benthic estuarine diatoms in sand sheets overlying tidal marsh peat indicate that the deposits came from intertidal or nearshore areas of puget sound on an abruptly uplifted mudflat at the landward end of hood canal at lynch cove washington tidal flat diatoms refute the possibility of a terrestrial source for the sand diatoms in 300 yr bp tsunami deposits on the niawiakum river washington confirm that the sand in these deposits had a marine source and help

biodiversity of foraminifera from late pleistocene to holocene coral reefs south sinai egypt tropical coral reefs are among the most diverse marine ecosystems in order to better understand temporal and spatial variation in late quaternary biodiversity foraminiferal faunas of two fossil raised reef terraces at the southern sinai peninsula were studied and compared to modern coral reef faunas eleven u series dates of shell fragments of the giant clam tridacna sp indicates deposition largely during marine isotope stage 5 mis 5 77 129 kyr bp for the two raised terraces in these terraces amphistegina a lessonii and a lobifera dominates the five fossil foraminiferal associations the fossil reef flat association 1 has common gypsina plana homotrema rubra and acervulina spp and fossil reef flat association 2 consists of amphistegina spp of the three fossil fore reef associations one has abundant porcelaneous taxa including sorites amphisorus peneroplis and borelis one has a mix of porcelaneous taxa and attached arborescent taxa homotrema and placopsilina and one has abundant attached and arborescent taxa miniacina gypsina acervulina and planogypsina the modern fringing reef is dominated by porcelaneous foraminifera and three modern associations are identified these include a lagoonal association with abundant peneroplis pertusus a reef flat association dominated by sorites orbiculus and a fore reef association with porcelaneous taxa plus common h rubra amphistegina lessonii and a lobifera based on our data and including additional published information on regional biodiversity it appears that during mis 5 foraminiferal biodiversity was higher and community structure was different than within the modern reefs these data and regional paleo climate patterns indicate that oceanographic conditions in the red sea were probably closer to normal marine conditions during the last interglacial than they are today

predecessors to the 2009 south pacific tsunami in the wallis and futuna archipelago abstract multi proxy studies of trench sediments from futuna island in the wallis and futuna archipelago have produced a record of two palaeotsunamis dated to around 1860 2000 bp and c 470 bp one of the most useful proxies in this study has been the archaeological data associated with occupations that immediately underlie the deposits associated with both palaeotsunamis the reworking of the archaeological material into the palaeotsunami deposits and the additional chronological control provided by artefacts have added value to interpretations based upon more conventional earth science proxies the identification of tsunamigenic sources for these events is tentative and based upon known potential sources based upon a comparison between the effects of the 2009 south pacific tsunami and those recorded in the trenches event 1 1860 2000 bp appears most likely to be associated with a large tsunami sourced from the tonga kermadec trench region there are only rare contemporaneous events reported from around the region although this appears to be largely due to a lack of similar research as opposed to a lack of evidence event 2 c 470 bp is markedly larger than event 1 with sedimentary evidence indicating significant inland inundation and runup around the entire island there are several lines of evidence for a contemporaneous event in the south pacific around 470 bp although much of this needs further verification determining a source for this event is problematic because it must take in to account the regional signal and the significant impacts recorded on futuna we propose that the source for this younger event was either a larger tonga kermadec trench related earthquake or the kuwae caldera collapse in 1452 1453 ad we recognise that as further research is carried out in the pacific we will greatly improve our abilities to identify past sources and the magnitude and frequency of past events from these areas this can only serve to improve our understanding of the regional risk from tsunamis

the sedimentary record of the 2005 hurricane season from the mississippi and alabama coastlines abstract the instrumental record of hurricane activity is too short to fully capture the occurrence of the rare but most destructive hurricanes therefore obtaining a record of present and past landfalling hurricanes and their extent of geological and ecological impacts is one means to assess future risk reveal the spatial and temporal variability of hurricane activity and decipher its relationship with global climatic changes we rapidly dispatched survey teams to collect the readily available but perishable data of hurricanes katrina and rita storm surge from two salt marshes in mississippi and one salt marsh in alabama in mississippi we recorded hurricane katrina storm surge heights greater than 7 5 m north american vertical datum 88 navd88 with inland extents in excess of 700 m whereas in alabama the maximum recorded storm surge was 3 43 m navd88 at one salt marsh in mississippi we recorded the maximum inland extent and elevation of maximum penetration of hurricane rita as 370 m and 3 43 m navd88 respectively we observed a three dimensional distribution of hurricane induced storm surge deposits that tapered landward overlying salt marsh sediment there was a sharp or erosional boundary between the pre storm surge and storm surge sedimentary units which was accompanied by a change in color and lithology the overlying storm surge sediment unit was coarser than the pre storm surge unit with a lower organic content the thickness of the hurricanes katrina and rita storm surge sediments ranged from 9 to 13 cm and approximately 7 cm respectively foraminiferal analyses revealed a virtual absence of tests within the storm surge sediments whereas abundant agglutinated foraminifera were found in the underlying salt marsh deposits

modern foraminiferal distribution and diversity in two atolls from the maldives indian ocean abstract foraminifera from the coral reef lagoons of two atolls are used to investigate the distribution and diversity of assemblages in the central indian ocean eight assemblages and 270 species of foraminifera are identified three assemblages are reefal and dominated by amphistegina and calcarina only one lagoon assemblage is present in both atolls which is characterized by abundant ammonia sp 1 and smaller miliolid foraminifera in ari atoll abundant amphistegina sp 1 operculina ammonoides amphistegina radiata and nummulites venosa characterize one lagoon assemblage and abundant neoeponides bradyi and textularia cf t cushmani characterize the other in rasdhoo atoll abundant textularia gr foliacea and spiroloculina nummiformis characterize one lagoon assemblage and abundant textularia cf t cushmani and textularia sp 5 characterize the other the assemblages compare well with sedimentological characteristics which is also reflected in their distributions species diversity in the maldives appears to be higher than the western indian ocean region due to the stronger influence of central indo pacific faunas it is not however as high as the central indo pacific region which may be due to lower habitat diversity

marine saline ponds as sedimentary archives of late holocene climate and sea level variation along a carbonate platform margin lee stocking island bahamas a 1500 year late holocene history of coastal and lacustrine carbonate sedimentation is preserved in shallow ponds on lee stocking island exuma cays bahamas details of environmental change have been extracted by integrating lithostratigraphy biostratigraphy macrobiota foraminifers ostracodes and chemical stratigraphy c o isotopes of foraminiferal and molluscan skeletal carbonate mgo wt of ostracode calcite with a well defined 14 ca ms radiocarbon chronology carbonate deposition began within physically restricted euryhaline coastal embayments with several pronounced changes in salinity defined by biotic and calculated salinity variation from mgo wt in shells of cyprideis americana by about 700 740 yr b p embayment closure occurred possibly related to changed longshore deposition associated with sea level rise and or regional change in climate previously documented with closure the initial euryhaline foraminifer assemblage was replaced by a predominant hypersaline biofacies e g triloculina sp with progressive basin fill ostracode assemblages calculated salinities and variation in abundance of the gastropod cerithidea sp may resolve higher order and some extreme salinity fluctuations throughout the remaining history of saline pond development foraminiferal isotope stratigraphy is compatible with that expected for hydrologically closed lake basins carbonate accumulation was effectively shut down 200 years ago replaced by stromatolitic growth present day salinities vary according to water balance governed by rainfall and evaporation a centuries scale 300 400 year flux of abraded reworked marine derived bioclasts admixed with skeletal remains of indigenous biota is also preserved in these ponds allochthonous sediment was transported by hurricane storm surges or related to abrupt transgressive events superimposed on an overall gradual rise in global sea level we discuss evidence for both as controls on sedimentation our study illustrates that saline ponds on bahamian islands are excellent sedimentary archives of local regional and possibly global paleoclimatic events of late holocene age 1999 elsevier science b v all rights reserved

carbonate sediment transport pathways based on foraminifera case study from frank sound grand cayman british west indies foraminifera can be used to determine the source s of carbonate sediment and the directions of sediment transport in shallow coastal lagoons such as frank sound on the south central coast of grand cayman these determinations based on the distribution of foraminiferal assemblages and tracer species numerically abundant species that live in known physiographic units and or ecological conditions show that the lagoonal sediments are a mixture of grains that originated in the lagoon and forereef the variable proportions of these foraminifera throughout the lagoon reflects the dynamic processes that control lagoonal sedimentation amphistegina gibbosa discorbis rosea and asterigerina carinata lived in the forereef environment the fact that these tracer species are found throughout frank sound and in the beach sands shows that they were transported across the reef crest and the lagoon abrasion resistant archaias angulatus a tracer species indicative of a lagoonal setting forms up to 50 of foraminiferal assemblages found in the lagoonal sediments preferential winnowing of small tests from these populations indicates sorting under high energy conditions the vertical distribution of the forereef and lagoonal foraminifera in the sediment blanket that covers the floor of frank sound indicates that these processes are temporally persistent transportation of forereef foraminifera into and around the lagoon and sorting of the lagoonal foraminifera cannot take place under normal conditions when the tranquil lagoon is characterized by weak currents storms and or hurricanes however generate short lived high energy events that can move and sort the sediment and foraminifera at the height of a storm water and sediment are moved over the reef and then piled and held onshore by the onshore winds and the constant flow of water over the reef and across the lagoon these currents can mix some of the lagoonal and forereef sediments as a storm wanes however the piled water flows offshore via strong rip currents that pass into the ocean through the channels which transect the reef these currents winnow and or strip sediment from the lagoon and may transport lagoonal sediments into the forereef area as a result residual lagoonal sediment is commonly characterized by larger and abrasion resistant foraminifera

sedimentary evidence of intense hurricane strikes from new jersey nine vibracores from the backbarrier marsh at whale beach new jersey reveal three large scale overwash deposits associated with historic and prehistoric storms the uppermost and smallest overwash fan was deposited in the ash wednesday northeaster of march 5 8 1962 a second more substantial overwash fan between 100 and 35 cm depth dates to the late eighteenth or early nineteenth century this fan was most likely deposited during the 1821 hurricane the only intense hurricane to make landfall in new jersey in the past 350 yr a third larger overwash fan between 200 and 300 cm depth was deposited between a d 1278 and 1438 and is likely the result of a prehistoric intense hurricane strike the combination of historical and stratigraphic evidence indicates that two intense hurricanes winds 50 ms 21 have likely made landfall on the southern new jersey coast in the past 700 yr resulting in an annual landfall probability of 0 3

impact of the 29 september 2009 south pacific tsunami on wallis and futuna the 29 september 2009 south pacific tsunami reached the islands of futuna and alofi 650 km to the west of its origin between 7 and 7 20 am on 30 september local time no warning was issued we measured run up heights and inundation distances at 41 sites around the islands the worst impact 4 5 m run up 85 m inundation 3 8 m flow depth was observed on alofi s nw beach on futuna maximum run ups of 4 4 m on the eastern tip and 4 3 m on the nw tip of the island are associated with maximum inundations of 95 and 72 m respectively a flow depth of 2 2 m was inferred on the ne tip the tsunami arrived as a drawdown of water with the reef exposed well below the lowest tides it was followed by two positive waves of similar amplitude ca 4 min apart damage was mainly limited to salt burnt vegetation and sediments deposited at the coast there were no casualties but a significant disaster was avoided because the tsunami arrived in the early morning at close to low tide this event together with a small tsunami triggered by a local earthquake in 1993 and an oral legend about a destructive wave indicate that the hazard is high for the 4500 inhabitants of futuna who live on the low lying narrow coastal strip the 70 min that the tsunami took to reach the island provided sufficient time for a warning to be issued but this was not done

sediment transport trends from a tropical pacific lagoon as indicated by homotrema rubra taphonomy wallis island polynesia the assessment of sediment transport pathways in carbonate settings is complicated by ecologically sourced sediment tracers such as foraminifera have previously been used in these settings to describe the movement of coastal sediments on spatial and temporal scales where traditional grain size methods have limited use the present study builds on the foraminifera based tracer method by using homotrema rubra a foraminifer with an attached life habit i e defined provenance in the reef to document modern sediment transport trends at wallis island a tropical pacific lagoon at wallis island homotrema taphonomic results discriminated amongst modern reef lagoon and island beach samples reef samples contained high concentrations of fragments that were large 250 m and exceptionally to well preserved e g intact chambers red color angularity in general concentrations and degree of taphonomic alteration decreased with distance landward from the reef lagoon samples were characterized by lower concentrations of homotrema that were smaller in size and less preserved e g pink in color no chamber structure rounding of edges at the greatest distance from the reef island beach samples contained the lowest concentrations of homotrema fragments that were small well rounded and bleached in this regard homotrema taphonomy is a useful indicator of the direction and forcing of sediment transport and will therefore be useful in detecting overwash deposits in tropical settings where distinguishing event deposits from surrounding sediment is problematic

on the circulation in the bay of bengal during northern spring inter monsoon march april 1987 abstract temperature and salinity data collected from the bay of bengal 22 march 28 april 1987 northern spring inter monsoon identified the seasonal anticyclonic gyre acg at 16 n 86 e characterized by warm 24 c and low salinity 34 85 psu at their cores the velocity of wbbc increased from 0 40 ms 1 at 12 n to 0 70 ms 1 at 17 5 n where it left the coast and turned eastward the mean northward transport of the wbbc in the upper 200 m was 12 sv 1 sv 10 6 m 3 s 1 these circulation features the acg wbbc and cyclonic eddies are well depicted in the maps of sea surface height ssh topography derived from the residual sshs of geosat altimeter for the period 12 february 28 april 1987 the results show that the wbbc flowed against the northeasterly winds during february and that the current sets up almost three months ahead of the wind reversal the acg and in turn the wbbc intensified with the wind reversal in april when the wind stress curl attained a negative maximum the ssh maps further indicate that formation of the acg started in february and reached its maximum intensity during april with the coalescence of two anticyclonic cells

intraseasonal variability of sea surface height in the bay of bengal intraseasonal variability isv of sea surface height ssh over the bay of bengal bob is studied using altimetry data and an eddy resolving ocean model in both the model hindcast and satellite observations large ssh isv is found along the eastern and northern coasts of the bob in the western bob and in a zonal band across the bay centered near 5 degrees n the isv displays a clear seasonality in the western bob it reaches its annual maximum in spring whereas it does so in summer and autumn southeast of sri lanka driven by equatorial intraseasonal winds equatorial kelvin waves propagate eastward reach the western coast of sumatra and reflect there to propagate around the perimeter of the bob as coastally trapped waves two distinct bands of high eddy activity are detected in the western and central bob respectively in both bands isolated eddies propagate southwestward eddy formation in the eddy train in the central bay is linked to the coastal wave as it bends around the corner of the irrawaddy delta off myanmar eddy activity contributes to the high isv in the central bay to some extent an energetics analysis indicates that high total eddy energy in the western bob is due to barotropic baroclinic instability of the mean current citation cheng x s p xie j p mccreary y qi and y du 2013 intraseasonal variability of sea surface height in the bay of bengal j geophys res oceans 118 816 830 doi 10 1002 jgrc 20075

estimation of the bed shear stress in vegetated and bare channels with smooth beds the shear stress at the bed of a channel influences important benthic processes such as sediment transport several methods exist to estimate the bed shear stress in bare channels without vegetation but most of these are not appropriate for vegetated channels due to the impact of vegetation on the velocity profile and turbulence production this study proposes a new model to estimate the bed shear stress in both vegetated and bare channels with smooth beds the model which is supported by measurements indicates that for both bare and vegetated channels with smooth beds within a viscous sublayer at the bed the viscous stress decreases linearly with increasing distance from the bed resulting in a parabolic velocity profile at the bed for bare channels the model describes the velocity profile in the overlap region of the law of the wall for emergent canopies of sufficient density frontal area per unit canopy volume a 4 3 m 1 the thickness of the linear stress layer is set by the stem diameter leading to a simple estimate for bed shear stress

the effects of fine scale surface roughness and grain size on 300 khz multibeam backscatter intensity in sandy marine sedimentary environments abstract high frequency acoustic backscatter intensity that is returned from sediment is affected by a number of seabed characteristics including sediment grain size distribution the nature and magnitude of seabed surface roughness and volume scattering by subsurface scatterers in order to develop quantitative remote sediment classification techniques it is important to determine the relative and combined effects of the dominant variables to which the acoustic signal is sensitive data used in this study were collected at two sandy sites off the south shore of long island new york and include 300 khz multibeam simrad em 3000 backscatter intensity data as well as grab samples and stereo bottom photographs multivariate statistical analyses were used to investigate the relationships between grain size properties seabed roughness and backscatter intensity at a number of sample locations at each study site encompassing a moderate range of backscatter intensities from 32 5 to 24 db the results of this study demonstrate that the relative importance of variables that affect backscatter intensity varies at different sites suggesting that backscatter intensity alone cannot be used to quantitatively predict seabed characteristics however our study indicates that in sandy sediments the median grain size the standardized magnitude of seabed roughness and the sorting of sediment can together be used to predict 300 khz backscatter intensity with high significance and that the relative importance of these variables varies from site to site we present an empirical model derived from a combined dataset that includes two sites of similar sedimentary and hydrodynamic conditions to predict the magnitude of seabed roughness based on backscatter intensity and sediment grain size characteristics the spatially coherent patterns in predicted seabed surface roughness revealed through the use of this kind of model greatly improve our understanding of variations in backscatter intensity in sandy marine sedimentary environments as a result the multivariate statistical approach that we employ improves our overall ability to remotely assess the details of the sedimentary environment that are significant with respect to benthic habitats and physical processes and are applicable to other geophysical datasets including sidescan sonar data

lagoonal facies ages and sedimentation in three atolls in the pacific abstract in order to investigate pacific atoll lagoonal facies and temporal evolution we collected and analyzed surface and core sediments from three pacific atoll lagoons of various sizes and depths kayangel of palau islands enewetak and majuro of the marshall islands the lagoons were divided into three facies calcarina facies calcarina heterostegina mixed facies and heterostegina facies these were based on the presence or absence of the tests of two larger benthic foraminifera calcarina and heterostegina as indicators of reef flat and deep lagoon environments respectively the calcarina facies is composed of allochthonous reef derived materials the calcarina heterostegina mixed facies is a mixture of reef derived and in situ lagoonal materials and the heterostegina facies is composed mainly of in situ lagoonal materials as both foraminifera are widely distributed in the western to central pacific region the facies classification presented in this study can be applicable to other pacific atolls based on the results of radiocarbon dating on samples obtained from cores at majuro lagoon the accumulation rates of the lagoonal sediments were estimated as 0 65 m kyr 1 calcium carbonate production was calculated on the basis of the accumulation rates and density of sediments to be 710 g caco 3 m 2 yr 1

turbulence structure in open channel flow with partially covered artificial emergent vegetation abstract an innovative approach was recently proposed to increase water depth and improve navigation in rivers by increasing overall roughness through an adaptive placement of artificial vegetation in this approach a section of the river width is covered with artificial vegetation constructed from an array of dampers that can be added or removed while maintaining sufficient width for navigational purposes the goal of the work here is to explore the mean flow and turbulent momentum transport properties of such flow in a controlled flume setting where the flow rate is steady the vegetation placement is uniform and the froude number is maintained at sub critical conditions the focus is on vegetation induced roughness alterations to the bulk flow statistics as well as the structure of turbulence impacted by the presence of such artificially engineered vegetation the canopy flow experimentally explored here differs from the well studied planar uniform emergent canopy flow because the interface between the vegetation and non vegetation areas occurs along a lateral direction instead of the vertical direction the flume experiments were conducted by partially covering the channel width with emergent artificial vegetation that is flexible and can interact with the flow the quantities studied are the equilibration distance of the flow statistics from the leading vegetation edge as such distance is essential to any engineering design moreover the mean flow and turbulence regimes at several longitudinal sections were analyzed using spectral analysis and conditional sampling to identify the main vortical structures and their contribution to momentum transport spectral analysis demonstrated that the sizes of the dominant vortices can be classified into stem scale small scale and shear scale larger scale vortices as conventional in canonical canopy flows the shear layer formed in the planar direction and its associated coherent vortices are spawned near the edge of the vegetated area in a manner analogous to a plane mixing layer quadrant analysis showed two contributions to the overall shear stress and lateral momentum exchange between the vegetated and non vegetated zone namely ejections and sweeps the measured ejection sweep contributions are short lived but significant to the overall turbulent momentum transport consistent with other canopy flow studies approximately 80 of the turbulent stress contributions at the interface occur within 30 of the time because the flume experiments were conducted at sufficiently high reynolds number and sufficiently low froude number the scalability of the experimental findings here to much larger settings encountered in engineering practice are briefly discussed

700 yr sedimentary record of intense hurricane landfalls in southern new england five intense category 3 or greater hurricanes occurring in 1635 1638 1815 1869 and 1938 have made landfall on the new england coast since european settlement historical records indicate that four of these hurricanes 1635 1638 1815 and 1938 and hurricane carol a strong category 2 storm in 1954 produced significant storm surges 3 m in southern rhode island storm surges of this magnitude can overtop barrier islands removing sediments from the beach and nearshore environment and depositing overwash fans across back barrier marshes lakes and lagoons in a regime of rising sea level accumulation of marsh lake or lagoon sediments on top of overwash deposits will preserve a record of overwash deposition we examined the record of overwash deposition at succotash salt marsh in east matunuck rhode island and tested the correlation with historical records of intense storms aerial photographs taken after hurricanes in 1954 and 1938 show overwash fans deposited at the site analysis of 14 sediment cores from the back barrier marsh confirmed the presence of these fans and revealed that 4 additional large scale overwash fans were deposited within the marsh sediments the four overwash fans deposited since the early seventeenth century at succotash marsh matches the historical record of significant hurricane induced storm surge these fans were most likely deposited by hurricanes in 1954 1938 1815 and either 1638 or 1635 radiocarbon dating of two prehistoric overwash fans indicated that these were deposited between a d 1295 1407 and 1404 1446 and probably represent intense hurricane strikes in the past 700 yr at least 7 intense hurricanes struck the southern rhode island coast and produced a storm surge that overtopped the barrier at succotash marsh

global observations of large oceanic eddies 1 ten years of sea surface height ssh fields constructed from the merged topex poseidon t p and ers 1 2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean the higher resolution of the merged dataset reveals that more than 50 of the variability over much of the world ocean is accounted for by eddies with amplitudes of 5 25 cm and diameters of 100 200 km these eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies respectively the vast majority of the eddies are found to be nonlinear

numerical simulation of the observed near surface east india coastal current on the continental slope we simulate the east india coastal current eicc using two numerical models resolution 0 1 circ times 0 1 circ an oceanic general circulation model ogcm called modular ocean model and a simpler linear continuously stratified lcs model and compare the simulated current with observations from moorings equipped with acoustic doppler current profilers deployed on the continental slope in the western bay of bengal bob we also carry out numerical experiments to analyse the processes both models simulate well the annual cycle of the eicc but the performance degrades for the intra annual and intraseasonal components in a model resolution experiment both models run at a coarser resolution of 0 25 circ times 0 25 circ simulate well the currents in the equatorial indian ocean eio but the performance of the high resolution lcs model as well as the coarse resolution ogcm which is good in the eicc regime degrades in the eastern and northern bob an experiment on forcing mechanisms shows that the annual eicc is largely forced by the local alongshore winds in the western bob and remote forcing due to ekman pumping over the bob but forcing from the eio has a strong impact on the intra annual eicc at intraseasonal periods local equatorial forcing dominates in the south north because the kelvin wave propagates equatorward in the western bob a stratification experiment with the lcs model shows that changing the background stratification from eio to bob leads to a stronger surface eicc owing to strong coupling of higher order vertical modes with wind forcing for the bob profiles these high order modes which lead to energy propagating down into the ocean in the form of beams are important only for the current and do not contribute significantly to the sea level

vortices of the mediterranean sea an altimetric perspective the presence of coherent vortices makes observed mesoscale fields of the ocean resemble twodimensional turbulence using this analogy a common definition of a coherent structure has been used to study the statistical properties of mediterranean sea vortices observed by satellite altimeters over a 7 yr period a vortex has been defined as the simply connected region with values of the okubo weiss parameter w 0 2w where w is the spatial standard deviation of w and the same sign of vorticity this definition is shown to be appropriate to detect and characterize statistically properties such as size mean kinetic energy and amplitude of vortices in the mediterranean basin from sea level anomaly maps corresponding to the period from october 1992 to october 1999 the distribution of such properties for the mediterranean vortices suggests a heuristic criterion to extract and select very coherent and long lived vortices from the whole set of structures identified in altimetric maps such coherent vortices appear to be selected for amplitudes greater than 2w where the amplitude has been defined in terms of the okubo weiss parameter rather than vorticity and strongly correspond to those reported from observations with independent data systematic locating and tracking of such vortices provide for the first time a general picture of their preferential paths in the mediterranean basin which are characterized by complex but rather well defined patterns

traditional and multivariate techniques in the interpretation of floodplain sediment grain size variations the vertical and horizontal variation of sedimentary fades is the raw data for the interpretation of flood plain history from which palaeohydrological inferences are frequently drawn mixed and fine floodplain sediments present problems of interpretation because of a large grain size range and frequent polymodality caused by the mixing of process associated grain size components this paper discusses the use of traditional grain size statistics and the use of the mode and multivariate statistics the mode although much neglected is indicative of up profile grain size changes and has practical advantages over the mean for mixed and fine floodplain sediments constrained cluster analysis and principal components analysis are used directly on coulter counter results these techniques can rapidly divide a floodplain profile into grain size units and indicate the principal vectors of grain size variation which will be related to the changing processes of deposition principal components analysis reveals the importance of the medium to fine silt category in accounting for grain size variations suggesting that a critical factor in determining the type of alluvial unit deposited is the degree to which it has received fine suspended material grain size data from the lower severn are used to construct a cm diagram which is compared with a texture triangle from both the cm and multivariate analysis a generalized backswamp profile is constructed which shows the existence of a coarser top unit caused by the addition of a fine to medium sand component to the underlying sediment during the late holocene

microfossils from coastal environments as indicators of paleo earthquakes tsunamis and storms abstract coastal risk assessment and hazard mitigation require datasets on centennial and millennial temporal scales to capture natural variability and multiple occurrences of the largest but least frequent events coastal sediments from low energy depositional environments archive geologic evidence of paleo earthquakes tsunamis and storms many of the best reconstructions of these events are derived from changes in microfossil diatoms foraminifera and pollen assemblages in this review we explain how microfossils are used to reconstruct records of paleoearthquakes by quantifying the amount of coseismic and interseismic vertical land movements along tectonically active coastlines examples from the united states alaska and the pacific northwest japan and chile show that microfossil based transfer functions may provide continuous records of vertical land movement during earthquake deformation cycles we discuss how microfossil habitat preferences and taphonomic character are used to constrain sediment provenance e g beach nearshore or offshore sources and identify overwash deposits and how this information can be used to reconstruct the recurrence of tsunamis and storms analysis of overwash deposits from thailand and malaysia indicates the ability of microfossils to resolve individual waves within tsunami sediments and an example from the sendai coastal plain in japan uses foraminifera to ascribe a beach to nearshore provenance for the 2011 tohoku tsunami deposit finally we present recent examples from the gulf of mexico on the use of foraminifera to estimate the volume and distance of transport of storm overwash from hurricanes

turbulent friction in flows over permeable walls 1 the experimental results of nikuradse and the concept of hydraulically smooth transitional and rough flow regimes are commonly used as a benchmark for data interpretation and modeling of hydraulic resistance however nikuradse s experiments were carried out in pipes with impermeable rough walls whereas many geophysical flows occur over permeable walls and thus the permeability effects need to be quantified and accounted for on the basis of our own experimental results it is shown that wall permeability influences flow resistance dramatically and that the conventional hydraulically rough regime for which the friction factor depends only on the ratio of the roughness size to the flow thickness does not apply to flows over permeable walls indeed even at high reynolds number re the friction factor progressively increases with increasing re possible mechanisms that explain this behavior as well as the implications of these results for modeling of the friction factors and hyporheic exchange in porous bed rivers are discussed

an experimental study of flow through rigid vegetation 1 better understanding of the role of vegetation in the transport of fluid and pollutants requires improved knowledge of the detailed flow structure within the vegetation instead of spatial averaging this study uses discrete measurements at multiple locations within the canopy to develop velocity and turbulence intensity profiles and observe the changes in the flow characteristics as water travels through a vegetation array simulated by rigid dowels velocity data was collected with a one dimensional laser doppler velocimeter under emergent and submerged flow conditions the effects of dowel arrangement density and roughness were also examined the results show that the velocity within the vegetation array is constant with depth and the velocity profile is logarithmic above it however the boundaries are marked by inflection points the strongest vortices and turbulence intensities can be found there especially in the region immediately downstream of a dowel these results support the idea that the flow in the region near the bed and at the top of the dowel array is very unstable leading to the formation of coherent structures and are areas of significant mass and momentum exchange

a new model evaluating holocene sediment dynamics insights from a mixed carbonate siliciclastic lagoon bora bora society islands french polynesia south pacific abstract mixed carbonate siliciclastic lagoons of barrier reefs provide great potential as sedimentary archives focusing on paleoenvironmental and paleoclimatic changes as well as on event deposition sediment sources include lagoonal carbonate production the marginal reef and the volcanic hinterland mixed carbonate siliciclastic continent attached coastal lagoons have been intensively studied however their isolated oceanic counterparts have been widely disregarded here we present a new model of holocene sediment dynamics in the barrier reef lagoon of bora bora based on sedimentological paleontological geochronological and geochemical data the lagoonal succession started with a pleistocene soil representing the lowstand systems tract as the rising holocene sea inundated the carbonate platform peat accumulated locally 10 650 9400 years bp mixed carbonate siliciclastic sedimentation started ca 8700 5500 years bp and represents the transgressive systems tract during that time sediments were characterized by relatively coarse grain size and contained high amounts of terrestrial material from the volcanic hinterland as well as carbonate sediments mainly produced within the lagoon siliciclastic content decreases throughout the holocene after the rising sea had reached its modern level sand aprons formed between reef crest and lagoon creating transport pathways for reef derived material leading to carbonate dominated sedimentation ca 6000 3000 years bp during the highstand systems tract however mainly fine material was transported and accumulated in the lagoon while coarser grains were retained on the prograding sand apron from ca 4500 500 years bp significant variations in grain size total organic carbon as indicator for primary productivity ca and cl element intensities as qualitative indicators for carbonate availability and lagoonal salinity are seen such patterns could indicate event re deposition and correlate with contemporaneous event deposits found in the lagoon of nearby tahaa which are supposed to be induced by elevated cyclone activity correspondingly enhanced erosion and run off from the volcanic hinterland as well as lower lagoonal salinity would be associated with intense rainfall during repeated cyclone landfall increased amounts of coarse grained sediment from marginal reef areas would be transported into the lagoon however ti ca and fe ca ratios as proxies for terrigenous sediment delivery have incessantly declined since the mid holocene also benthic foraminiferal faunas do not validate reef to lagoon transport of sediment alternatively the apparent onset of higher hydrodynamic energy conditions can be explained by more permanent southeast trade winds and higher than present sea level which are supposed for the mid late holocene in the south pacific sustained winds would have flushed higher amounts of open ocean water into the lagoon enhancing primary productivity and the amount of pelagic organisms within the lagoon while lowering lagoonal salinity we propose the shift towards coarser grained sedimentation patterns during the mid late holocene to reflect sediment load shedding of sand aprons due to oversteepening of slopes at sand apron lagoon edges during times of stronger trades and higher than present sea level of the highstand systems tract which led to redeposition of sediment even within the lagoon center modern conditions including a sea level fall to modern level were reached ca 1000 years bp and lagoonal infill has been determined to a large part by fine grained carbonate dominated sediments produced within the lagoon and derived from the marignal reef infill of lagoonal accommodation space via sand aprons is estimated to be up to six times higher than infill by lagoonal background sedimentation and emphasizes the importance of the progradation of sand aprons contrary to the commonly supposed assumption that coarse grained sediment layers within fine grained lagoonal successions represent overwash events induced by storms or periods of higher storm activity we postulate a new model of long term lagoonal sediment dynamics including sea level climatic change and geomorphological variation of the barrier reef lagoon

analytical solution of the depth averaged flow velocity in case of submerged rigid cylindrical vegetation a new model for the depth averaged velocity for flow in presence of submerged vegetation is developed the model is based on a two layer approach where flow above and through the vegetation layer is described separately vegetation is treated as a homogeneous field of identical cylindrical stems and the flow field is considered stationary and uniform it is demonstrated that scaling considerations of the bulk flow field can be used to avoid complications associated with smaller scale flow processes and that still the behavior of depth averaged flow over vegetation is described accurately the derived scaling expression of the average flow field is simple in form it follows fundamental laws of fluid flow and it shows very good agreement with laboratory flume experiments the new model can be used for quick evaluation of a river s hydraulic response in cases where vegetated floodplains are inundated

foraminiferal zonations on the fraser river delta and their application to paleoenvironmental interpretations abstract well defined elevational zonations of foraminiferal species were found over the intertidal surface of the sand rich fraser river delta a zonation of foraminiferal species according to depth is also apparent on the delta foreslope although data here are more limited application of these findings to the interpretation of depositional environments within drill cores from the delta provided independent evidence of a 4 to 5 m lower sea level during the mid holocene this finding is in good agreement with a sea level curve developed for the fraser lowland region

average circulation seasonal cycle and mesoscale dynamics of the peru current system a modeling approach h isolines the pccc appears to be directly forced by the cyclonic wind stress curl the model is able to produce the upwelling front the cold water tongue which extends toward the equator and the equatorial front as described in the literature model seasonal changes in sst and ssh are compared to measurements for the central pcs model eke is 10 to 30 lower than the observations the model eddy diameters follow a strong equatorward increase the injection length scales derived from the energy spectra strongly correlate to the rossby radius of deformation confirming the predominant role of baroclinic instability at 3 s the model solution appears to switch from a turbulent oceanic regime to an equatorial regime dominated by zonal currents

secular trends in ocean tides observations and model results 1 during the last century the response of the oceans to tidal forces has changed significantly this study focuses on an analysis of long term sea level records located in the atlantic and pacific primarily in the northern hemisphere it shows that changes of tidal amplitude and or phase have taken place over large scales the principal solar semidiurnal s2 tide shows the largest trends at some locations the change in the mean tidal range due to tidal trends is significant compared with the trend in mean sea level thus it might be advisable to consider these changes in studies of the impact of rising sea level numerical simulations of the principal lunar semidiurnal tide m2 demonstrate a model sensitivity in the north atlantic to changes in glacial isostatic adjustment and sea level rise which captures 30 40 of the magnitude of the trends in observations however the spatial patterns do not agree well with those inferred from observations suggesting that forward global models are currently useful for qualitative but not quantitative understanding of the observed trends a global free oscillation synthesis indicates that sea level rise due to glacial isostatic adjustment leads to decreasing global resonant periods and increasing damping in the system and a coupled oscillator model shows that changes in sea level on the shelf are much more effective at perturbing shelf and ocean tides than sea level changes in the deep ocean