evidence of greenland sea water in the iceland basin 1 this study evaluates the presence of intermediate water from the greenland sea in the iceland basin deduced from the observed excess of the tracer sulphur hexafluoride sf6 released in the central greenland sea in 1996 the large tracer release experiment has served a unique opportunity to follow the spread of greenland sea intermediate water to the adjacent basins of the nordic seas and to the areas bordering this region in the present study using data from may june 2001 the released tracer was detected at the sill in the faroe bank channel and at several locations in the iceland basin of the north atlantic just downstream the sill and southeast of iceland the estimated excess of the released tracer at the icelandic slope combined with reported values of the volume flow at this location suggest an annual transport rate of approximately 1 4 kg excess sf6 the results suggest an upper transit time from the central greenland sea to the area southeast of iceland of approximately 4 years

from swallow floats to argo the development of neutrally buoyant floats neutrally buoyant floats have been a vital tool in the exploration of the global ocean circulation and now provide a central element of the in situ ocean observing system through the argo project the paper traces the development of neutrally buoyant floats from their origins in the mid 1950s to the present day and highlights areas of ocean science to which floats made significant contributions

importance of pre existing oceanic conditions to upper ocean response induced by super typhoon hai tang 1 this study investigates upper ocean response to super typhoon hai tang the most intense typhoon in 2005 in the western north pacific using multi satellite microwave data typhoon data and argo profiles sequential merged microwave sea surface temperature sst images show that hai tang induced four separately cooling responses after its trail in the western north pacific during 11 18 july comparison between upper ocean responses of cooling sst and pre typhoon sea surface height suggests that these cooling responses of the upper ocean to hai tang are closely associated with pre existing cyclonic circulation denoted by pre existing negative sea surface features furthermore applying argo profiles the physical mechanism is confirmed to be associated with pre existing cyclonic circulations provide a relatively unstable thermodynamic structure and therefore cold water would be brought up readily this paper provides the rather convincing evidence that cyclonic flow and uplifted thermocline are the pre existing conditions for intensive cooling following the typhoon passage

flow deflection over a foredune flow deflection of surface winds is common across coastal foredunes and blowouts incident winds approaching obliquely to the dune toe and crestline tend to be deflected towards a more crest normal orientation across the stoss slope of the foredune this paper examines field measurements for obliquely incident winds and compares them to computational fluid dynamics cfd modelling of flow deflection in 10 increments from onshore 0 to alongshore 90 wind approach angles the mechanics of flow deflection are discussed followed by a comparative analysis of measured and modelled flow deflection data that shows strong agreement cfd modelling of the full range of onshore to alongshore incident winds reveals that deflection of the incident wind flow is minimal at 0 and gradually increases as the incident wind turns towards 30 to the dune crest the greatest deflection occurs between 30 and 70 incident to the dune crest the degree of flow deflection depends secondarily on height above the dune surface with the greatest effect near the surface and toward the dune crest topographically forced flow acceleration speed up across the stoss slope of the foredune is greatest for winds less than 30 i e roughly perpendicular and declines significantly for winds with more oblique approach angles there is less lateral uniformity in the wind field when the incident wind approaches from 60 because the effect of aspect ratio on topographic forcing and streamline convergence is less pronounced

mindoro strait and sibutu passage transports estimated from satellite data 1 this study investigates the mindoro strait and sibutu passage transports using remotely sensed sea surface height ssh and ocean bottom pressure obp data the analysis reveals the existence of a persistent baroclinic pressure gradient that drives a deepwater overflow from the south china sea into the sulu sea the application of hydraulic theory combined with the geostrophic control formula yields a mean transport estimate of about 2 4 sv 1 sv 106 m3 s 1 through the mindoro strait and about 2 8 sv through the sibutu passage most of this water enters the sulu sea through the bottom layer of the mindoro strait and exits the sulu sea in the upper layer of the sibutu passage the analysis also provides the first satellite based observational evidence on the seasonal and interannual variation of the mindoro strait and sibutu passage transports for the period from january 2004 to december 2007

secondary flow deflection in the lee of transverse dunes with implications for dune morphodynamics and migration measurements of lee side airflow response from an extensive array of meteorological instruments combined with smoke and flow streamer visualization is used to examine the development and morphodynamic significance of the lee side separation vortex over closely spaced transverse dune ridges a differential deflection mechanism is presented that explains the three dimensional pattern of lee side airflow structure for a variety of incident flow angles these flow patterns produce reversed along dune and deflected surface flow vectors in the lee that are inferred to result in net lateral diversion of sand transport over one dune wavelength for incident angles as small as 10 from crest transverse i e 80 from the crest line this lateral displacement increases markedly with incident flow angle when expressed as the absolute value of the total deflection in degrees reversed and multi directional flow occurs for incident angles between 90 and 50 these results document the three dimensional nature of flow and sand transport over transverse dunes and provide empirical evidence for an oblique migration model copyright 2013 john wiley sons ltd

aeolian processes across transverse dunes i modelling the air flow this paper discusses a two dimensional second order closure model simulating air flow and turbulence across transverse dunes input parameters are upwind wind speed topography of the dune ridge and surface roughness distribution over the ridge the most important output is the distribution of the friction velocity over the surface this model is dynamically linked to a model that calculates sand transport rates and the resulting changes in elevation the sand transport model is discussed in a separate paper the simulated wind speeds resemble patterns observed during field experiments despite the increased wind speed over the crest the friction velocity at the crest of a bare dune is reduced compared to the upstream value because of the effect of stream line curvature on turbulence these curvature effects explain why desert dunes can grow in height in order to obtain realistic predictions of friction velocity it was essential to include equations for the turbulent variables in the model in these equations streamline curvature is an important parameter the main flaw of the model is that it cannot deal with flow separation and the resulting recirculation vortex as a result the increase of the wind speed and friction velocity after a steep dune or a slipface will be too close to the dune foot in the sand transport model this was overcome by defining a separation zone copyright 1999 john wiley sons ltd

simulation and measurement of surface shear stress over isolated and closely spaced transverse dunes in a wind tunnel topographic interactions generate multidirectional and unsteady air ow that limits the application of velocity pro le approaches for estimating sediment transport over dunes results are presented from a series of wind tunnel simulations using irwin type surface mounted pressure sensors to measure shear stress variability directly at the surface over both isolated and closely spaced sharp crested model dunes findings complement existing theories on secondary air ow effects on stoss transport dynamics and provide new information on the in uence of lee side air ow patterns on dune morphodynamics for all speeds investigated turbulent unsteadiness at the dune toe indicates a greater more variable surface shear despite a signi cant drop in time averaged measurements of streamwise shear stress at this location this effect is believed suf cient to inhibit sediment deposition at the toe and may be responsible for documented intermittency in sand transport in the toe region on the stoss slope streamline compression and ow acceleration cause an increase in ow steadiness and shear stress to a maximum at the crest that is double that at the toe of the isolated dune and 60 70 per cent greater than at ow reattachment on the lower stoss of closely spaced dunes streamwise ow accelerations rather than turbulence have greater in uence on stress generation on the stoss and this effect increases with stoss slope distance and with incident wind speed reversed ow within the separation cell generates signi cant surface shear 30 40 per cent of maximum values for both spacings this supports eld studies that suggest reversed ow is competent enough to return sediment to the dune directly or in a de ected direction high variability in shear at reattachment indicates impact of a turbulent shear layer that despite low values of time averaged streamwise stress in this region would inhibit sediment accumulation downwind of reattachment shear stress and ow steadiness increase within 6 h h dune height of reattachment and approach upwind values by 25 h a distance of at least 30 h is suggested for full boundary layer recovery which is comparable to uvial estimates the irwin sensor used in this study provides a reliable means to measure skin friction force responsible for sand transport and its robust simple and cost effective design shows promise for validating these ndings in natural dune settings copyright 2003 john wiley sons ltd

spatial temporal evolution of aeolian blowout dunes at cape cod abstract this paper explores historical evolution of blowouts at cape cod national seashore ccns usa a site that hosts one of the world s highest densities of active and stabilized blowouts the spatial temporal analysis of moving polygons stamp method is applied to a multi decadal dataset of aerial photography and lidar to extract patterns of two dimensional movement and morphometric changes in erosional deflation basins and depositional lobes blowout development in ccns is characterized by several geometric overlap and movement proximity responses including i generation and disappearance ii extension and contraction iii union or division iv clustering and v divergence by stabilization other possible movement events include migration amalgamation and proximal stabilization but they were not observed in this study generation events were more frequent than disappearance events the former were highest between 1985 and 1994 while the latter were highest between 2000 and 2005 high rates of areal change in erosional basins occurred between 1998 and 2000 3932 m2 a 1 the lowest rate 333 m2 a 1 between 2005 and 2009 and the maximum rate 4589 m2 a 1 between 2009 and 2011 union events occurred mostly in recent years 2000 2012 while only one division was observed earlier 1985 1994 net areal changes of lobes showed gradual growth from a period of contraction 1119 m2 a 1 between 1998 and 2000 to rapid extension 2030 m2 a 1 by 2010 which is roughly concurrent with rapid growth of erosional basins between 2005 and 2009 blowouts extended radially in this multi modal wind regime and despite odd shapes initially they became simpler in form more circular and larger over time net extension of erosional basins was toward ese 109 while depositional lobes extended sse 147 lobes were aligned with the strongest winter sand drift vector although their magnitude of areal extension was only 33 that of the basins these differences in extension responses likely result from more complex and evolving flow form interactions inside erosional basins historical photographs and ccns documents suggest that blowout evolution may be influenced by land use changes such as revegetation campaigns in 1985 that were followed by high blowout generation high magnitude regional storm events e g hurricanes also play a role the analytical framework presented provides a systematic means for two dimensional geomorphic change detection and pattern analysis that can be applied to other landscapes

nebkha flow dynamics and shadow dune formation in this study wind flow is simulated via cfd over five nebkha dune forms that range in shape from a cone to a hemisphere approximately and to a dome in order to examine the structure of the wake zone formed downwind and the effect on the leeward flow separation zone and shadow dune formation dune height was fixed at 0 5 m while the nebkha diameter increased in 0 25 m increments from 0 5 m to 1 5 m and aspect ratio h d from 1 0 to 0 3 the mean flow comprises an upwind region of reduced velocity which expands as nebkha width increases high velocity marginal wings and paired counter rotating reversing vortices leeward of the nebkha the point at which flow separation occurs moves further downwind as the nebkha diameter increases the core regions of the reversing vortices are situated further downwind behind the smaller nebkha than in the case of the larger nebkha these factors in combination allow for higher velocity perturbations tke and narrower wake behind the smaller nebkha and the suppression of downwind wake development in the case of the increasingly larger nebkha shadow dune length increases as nebkha width increases for lower incident velocity flow and is barely affected by nebkha width at higher flows the extent of the leeward separation or wake zone and hence shadow dune length more strongly varies as a function of wind velocity

modeling the development of wave cut shore platforms abstract a mathematical model was used to investigate the development of wave cut shore platforms with constant sea level the model considered the effects of deep water wave height spectra period and wavelength breaker height and depth breaker type the width and bottom roughness of the surf zone the gradient of the submarine slope an erosional threshold related to the strength of the rocks the number of hours each year in which the water level is at each intertidal elevation and the amount and persistence of the debris at the cliff foot intertidal erosion rates were calculated according to the force of the surf reaching the shoreline whereas submarine erosion rates were determined using a depth decay variable each of the two hundred and fifty model runs consisted of 300 000 iterations platform width increased and gradient progressively decreased through model runs and states of static equilibrium were attained by the end of one hundred and nine runs when the wave induced force at each point in the intertidal zone had became too weak to continue eroding the rock runs with mesotidal spring tidal range 3 m generally produced subhorizontal platforms with cliff platform junctions at the mean low water neap tidal level a greater variety of profiles was produced in runs with macrotidal spring tidal ranges 9 m although almost 30 of these runs produced gently sloping platforms with average gradients of only 0 3 about two thirds of the simulated profiles had average gradients ranging from about 1 to 3 simulated platform width increased with tidal range and decreased with the rate of submarine erosion rock resistance the roughness or irregularity of the platform surface the amount and persistence of the cliff foot debris and wave period because higher waves break in deeper water than lower waves there was no consistent relationship between simulated platform width and wave height

uranium series age of the eel point terrace san clemente island california uranium series analysis of the coral allopora californica verrill from the 2nd 32 m eel point terrace on san clemente island california has yielded an age of 127 000 7 000 yr the eel point terrace is thus correlative with numerous terrace localities on the southern california mainland with coral reefs on barbados and new guinea dated about 120 000 yr and with substage 5e of the marine oxygen isotope record a tectonic uplift rate of about 0 20 m 1 000 yr has been calculated assuming a sea level slightly higher than the present one at the time of terrace formation extrapolation of this uplift rate allows age estimates to be made for other terraces on the island

relations between dune morphology air flow and sediment flux on reversing dunes silver peak nevada relations between wind speed sediment flux and dune morphology were measured for two reversing dunes situated in the south western part of the silver peak dunefield in clayton valley west central nevada the larger dune was 120 m in length with a height of 12ae5 m and the smaller dune 80 m long and 6 m high both dunes were sharp crested aligned approximately e w perpendicular to the dominant wind direction and had slightly concave stoss profiles twenty seven rotating cup anemometers were placed 0ae3 m elevation along n s transects on each of the dunes at each anemometer site a passive wedge shaped sediment trap was used to measure sediment flux amplification of wind speed was observed towards the crest on the stoss side of both dunes with speed up factors ucrest ubase ranging from 1ae50 3ae19 with a corresponding increase in sediment flux by 1 2 orders of magnitude in general the ratio of crest flux to base flux qc qb increased with increasing incident basal wind speed on both dunes direct measurements of the stoss slope variation in sediment flux relative to the dune crest are in good agreement with owen s transport model friction speed u was approximated from near surface 0ae3 m point wind speed although not all assumptions of the owen model are upheld the modified model performance is sufficiently robust to predict short term variation in stoss sediment flux on the study dunes improved models that adequately account for variation in sediment flux under changing air flow and transport conditions are necessary for the prediction of longterm evolution of dunes in this regard further progress in model development will require increased understanding of the spatial and temporal variability of airflow and the short term response of sediment flux to these flow conditions

abnormal upwelling and chlorophyll a concentration off south vietnam in summer 2007 the present study investigates a strong upwelling and concurrent phytoplankton bloom off the south vietnam coast in august 2007 analysis of the alongshore wind offshore ekman transport wind stress curl and other parameters indicates the southwesterly summer monsoon plays an important role in this peculiar case the change of monsoonal wind involves variations of atmospheric circulation on multiple time scales on the interannual time scale a positive indian ocean dipole iod in 2007 accompanying with a la nina event acts to enhance the southwesterly monsoon over the south china sea scs the enhanced southwesterly wind is regarded as a major factor in promoting the upwelling and the phytoplankton bloom off the south vietnam coast on the intraseasonal time scale variations of the sea surface temperature sst and sea surface wind at 30 60 day periods reveal that the sst cooling develops with the evolution of the southwesterly wind anomalies with nearly one week delay implying the great significance of the madden julian oscillation mjo moreover a tropical storm formed in the western scs in early august reinforces the westerly wind and sst cooling among multiple factors on different time scales the mjo event is considered as the major cause since it induces the maximum velocity 4 m s of the southwesterly wind anomalies as a result the high chlorophyll a concentration 0 56 mg m 3 and low sst center 27 degrees c develops in the region off the south vietnam coast and advects to the central scs riding on the northern rim of the southern anticyclonic gyre

response of a preexisting cyclonic ocean eddy to a typhoon abstractthe three dimensional responses of a cyclonic ocean eddy coe for 1 2 months following a typhoon were investigated using altimeter data and numerical experiments two significant features were found 1 the cyclonic eddy was enhanced and the three dimensional structure was changed and 2 the cyclonic eddy underwent two processes elliptical deformation and reaxisymmetrization in the horizontal plane these two features are generally associated with typhoon induced upwelling and the dynamic processes of eddy adjustment these results imply that the local ocean processes can be affected by a typhoon through low frequency response

mineralogy and provenance of pleistocene outwash plain and modern beach sands of outer cape cod massachusetts usa abstract sand and pebbles of the beaches of outer cape cod are derived from eroding coastal cliffs of lacustrine fluvial outwash plains of wisconsin age the beach sands and the sands of the older and younger wellfleet highland and truro plains have similar mineralogically mature quartzose compositions these sands are quartz arenites to subarkoses with small amounts of glauconite pellets the complete samples of the combined outwash and beach groups average 89 quartz and 4 feldspar the medium sand fractions average 91 quartz and 5 feldspar the non opaque non micaceous heavy minerals in the medium sand fraction of the beaches average 42 tourmaline 16 staurolite 14 garnet 13 sillimanite 5 amphibole 5 andalusite and 5 others although the proportions of heavy minerals in the outwash sands vary among samples the average composition is similar to the beach sands 40 tourmaline 16 staurolite 16 sillimanite 12 garnet 6 andalusite 4 amphibole and 6 others a common provenance for outwash and beach sands is also reflected in the nearly uniform ratios of color varieties of tourmaline in all samples most of the quartzose sand of the beaches and outwash has a long history of recycling from atlantic coastal plain strata of cretaceous to tertiary age these sands were entrained by illinoian glacial ice which deposited gravel and sand in till and outwash over the gulf of maine sangamon marine reworking of the surface of these deposits mantled them with glauconitic quartzose sand and gravel wisconsin ice moved southeastward stripping the floor of the gulf of maine down to crystalline rocks and remnants of cretaceous to tertiary strata melt water streams flowed southwestward from the south channel lobe into lakes building the outwash plains with quartzose sand and lithic pebbles the shapes and surfaces of many round subspherical quartz grains were modified by grinding during transport in the ice producing conchoidal fractures flat edged plate like fragments sharp edges sliver like chips and grooves subsequent longshore transport of the quartzose sand and lithic pebbles north and south from a nodal zone has somewhat rounded the grains but has not made the medium sand fraction more quartzose the nodal zone is northeast of wellfleet as evidenced by an increase in hydraulic equivalent ratios for tourmaline sillimanite staurolite garnet and hornblende north and south along the coast from this location

a one million year long sequence of marine terraces on sumba island indonesia abstract an exceptional sequence of raised coral reef terraces is visible at cape laundi on the north coast of the island of sumba in the savu sea in which at least eleven terraces wider than 100 m six of them even being over half a kilometer wide are geomorphologically distinguishable between an ancient patch reef now at 475 m and the present sea level esr date estimations of almost unrecrystallized corals most of them in situ make possible a tentative identification of the terraces corresponding to isotope stages 15 ca 600 ka ago and 9 ca 330 ka ago when the uplift trend deduced from the present altitude of dated terraces 0 49 0 01 mm yr is extrapolated to the whole raised section most geomorphological features appear to correspond to interglacial stages of the astronomically calibrated oxygen isotope record up to stage 27 ca 0 99 ma beyond the matuyama jaramillo geomagnetic boundary the upper terraces would in this case be twice as old as previously estimated ca 0 5 ma main terraces seem to correspond to high sea levels at certain interglacial stages and substages but in some cases the action of low sea levels at glacial stages cannot be ruled out for terraces between 30 and 70 m in altitude th u and esr dates reveal that aragonitic corals at similar elevations may differ in age as much as 100 ka this can be explained by taking into account a polycyclic origin for several terraces reconstructions available of changes in the eustatic sea level during the last 250 kyr and the fact that coral reef development may have been scattered at some periods only without totally covering subjacent older formations the sumba sequence of marine terraces at cape laundi is among the longest and most complete for the past million years reported in the literature its relatively good state of preservation will probably give impetus to a number of new studies on the chemical physical isotopic morphological palaeoclimatic pedological ecological and diagenetic changes which have occurred during the past one million years

foredunes and blowouts initiation geomorphology and dynamics this paper reviews the initiation dynamics geomorphology and evolution of incipient foredunes established foredunes and blowouts incipient foredunes may be initiated in a variety of ways leading to the formation of ramps terraces or ridges depending on progradation rates vegetation type and cover sediment transport rates and scale of erosional processes vegetation cover morphology growth rates and types combine with aerodynamic processes to determine dune and swale morphology established foredunes are classified into five morpho ecological types and the flow behaviour over two types is detailed a new model of foredune evolutionary paths at various possible time scales is presented blowout initiation dynamics and sediment transport and evolution is examined throughout the review the gaps in present understanding of dune processes and a range of ideas for new research possibilities are provided

topographic changes associated with coastal dune blowouts at island beach state park new jersey topographic changes in two blowouts located in island beach state park new jersey usa were monitored over the winter of 1981 1982 elevation changes were measured with erosion pins and sediment traps placed at comparable locations in each blowout monitored the amount of sand moved by the wind discrete wind events were identified from regional data and morphological data for the intervals with the highest onshore and offshore wind speeds are examined in detail vegetation is the primary influence on the development of the two blowouts blowout a is characterized by eroding sidewalls a stable base and an accreting blowout rim high rates of sediment transport occur through the blowout throat which results in accretion on the vegetated rim this blowout is an active sediment transfer system vegetation causes a large amount of deposition in the throat of blowout b as vegetation was buried over the winter the area of deposition migrated inland sidewall erosion also occurred in blowout b little change was recorded on the blowout rim blowout b is a recovering system where sediment is delivered to the blowout floor from the beach by onshore winds and from the blowout rim by offshore winds where it is stabilized by vegetation the development of foredune blowouts is governed largely by vegetation cover on the dune crest and by sidewall erosion during offshore and onshore winds blowout recovery depends on vegetation growth and sediment deposition in the throat and on the role of the sidewalls as sources of sediment which is deposited elsewhere within the system foredune blowouts are dynamic systems in which positive feedbacks in sediment availability and vegetation growth lead to a cycle of development and closure

flow and sediment transport dynamics in a slot and cauldron blowout and over a foredune mason bay stewart island rakiura nz abstract this study is the first to simultaneously compare flow and sediment transport through a blowout and over an adjacent foredune and the first study of flow within a highly sinuous slot and cauldron blowout flow across the foredune transect is similar to that observed in other studies and is primarily modulated by across dune vegetation density differences flow within the blowout is highly complex and exhibits pronounced accelerations and jet flow it is characterised by marked helicoidal coherent vortices in the mid regions and topographically vertically forced flow out of the cauldron portion of the blowout instantaneous sediment transport within the blowout is significant compared to transport onto and or over the adjacent foredune stoss slope and ridge with the blowout providing a conduit for suspended sediment to reach the downwind foredune upper stoss slope and crest medium term 4 months aeolian sedimentation data indicates sand is accumulating in the blowout entrance while erosion is taking place throughout the majority of the slot and deposition is occurring downwind of the cauldron on the foredune ridge the adjacent lower stoss slope of the foredune is accreting while the upper stoss slope is slightly erosional longer term 16 months pot trap data shows that the majority of foredune upper stoss slope and crest accretion occurs via suspended sediment delivery from the blowout whereas the majority of the suspended sediment arriving to the well vegetated foredune stoss slope is deposited on the mid stoss slope the results of this study indicate one mechanism of how marked alongshore foredune morphological variability evolves due to the role of blowouts in topographically accelerating flow and delivering significant aeolian sediment downwind to relatively discrete sections of the foredune

aeolian dynamics of beach scraped ridge and dyke structures abstract where urban areas are situated close to a beach sand dunes act as protection from flooding and erosion when a dune has been removed or damaged by erosion dune ridge or dyke re building using heavy machinery a process known as beach scraping is a common method of restoration following construction natural accretion of sediment on the backshore is preferable as it facilitates sustained natural dune building growth of vegetation and habitat creation and reduces the need for further beach scraping this study investigates the near surface flow and transport potential for three artificial structure designs a single ridge a double ridge and a dyke the three shapes contained an identical volume of sand and were preceded by 50 m of beach at an angle of 3 a computational fluid dynamic model cfd was created for each scenario to calculate wind flow and shear velocity from 4 different wind directions at 22 5 intervals from 0 onshore to 67 5 from this data sediment flux was predicted along a two dimensional transect for each of the scenarios for all structures shear velocity on the beach and stoss slope decreased as incident wind direction became more oblique conversely shear velocity in the lee of the crest increased a reduction in shear velocity at the foot of each structure also occurred and appears related to stoss slope with the greatest reduction at the toe of the dyke structure stoss slope 34 and the least before the single ridge stoss slope 17 specifically the results suggest that the double ridge structure is the most resilient to aeolian erosion shear velocity reduction on the back beach is comparable to the dyke and sediment flux from the stoss slope of the double ridge structure may become trapped in the swale between the two ridges encouraging sediment deposition thus reducing sediment transport beyond the dunes and backshore although the dyke structure underwent the greatest reduction in shear velocity on the back beach it experienced substantial sediment flux at the crest and along the top of the structure making it susceptible to erosion during a strong wind event the highest sediment transport rate was calculated at the crest of the single ridge and the single ridge structure also created the smallest reduction of shear velocity on the back beach thus making it less desirable than the double ridge

flow dynamics and geomorphology of a trough blowout the dynamics and geomorphological development of a trough blowout located at fiona beach in the myall lakes national park in nsw australia are examined wind speeds velocities and flow structure were measured utilizing an array of miniature rimco cup anemometers gill bivane and uvw instruments and wind vanes flow measurements indicate that when the wind approaches the trough blowout parallel to the throat orientation jets occur both in the deflation basin and along the erosional walls relative flow deceleration and expansion occurs up the depositional lobe jets are formed over the depositional lobe crest accompanied by downwind flow separation on the leeward side of the lobe and flow separation and the formation of corkscrew vortices occur over the crests of the erosional walls maximum erosion and transport occurs up the deflation basin and onto the depositional lobe trough blowout morphologies are explained as a function of these flow patterns when the wind approaches the blowout obliquely the flow is steered considerably within the blowout and the degree and complexity of topographic steering is dependent on the blowout topography the flow is usually extremely turbulent and large corkscrew vortices are common the local topography of a blowout can be very important in determining overall sand transport and blowout evolutionary conditions and paths estimates of potential sand transport within the blowout may be up to two orders of magnitude lower than actual rates if remotely sensed wind data are used

aeolian processes across transverse dunes ii modelling the sediment transport and profile development this paper discusses a model which simulates dune development resulting from aeolian saltation transport the model was developed for application to coastal foredunes but is also applicable to sandy deserts with transverse dunes sediment transport is calculated using published deterministic and empirical relationships describing the influence of meteorological conditions topography sediment characteristics and vegetation a so called adaptation length is incorporated to calculate the development of transport equilibrium along the profile changes in topography are derived from the predicted transport using the continuity equation vegetation height is incorporated in the model as a dynamic variable vegetation can be buried during transport events which results in important changes in the sediment transport rates the sediment transport model is dynamically linked to a second order closure air flow model which predicts friction velocities over the profile influenced by topography and surface roughness modelling results are shown for a the growth and migration of bare initially sine shaped dunes and b dune building on a partly vegetated and initially flat surface results show that the bare symmetrical dunes change into asymmetric shapes with a slipface on the lee side this result could only be achieved in combination with the secondorder closure model for the calculation of air flow the simulations with the partly vegetated surfaces reveal that the resulting dune morphology strongly depends on the value of the adaptation length parameter and on the vegetation height the latter result implies that the dynamical interaction between aeolian activity and vegetation reaction to burial growth rates is highly relevant in dune geomorphology and deserves much attention in future studies copyright 1999 john wiley sons ltd

the boundary layer of tropical cyclone kerry 1979 abstract the boundary layer structure of tropical cyclone kerry 1979 is investigated using composite analysis of research aircraft surface ship and automatic weather station observations the boundary layer was moist convective and strongly confluent to the east of the tropical cyclone center but was dry subsident and diffluent to the west the vertical momentum transport in the eastern convective sector of kerry was around two to three times the surface frictional dissipation in contrast the stable boundary layer in the western sector consisted of a shallow mixed layer capped by an equivalent potential temperature minimum and a low level jet which underwent a marked diurnal oscillation three mechanisms appear to have contributed to the observed asymmetry 1 a general zonal distortion arose from cyclonic rotation across a gradient of earth vorticity 2 a westerly environmental vertical shear produced forced ascent on the east side of the storm and subsidence on the west side throughout the

estimate of ocean mixed layer deepening after a typhoon passage over the south china sea by using satellite data abstractthe ocean responses to typhoon cimaron which influenced the south china sea scs from 1 to 8 november 2006 are analyzed based on satellite observed sea surface temperature sst and climatological temperature profiles in the scs mixed layer deepening an important parameter characterizing turbulent mixing and upwelling driven by strong typhoon winds is derived corresponding to the sst drop of 4 4 c on 3 november 2006 the mixed layer deepened by 104 5 m relative to the undisturbed depth of 43 2 m which is consistent with a simulation result from a mixed layer model furthermore baroclinic geostrophic velocity and vorticity are calculated from the surface temperature gradient caused by the typhoon the negative vorticity associated with the typhoon cooling indicated an anticyclonic baroclinic circulation strongest at the base of the mixed layer and at the depth of 50 m the geostrophic speed reached as high as 0 2 m s 1 typhoon cimaron proceeded slowly 1 7 m s 1 when it was making a s

comment on importance of pre existing oceanic conditions to upper ocean response induced by super typhoon hai tang by z w zheng c r ho and n j kuo 1 understanding the impact of pre existing oceanic conditions on the upper ocean response to tropical cyclones tcs is one of the important issues for understanding the short term occurrence of tc ocean interaction and its impact on tc intensity zheng et al 2008 showed that preexisting cyclonic flow represented by negative sea surface height anomalies ssha played a crucial role in enhancing sea surface cooling ssc caused by typhoon hai tang in 2005 on the other hand the impact of initial oceanic mixedlayer depth and the vertical sea temperature gradient in the thermocline on the amplitude of ssc has been considered to be small compared with that of the ekman pumping and entrainment vertical turbulent mixing e g wada 2002 therefore we hardly accept the discussion of zheng et al 2008 that the impact of ekman pumping on ssc is less significant for local ssc occurred in certain areas than that of pre existing oceanic condition 2 zheng et al 2008 provide no quantitative evidence that ssc caused by the passage of hai tang is irrelevant to the ekman pumping or that the amplitude of ssc caused by the ekman pumping is negligibly smaller than that due to relatively low sea surface height ssh in this paper we revisit the relationship between ssc and ssh using a daily oceanic reanalysis dataset wada and usui 2007 produced by the north pacific version of the japan meteorological agency meteorological research institute multivariate ocean variational estimation system move usui et al 2006 in section 2 in section 3 we revisit the impact of the pre existing oceanic condition on the ocean response to haitang using the argo profiling float data section 4 presents our concluding remarks

erosion processes in a dune landscape along the dutch coast abstract the landscape of the dunes along the dutch coast is the result of the interaction of biological and geomorphological processes where the latter prevail new landforms are created blowouts by wind erosion and rills and accumulation footslopes by overland flow spatial extent and rate of the erosion processes have been assessed by mapping and by measuring it appears that dune sand is either sensitive to erosion by wind or erosion by water depending on the presence of organic material clean yellow sand is cohesionless and easily blown away but has no surface runoff grey sand containing organic matter on the other hand will resist wind erosion but it is waterrepellent and will be washed from slopes when rain follows a period of dry weather once the grey surface sand is removed from the surfaces by water erosion wind erosion begins in the underlying yellow sand present day geomorphological processes reshape the slopes of the original parabolic dunes wind is particularly active in summit areas where new blowouts are formed whereasoverland flow creates concave south exposed slopes the stepped surface of the north exposed slopes is due to mass movements following rabbit activity

secondary airflow and sediment transport in the lee of a reversing dune lee side windspeed and sediment transport were measured over a small 1 2 m transverse ridge in the silver peak dunefield west central nevada usa using an intensive array of 25 cup anemometers and seven total flux traps during crest transverse and transporting flow conditions u0 3crest 8 4 m s 1 windspeed near the surface of the lee slope averaged half 48 per cent that of crest speeds dimensionless speeds in the separation zone ranged from 0 2 to 0 8 that of the outer flow u12 along the boundary of the separation cell windspeed increased by 10 per cent of the crest speed before separation equilibrium of upper and lower wake regions was not observed by the documented eight dune heights suggesting that wake recovery may not occur over closely spaced dunes sediment transport measured directly on both the lee slope and interdune surfaces averaged approximately 15 per cent of crest inputs this suggests that a significant amount c 70 95 per cent of sediment transported over the crest moved as fallout for this data set flux was approximately proportional to the cube of the near surface windspeed u0 3 and in general there was an order of magnitude difference between flux measured at the crest and that measured within the separation zone transport direction in the separation zone was acutely oblique to the incident direction owing to secondary flow deflection beyond the interdune transport direction progressed from oblique to crest transverse this indicates that an appreciable amount of sediment may move laterally along the lee slope and interdune corridor under crest transverse flows regarding the grain size and sorting properties of transported sediment there was no significant difference in mean grain size over the dune although in general particles were finer and more poorly sorted in the lee copyright 1999 john wiley sons ltd

potential inertial effects in aeolian sand transport preliminary results most models to predict aeolian sand transport rates incorporate a threshold shear velocity term to specify the condition when sand flux begins this term usually takes the form derived by the equation of bagnold 1936 when shear velocity falls below the threshold value the transport equations predict an immediate cessation of sediment movement however under some conditions this is not so and transport may continue for a period this paper describes field observations of an inertia like process that be considered when wind velocity fluctuates at near threshold values this study found that although wind conditions had decreased to below threshold levels transport was still taking place therefore using standard models that incorporate a threshold term an underestimation of sediment transport would occur

jet flow over foredunes jet flows which are localized flows exhibiting a high speed maxima are relatively common in nature and in many devices they have only been occasionally observed on dunes and their dynamics are poorly known this paper examines computational fluid dynamic cfd two dimensional 2d modelling of jet flow over a foredune topography flow was simulated in 10 increments from onshore 0 to highly oblique alongshore 70 incident wind approach angles cfd modelling reveals that the formation of a jet is not dependent on a critical wind speed and an increase in incident wind velocity does not affect the magnitude of jet flow a jet is first formed at 1 0m seawards of the foredune crest on the prince edward island foredune morphology example examined here a jet is not developed when the incident wind is from an oblique approach angle greater than 50 because there is significantly less flow acceleration across a much lower slope at this incident angle the presence of a scarp does influence the structure of the crest jet in that the jet is more pronounced where a scarp is present surface roughness affects the magnitude of jet expansion and jets are better developed on bare surfaces compared to vegetated ones

airflow and aeolian sediment transport patterns within a coastal trough blowout during lateral wind conditions blowouts are depressions that occur on coastal dunes deserts and grasslands the absence of vegetation in blowouts permits high speed winds to entrain and remove sediment whereas much research has examined patterns of wind flow and sediment transport on the stoss slopes and lee of sand dunes no study has yet investigated the connections between secondary air flow structures and sediment transport in a blowout where zones of streamline compression expansion and steering are less clearly delineated in this study we investigated the variability of sediment flux and its relation to near surface wind speed and turbulence within a trough blowout during wind flow that was oblique to the axis of the blowout wind flow was measured using six three dimensional 3d ultrasonic anemometers while sediment flux by eight sand traps all operating at 25 hz results demonstrated that sediment flux rates were highly variable throughout the blowout deflation basin even over short distances 0 5 m where flow was steadiest flux was greatest consequently the highest rates of sediment transport were recorded on the erosional wall crest where flow was compressed and accelerated the strength of correlation between sediment flux and wind parameter improved with an increase in averaging interval from 10 seconds to 1 minute at an interval of 10 seconds however wind speed correlated best with flux at seven of eight traps whereas at an interval of one minute turbulent kinetic energy tke provided the best correlation with flux at six of the eight traps correlation between sediment flux and wind parameters was best in the centre of the blowout and poorest on the erosional wall crest the evidence from this paper suggests for the first time that tke may be a better predictor of sediment transport at minute scale averaging intervals particularly over landforms where wind flow is highly turbulent

effects of preexisting cyclonic eddies on upper ocean responses to category 5 typhoons in the western north pacific 1 this study examines the impacts of preexisting mesoscale cyclonic eddies pces on successive enhanced sea surface cooling in response to the passage of super typhoon hai tang in the western north pacific in 2005 using numerical simulation methods we have done two numerical experiments one with the presence of these pces resolved by the hybrid coordinate ocean model navy coupled ocean data assimilation system exphyc and another with world ocean atlas 2001 climatology as initial conditions expwoa the results show that the cooling response simulated by expwoa is only half of that simulated by exphyc which is close to satellite observations this suggests that an accurate representation of the upper dynamic conditions is required to estimate the sea surface cooling to a typhoon accurately subsequently the effects of the pces on successive cooling response to most major typhoons are evaluated by conducting a systematical analysis with a focus on category 5 typhoons occurring in the region from 2003 to 2008 satellite altimeter sea surface height anomaly data and merged tropical rainfall measuring mission microwave imager advanced microwave scanning radiometer for eos microwave sea surface temperatures sst are used to characterize pces and cooling responses to those typhoons the results identify the relationship between pces and successive enhanced sst cooling for most strong typhoons in the western north pacific

air flow over foredunes and implications for sand transport more than 4000 hourly wind profiles measured on three topographically different foredunes are analysed and discussed wind flow over the foredunes is studied by means of the relative wind speed the ratio between wind speed at a certain location and the reference wind speed at the same height relative wind speeds appear to be independent of general wind speed but dependent on wind direction for perpendicular onshore winds the flow over the foredune is accelerated due to topographic changes and decelerated due to changes in surface roughness accelerations dominate over decelerations on the seaward slope the pattern of acceleration and deceleration in relation to wind direction is more or less comparable for different foredunes but the magnitudes differ an increase in foredune height from 6 to 10m leads to an increase in speed up near the top of the seaward slope from 110 to 150 per cent during onshore wind but further increase of foredune height from 10 to 23 m appears to have little effect due to increased roughness and deflection of flow topography also influences the direction of the flow between beach and top the flow deflects in the direction of the normal during onshore winds during offshore winds the flow is deflected to the parallel near the dunefoot deflection is always in the direction of the parallel and increases with steeper topography the maximum deflection near the dunefoot was 90 over a 23 m high dune observed during offshore winds patterns of erosion and sedimentation resulting from winds from different directions can be explained by the observed accelerations and decelerations owing to speed up on the seaward front of the foredune sand transport capacity of the wind increases which results in erosion if vegetation is absent during strong onshore wind sand is lifted near the dunefoot and moves over the foredune in suspension during weaker winds vertical wind velocities do not exceed fall velocities of the sand grains and most of the sand is deposited near the dunefoot

high resolution measured and modelled three dimensional airflow over a coastal bowl blowout abstract blowouts are common landforms found within coastal dunes their dynamics are primarily driven by aeolian transport caused by surface wind stress though patterns of deflation and deposition within blowouts are poorly understood as near surface wind flow is complex three dimensional wind flows around blowouts have yet to be properly quantified especially within zones of separation re attachment and acceleration this has been largely due to inadequate measurement of airflow and a lack of suitable airflow models with this in mind we present results from a study that has quantified alongshore and oblique onshore wind flow dynamics over a bowl blowout on the belmullet peninsula ireland using ultrasonic three dimensional anemometry measuring at 50 hz and three dimensional computational fluid dynamic cfd modelling we measure and model for the first time in 3d a detailed picture of the heterogeneity of wind flow over this type of terrain during alongshore wind conditions wind speeds within the deflation basin were retarded by 50 compared to the foredune zone and flow separation restricted to a small zone in lee of the windward rim wind was directed into the deflation basin through a gap in a western erosional wall termed the blowout throat in oblique onshore wind airflow orientated with the blowout throat remained unchanged in direction and slowed by only 30 compared to wind speed on the foredune in lee of the erosional wall adjacent to the blowout throat small zones of flow separation occurred close to the erosional wall in both cases the highest variation in wind speed and direction occurred in zones of separation and attachment whilst flow increased in steadiness with height over the erosional walls the results illustrate that wind is manipulated according to localised topography within the bowl blowout itself resulting zones of potential sediment transport erosion and deposition are spatially complex and alter with wind direction the presence of a blowout throat has a significant influence on airflow patterns within a deflation basin modelled cfd and measured anemometer data demonstrated excellent comparisons for wind direction and speed allowing much greater spatial measurement resolution than physical instrumentation simulated turbulence did not correlate well with measured data highlighting the requirement for high frequency three dimensional anemometry in areas of complex flow

modeling the effect of late quaternary interglacial sea levels on wave cut shore platforms abstract a mathematical wave erosional model was used to study the effect of high sea levels during the penultimate oxygen isotopic stage 7 and last interglacials substage 5e and in the late holocene stage 1 on the present morphology of wave cut shore platforms sea level was considered to have been either the same as today or 2 25 m lower during the penultimate interglacial and 2 25 4 5 or 6 75 m higher than today during the last interglacial stage the model suggested that inherited gently sloping shore platforms in resistant rocks may be essentially protected today from erosion by high storm waves the lowest platform gradients were in runs with mesotidal 3 m range and usually with low wave periods low surf attenuation rates and weak rocks modern platform gradients increased with the difference in elevation between sea levels during successive interglacial stages shore platforms were widest in runs in which sea level was the same as today in the penultimate interglacial and 4 5 m higher than today during the last interglacial constant sea level and high last interglacial sea levels with considerable overlapping between the zones of high duration values between the mean neap high and low tidal levels in stages 7 5e and 1 were conducive to the development of wide shore platforms whereas sea levels lower than today s in stage 7 tended to produce narrower platforms in general higher sea levels during the last interglacial tended to produce higher cliff platform junctions than constant sea level unless the sea was lower than today during the penultimate interglacial stage there was a lack of supratidal ledges in macrotidal 9 m model runs with high initial gradients this suggests that gently sloping inherited shore platforms are essential for the subsequent development of supratidal nonstructural ledges in high tidal environments during periods of higher sea level intertidal ledges developed in the upper portion of the modern intertidal zone under a variety of tidal and sea level conditions these ledges can develop independently of lithological or structural influences and without any change in sea level a single high sea level may also simultaneously produce two ledges at different supratidal elevations in mesotidal environments

modelling the quaternary evolution of shore platforms and erosional continental shelves a mathematical model was used to investigate the effect of glacially induced fluctuations in sea level on the evolution of wave cut shore platforms and erosional continental shelves during the quaternary the model used two deep water wave sets which were used to calculate breaker height and depth and the force of the waves at the waterline according to the width and bottom roughness of the surf zone and the gradient of the submarine slope the model also incorporated an erosional threshold related to the strength of the rocks the number of hours each year in which the water level is at each intertidal elevation and the amount and persistence of the debris at the cliff foot most runs were made using a sea level model that consisted of 26 glacial cycles from 2 million to 0 9 million years ago and nine of approximately twice the amplitude and wavelength in the last 0 9 million years the model emphasized the dynamic association between the contemporary intertidal platform and the continental shelf both surfaces trend towards a state of static equilibrium under oscillating sea level conditions when attenuated waves are unable to continue eroding the rock if there has not been enough time to reduce the gradient of the shallower portions of the continental shelf however intertidal shore platforms can be in a temporary though possibly long lasting state of dynamic equilibrium the model suggests that most platforms are at least in part inherited from one or in many cases more interglacial stages when sea level was similar to today s copyright 2001 john wiley sons ltd

hurricane forced upwelling and chlorophyll a enhancement within cold core cyclones in the gulf of mexico 1 clear skies subsequent to hurricane ivan s passage across the gulf of mexico in september 2004 provided a unique opportunity to investigate upper ocean responses to a major hurricane oceanic cyclonic circulation was rapidly intensified by the hurricane s wind field 59 62 m s 1 maximizing upwelling and surface cooling 3 7 c in two large areas along ivan s track upward isothermal displacements of 50 65 m computed from wind stress and sea surface height changes caused rapid ventilation of thermoclines and nutriclines leading to phytoplankton blooms with peak concentrations 3 4 days later wind speed changes along ivan s track demonstrated that the cool waters 20 26 c provided immediate negative feedback to the hurricane s intensity although our study focused on a relatively small ocean area it revealed that mesoscale cyclones in addition to warm anticyclones may play an important role in producing along track hurricane intensity changes

transient modulation of kuroshio upper layer flow by directly impinging typhoon morakot in east of taiwan in 2009 this study deals with the modulation of the kuroshio upper layer flow kulf in response to the passage of typhoon morakot in 2009 using regional oceanic modeling system roms and in situ measurements from argos drifters and argo floats the analysis of the simulated current fields near the typhoon track revealed an intermittency phenomenon of the kulf which was almost shut down for at least 6 hours the process begun 2 days prior to the approach of typhoon center due to blockage of the kulf by the steadily northerly winds and lasted for more than 2 days simultaneously shifting the kuroshio main stream kms path when the morakot gradually moved closely to the kuroshio the kms shifted vertically from the surface layer to deeper layer of 50 100 m depth and the maximum current speed in the kms decreased from more than 1 3 m s 1 to less than 1 1 m s 1 when the morakot center approached about 100 km to the original position of the kuroshio the kulf spread eastward for 1 5 degrees at 24 n when the morakot center moved to the original position of the kms the kuroshio abruptly rushed with a maximum speed near 1 4 m s 1 meanwhile an offshore cool jet originating from southeastern tip of taiwan was generated and extended northward along the kuroshio in the cool jet the lowest temperature reached about 5 c lower than the ambient waters modeled current variations and the cool jet during the morakot passage were validated by in situ measurements

the effects of surface moisture on aeolian sediment transport threshold and mass flux on a beach this paper presents results from a study designed to explore the effects of beach surface moisture and fetch effects on the threshold of movement intensity of sand transport by wind and mass flux the experiment was carried out over a period of five weeks at greenwich dunes prince edward island canada in may and june 2002 moisture content was measured with a delta t moisture probe over a 50 m by 25 m grid established on the beach measurements of wind speed and direction were made with arrays of cup anemometers and a two dimensional sonic anemometer transport intensity was measured at a height of 2 4 cm above the bed using omnidirectional saltation probes which count the impact of saltating grains on a piezoelectric crystal anemometers and saltation probes were sampled at 1 hz sand transport was measured with vertical integrating sand traps over periods of 10 20 minutes results show that where there is a considerable supply of dry sand the saltation system responds very rapidly 1 2 s to fluctuations in wind speed i e to wind gusts where sand supply from the surface is limited by moisture mean transport rates are much lower and this reflects in both a reduction in the instantaneous transport rate and in a transport system that becomes increasingly intermittent threshold wind speed is significantly correlated with an increase in surface moisture content near the upwind end of the beach fetch but the relationship is not significant at the downwind end where sediment transport is initiated primarily by saltation impact from upwind mass flux increases with increasing fetch length and the relationship is described best by a power function further work is necessary to develop a theoretical function to predict the increase in transport with fetch distance as well as the critical fetch distance copyright 2007 john wiley sons ltd

prediction of erosion intermittency using large eddy simulation abstract the present cfd computational fluid dynamics study investigates the triggering of aeolian erosion which takes place on two transverse sand piles placed in tandem the urans unsteady reynolds averaged navier stokes des detached eddy simulation and les large eddy simulation approaches are evaluated on their prediction capability of the friction velocity each predicted friction velocity is evaluated against a proposed threshold condition which considers the surface slope along with the near surface flow direction to be compliant with established recirculation regions the des and les approaches are found to be capable of predicting aeolian erosion intermittency a phenomenon characterized by burst activity the urans approach by yielding a nearly steady state solution predicts erosion only on a time averaged basis des and les approaches corroborate the reshaping observed in the wind tunnel tests where the erosion is substantial on the leeward pile and insignificant on the windward one