rocket triggered lightning propagation paths relative to preceding natural lightning activity and inferred cloud charge lightning mapping array lma data are used to compare the propagation paths of seven rocket triggered lightning flashes to the inferred charge structure of the thunderstorms in which they were triggered this is the first lma study of florida thunderstorm charge structure three sequentially within 16 min triggered lightning flashes whose initial stages were the subject of hill et al 2013 are reexamined by comparing the complete flashes to the preceding natural lightning to demonstrate that the three rocket triggered flashes propagated through an inferred negative charge region that decreased from about 6 8 to about 4 4 km altitude as the thunderstorm dissipated two other flashes were also sequentially triggered within 9 min in a thunderstorm that contained a convectively intense region ahead of a stratiform region with similar observed results finally two unique cases of triggered lightning flashes are presented in the first case the in cloud portion of the triggered lightning flash after ascending to and turning horizontal at 5 3 km altitude just above the 0 c level was observed to very clearly resemble the geometry of the in cloud portion of the preceding natural lightning discharges in the second case a flash was triggered relatively early in the storm s lifecycle that did not turn horizontal near the 0 c level as is usually the case for triggered lightning in dissipating storms but ascended to nearly 7 5 km altitude before exhibiting extensive horizontal branching

electric and kinematic structure of the oklahoma mesoscale convective system of 7 june 1989 abstract balloon soundings of electric field in oklahoma mesoscale convective systems mcs s were made by the national severe storms laboratory nssl during the spring of 1989 a sounding made in the rearward edge of an mcs stratiform rain area on 7 june 1989 is the centerpiece of this study we used data from doppler radars a lightning ground strike location system satellite and other sources to relate the mesoscale attributes of the mcs to the observed electric field profile the stratiform area did not lag an organized convective line but was apparently initiated by anvil precipitation downwind of convective cells that were at the west and southwest flanks of the mcs the mature system produced a bipolar cloud to ground lightning pattern in which most flashes of positive polarity came to ground in the downshear anvil or stratiform region the bipole was oriented from 220 parrallel to upper level geostrophic flow and its length was 190 km we visually observed lightning flashes in the stratifo

three dimensional numerical modelling of wind driven circulation in a shallow homogeneous lake abstract the development validation and application of a three dimensional deterministic numerical model of the wind induced circulation in a shallow homogeneous lake are described the governing equations expressing the conservation of fluid mass and momentum are solved in the model using an implicit finite difference initial value method particular attention is paid to the representation of the bed friction the wind shear stress and turbulent diffusion the model was compared with analytical solutions for three idealised flows before being calibrated and verified with field data from esthwaite water in cumbria the model was tested for stability and parameter sensitivity and then used to generate typical circulation patterns for a variety of steady state conditions comparisons with field measurements suggest that the model is better at predicting water movements in the open water than in the sheltered bays

winter storm induced hydrodynamics and morphological response of a shallow transgressive shoal complex northern gulf of mexico abstract using extended deployments during seasons of low and high discharge from the atchafalaya river meteorological hydrodynamic and bottom boundary layer parameters were monitored from tiger and trinity shoal complex off louisiana coast usa during winter storms the surface current speed measured at both shoals exceeded 0 5 m s and the entire water column followed the prevailing wind direction the current speed close to the bottom exceeded 0 3 m s during high energy northerly winds the mean water level in the shoal complex increased during southerly winds and decreased during northerly winds such that the difference between wind set up and set down exceeded 0 7 m in tiger shoal and 0 6 m in trinity shoal during high energy frontal passages the swell height was inversely correlated with mean water level and increased during pre frontal phase and decreased during post frontal phase of winter storms the sea short waves height responded quickly to wind direction and speed and within a few hours after the wind shifted and blowing from the north the sea height increased during both deployments bimodal wave frequency spectrum was observed during wind veering from southerly to northerly when both sea and swell intensities were significant the tiger shoal bed sediment texture transformed drastically from mud to shell and shell hash assemblage within a period of two weeks during the december 2008 deployment backscatter signal intensity from a pulse coherent acoustic doppler profiler pcadp and its velocity estimates were used to determine the vertical extend and timing of mud resuspension and their eventual flushing out from the shoal environment when exposed to high energy winter storm passages the computed time frame for a total transformation of bottom sediment texture from muddy bottom to shell and shell hash assemblage was supported by the combined wave and bottom current induced shear stress at shoal bed the bed samples collected from tiger shoal before and after the deployment in spring 2009 consisted of more than 80 shell and shell hash which again confirmed a stable bottom as predicted from the pcadp data however the fine sand and mud dominated bed at trinity shoal was highly dynamic and experienced a few cm of ephemeral sediment deposition during the passage of each cold front as revealed from the analysis of acoustic backscatter data from the pcadp suspended sediment concentration estimated from optical backscatterance sensors obs and pcadp were in good agreement during low river discharge events in december 2008 but significantly diverged during the spring 2009 deployment when a high suspended sediment load was discharged into the shelf from the atchafalaya river and subsequently pushed farther offshore into the deployment sites by wind induced strong currents during the passage of cold fronts

on abandoning the thunderstorm tripole charge paradigm we reexamine the original half century old in situ measurements of simpson and colleagues used to justify the tripole model of charge structure of a thunderstorm that became the paradigm for the charge structure of mature thunderstorms we find that the original measurements violate the criteria of the tripole model in 49 of the cases we also reexamine our soundings of electric field in thunderstorms and mesoscale convective systems in the same way as the original soundings were our soundings do not fit the tripole model in at least 86 of the storms even when we consider only the major features in the electric field profiles our data show noncompliance with the tripole model in 45 of the cases we conclude that we must abandon the paradigm of the tripole charge structure of thunderstorms

wave mud interactions over the muddy atchafalaya subaqueous clinoform louisiana united states wave supported sediment transport 1 near bottom fluid mud layers were observed during two experiments conducted on the muddy atchafalaya inner shelf subaqueous clinoform louisiana united states on the face of the subaqueous delta 4 7 m water depth first experiment fluid mud layers are produced by seafloor liquefaction and resuspension forced by swells associated with cold front passages and supported by near bed wave induced turbulence the layers are episodic lifetime of 9 12 h form prior to significant postfrontal settling of sediment in the overlying water column and flow seaward downslope at about 5 cm s farther westward on the delta front finer grain size with negligible sand or coarse silt content second experiment similar wave supported fluid mud layers are observed to last longer 2 days show weaker alongshore westward flow of about 1 3 cm s the results suggest a sequence of near bed sediment transport processes triggered by frontal swell activity bed liquefaction resuspension and advection modulated by the bathymetric characteristics of the clinoform that contribute to the formation of clinoform stratigraphy of muddy subaqueous deltas

seismicity normal faulting and the geomorphological development of the gulf of corinth greece the corinth earthquakes of february and march 1981 three major destructive earthquakes of m s 6 7 6 4 6 4 occurred in the eastern part of the gulf of corinth in february and march 1981 associated normal faulting was observed on both the north and the south sides of the gulf examination of teleseismic local seismic surface faulting and geomorpbological data suggests that the first and second of these shocks activated major north dipping normal faults these faults control the topography and bathymetry and are related to the recent uplift and subsidence of the coastline it is probable that the first earthquake occurred on a faultwhich outcrops underwater and the second on a fault which is visible on land it appears that the third shock activated an antithetic normal fault dipping southwards on the north side of the gulf and that the overall structure of the gulf of corinth graben is asymmetric the northern antithetic fault clearly demonstrates the geomorphological changes associated with developing young normal faulting in addition we suggest that observations of recent coastline movement provide a powerful tool for identifying major active fault systems and predicting their historical role in the paleogeography of an area

storm surge induced flux through multiple tidal passes of lake pontchartrain estuary during hurricanes gustav and ike abstract in september 2008 hurricanes gustav and ike generated major storm surges which impacted the lake pontchartrain estuary in louisiana this paper presents analyses of in situ measurements acquired during these storm events the main data used in the analyses were from three bottom mounted moorings equipped with conductivity temperature and depth sensors acoustic doppler current profilers adcps and a semi permanent laterally mounted horizontal acoustic doppler profiler adp these moorings were deployed in the three major tidal channels that connect lake pontchartrain with the coastal ocean a process similar to tidal straining was observed the vertical shear of the horizontal velocity was negligible during the inundation stage but a shear of 0 8 m s over a less than 5 m water column was recorded during the receding stage 2 3 times the normal tidal oscillations the surge reached its peak in the industrial canal 1 4 2 1 h before those in the other two channels the inward flux of water lasted for a shorter time period than that of the outward flux the inward flux was also observed to have much smaller magnitude than the outward flux 960 1200 vs 2100 3100 million m 3 the imbalance was believed to have been caused by the additional water into lake pontchartrain through some small rivers and inundation over the land plus rainfall from the hurricanes the flux through the industrial canal was 8 12 while the flux through the other two tidal passes ranged between 17 and 70 of the total but mostly split roughly half half of the remaining 88 92 of the total

on the nature of transverse variability in a coastal plain estuary even though estuarine processes are inherently three dimensional most of the previous studies have focused primarily on the axial longitudinal and vertical variabilities recent surveys in the lower delaware bay indicate the presence of significant transverse variability in the salinity distribution and residual circulation pattern conceptual models are developed to examine the mechanisms which might explain the observed transverse structure results indicate that both the gravitational effect and wind forcing are capable of generating substantial transverse structure in drowned river valley estuaries with triangular cross sections

horizontal distribution of electrical and meteorological conditions across the stratiform region of a mesoscale convective system abstract five soundings of the electric field and thermodynamic properties were made in a mesoscale convective system mcs that occurred in oklahoma and texas on 2 3 june 1991 airborne doppler radar data were obtained from three passes through the stratiform echo from these electrical kinematical and reflectivity measurements a conceptual model of the electrical structure of an mcs is developed low level reflectivity data from the storm s mature and dissipating stages show typical mcs characteristics the leading convective region is convex forward and the back edge of the stratiform echo is notched inward the maximum areal extent of the low level echo is about 250 km 550 km and the radar bright band is intense reflectivity 45 50 dbz through an area of at least 50 km 100 km the reflectivity above the bright band is horizontally stratified with decreasing intensity and echo top height toward the rear of the system analyses of the velocity data reveal a convective line relative flow struct

variations of chemical features in a monsoon glacier watershed southeastern tibet plateau the ph ec electric conductivity 18o and major ions in melt water precipitation runoff and groundwater samples which were collected in baishui basin were analyzed based on chemical analysis the characteristic variations are analyzed in this paper the melt water precipitation runoff and groundwater were ca2 mg2 hco3 type with similar ion compositions but showed different ion concentrations normally the content is high in groundwater and runoff water but low in melt water and precipitation from the upper basin glacier downward there was a general increasing trend for the total ion concentrations in basin hco3 and ca2 accounted for more than 80 of total ions in samples indicating that ions mainly came from limestone and water typical of carbonate solution water water rock interaction is the significant contributor to water geochemistry the concentration of inorganic ion in melt water had an obvious diurnal variation with temperature change the 18o values increases with the altitude decrease the similarity of 18o in runoff and groundwater samples was due to their frequent transformation in karst regions

mid to late holocene shoreline reconstruction and human occupation in ancient eretria south central euboea greece few studies have aimed to reconstruct landscape change in the area of eretria south central euboea greece during the last 6000 years the aim of this paper is to partially fill in this gap by examining the interaction between mid to late holocene shoreline evolution and human occupation which is documented in the area from the late neolithic to the late roman period with discontinuities evidence of shoreline displacements is derived from the study of five boreholes maximum depth of 5 25 m below the surface drilled in the lowlands of eretria based on sedimentological analyses and micro macrofaunal identifications different facies have been identified in the cores and which reveal typical features of deltaic progradation with marine lagoonal fluvio deltaic and fluvial environments in addition a chronostratigraphy has been obtained based on 20 ams 14c radiocarbon dates performed on samples of plant remains and marine lagoonal shells found in situ the main sequences of landscape reconstruction in the plain of eretria can be summarized as follows a marine environment predominated from ca 4000 to 3200 cal bc and a gradual transition to shallow marine conditions is observed ca 3200 3000 cal bc due to the general context of deltaic progradation west of the ancient city subsequently from ca 3000 to 2000 cal bc a lagoon occupied the area in the vicinity of the temple of apollo and the settlement s development was restricted to several fluvio deltaic levees thus severely limiting human activities in the plain from ca 2000 to 800 cal bc a phase of shallow marine presence prevailed and constrained settlement on higher ground forcing abandonment of the major part of the plain finally since the eighth century bc the sea has regressed southward and created the modern landscape

first evidence of a lake at ancient phaistos messara plain south central crete greece reconstructing paleoenvironments and differentiating the roles of human land use and paleoclimate from minoan to roman times phaistos was one of the most important minoan palaces in crete and previous studies have addressed its relationship with the paleo seashore position during historical times here we reconstruct the environmental evolution of phaistos from early minoan to roman times study of two stratigraphic sections and nine boreholes drilled in the westernmost part of the messara plain has revealed the stratigraphy of the mid to late holocene sediments laboratory analyses comprise granulometry magnetic susceptibility measurements and identification of mollusks diatoms and pollen grains eighteen radiocarbon dates provide a robust chronostratigraphy in addition a geophysical survey electric resistivity tomography ert method was conducted to reveal the sub surface morphology in the coring area the results reveal that a freshwater lake existed from ca 2100 2000 bc to ca 1200 1100 bc which subsequently became swampland until ca 700 bc a lake retreat is identified at ca 1200 1000 bc and can be interpreted as resulting from the 3 2 cal kyr bp rapid climate change rcc dry event observed elsewhere in the eastern mediterranean subsequently from the 7th to the 5th century bc there was the input of detrital material and fluvial dynamics prevailed until at least roman times the origin of the lake and its disappearance are discussed in the context of regional climate change and local tectonic activity without excluding possible human influences we also reconstruct the vegetation history for the period from the late minoan to the early archaic period pollen analysis reveals a mediterranean maquis landscape dominated by olea together with hygrophilous vegetation and highlights a clear transition from limnic to swampy environmental conditions around 1100 bc the pollen sequence is also important for assessing the impact of the 3 2 cal kyr bp rcc event and for assessing the possibility of an abrupt discontinuity in human activity around phaistos after the demise of the minoan civilization

electrical structure in thunderstorm convective regions 3 synthesis in this paper results from nearly 50 electric field soundings through convective regions of mesoscale convective systems mcss isolated supercells and isolated new mexican mountain storms are compared and synthesized these three types of thunderstorm convection are found to have a common basic electrical structure within convective updrafts the basic charge structure has four charge regions alternating in polarity and the lowest is positive outside updrafts of convection there are typically at least six charge regions alternating in polarity and the lowest is again positive among the three storm types there are differences in the heights and temperatures at which the basic four charge regions are found in updrafts the height temperature of the center of the main negative charge region averages 6 93 km 16 c in mcs convective region updrafts 9 12 km 22 c in supercell updrafts and 6 05 km 7 c in new mexican mountain storm updrafts in updraft soundings through all three storm types the center height of the main negative charge region increases with increasing average balloon ascent rate and updraft speed at a rate of about 0 3 km per 1 m s 1 with a correlation coefficient of 0 94 a schematic illustrates the basic four and six charge structure for thunderstorm convective regions and it is offered as an improved model for thunderstorm charge structure

temporal and spatial variability of sea level and volume flux in the murderkill estuary abstract the instantaneous sea level determined at two sites in the murderkill estuary a tributary of delaware bay results from the superposition of temporal variability operating over different time and spatial scales over the relatively short tidal time scales the semidiurnal tides that represent the dominant tidal constituents in lower delaware bay show a modest increase in tidal amplitudes from the bay mouth lewes delaware up to bowers beach the mouth of the murderkill estuary however as the tides propagate into the murderkill estuary the semidiurnal constituents undergo heavy attenuation resulting in a 48 reduction in tidal amplitude from bowers to frederica approximately the extent of saline intrusion the diurnal tide on the other hand experiences only a 25 reduction in amplitude the limited tidal asymmetry that is observed may be a result of interaction between flows in the tidal channel and the adjacent salt marsh at longer time scales the subtidal sea level experiences no attenuation the murderkill estuary thus behaves like a low pass filter to preferentially damp out high frequency sea level forcing from lower delaware bay the subtidal volume flux in the murderkill is highly coherent with the time rate of change of sea level indicating that the murderkill basically co oscillates with delaware bay in a standing wave fashion over the subtidal time scale this remote coupling controls more than 90 of the variance in subtidal sea level in the estuary the surface slopes in the lower bay and the murderkill estuary are closely correlated with winds along the orientation of the two waterways consistent with the effect of local wind on subtidal sea level

flash propagation and inferred charge structure relative to radar observed ice alignment signatures in a small florida mesoscale convective system a series of vertical cross sections taken through a small mesoscale convective system mcs observed over florida by the dual polarimetric smart radar were combined with vhf radiation source locations from a lightning mapping array lma to examine the lightning channel propagation paths relative to the radar observed ice alignment signatures associated with regions of negative specific differential phase kdp additionally charge layers inferred from analysis of lma sources were related to the ice alignment signature it was found that intracloud flashes initiated near the upper zero kdp boundary surrounding the negative kdp region the zero kdp boundary also delineated the propagation path of the lightning channel with the negative leaders following the upper boundary and positive leaders following the lower boundary very few lma sources were found in the negative kdp region we conclude that rapid dual polarimetric radar observations can diagnose strong electric fields and may help identify surrounding regions of charge

observations of wind induced subtidal variability in the delaware estuary sea level and current observations made in the delaware estuary during autumn of 1982 were examined for evidence of wind forced subtidal variability the large subtidal sea level fluctuations at the mouth of the delaware were found to be forced primarily by the wind stress component over the continental shelf nearly parallel to shore indicating coastal ekman transport to the right of the wind local wind forcing within the estuary is shown to be insignificant the subtidal sea level in the interior of the estuary was found to be driven by the wind through a combination of two remote forcing mechanisms one acting at the mouth of the delaware through direct estuary shelf coupling and a second acting locally over the chesapeake bay and being transmitted from the upper chesapeake through the chesapeake and delaware canal which links the two estuaries in the upper delaware estuary we found predominantly barotropic subtidal current fluctuations superimposed on a much weaker two layer gravitational circulation these current fluctuations were produced primarily by the local subtidal surface slope generated by the difference between the two remote forcing mechanisms the evidence strongly suggests that the chesapeake and delaware canal plays a critical role in the subtidal circulation of the delaware estuary

electrical and kinematic structure of the stratiform precipitation region trailing an oklahoma squall line abstract an electric field sounding through the transition zone precipitation minimum that trailed an oklahoma squall line on 18 june 1987 provides information about the electrical structure within a midlatitude trailing stratiform cloud a single doppler radar analysis concurrent with the flight depicts a kinematic structure dominated by two mesoscale flow regimes previously identified in squall line systems a strong midlevel front to rear flow coinciding with the stratiform cloud layer and a descending rear inflow that sloped from 6 5 km agl at the stratiform cloud s trailing edge to 1 5 km agl at the convective line electric field magnitudes as high as 113 kv m 1 were observed by the electric field sounding which reveals an electric field structure comparable in magnitude and complexity to structures reported for convective cells of thunderstorms the charge regions inferred with an approximation to gauss law have charge density magnitudes of 0 2 4 1 nc m 3 and vertical thicknesses of 130 1160 m

observations of nearshore wave dissipation over muddy sea beds 1 wave propagation on the louisiana inner shelf is studied using concurrent measurements at two shallow water ocean observatory sites in sedimentary environments dominated by mud at one site and sand at the other contrary to the widely accepted hypothesis that mud induced wave dissipation is important only for long waves observations show significant damping of high frequency short waves which interact weakly with the bottom the mechanism of short wave dissipation is not understood numerical simulations show that other dissipative processes such as refraction or depth limited breaking do not account for the magnitude of the observed effects independent observations of strong sediment re working during storms suggest that these effects are related to sediment resuspension processes

fish tanks of eastern crete greece as indicators of the roman sea level abstract the ancient fish tanks and fish traps of crete are relics of the roman domination of the island they were usually constructed near the major urban centers of that period the direct relationship of their various functional characteristics with past sea levels and the relatively accurate determination of their construction dates establish them as sensitive indicators of sea level change through space and time the fish tanks presented in detail in this study namely those of matala chersonissos mochlos and sitia and the fish trap in the gulf of zakros have all been reported recorded and or interpreted in regard to their operation by previous researchers in the absence of a comprehensive interdisciplinary approach to the issue uneven methodologies inaccurate data and wrong measurements have led to erroneous conclusions about sea level during their operation and about the size and direction of vertical tectonic movements in eastern crete during the upper holocene the present study is based on a new underwater survey in the course of which the architectural and functional features of the ancient constructions were reexamined precisely their depth from modern sea level was measured and their relationship with coastal landforms indicative of a past sea levels was investigated a review of their manner of operation and their modern submerged position allowed the definition of a roman mean sea level 1 24 m 0 09 m below the present one the submersion of the central and eastern parts of crete included in the same tectonic block with a total length of at least 150 km at an average tectonic rate of 0 65 mm year during the last 1900 100 years occurred as is shown by historical evidence during a paroxysmal tectonic event probably related to the strong earthquake of 1604

abstract geologic framework processes and rates of subsidence in the mississippi river delta plain abstract since the 1930 s louisiana has lost an estimated 3 950 km2 of coastal wetlands and barrier islands the loss of these coastal lands resulted primarily from subsidence and erosion rather than the draining and filling of wetlands more than 40 of the coastal wetlands in the u s are found in louisiana and 80 of our nation s total wetland loss occurs here at alarming rates beach erosion rates exceed 10 m yr and the rate of wetland loss is currently measured at 75 km2 yr the causes of louisiana s coastal land loss include delta switching storm impacts man s impacts on this deltaic system and high rates of subsidence recent studies indicate that the highest subsidence and coastal land loss rates occur where the underlying holocene sediments are the thickest this relationship suggests that subsidence through the consolidation and settlement of these young deposits is of primary importance to the coastal land loss problem found in louisiana to understand the role of subsidence in louisiana s coastal land loss problem requires a knowledge of the late quaternary history of the lower mississippi river of the infilling of its incised valley during the holocene transgression and of the processes of delta switching end of record last page 644

a simple model of estuarine subtidal fluctuations forced by local and remote wind stress observations of estuarine low subtidal sea level and current fluctuations have often shown domination by the remote effects of the wind acting on the adjacent coastal ocean over the local surface stress acting on the estuary itself the remote effects are transmitted to the estuary by impressment on its mouth of sea level change indtlced by the onshore component of coastal ekman transport and become increasingly dominant as the frequency decreases a simple barotropic model is developed to investigate the joint action of these two wind forcing mechanisms the relative shortness of most estuaries relative to low subtidal estuarine wavelengths explains the dominance of the remote effect for both sea level and barotropic current fluctuations in the estuary for the same reason however surface slope is dominated by local wind setup for an estuary with axis nearly parallel to the coast the two effects will operate either in concert or in opposition depending on hemisphere and orientation of the estuary axis relative to the coast for the geometries of both chesapeake bay and the delawm e estuary the model predicts opposition with the remote effect dominant at lower frequencies consistent with recent observations

tidal modulation on the changjiang river plume in summer 1 tide effects on the structure of the near field changjiang river plume and on the extension of the far field plume have often been neglected in analysis and numerical simulations which is the focus of this study numerical experiments highlighted the crucial role of the tidal forcing in modulating the changjiang river plume without the tidal forcing the plume results in an unrealistic upstream extension along the jiangsu coast with the tidal forcing the vertical mixing increases resulting in a strong horizontal salinity gradient at the northern side of the changjiang river mouth along the jiangsu coast which acts as a dynamic barrier and restricts the northward migration of the plume furthermore the tidal forcing produces a bidirectional plume structure in the near field and the plume separation is located at the head of the submarine canyon a significant bulge occurs around the head of the submarine canyon and rotates anticyclonically which carries a large portion of the diluted water toward the northeast and merges into the far field plume a portion of the diluted water moves toward the southeast which is mainly caused by tidal rectification this bidirectional plume structure is more evident under certain wind conditions during the neap tide with the reduced tidal energy the near field plume extends farther offshore and the bulge becomes less evident these dynamic behaviors are maintained and are fundamentally important in the region around the river mouth even under the summer monsoon and the shelf currents although in the far field the wind forcing and shelf currents eventually dominate the plume extension

subtidal salinity and velocity in the hudson river estuary observations and modeling a tidally and cross sectionally averaged model based on the temporal evolution of the quasi steady hansen and rattray equations is applied to simulate the salinity distribution and vertical exchange flow along the hudson river estuary the model achieves high skill at hindcasting salinity and residual velocity variation during a 110 day period in 2004 covering a wide range of river discharges and tidal forcing the approach is based on an existing model framework that has been modified to improve model skill relative to observations the external forcing has been modified to capture meteorological time scale variability in salinity stratification and residual velocity due to sea level fluctuations at the open boundary and alongestuary wind stress to reflect changes in vertical mixing due to stratification the vertical mixing coefficients have been modified to use the bottom boundary layer height rather than the water depth as an effective mixing length scale the boundary layer parameterization depends on the tidal amplitude and the local baroclinic pressure gradient through the longitudinal richardson number and improves the model response to spring neap variability in tidal amplitude during periods of high river discharge finally steady state model solutions are evaluated for both the hudson river and northern san francisco bay over a range of forcing conditions agreement between the model and scaling of equilibrium salinity intrusions lends confidence that the approach is transferable to other estuaries despite significant differences in bathymetry discrepancies between the model results and observations at high river discharge are indicative of limits at which the formulation begins to fail and where an alternative approach that captures two layer dynamics would be more appropriate

tidal and subtidal water volume exchange in an estuarine system abstract estuarine water movements occur over a broad range of time scales in this study moored current meter data were used to investigate water volume exchange in the tidal passes of lake pontchartrain louisiana on the tidal and subtidal time scales a calibration technique employing cross channel measurements of water velocity was used to calibrate the moored current meters thus allowing for calculation of volume flow over a 35 day period the local diurnal tide accounted for 50 of the total volume exchange the rest being due to subtidal events frontal passage this subtidal exchange occurs primarily as large scale events characterized by volume fluxes up to six times greater than the normal tidal prism neglecting this subtidal component in the determination of the volume fluxes for a system such as lake pontchartrain could result in substantial underestimation by as much as 50 of these volume and their corresponding material fluxes

the seismicity geomorphology and structural evolution of the corinth area of greece in the eastern gulf of corinth geological structure is closely reflected in the topography in the 1981 corinth earthquakes ground deformation accentuated existing geomorphological patterns we explore the relationship between seismicity and landforms in space and time the area examined extends beyond the epicentral region of the 1981 events and its evolution is traced over the last 40000 years to understand the relation between deep and superficial structures we discuss processes that occurred in the 1981 earthquakes and go on to propose that surface faulting appears only above linear faults at depth that move in earthquakes with magnitudes m s greater than six where faults at depth intersect or bend the faulting becomes distributed and prim ary faulting does not reach the surface here the surface manifestation of faulting at depth is surface folding and secondary faulting such regions are identified in maps of the eastern gulf of corinth evidence for the evolution of the fault systems is provided by eyewitness accounts of shoreline changes following the recent earthquakes historical and archaeological data pertaining to old sea levels and 14 c dates for molluscs collected from fossil shorelines the results of these studies broadly confirm an earlier view of j a jackson et al earth planet sci lett 57 377 397 1982 that motion has shifted from faulting south of the city of corinth to faulting in the perachora peninsula but the transfer is not complete areas lying between the two fault systems have moved up and down in historical and archaeological times indicating that both systems are still active the evidence for activity of the northern system points to a repeat time of 300 years for earthquakes com parable with those of 1981 the work discussed in this paper suggests that some of the features previously described as m arine terraces are fault controlled continental surfaces furtherm ore beach deposits at a num ber of different levels long regarded as successive shorelines are in fact contemporaneous the critical ages were obtained by radiocarbon dating of shell carbonate a technique which yields dependable results if applied to samples which have been carefully selected and pretreated palaeontological dating of the terraces in contrast is found to be misleading because the faunas are environm entally controlled and consequently diachronous

rocket and balloon observations of electric field in two thunderstorms instruments that measure the intense electric field strengths in thunderclouds 100 kv m 1 are designed to minimize the production of ions by small electrical discharges coronas emanating from the instruments themselves the nearby charge of these ions would unpredictably disturb the natural field of the cloud in an attempt to assess this disturbance two different instruments one carried by a rocket and one carried by a balloon were launched on two occasions into thunderstorms in spite of differing trajectories the soundings were similar which gives us some confidence in both instruments in addition the measurements revealed some interesting features of the two storms each storm appeared to have six significant and distinct regions of charge the balloon soundings also revealed that lightning flashes temporarily increased the electric field strength above the thunderclouds at altitudes from 9 7 to 14 3 km by amounts up to 10 kv m 1 after which the fields decayed away in 50 to 125 s one pair of ascent and descent rocket soundings separated in time by a maximum of 60 s and horizontally by 1 to 3 km showed little change in the thunderstorm electric field between ground and 7 5 km altitude

600 year sedimentary archive of hurricane strikes in a prograding beach ridge plain southwestern louisiana abstract this study tests a novel approach to paleotempestology substituting the lateral time depth of a prograding beach ridge plain for the vertical time depth of an aggrading coastal lake pond lagoon swamp or marsh trenching and coring of a beach ridge plain in southwestern louisiana revealed six sand beds and one shell bed interpreted as hurricane washover deposits the sand beds are readily distinguished from enclosing marsh sediments by their higher sand content lower organic content and contrasting microfossil assemblages based on the modern analogs of hurricanes audrey 1957 rita 2005 and ike 2008 and consideration of nearby landfalling hurricanes in the historical record it was determined that the storm intensity threshold of the study site is equivalent to a category 3 hurricane there is a wide variation in hurricane strike frequency between this site and other sites bordering the gulf of mexico this variation results from differences in site sensitivity and the nature of geologic or geochemical proxies used to derive hurricane strike records the approach demonstrated by this study could have applicability at other sites around the world where beach ridge plains are subject to tropical cyclone strikes

winter storm impacts on the chenier plain coast of southwestern louisiana abstract stormy conditions associated with periodic winter cold front passages are closely related to transport of suspended sediment to the continental shelf coastal erosion and coastal progradation along shoreline sectors where abundant fine grained sediments are stored on the inner shelf cold front passages occur between october and april on three to five day cycles their typical nw to se direction of approach large spatial scales and numerous yearly occurrences 20 30 events year drive physical processes that cause significant coastal change both remotely sensed multispectral and high quality photographic data have been collected from altitudes of 0 9 mi 1500 m 5 6 mi 9000 m and 13 mi 21 000 m before and after cold front passages to form a data base for evaluating coastal change and suspended sediment transport pathways satellite imagery provide a longer term perspective on coastal change remotely sensed data sets are augmented with ground truth measurements of coastal configuration sedimentology and water quality physical processes active in the prefrontal phases of a winter cold front passage are considerably different from those of the post frontal phase along the chenier plain coast prefrontal stages are characterized by prolonged periods on the order of several days of high wave action from the southerly quadrants water level setup along the coast and strong alongshore as well as onshore sediment transport at these times mud from the atchafalaya river stored on the nearshore shelf is transported onshore and alongshore to slightly prograde the chenier coast post frontal conditions bring dry cold winds from the northerly quadrants causing water level setdown along the coast a significant reduction in nearshore wave energy and drying of the newly deposited mudflats fronting the chenier plain rapid drying causes an important increase in sediment strength mud crack formation and effective armoring of the mud flats by dried mud clasts that resist erosion in subsequent cycles

sea level rise trends in the attico cycladic region aegean sea during the last 5000 years abstract sea level change during the last 18 000 years is a combination of eustatic isostatic and tectonic contributions in an effort to minimize the tectonic contributions our study of sea level changes in the aegean sea within historical times is focused on the aseismic attico cycladic geotectonic zone on the basis of archaeological information and radiocarbon dating of coastal sedimentological formations a sea level curve for the attico cycladic massif has been constructed for the past 5000 years and compared with existing curves according to this curve the rapid increase of sea level concluded prior to 5 5 ka and was followed by a slow steady rise at a rate of 0 9 mm a up to its present stage the latter is attributed primarily to the process of thermal expansion and secondarily to the residual melting of the glaciers and existing ice caps by extrapolation of the curve the sea level at the end of the 20th century is predicted to be about 9 cm higher than the present level this value is much lower than the prediction of the last ipcc report 49 cm if higher slr rates are realised in the next few decades then the excess 40 cm of the ipcc prediction can be attributed to human induced global climatic change

circular plumes in lake pontchartrain estuary under wind straining circular shaped density plumes of low turbidity low fecal indicator escherichia coli and enterococci concentrations and high salinity have been observed near the industrial canal in lake pontchartrain north of the city of new orleans a conceptual model in polar coordinates and a numerical model are developed together with data analysis to illustrate the dense plume it is demonstrated that the northward expansion of the plume occurs under northerly winds the northward expansion of the plume occurs under northerly winds that drive downwind flow at the surface and upwind radial flow at the bottom northerly wind induced straining similar to tidal straining promotes vertical stratification as a result the water becomes stratified near a thin bottom layer 1 m within which density currents are facilitated the stability of the stratified plume suppresses wind induced turbulent mixing inside the plume the bottom water outside of the plume is more effectively stirred by the wind the result being that the suspended sediment concentration outside of the plume area is much higher than inside this contrast in mixing makes the plume visible from the surface by satellites even though the stratification is at the bottom laterally wind stress produces a torque vorticity in areas of non uniform depth such that upwind flow is developed in deep water and downwind flow in shallow water the continuity requirement produces an upwind flow along the axis of the industrial canal ic the upwind flow is balanced by the downwind flow over the shallower peripheral areas along the coast

the terraces of corinth gerrce a detailed record of eustatic sea level variations during the last 500 000 years abstract between corinth and xylokastro 20 marine terraces reflect the interaction of the northern peloponnese uplift and the global eustatic sea level fluctuations during the last 500 000 years correlation of the terraces with oxygen isotope records in deep sea cores allowed accurate dating of these fossilized transgressive shorelines curves of altitude versus age have been plotted they show a regular decrease of the uplift rate and a frequent return of the sea level very close to the present day one not only during the interglacial periods 5 7 9 11 13 but also during glacial periods 3 1 3 3 6 8 the alternative would be to suppose very complicated and highly improbable vertical movements of the substratum to explain the regularity of the curves the rhythm of these high sea levels is around 20 30 ka since at least 330 000 years ago

spatial variation of cold front wind driven circulation and quasi steady state balance in lake pontchartrain estuary abstract circulation in a low salinity estuary with restricted openings to the ocean is mainly driven by wind and to a lesser extent by water level fluctuations at the open boundaries numerical model experiments are conducted using a baroclinic finite volume community ocean model fvcom for wind driven circulations during a period encompassing a total of 16 cold fronts in the lake pontchartrain estuary the work is focused on the examination of the spatial structure of circulation in response to local and remote winds a quasi steady state balance between the surface slope and wind stress is further analyzed the accuracy of the balance is evaluated by comparing the fvcom calculated surface slope with that from the steady state balance equation results show that this balance is more accurate in the cross estuary direction than that in the along estuary direction r2 0 94 vs 0 60 this difference in the accuracy of the quasi steady state balance between the cross and along estuary directions is caused by the open boundary a tidally induced mean slope exists in addition even if the tidal effect is removed the accuracy still decreases toward the open end for slopes in both directions remote wind effect and residual flow through the eastern open boundary tend to introduce a departure from the quasi steady state balance in both along and cross estuary directions remote wind effect decreases into the interior due to bottom friction local wind effect tends to produce downwind flows in coastal shallow water regions and on the surface but upwind flows near the bottom a result consistent with barotropic wind driven circulations while the remote wind effect is important mostly near the open boundary furthermore quasi steady state balance is more accurate in the along estuary direction before cold front passages then after because of the relatively higher occurrence of the wind in that direction before the cold fronts than after in contrast this quasi steady state balance is less accurate in the cross estuary direction before cold front passages than after because of the relatively lower occurrence of the wind in that direction before the cold fronts than after

an updated database of holocene relative sea level changes in ne aegean sea abstract the reconstruction of holocene relative sea levels has several implications ranging from the investigation of coastal vertical movements to the calibration of earth rheology models and ice sheet reconstructions the north eastern aegean sea is among the tectonically complex sectors of the eastern mediterranean mainly influenced by the activity of the north anatolian fault in this paper we created a relative sea level rsl database by expanding upon the previous compilation with recently published geological and archaeological data we reconstruct the rsl history in those aegean coastal sectors located within the south marmara microplate a broad shear zone located between western anatolia and central greece and affected by dominant strike slip faulting at times combined with a normal component then we compared it with the rsl histories obtained for the surrounding coastal sectors the analysis of the database indicated that it is not possible to define a common holocene rsl curve for the entire ne aegean as rsl history here is majorly influenced by changes in deformation patterns in addition data in our database are consistent with a continuous rsl rise in the last 6 0 ka bp in the whole ne aegean sea and cannot support the hypothesis of a mid holocene rsl highstand in the area finally we present our best estimates of late holocene rates of rsl prior to any possible acceleration during the twentieth century in the broad area of ne aegean here we identified the fastest rising rate 0 9 mm a 1 in that sector whose active tectonic deformation is mainly controlled by the north anatolian fault activity

evolving complex electrical structures of the steps 25 june 2000 multicell storm abstract data from a three dimensional lightning mapping array lma and from two soundings by balloon borne electric field meters efms were used to analyze the electrical structures of a multicell storm observed on 25 june 2000 during the severe thunderstorm electrification and precipitation study steps this storm had a complex multicell structure with four sections each of whose electrical structure differed from that of the others during all or part of the analyzed period the number of vertically stacked charge regions in any given section of the storm ranged from two to six the most complex charge and lightning structures occurred in regions with the highest reflectivity values and the deepest reflectivity cores intracloud flashes tended to concentrate in areas with large radar reflectivity values though some propagated across more than one core of high reflectivity or into the low reflectivity anvil intracloud lightning flash rates decreased as the vertical extent and maximum value of ref

wind driven circulation patterns in a shallow estuarine lake st lucia south africa abstract the spatiotemporal structure of wind driven circulation patterns and associated water exchanges or residence times can drive important bio hydrodynamic interactions in shallow lakes and estuaries the st lucia estuarine lake in south africa is an example of such a system it is a unesco world heritage site and ramsar wetland of international importance but no detailed research on its circulation patterns has previously been undertaken in this study a hydrodynamic model was used to investigate the structure of these circulations to provide insights into their role in transport and water exchange processes a strong diurnal temporal pattern of wind speeds together with directional switching between two dominant directions drives intermittent water exchanges and mixing between the lake basins high speed flows in shallow nearshore areas with slower upwind counter flows in deeper areas linked by circulatory gyres are key features of the circulation these patterns are strongly influenced by the complex geometry of st lucia and constrictions in the system water exchange time scales are non homogeneous with some basin extremities having relatively long residence times the influence of the circulation patterns on biological processes is discussed

wind induced circulation in semienclosed homogeneous rotating basins the wind induced circulation over laterally varying bathymetry was investigated in homogeneous systems using the three dimensional regional ocean model system roms the investigation focused on the influence of the earth s rotation on the lateral distribution of the flow with particular emphasis on the transverse circulation along basin wind stress with no rotation caused a circulation dominated by an axially symmetric transverse structure consisting of downwind flow over the shoals and upwind flow in the channel along the whole domain transverse circulation was important only at the head of the system where the water sank and reversed direction to move toward the mouth the wind induced flow pattern under the effects of the earth s rotation depended on the ratio of the maximum basin s depth h to the ekman depth d the solution tended to that described in a nonrotating system as h d remained equal to or below 1 for higher values of h d the longitudinal flow was axially asymmetric maximum downwind flow was located over the right shoal in the northern hemisphere looking downwind the transverse component of velocity described three gyres the main gyre was clockwise looking downwind and occupied the entire basin cross section as expected from the earth s rotation and the presence of channel walls the other two gyres were small and localized and were linked to the lateral distribution of the along channel velocity component which in turn was dictated by bathymetry these results compared favorably with a limited set of observations and are expected to motivate future measurements

mixed energy process interactions read from a compound clinoform delta paleo orinoco delta trinidad preservation of river and tide signals by mud induced wave damping

electrical structure and updraft speeds in thunderstorms over the southern great plains we have acquired 11 balloon soundings of the electric field and thermodynamics in large and sometimes severe and tornadic thunderstorms over the southern great plains the ascent rates of the balloons were used to divide the soundings into weak and strong updrafts all 11 soundings had magnitudes of charge densities and thicknesses of charge regions similar to those reported previously in small thunderstorms the five weak updraft soundings had complex charge structures of 7 9 charge regions below 10 km altitude the magnitude of the maximum measured electric field in these soundings was 100 150 k v m 1 the four soundings in strong updrafts had balloon ascent rates of at least 15 m s 1 for at least 1 km these soundings had simpler electrical structures of 3 5 charge regions below 10 km altitude their maximum measured electric fields ranged from 85 to 130 kv m 1 the data may support an earlier hypothesis that charge is elevated in strong updrafts in addition the data may suggest that simpler charge structures are associated with proximity to strong updrafts rather than with different storm types

upper holocene sea level changes paleogeographic evolution and its impact on coastal archaeological sites and monuments the paper presents the evolution of the geographic environment imposed by sea level changes in selected sites of the aegean sea region during the upper holocene the changes are due mainly to paroxysmic phases of the actual neotectonic evolution and to differential in time and space block movements and emerged or submerged coasts the reconstitution of these coasts is presented and in some cases natural harbor morphology is revealed the use and evolution of these sites is discussed other sites concern coastal or inland ancient settlements or constructions affected by submersion by the sea by the rise of the groundwater table or by uplift movements a general discussion on engineering measures to be applied for protection of the antiquities affected by these geographic changes closes the presentation

three dimensional fractal modeling of intracloud lightning discharge in a new mexico thunderstorm and comparison with lightning mapping observations 1 the direct comparison of lightning mapping observations by the new mexico tech lightning mapping array lma with realistic models of thundercloud electrical structures and lightning discharges represents a useful tool for studies of electrification mechanisms in thunderstorms initiation and propagation mechanisms of different types of lightning discharges as well as for understanding of electrical and energetic effects of tropospheric thunderstorms on the upper regions of the earth s atmosphere this paper presents the formulation of a new three dimensional probabilistic model for investigating the structure and development of bidirectional positive and negative lightning leaders the results closely resemble structures observed by the lma during intracloud discharges the model represents a synthesis of the original dielectric breakdown model based on fractal approach proposed by niemeyer et al 1984 and the equipotential lightning channel hypothesis advanced by kasemir 1960 and places special emphasis on obtaining self consistent solutions preserving complete charge neutrality of the discharge trees at any stage of the simulation a representative simulation run is compared to a typical intracloud discharge measured by lma in a new mexico thunderstorm on 31 july 1999 following the conclusions from coleman et al 2003 the comparison of the model and observed discharges reveals that an adequate choice of the electrical structure of the model thundercloud permits the development of a model intracloud discharge reproducing principal features of the observed event including the initial vertical extension of the discharge between the main negative and upper positive charge regions of the thundercloud and the subsequent horizontal propagations in these regions also consistent with observations e g coleman et al 2003 negative and positive leaders mainly develop in the upper positive and main negative charge regions respectively for the particular model case presented in this paper the total charge transfer the vertical dipole moment and the average linear charge density associated with the development of bidirectional structure of leader channels are estimated to be 37 5 c 122 c km and 0 5 mc m respectively in good agreement with related data reported in the refereed literature the model results also demonstrate that the bulk charge carried by the integral action of positive and negative leaders leads to a significant up to 80 reduction of the electric field values inside the thundercloud significantly below the lightning initiation threshold

archaeological and geomorphological indicators of the historical sea level changes and the related palaeogeographical reconstruction of the ancient foreharbour of lechaion east corinth gulf greece abstract study of the architectural morphological and constructional features of the coastal harbour installations of the ancient foreharbour of lechaion indicates that they were built or rebuilt during the period of the roman domination of corinth and has facilitated the reconstruction of the vertical movements and the palaeogeography of the coast on the basis of the current position of the sea level indicators including beachrocks fossilized uplifted and submerged marine notches and ancient coastal harbour installations and the relationship between them the sea level during the roman operation of the harbour was determined to be 0 90 m lower than at present furthermore the subsequent abandonment of the harbour and the siltation of its constructions were determined during two successive tectonic subsidence co seismic events the sea level rose by 2 0 m in total 1 60 m during the first event and 0 40 m during the second one a strong uplift tectonic event followed and the sea level dropped by 1 10 m this regression of the sea was responsible for the present shoreline morphology determination of the sea level fluctuation at the shore of the ancient harbour of lechaion allowed the palaeogeographical reconstruction of the coast in different stages related to these changes

a life cycle model for wave dominated tidal inlets along passive margin coasts of north america abstract a regional overview of 107 wave dominated tidal inlets along the u s atlantic coast u s gulf of mexico coast and canadian gulf of st lawrence coast yielded a generalized wave dominated tidal inlet life cycle model that recognized the rotational nature of tidal inlets tidal inlets are influenced by concurrently acting processes transpiring over two timescales short term event driven processes and long term evolutionary processes wave dominated tidal inlets are classified into three rotational categories based on net longshore sediment transport direction and rotation direction along the landward back barrier portion of the inlet channel downdrift channel rotation updrift channel rotation or little to no channel rotation lateral shifting of the flood tidal delta depocenter in response to available estuarine accommodation space appears to control inlet channel rotation flood tidal delta deposits fill accommodation space locally within the estuary i e creating bathymetric highs causing the tidal inlet channel to rotate external influences such as fluvial discharge pre existing back barrier channels and impeding salt marsh will also influence inlet channel rotation storm events may rejuvenate the tidal inlet by scouring sediment within the flood tidal delta increasing local accommodation space wave dominated tidal inlets are generally unstable and tend to open concurrently migrate laterally and rotate infill and close channel rotation is a primary reason for wave dominated tidal inlet closure during rotation the inlet channel lengthens and hydraulic efficiency decreases thus causing tidal prism to decrease tidal prism estuarine accommodation space and sediment supply to the flood tidal delta are the primary variables responsible for tidal inlet rotation stability of wave dominated tidal inlets is further explained by stability s tidal prism estuarine accommodation space v volume of annual sediment supply mt rotating wave dominated tidal inlets follow a six stage evolutionary model whereas wave dominated tidal inlets that exhibit little to no rotation follow a five stage evolutionary model

multi instrumental observations of a positive gigantic jet produced by a winter thunderstorm in europe 1 at 2336 56 utc on 12 december 2009 a bright gigantic jet gj was recorded by an observer in italy forty nine additional sprites elves halos and two cases of upward lightning were observed that night the location of the gj corresponded to a distinct cloud top 34 c west of ajaccio corsica the gj reached approximately 91 km altitude with a trailing jet reaching 49 59 km matching with earlier reported gjs the duration was short at 120 160 ms this is the first documented gj which emerged from a maritime winter thunderstorm only 6 5 km tall showing high cloud tops are not required for initiation of gjs in the presence of strong vertical wind shear the meteorological situation was different from typical outbreaks of fall and winter thunderstorms in the mediterranean during the trailing jet phase of the gj a sprite with halo triggered by a nearby cloud to ground lightning flash occurred at a relatively low altitude 72 km at the same time the trailing jet and beads were reilluminated electromagnetic waveforms from hungary poland and the usa revealed this gj is the first reported to transfer negative charge approximately 136 c from the ionosphere to the positively charged origins in the cloud i e a positive cloud to ionosphere discharge ci with a large total charge moment change of 11600 c km and a maximum current of 3 3 ka early vlf transmitter amplitude perturbations detected concurrently with the gj confirm the production of large conductivity changes due to electron density enhancements in the d region of the ionosphere

fvcom validation experiments comparisons with roms for three idealized barotropic test problems 1 the unstructured grid finite volume coastal ocean model fvcom is evaluated using three idealized benchmark test problems the rossby equatorial soliton the hydraulic jump and the three dimensional barotropic wind driven basin these test cases examine the properties of numerical dispersion and damping the performance of the nonlinear advection scheme for supercritical flow conditions and the accuracy of the implicit vertical viscosity scheme in barotropic settings respectively it is demonstrated that fvcom provides overall a second order spatial accuracy for the vertically averaged equations i e external mode and with increasing grid resolution the model computed solutions show a fast convergence toward the analytic solutions regardless of the particular triangulation method examples are provided to illustrate the ability of fvcom to facilitate local grid refinement and speed up computation comparisons are also made between fvcom and the structured grid regional ocean modeling system roms for these test cases for the linear problem in a simple rectangular domain i e the winddriven basin case the performance of the two models is quite similar for the nonlinear case such as the rossby equatorial soliton the second order advection scheme used in fvcom is almost as accurate as the fourth order advection scheme implemented in roms if the horizontal resolution is relatively high fvcom has taken advantage of the new development in computational fluid dynamics in resolving flow problems containing discontinuities one salient feature illustrated by the three dimensional barotropic winddriven basin case is that fvcom and roms simulations show different responses to the refinement of grid size in the horizontal and in the vertical

crustal block movements from holocene shorelines crete and antikythira greece abstract marks of several shorelines left by sea level stands during the last 4000 yrs occur along the coasts of the islands of crete and antikythira in this area recent movements of the earth s crust were identified by using a systematic survey based on multidisciplinary analyses strengthened by 60 radiometric datings between 4000 and 1700 yr b p a block of lithosphere a about 150 km long fig 10 which included antikythira and the levka mountains in crete underwent a series of ten rapid subsidences from 10 to 25 cm each time without noticeable tilting these movements ended about 1 530 40 yr b p a further block of lithosphere b approximately 200 km long was then uplifted about 10 m and inclined northeastwards in a single event block b includes block a and extends 50 km further eastwards beyond the ida mountains as far as the iraklion sedimentary basin the tectonic movements were preceded by vertically reversed displacements of short duration on at least three occasions if the a block subsidences can be ascribed to gravitational forces then the b block uplift suggests a cause that originated at depth crustal consumption and elastic rebound to the east of the ierapetra graben the sitian peninsula appears to belong to a block of lithosphere c affected by a northeast tilting and separated by an active fault from the crustal block of khrisi koufonisi

hydrodynamic and sedimentary responses to two contrasting winter storms on the inner shelf of the northern gulf of mexico abstract results are presented from the deployment of three bottom mounted instrumentation systems in water depths of 6 9 m on the sandy inner shelf of louisiana usa the 61 day deployment included nine cold front passages that were associated with large increases in wind speed two of the most energetic cold front passages were characterized by distinct meteorological hydrodynamic bottom boundary layer and sedimentary responses and may potentially be treated as end member types on a continuum of regional cold front passages arctic surges ac storms have a very weak pre frontal phase followed by a fairly powerful post frontal phase when northeasterly winds dominate migrating cyclones mc storms are dominated by a strong low pressure cell and have fairly strong southerly winds prior to the frontal passage followed by strong northwesterly winds on the basis of measurements taken during this study ac storms are expected to have a lower average significant wave height than mc storms and are dominated by short period southerly waves subsequent to the frontal passage currents are weak and northerly during the pre frontal phase but become very strong and southwesterly following the passage sediment transport rate during as storms was not as high as during mc storms and the mean and overall direction tended to be southwesterly to westerly with low frequency flows producing easterly transport and wind wave flows producing southeasterly transport mc storms had the most energetic waves of any storm type with peaks in significant wave height occurring during both the pre and post frontal phases the wave field during mc storms tended to be more complex than during as storms with an energetic northerly swell band gradually giving way to a southerly sea band as the post frontal phase progressed currents during mc storms were moderate and northerly during the pre frontal phase but became much stronger and southeasterly during the post frontal phase shear velocity was high during both the pre and post frontal phases of the storm although sediment transport was highest following the frontal passage mean and overall sediment transport was directed southeasterly during mc storms with low frequency and wind wave flows producing northerly transport in summary the data sets presented here are unique and offer insight into the morphosedimentary dynamics of mid latitude micro tidal coasts during extratropical storms

the mississippi delta region past present and future the mississippi delta region of south louisiana houses a wealth of resources within a dynamic subsiding landscape foundations for the delta region reflect neogene evolution of the depocenter whereas details of the modern landscape reflect late pleistocene to holocene evolution of the alluvial deltaic plain the holocene delta plain was constructed by cyclical growth of deltaic headlands followed by avulsion and relocation of the fluvial sediment source abandoned headlands were then submerged and reworked while a new headland was created at the site of active fluvial sediment input historic period levees have decoupled the delta plain from its fluvial sediment source at the same time global sea level rise was accelerating which has accelerated delta plain submergence diversions of mississippi river water and sediment are necessary to achieve delta plain sustainability but upstream dams trap 50 of the total sediment load and there is not enough supply to keep pace with subsidence and accelerated

deep water deposits of the tanqua and laingsburg subbasins southwest karoo basin south africa analog for the gulf of mexico abstract the tanqua and laingsburg subbasins in south africa had near contemporaneous formation and filling and contain permian age basin floor and slope fans that display characteristics similar to deposits in the northern gulf of mexico outcrop area for each subbasin is about 650 km2 and individual fans range from 150 to 450 km2 with lateral continuity of individual fans up to 34 km with a sandstone shale ratio of 75 90 the arenaceous fans vary in thickness from 20 to 60 m with interlying shales ranging from 20 to 75m in thickness both subbasins were influenced in their formation and in the architecture of their deposits by structures and events associated with the cape fold belt having undergone little tectonic tilting the highly continuous outcrops in the tanqua subbasin expose two fans continuing from mid fan channel complexes with associated levee overbank deposits to sheet like outer fan lobes while three other fans expose outer fan depositional lobes paleocurrent directions for four of the fans are from ssw to s and a direction of w to wnw for the fifth these fans most likely had a single point source which migrated over the time of basin fill unrestricted deposition suggests an open basin depositional setting the laingsburg subbasin was strongly influenced by the tectonism associated with the cape fold belt deposition occurred in a deeper and narrower basin and the deposits except for the overlying deltaics cannot be correlated with those of the tanqua subbasin the two subbasins while associated with an active margin were likely filled at slightly different times both had a distant source area which led to deposits exhibiting characteristics of a passive margin depositional environment understanding the evolution of the subbasins and the tectonic conditions under which the submarine fans were deposited leads to the determination of the mechanisms that influenced the formation of the fans and their resulting architecture these fans permit detailed studies on their architecture necessary to 1 increase our understanding of fine grained low sandstone shale ratio fans 2 determine influences of paleostructures and tectonics on basin fill 3 carry out detailed reservoir simulation programs and 4 make predictive models of deep water sands in the northern gulf of mexico end of record last page 646

summertime tidal flushing of barataria bay transports of water and suspended sediments the edges of the inlet the net flux of total suspended sediment out of the bay was determined to be 8800 t of which 20 was organic matter demonstrating a significant source of organic matter to the base of the coastal ocean detrital food chain the time evolution and net fluxes of water and suspended sediments showed that the net flow resembles conventional estuarine circulation patterns with net outward flow on the surface and shallow ends of the inlet and with net inward flow in the center and at the bottom of the center of the inlet the west side has a much larger outward flow than the east side while the east side is fresher these differences suggest that the louisiana coastal current from around the bird s foot delta derived from the mixing of shelf water with the mississippi river freshwater may have entered the bay this must have been mostly from the east side during the survey which resulted in a smaller outward flow on the eastern side a numerical experiment further confirmed this assumption and the model was verified by field observations on 5 may 2010

vertical land movements and sea level changes along the coast of crete greece since late holocene abstract geomorphological survey along the coasts of crete revealed widespread evidence of uplifted and submerged tidal notches different phases of beachrock formation and many relics of ancient coastal constructions about 1 6 ka bp when the sea level was at 1 25 0 05 m the western tectonic block of the island uplifted by 9 15 0 20 m in its westernmost extremity and by 2 00 m approximately in its eastern boundary and tilted southeastward repeated preceding episodes of subsidence submerged the western part of the island by 1 60 m in a period of 2300 years along the western coast the younger phase of the submerged beachrocks was identified and measured at nineteen locations together with the submerged tidal notches and archaeological remains land subsidence by 1 25 0 05 m subsequent to the uplift of the western part occurred after the late venetian occupation period ad 1600 coincident with the submersion of the eastern part of the island in central and eastern crete the relative sea level change evidence from tidal notches and beachrocks revealed five distinct sea level stands at 6 55 0 55 m 3 95 0 35 m 2 70 0 15 m 1 25 0 05 m and 0 55 0 05 m the lowest sea level stand can be identified with the oldest dated tidal notch of western crete between 4200 90 b p and 3930 90 b p two subsequent sea levels can be linked with the protopalatial 1900 1700 b c or 1600 b c and neopalatial period 1600 1450 b c of the minoan civilization according to submerged prehistoric morphologies and inundated minoan constructions the change of sea level from 2 70 0 15 m to 1 25 0 05 m is placed between 1450 b c and the fourth century bc the dating of 1 25 0 05 m sea level stand was based on the measurement and interpretation of ancient coastal installations built along the coast of central and eastern crete during classical hellenistic roman byzantine and venetian periods historical sources report a relative sea level rise by 0 70 m during the ad 1604 paroxysmal event over the last 400 years the relative sea level rose by 0 55 m the uplift of the coast of western crete and the submersion in its central and eastern coast indicate that during the ad 365 paroxysmal event the island was split along a tectonic boundary identified with the neotectonic graben of spili and its northern and southern prolongation

palaeoenvironmental evolution of the ancient harbor of lechaion corinth gulf greece were changes driven by human impacts and gradual coastal processes or catastrophic tsunamis abstract the corinth gulf central greece is one of the most rapidly widening tectonic rifts on earth where large earthquakes with magnitudes of up 7 0 have been documented not only by instrumental records but also assessed from historical reports extending back to the 5th century bce several of these earthquakes were associated with tsunamis particularly in the western part of the gulf of particular interest is the ancient harbor of lechaion in the eastern side of corinth gulf we reexamine the hypothesis that lechaion was hit by high energy tsunami waves in the 8th 6th century bce 1st 2nd century ce and during the 6th century ce on the basis of sedimentological seismotectonic archaeological and historical data completed with field observations we support that there is no evidence for tsunami impact in lechaion local stratigraphy and environmental changes are rather interpreted by human impacts and gradual coastal processes such interpretations confirm that the tsunami potential in the east corinth gulf is relatively low

subtidal water level variations in lake pontchartrain louisiana lake pontchartrain louisiana has two major tidal passes connecting it to the mississippi sound and thence to the gulf of mexico the subtidal variability in this system and its relation to wind forcing over a 7 month period were examined the coherence of water level fluctuations in the lake and passes with those of the sound was high at all time scales and the water level in all data sets responded to the east west wind at time scales shorter than 15 days since the local coastline is approximately in the east west direction the results suggest a coupled coastal ocean lake response a linear friction model was developed and it accounted for most of the observed features

subtidal eulerian currents in the upper and lower east river tidal strait spring 1981 subtidal eulerian currents determined from long term current moorings in the east river tidal strait connecting the lower hudson river with long island sound show a well defined two layer circulation pattern within the eastern upper part of the east river mean surface currents flow toward the sound and current at depth flows toward the hudson within the western part of the east river residual currents are vertically sheared but flow is directed toward the sound at all depths with stronger flow near the surface mean current magnitudes are of the order of 5 cm s 1 results from frequency domain regression show that in the western lower portion of the strait current fluctuations at frequencies of 0 25 cycles per day and higher are associated primarily with a barotropic response to fluctuations in hydraulic head at lower frequencies currents exhibit a baroclinic response to fluctuations in the discharge of the hudson river within the upper part of the strait currents respond to along channel winds response to fluctuations in sea level head and hudson river discharge is detectable but not as well defined as within the lower east river these results can provide insight into the relative importance of different forcing functions in maintaining the residual flow through the strait the difference in the response characteristics of the western and eastern segments of the strait could be related to differences in the intensity of tidal mixing along the strait and the degree of water column stratification