timing and origin of recent regional ice mass loss in greenland within the last decade the greenland ice sheet gris and its surroundings have experienced record high surface temperatures mote 2007 box et al 2010 ice sheet melt extent fettweis et al 2011 and record low summer sea ice extent nghiem et al 2007 using three independent data sets we derive for the first time consistent ice mass trends and temporal variations within seven major drainage basins from gravity fields from the gravity recovery and climate experiment grace tapley et al 2004 surface ice velocities from inteferometric synthetic aperture radar insar rignot and kanagaratnam 2006 together with output of the regional atmospheric climate modelling racmo2 gr ettema et al 2009 and surface elevation changes from the ice cloud and land elevation satellite icesat sorensen et al 2011 we show that changing ice discharge d surface melting and subsequent run off m r and precipitation p all contribute in a complex and regionally variable interplay to the increasingly negative mass balance of the gris observed within the last decade interannual variability in p along the northwest and west coasts of the gris largely explains the apparent regional mass loss increase during 2002 2010 and obscures increasing m r and d since the 1990s in winter 2002 2003 and 2008 2009 accumulation anomalies in the east and southeast temporarily outweighed the losses by m r and d that prevailed during 2003 2008 and after summer 2010 overall for all basins of the gris the decadal variability of anomalies in p m r and d between 1958 and 2010 w r t 1961 1990 was significantly exceeded by the regional trends observed during the grace period 2002 2011 2012 elsevier b v

rapid circulation of warm subtropical waters in a major glacial fjord in east greenland the recent rapid increase in mass loss from the greenland ice sheet is primarily attributed to an acceleration of outlet glaciers oceanographic data obtained in summer 2008 show that subtropical waters that reside year round in the shelf ocean off greenland continuously enter a large glacial fjord in east greenland and contribute to melting at the glacier terminus the recent rapid increase in mass loss from the greenland ice sheet1 2 is primarily attributed to an acceleration of outlet glaciers3 4 5 one possible cause of this acceleration is increased melting at the ice ocean interface6 7 driven by the synchronous warming8 9 10 of subtropical waters offshore of greenland however because of the lack of observations from greenland s glacial fjords and our limited understanding of their dynamics this hypothesis is largely untested here we present oceanographic data collected in sermilik fjord east greenland by ship in summer 2008 and from moorings our data reveal the presence of subtropical waters throughout the fjord these waters are continuously replenished through a wind driven exchange with the shelf where they are present all year the temperature and renewal of these waters indicate that they currently cause enhanced submarine melting at the glacier terminus key controls on the melting rate are the volume and properties of the subtropical waters on the shelf and the patterns of along shore winds suggesting that the glaciers acceleration has been triggered by a combination of atmospheric and oceanic changes our measurements provide evidence for a rapid advective pathway for the transmission of oceanic variability to the ice sheet margins

melting glaciers stimulate large summer phytoplankton blooms in southwest greenland waters each summer large quantities of freshwater and associated dissolved and particulate material are released from the greenland ice sheet gris into local fjords where they promote local phytoplankton growth whether the influx of freshwater and associated micronutrients in glacial meltwater is able to stimulate phytoplankton growth beyond the fjords is disputed however here we show that the arrival of freshwater discharge from outlet glaciers from both southeast and southwest gris coincides with large scale blooms in the labrador sea that extend over 300 km from the coast during summer this summer bloom develops about a week after the arrival of glacial meltwater in early july and persists until the input of glacial meltwater slows in august or september accounting for 40 of annual net primary production for the area in view of the absence of a significant change in the depth of the mixed layer associated with the arrival of glacial meltwater to the labrador sea we suggest that the increase in phytoplankton biomass and productivity in summer is likely driven by a greater nutrient supply most likely iron our results highlight that the ecological impact of meltwater from the gris likely extends far beyond the boundaries of the local fjords encompassing much of the eastern labrador sea such impacts may increase if melting of the gris accelerates as predicted

irminger water variability in the west greenland current 1 we examine the historical variability of irminger water iw along 3 sections across the west greenland current over 1950 2005 significant variability in the salinity size and position of the iw core are seen over time some of the saltiest and warmest iw ever recorded have been seen since 1995 comparable to previous maximums in the 1960s during these periods the volume of iw is also larger leading to larger transports into the labrador sea for the period 1984 2005 transports at cape farewell are 3 8 0 9 sv 7 5 2 2 1013 j and 8 5 1 8 msv of salt referenced to 35 0 lsw formation is also correlated to iw transport at cape farewell with a lag of one year 0 51

coral islands defy sea level rise over the past century records from a central pacific atoll the geological stability and existence of low lying atoll nations is threatened by sea level rise and climate change funafuti atoll in the tropical pacific ocean has experienced some of the highest rates of sea level rise 5 1 0 7 mm yr totaling 0 30 0 04 m over the past 60 yr we analyzed six time slices of shoreline position over the past 118 yr at 29 islands of funafuti atoll to determine their physical response to recent sea level rise despite the magnitude of this rise no islands have been lost the majority have enlarged and there has been a 7 3 increase in net island area over the past century a d 1897 2013 there is no evidence of heightened erosion over the past half century as sea level rise accelerated reef islands in funafuti continually adjust their size shape and position in response to variations in boundary conditions including storms sediment supply as well as sea level results suggest a more optimistic prognosis for the habitability of atoll nations and demonstrate the importance of resolving recent rates and styles of island change to inform adaptation strategies

response of jakobshavn isbrae greenland to holocene climate change rapid fluctuations in the velocity of greenland ice sheet gis outlet glaciers over the past decade have made it difficult to extrapolate ice sheet change into the future this significant short term variability highlights the need for geologic records of preinstrumental gis margin fluctuations in order to better predict future gis response to climate change using 10 be surface exposure ages and radiocarbon dated lake sediments we constructed a detailed chronology of ice margin fluctuations over the past 10 k y for jakobshavn isbrae greenland9s largest outlet glacier in addition we present new estimates of corresponding local temperature changes using a continuous record of insect chironomidae remains preserved in lake sediments we find that following an early holocene advance just prior to 8 ka jakobshavn isbrae retreated rapidly at a rate of 100 m yr 1 likely in response to increasing regional and local temperatures ice remained behind its present margin for 7 k y during a warm period in the middle holocene with sustained temperatures 2 c warmer than today then the land based margin advanced at least 2 4 km between a d 1500 1640 and a d 1850 the ice margin near jakobshavn thus underwent large and rapid adjustments in response to relatively modest centennial scale holocene temperature changes which may foreshadow gis response to future warming

rapid submarine melting of the calving faces of west greenland glaciers widespread glacier acceleration has been observed in greenland in the past few years oceanographic observations taken in summer 2008 show that ocean waters melted a substantial fraction of ice along the calving fronts of three west greenland glaciers indicating that submarine melting has a profound influence on grounding line stability widespread glacier acceleration has been observed in greenland in the past few years1 2 3 4 associated with the thinning of the lower reaches of the glaciers as they terminate in the ocean5 6 7 these glaciers thin both at the surface from warm air temperatures and along their submerged faces in contact with warm ocean waters8 little is known about the rates of submarine melting9 10 11 and how they may affect glacier dynamics here we present measurements of ocean currents temperature and salinity near the calving fronts of the eqip sermia kangilerngata sermia sermeq kujatdleq and sermeq avangnardleq glaciers in central west greenland as well as ice front bathymetry and geographical positions we calculate water mass and heat budgets that reveal summer submarine melt rates ranging from 0 7 0 2 to 3 9 0 8 m d 1 these rates of submarine melting are two orders of magnitude larger than surface melt rates but comparable to rates of iceberg discharge we conclude that ocean waters melt a considerable but highly variable fraction of the calving fronts of glaciers before they disintegrate into icebergs and suggest that submarine melting must have a profound influence on grounding line stability and ice flow dynamics

the importance of large benthic foraminifera to reef island sediment budget and dynamics at raine island northern great barrier reef low lying reef islands are among the most vulnerable environments on earth to anthropogenic induced climate change and sea level rise over the next century because they are low composed of unconsolidated sediment that is able to be mobilised by waves and currents and depend on sediments supplied by reef organisms that are particularly sensitive to environmental changes e g ocean temperatures and chemistry therefore the spatial and temporal links between active carbonate production and island formation and dynamics are fundamental to predicting future island resilience yet remain poorly quantified in this paper we present results of a detailed geomorphological and sedimentological study of a reef and sand cay on the northern great barrier reef we provide an empirical investigation of the temporal linkages between sediment production and reef island development using a large collection of single grain ams 14c dates large benthic foraminifera lbf are the single most important contributor to contemporary island sand mass 47 ranging from 36 to 63 at raine island reflecting rapid rates of sediment production and delivery standing stock data reveal extremely high production rates on the reef 1 8 kg m 2 yr 1 while ams 14c dates of single lbf tests indicate rapid rates of sediment transferral across the reef we also demonstrate that age is statistically related to preservation and taphonomic grade severely abraded tests moderately abraded tests pristine tests we construct a contemporary reef and island sediment budget model for raine island that shows that lbf baculogypsina marginopora and amphistegina contribute 55 of the sediment produced on the reef annually of which a large proportion 54 contribute to the net annual accretion of the island the tight temporal coupling between lbf growth and island sediment supply combined with the sensitivity of lbf to bleaching and ocean acidification suggests that islands dominated by lbf are likely to be very sensitive to short and long term climate change projections potential outcomes of this work relate to improving the understanding of the future change dynamics of reef islands in response to climate change

geomorphic changes of a coral shingle cay measured using kite aerial photography measurements of geomorphic change in the intertidal zones of coral reefs are made using a variety of remote sensing and in situ techniques where variations in the coverage and spatial temporal precision achieved are directly related to the cost of data acquisition we present a novel low cost technique for measuring high resolution changes in reef environments based on kite aerial photography kap and photogrammetry structure from motion post processing kap images are used to measure fine scale changes in intertidal topography and sediment texture characteristics including rubble particle size of a coral shingle cay at one tree island great barrier reef in the context of storm activity validation using real time kinematic dgps demonstrates the ability to measure topographic elevation with an error of 5 53 cm rmse and a spatial resolution of 5 cm per point an accuracy resolution that is superior to airborne lidar and equivalent to terrestrial lidar but at a fraction of the equipment cost

the geology of the broken hill type pinnacles pb zn ag deposit western new south wales australia the pb zn ag pinnacles deposit lies in the proterozoic rocks of the willyama supergroup of western new south wales and consists of a series of stacked strata bound sulfide lenses hosted in a mixed suite of pelites psammopelites and inferred meta exhalites sulfur isotope data for the orebodies have delta 34 s values close to zero but show some variation between sulfide lenses meta exhalites include garnetites quartz gahnite rocks and quartz garnet rocks in immediate association with the mineralized rocks and the quartz magnetite rocks as country rocks nearby the deposit has been subject to granulite facies prograde metamorphism and kyanite grade retrograde metamorphism and is associated with four phases of folding d sub 1 4 and crosscutting retrograde shear zones d 5 the pinnacles and broken hill deposits have many features in common e g associated rock types and geochemical trends including isotopic composition and ree concentrations however there are also several important differences including lithological associations fe mn ratios inferredf sub o 2 during sulfide precipitation and size these similarities and differences have direct bearing on genetic models for the formation of broken hill type deposits the geologic setting of the pinnacles deposit is discussed in terms of temporal and or spatial facies changes the implications of these findings and observations are significant for the exploration of broken hill type deposits

channelized bottom melting and stability of floating ice shelves 1 the floating ice shelf in front of petermann glacier in northwest greenland experiences massive bottom melting that removes 80 of its ice before calving into the arctic ocean detailed surveys of the ice shelf reveal the presence of 1 2 km wide 200 400 m deep sub ice shelf channels aligned with the flow direction and spaced by 5 km we attribute their formation to the bottom melting of ice from warm ocean waters underneath drilling at the center of one of channel only 8 m above sea level confirms the presence of ice shelf melt water in the channel these deep incisions in ice shelf thickness imply a vulnerability to mechanical break up and climate warming of ice shelves that has not been considered previously

ice front variation and tidewater behavior on helheim and kangerdlugssuaq glaciers greenland we used satellite images to examine the calving behavior of helheim and kangerdlugssuaq glaciers greenland from 2001 to 2006 a period in which they retreated and sped up these data show that many large iceberg calving episodes coincided with teleseismically detected glacial earthquakes suggesting that calving related processes are the source of the seismicity for each of several events for which we have observations the ice front calved back to a large pre existing rift these rifts form where the ice has thinned to near flotation as the ice front retreats down the back side of a bathymetric high which agrees well with earlier theoretical predictions in addition to the recent retreat in a period of higher temperatures analysis of several images shows that helheim retreated in the 20th century during a warmer period and then re advanced during a subsequent cooler period this apparent sensitivity to warming suggests that higher temperatures may promote an initial retreat off a bathymetric high that is then sustained by tidewater dynamics as the ice front retreats into deeper water the cycle of frontal advance and retreat in less than a century indicates that tidewater glaciers in greenland can advance rapidly greenland s larger reservoir of inland ice and conditions that favor the formation of ice shelves likely contribute to the rapid rates of advance

warming of the polar water layer in disko bay and potential impact on jakobshavn isbrae a number of recent studies have shown enhanced retreat of tidewater glaciers over much of southern and western greenland one of the fastest retreats has occurred at jakobshavn isbrae with the rapid retreat linked to the arrival of relatively warm and saline irminger water along the west coast of greenland similar links to changes in ocean water masses on the coastal shelf of greenlandwere also seen on the east coast this study presents hydrographic data from disko bay additionally revealing that there was also a significant warming of the cold polar water entering disko bay from the mid to late 1990s onward this layer which lies at a depth of 30 200m warmedby 18 28c the heat content of the polar water layer increased by a factor of 3 6 for the post 1997 period compared to the period prior to 1990 the heat content in the west greenland irminger water layer between the same periods increased only by a factor of 2 but contained more total heat the authors suggest that the changes in the polar water layer are related to circulation changes in baffin bay

seasonal and interannual variability of the west greenland current system in the labrador sea in 1993 2008 the west greenland current system wgcs transports heat and freshwater into the labrador sea influencing the formation of labrador sea water a key component of the atlantic meridional overturning circulation notwithstanding its importance relatively little is known about the structure and transport of this current system and its seasonal and interannual variability here we use historical hydrographic data from 1992 to 2008 combined with aviso satellite altimetry to diagnose the mean properties as well as seasonal and interannual variability of the boundary current system we find that while the surface fresh cold west greenland current is amplified in summer the subsurface warm salty irminger current has maximum transport in winter when its waters are also warmer and saltier seasonal changes in the total transport are thus mostly due to changes in the baroclinic structure of the current by contrast we find a trend toward warmer saltier waters and a slowdown of the wgcs within the period studied the latter is attributed to changes in the barotropic component of the current superimposed on this trend warm and salty anomalies transit through the system in 1997 and 2003 and are associated with a rapid increase in the transport of the boundary current due to changes in the baroclinic component the boundary current changes precede similar changes in the interior with a 1 2 year lag indicating that anomalies advected into the region by the boundary current can play an important role in the modulation of convection in the labrador sea

a meta analysis of reef island response to environmental change on the great barrier reef reef islands on the great barrier reef are influenced by a range of environmental factors a meta analysis of 103 islands is presented to express variation in island size area and volume as a function of latitudinal and cross shelf gradients in regional oceanographic factors exposure to incident waves tidal range and tropical cyclone frequency and local physical factors position on the shelf area length and depth of supporting reef platform vegetative cover models performed well for unvegetated sandcays r2 0 89 vegetated sandcays r2 0 72 and low wooded islands r2 0 78 with a moderate level of variation explained when all islands were simultaneously regressed r2 0 58 future island dynamics were simulated for anticipated changes in cyclone regime wave activity and sea level for 38 islands mapped on the 1973 royal society and universities of queensland expedition to the northern great barrier reef change over the same 22 year period 1973 1995 was determined and the relative magnitude of observed and modelled changes was compared and found to be consistent through rank correlation analysis 0 84 for unvegetated sandcays 0 81 for vegetated sandcays simulations of island area or volume change from 2000 to 2100 indicated that under a 30 decrease in tropical cyclone activity unvegetated sandcays continue to accrete at a lower rate whereas all island types erode under a 38 increase in tropical cyclone activity vegetated sandcays initially accrete at higher levels of cyclone activity entering an erosive state with a 60 increase in activity low wooded islands are unresponsive to environmental changes modelled a sensitivity analysis of vegetated and unvegetated sandcays indicated that the presence of vegetation increases the tropical cyclone activity threshold at which islands begin to erode greatest sedimentary losses occur within the central band of high cyclone activity between cooktown and mackay copyright 2015 john wiley sons ltd

sensitivity of the atlantic meridional overturning circulation to the melting from northern glaciers in climate change experiments 1 a weakening of the atlantic meridional overturning circulation amoc in the next century is simulated by most state of the art coupled models but none of them accounted for land ice melting here we evaluate the impact of this melting on future climate projection using the ipsl cm4 coupled ocean atmosphere model for this purpose we use two different versions of the model one with a crude land ice melting parameterization and the other without the analysis compares results of experiments where atmospheric co2 increases by 1 yr performed with the two versions of this model the amoc is reduced by 47 when the melting of land ice is considered and represents an extreme melting scenario this reduction is of 21 without this melting it is shown that this difference in amoc impacts the northern hemisphere mostly through the sea ice cover feedback

a reconciled estimate of ice sheet mass balance we combined an ensemble of satellite altimetry interferometry and gravimetry data sets using common geographical regions time intervals and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of earth s polar ice sheets we find that there is good agreement between different satellite methods especially in greenland and west antarctica and that combining satellite data sets leads to greater certainty between 1992 and 2011 the ice sheets of greenland east antarctica west antarctica and the antarctic peninsula changed in mass by 142 49 14 43 65 26 and 20 14 gigatonnes year 1 respectively since 1992 the polar ice sheets have contributed on average 0 59 0 20 millimeter year 1 to the rate of global sea level rise

emerging impact of greenland meltwater on deepwater formation in the north atlantic ocean the greenland ice sheet has experienced increasing mass loss since the 1990s1 2 the enhanced freshwater flux due to both surface melt and outlet glacier discharge is assuming an increasingly important role in the changing freshwater budget of the subarctic atlantic3 the sustained and increasing freshwater fluxes from greenland to the surface ocean could lead to a suppression of deep winter convection in the labrador sea with potential ramifications for the strength of the atlantic meridional overturning circulation4 5 6 here we assess the impact of the increases in the freshwater fluxes reconstructed with full spatial resolution3 using a global ocean circulation model with a grid spacing fine enough to capture the small scale eddying transport processes in the subpolar north atlantic our simulations suggest that the invasion of meltwater from the west greenland shelf has initiated a gradual freshening trend at the surface of the labrador sea although the freshening is still smaller than the variability associated with the episodic great salinity anomalies the accumulation of meltwater may become large enough to progressively dampen the deep winter convection in the coming years we conclude that the freshwater anomaly has not yet had a significant impact on the atlantic meridional overturning circulation

the influence of high frequency atmospheric forcing on the circulation and deep convection of the labrador sea abstractthe influence of high frequency atmospheric forcing on the circulation of the north atlantic ocean with emphasis on the deep convection of the labrador sea was investigated by comparing simulations of a coupled ocean ice model with hourly atmospheric data to simulations in which the high frequency phenomena were filtered from the air temperature and wind fields in the absence of high frequency atmospheric forcing the strength of the atlantic meridional overturning circulation and subpolar gyres was found to decrease by 25 in the labrador sea the eddy kinetic energy decreased by 75 and the average maximum mixed layer depth decreased by between 20 and 110 depending on the climatology in particular high frequency forcing was found to have a greater impact on mixed layer deepening in moderate to warm years whereas in relatively cold years the temperatures alone were enough to facilitate deep convection additional simulations in which either the wind or temperature was filtered revealed that

subsurface iceberg melt key to greenland fjord freshwater budget liquid freshwater fluxes from the greenland ice sheet affect ocean water properties and circulation on local regional and basin wide scales with associated biosphere effects the exact impact however depends on the volume timing and location of freshwater releases which are poorly known in particular the transformation of icebergs which make up roughly 30 50 of the loss of the ice sheet mass to liquid freshwater is not well understood here we estimate the spatial and temporal distribution of the freshwater flux for the helheim sermilik glacier fjord system in southeast greenland using an iceberg melt model that resolves the subsurface iceberg melt by estimating seasonal variations in all the freshwater sources we confirm quantitatively that iceberg melt is the largest annual freshwater source in this system type we also show that 68 78 of the iceberg melt is released below a depth of 20 m and seasonally about 40 100 of that melt is likely to remain at depth in contrast with the usual model assumptions iceberg melt also peaks two months after all the other freshwater sources peak our methods provide a framework to assess individual freshwater sources in any tidewater system and our results are particularly applicable to coastal regions with a high solid ice discharge in greenland iceberg melt is the largest annual freshwater source in a south greenland fjord with release largely below 20 m depth according to iceberg model simulations furthermore iceberg melt peaks later in the year than other sources of freshwater

wind induced interannual variability of sea level slope along shelf flow and surface salinity on the northwest atlantic shelf in this study we examine the importance of regional wind forcing in modulating advective processes and hydrographic properties along the northwest atlantic shelf with a focus on the nova scotian shelf nss gulf of maine gom region long term observational data of alongshore wind stress sea level slope and along shelf flow are analyzed to quantify the relationship between wind forcing and hydrodynamic responses on interannual time scales additionally a simplified momentum balance model is used to examine the underlying mechanisms our results show significant correlation among the observed interannual variability of sea level slope along shelf flow and alongshore wind stress in the nss gom region a mechanism is suggested to elucidate the role of wind in modulating the sea level slope and along shelf flow stronger southwesterly northeastward winds tend to weaken the prevailing southwestward flow over the shelf building sea level in the upstream newfoundland shelf region whereas weaker southwesterly winds allow stronger southwestward flow to develop raising sea level in the gom region the wind induced flow variability can influence the transport of low salinity water from the gulf of st lawrence to the gom explaining interannual variations in surface salinity distributions within the region hence our results offer a viable mechanism besides the freshening of remote upstream sources to explain interannual patterns of freshening in the gom

north atlantic warming and the retreat of greenland s outlet glaciers mass loss from the greenland ice sheet quadrupled over the past two decades contributing a quarter of the observed global sea level rise increased submarine melting is thought to have triggered the retreat of greenland s outlet glaciers which is partly responsible for the ice loss however the chain of events and physical processes remain elusive recent evidence suggests that an anomalous inflow of subtropical waters driven by atmospheric changes multidecadal natural ocean variability and a long term increase in the north atlantic s upper ocean heat content since the 1950s all contributed to a warming of the subpolar north atlantic this led in conjunction with increased runoff to enhanced submarine glacier melting future climate projections raise the potential for continued increases in warming and ice mass loss with implications for sea level and climate

recent large increases in freshwater fluxes from greenland into the north atlantic 1 freshwater fw fluxes from river runoff and precipitation minus evaporation for the pan arctic seas are relatively well documented and prescribed in ocean gcms fluxes from greenland on the other hand are generally ignored altogether despite their potential impacts on ocean circulation and marine biology here we present a reconstruction of the spatially distributed fw flux from greenland for 1958 2010 we find a modest increase into the arctic ocean during this period fluxes into the irminger basin however have increased by fifty percent 6 3 0 5 km3 yr 2 in less than twenty years this greatly exceeds previous estimates for the ice sheet as a whole the rate of increase since 1992 is 16 9 1 8 km3 yr 2 the cumulative fw anomaly since 1995 is 3200 358 km3 which is about a third of the magnitude of the great salinity anomaly gsa of the 1970s if this trend continues into the future the anomaly will exceed that of the gsa by about 2025

an improved mass budget for the greenland ice sheet extensive ice thickness surveys by nasa s operation icebridge enable over a decade of ice discharge measurements at high precision for the majority of greenland s marine terminating outlet glaciers prompting a reassessment of the temporal and spatial distribution of glacier change annualmeasurements for 178 outlet glaciers reveal that despite widespread acceleration only 15 glaciers accounted for 77 of the 739 29 gt of ice lost due to acceleration since 2000 and four accounted for 50 among the top sources of loss are several glaciers that have received little scientific attention the relative contribution of ice discharge to total loss decreased from 58 before 2005 to 32 between 2009 and 2012 as such 84 of the increase in mass loss after 2009 was due to increased surface runoff these observations support recentmodel projections that surface mass balance rather than ice dynamics will dominate the ice sheet s contribution to 21st century sea level rise

study of wave runup using numerical models and low altitude aerial photogrammetry a tool for coastal management monitoring the impact of sea storms on coastal areas is fundamental to study beach evolution and the vulnerability of low lying coasts to erosion and flooding modelling wave runup on a beach is possible but it requires accurate topographic data and model tuning that can be done comparing observed and modeled runup in this study we collected aerial photos using an unmanned aerial vehicle after two different swells on the same study area we merged the point cloud obtained with photogrammetry with multibeam data in order to obtain a complete beach topography then on each set of rectified and georeferenced uav orthophotos we identified the maximum wave runup for both events recognizing the wet area left by the waves we then used our topography and numerical models to simulate the wave runup and compare the model results to observed values during the two events our results highlight the potential of the methodology presented which integrates uav platforms photogrammetry and geographic information systems to provide faster and cheaper information on beach topography and geomorphology compared with traditional techniques without losing in accuracy we use the results obtained from this technique as a topographic base for a model that calculates runup for the two swells the observed and modeled runups are consistent and open new directions for future research

the effect of arctic freshwater pathways on north atlantic convection and the atlantic meridional overturning circulation abstractthis study examines the relative roles of the arctic freshwater exported via different pathways on deep convection in the north atlantic and the atlantic meridional overturning circulation amoc deep water feeding the lower branch of the amoc is formed in several north atlantic marginal seas including the labrador sea irminger sea and the nordic seas where deep convection can potentially be inhibited by surface freshwater exported from the arctic the sensitivity of the amoc and north atlantic to two major freshwater pathways on either side of greenland is studied using numerical experiments freshwater export is rerouted in global coupled climate models by blocking and expanding the channels along the two routes the sensitivity experiments are performed in two sets of models cm2g and cm2m with different control simulation climatology for comparison freshwater via the route east of greenland is found to have a larger direct impact on labrador sea convection in response to the changes of

did the giant broken hill australia zn pb ag deposit melt abstract recent published research has proposed that some metamorphosed massive sulfide deposits including the broken hill deposit australia have partially melted here we discuss the evidence for and against this process the broken hill deposit is located in the curnamona craton within a rift in an apparent upward coarsening sequence of clastic metasediments into which paleoproterozoic mafic and felsic melts intruded the deposit was metamorphosed to granulite facies conditions 750 800 c and 5 6 kbar and was subjected to at least five periods of deformation at peak p t conditions a melt phase was produced in silicate rocks especially granitoids and psammopelites and in ore characterized by the systems cu as s ag pb s ag sb as s cu sb pb s sb as s cu sb s and fe as s however the proportion of minerals in these s bearing systems is insignificant 2 feo mno cao al 2 o 3 p 2 o 5 co 2 zns pbs fes feass feas 2 which is the most relevant system to broken hill ores p t conditions were never high enough to produce a melt phase in this system authors arguing for sulfide rock melting suggest that mn rich lithologies garnetite and quartz garnetite which are intimately associated with the pb rich ores at the broken hill deposit were produced by a reaction between mn rich sphalerite and aluminous wall rocks however to produce such rocks would require mn contents of sphalerite compositions that are unrealistically high and yet to be found in nature moreover the implication of the melt model is that wherever mn rich quartz garnetite and garnetite are found sphalerite should be located next to them this is clearly not the case the presence of polyphase sulfide inclusions within garnet in garnetite has also been considered by some in the literature to be sulfide melt inclusions with the implication that the enclosing garnet was a product of melting however we consider these sulfides to be products of hydrothermal processes during retrograde metamorphism it is impossible to form garnetite and quartz garnetite in rocks within the curnamona craton that formed at upper greenschist lower amphibolite facies conditions by partial melting p t conditions were too low we consider that the fe and mn component of garnetite and quartz garnetite are products of exhalation and inhalation at or near the sea floor and that these rocks are meta exhalites or meta inhalites some garnet rich rocks also formed by metasomatic processes throughout the protracted metamorphic history that affected the curnamona craton

greenland freshwater pathways in the sub arctic seas from model experiments with passive tracers accelerating since the early 1990s the greenland ice sheet mass loss exerts a significant impact on thermohaline processes in the sub arctic seas surplus freshwater discharge from greenland since the 1990s comparable in volume to the amount of freshwater present during the great salinity anomaly events could spread and accumulate in the sub arctic seas influencing convective processes there however hydrographic observations in the labrador sea and the nordic seas where the greenland freshening signal might be expected to propagate do not show a persistent freshening in the upper ocean during last two decades this raises the question of where the surplus greenland freshwater has propagated in order to investigate the fate pathways and propagation rate of greenland meltwater in the sub arctic seas several numerical experiments using a passive tracer to track the spreading of greenland freshwater have been conducted as a part of the forum for arctic ocean modeling and observational synthesis effort the models show that greenland freshwater propagates and accumulates in the sub arctic seas although the models disagree on the amount of tracer propagation into the convective regions results highlight the differences in simulated physical mechanisms at play in different models and underscore the continued importance of intercomparison studies it is estimated that surplus greenland freshwater flux should have caused a salinity decrease by 0 06 0 08 in the sub arctic seas in contradiction with the recently observed salinification by 0 15 0 2 in the region it is surmised that the increasing salinity of atlantic water has obscured the freshening signal

hydrologic drainage of the greenland ice sheet a simple hydrologic drainage network for the greenland ice sheet is modelled from available digital elevation models dems of bedrock and surface topography and assumptions of hydrostatic water pressure uniform hydraulic conductivity and no conduit flow within the ice sheet as such it is a first order model best suited for broad scale hydrological assessment results identify 293 distinct hydrologic basins 185 117 000 km2 together with their realized wet and unrealized dry drainage patterns intersection with 1991 2000 polar mm5 pmm5 mesoscale climate model hindcasts of meltwater runoff suggest that these basins route varying amounts of water to the ice edge ranging from 0 to 16 km3 annually and totalling 242 km3 year for the entire ice sheet regionally speaking average annual volumetric meltwater production km3 year is highest in southwest and lowest in northeast greenland with greater hydrologic activity in western regions than in eastern regions for a given latitude the extent to which meltwater truly reaches the ice margin as modelled is difficult to test however the simulated flow outlet locations show qualitative agreement with the locations of 460 observed meltwater outlets proglacial lakes streams and rivers and sediment plumes into fjords mapped continuously along the ice sheet perimeter on average about 36 of the modelled drainage network was activated i e received water over the 1991 2000 study period remaining areas barring dynamic changes to ice surface topography would presumably activate if surface melt penetrates deeper into the ice sheet interior both new datasets are freely available for scientific use at the national snow and ice data center ftp sidads colorado edu pub datasets parca nsidc 0372 hydrologic outlets ftp sidads colorado edu pub datasets parca nsidc 0371 hydrologic sub basins copyright 2009 john wiley sons ltd

submarine melting of the 1985 jakobshavn isbrae floating tongue and the triggering of the current retreat 1 photogrammetric reanalysis of 1985 aerial photos has revealed substantial submarine melting of the floating ice tongue of jakobshavn isbrae west greenland the thickness of the floating tongue determined from hydrostatic equilibrium tapers from 940 m near the grounding zone to 600 m near the terminus feature tracking on orthophotos shows speeds on the july 1985 ice tongue to be nearly constant 18 5 m d 1 indicating negligible dynamic thinning the thinning of the ice tongue is mostly due to submarine melting with average rates of 228 49 m yr 1 0 62 0 13 m d 1 between the summers of 1984 and 1985 the cause of the high melt rate is the circulation of warm seawater thermal forcing of up to 4 2 c beneath the tongue with convection driven by the substantial discharge of subglacial freshwater from the grounding zone we believe that this buoyancy driven convection is responsible for a deep channel incised into the sole of the floating tongue a dramatic thinning retreat and speedup began in 1998 and continues today the timing of the change is coincident with a 1 1 c warming of deep ocean waters entering the fjord after 1997 assuming a linear relationship between thermal forcing and submarine melt rate average melt rates should have increased by 25 57 m yr 1 sufficient to destabilize the ice tongue and initiate the ice thinning and the retreat that followed

oceanic boundary conditions for jakobshavn glacier part ii provenance and sources of variability of disko bay and ilulissat icefjord waters 1990 2011 abstractjakobshavn glacier west greenland has responded to temperature changes in ilulissat icefjord into which it terminates basin waters in this fjord exchange with neighboring disko bay waters of a particular density at least once per year this study determined the provenance of this isopycnic layer for 1990 2011 using hydrographic data from cape farewell to baffin bay the warm atlantic origin core of the west greenland current never filled deep disko bay or entered the fjord basin because of bathymetric impediments on the west greenland shelf instead equal parts of atlantic water and less saline polar water filled the fjord basin and bathed jakobshavn glacier the polar water fraction was often traceable to the east west greenland current but sometimes to the colder baffin current the huge annual temperature cycle on west greenland current isopycnals did not propagate into deep disko bay or the fjord basin because isopycnals over the west greenland shelf were depressed during the warm autumn

a 100 yr record of ocean temperature control on the stability of jakobshavn isbrae west greenland an understanding of the interaction between ice sheet dynamics and forcing mechanisms such as oceanic and atmospheric circulation is important because of the potential contribution of these processes to constraining models that seek to predict future rates of sea level change here we report new benthic foraminiferal data from disko bugt west greenland showing a close correlation between subsurface ocean temperature changes and the ice margin position of the glacier jakobshavn isbrae over the past 100 yr in particular our faunal data show that warm ocean currents entered a bay disko bugt during the retreat phases of jakobshavn isbrae from a d 1920 to 1950 and since 1998 we also show a link between west greenland ocean temperature and the atlantic multidecadal oscillation a key climate indicator in the north atlantic ocean the close coupling between the oceans and the cryosphere identified here should be assessed in future projections of sea level change

ice flow in greenland for the international polar year 2008 2009 a digital representation of ice surface velocity is essential for a variety of glaciological geologic and geophysical analyses and modeling here we present a new reference comprehensive high resolution digital mosaic of ice motion in greenland assembled from satellite radar interferometry data acquired during the international polar year 2008 to 2009 by the envisat advanced synthetic aperture radar asar the advanced land observation system alos s phase array l band sar palsar and the radarsat 1 sar that covers 99 of the ice sheet in area the best mapping performance is obtained using alos palsar data due to higher levels of temporal coherence at the l band frequency but c band frequency sar data are less affected by the ionosphere the ice motion map reveals various flow regimes ranging from patterned enhanced flow into a few large glaciers in the cold low precipitation areas of north greenland to diffuse enhanced flow into numerous narrow fast moving glaciers in the warmer high precipitation sectors of northwest and southeast greenland we find that the 100 fastest glaciers v 800m yr drain 66 of the ice sheet in area marine terminating glaciers drain 88 of greenland and basal sliding motion dominates internal deformation over more than 50 of the ice sheet this view of ice sheet motion provides significant new constraints on ice flow modeling copyright 2012 by the american geophysical union

katabatic wind driven exchange in fjords the general issue of katabatic wind driven exchange in fjords is considered using an idealized numerical model theory and observations two regimes are identified for fjords narrower than a viscous boundary layer width the exchange is limited by a balance between wind and friction in lateral boundary layers for the nonlinear viscous parameterization used here this boundary layer thickness depends on the properties of the fjord such as stratification and length as well as on the wind stress and numerical parameters such as grid spacing and an empirical constant for wider fjords typical of east greenland the balance is primarily between wind the along fjord pressure gradient and acceleration in general agreement with previous two layer nonrotating theories it is expected that o 10 of the surface layer will be flushed out of the fjord by a single wind event application of the idealized model to a typical katabatic wind event produces outflowing velocities that are in general agreement with observations in sermilik fjord the presence of a sill has only a minor influence on the exchange until the sill penetrates over most of the lower layer thickness in which cases the exchange is reduced it is concluded that the multiple katabatic wind events per winter that are experienced by the fjords along east greenland represent an important mechanism of exchange between the fjord and shelf with implications for the renewal of warm salty waters at depth and for the export of glacial freshwater in the upper layer

circulation and transport in the western boundary currents at cape farewell greenland the circulation and volume transports in the western boundary currents around cape farewell greenland are derived from full depth hydrographic and velocity measurements from august september 2005 the western boundary currents from surface to seafloor transport 40 5 8 1 sv southwards in the irminger sea and 53 8 10 8 sv northwards in the labrador sea the deep western boundary current dwbc defined as water with potential density greater than 27 80 kg m 3 transports 12 3 2 5 sv southwards in the irminger sea the deep water transport is reduced south of cape farewell where it changes flow direction from southwards to northwards the south corner at a section over the eirik ridge a bathymetric feature extending southwest of cape farewell the dwbc transports 8 7 1 7 sv westwards the reduction in transport at the south corner is associated with decreased velocities within the deepest layers and the volumetric loss of the most saline deep water types the observations suggest that the part of the shallow and deep western boundary currents diverge at the south corner downstream in the eastern labrador sea the deep water transport is increased to 19 7 3 9 sv northwards with the addition of recirculating denser deep waters the representativeness of the results from the semi synoptic survey are discussed with reference to companion current meter measurements of the dwbc

the potential of small unmanned aircraft systems and structure from motion for topographic surveys a test of emerging integrated approaches at cwm idwal north wales novel topographic survey methods that integrate both structure from motion sfm photogrammetry and small unmanned aircraft systems suas are a rapidly evolving investigative technique due to the diverse range of survey configurations available and the infancy of these new methods further research is required here the accuracy precision and potential applications of this approach are investigated a total of 543 images of the cwm idwal moraine mound complex were captured from a light b5 kg semi autonomous multi rotor unmanned aircraft system using a consumer grade 18 mp compact digital camera the imageswere used to produce a dsm digital surfacemodel of themoraines the dsmis in good agreement with 7761 total station survey points providing a total verticalrmse value of 0 517mand verticalrmse values as lowas 0 200mfor less densely vegetated areas of the dsm high precision topographic data can be acquired rapidly using this technique with the resulting dsms and orthorectified aerial imagery at sub decimetre resolutions positional errors on the total station dataset vegetation and steep terrain are identified as the causes of vertical disagreement whilst this aerial survey approach is advocated for use in a range of geomorphological settings care must be taken to ensure that adequate ground control is applied to give a high degree of accuracy

on the origins of water masses exported along both sides of greenland a lagrangian model analysis the origin of the water masses exported from the arctic to the north atlantic along both sides of greenland is investigated using an original numerical method a quantitative lagrangian analysis is applied to the monthly climatological 3 d output of a global ocean sea ice high resolution model it allows quantification of the different branches of the export to the north atlantic as well as related timescales and water mass transformations in the model the outflow through davis strait consists in equal parts of pacific and atlantic water whilst the export through fram strait consists almost fully of atlantic water contrary to observations pacific water is transferred quickly o 10 years to the north atlantic through the beaufort gyre where gradual warming and salinification occur atlantic water exiting in the surface layer along both sides of greenland remains about 10 years in the arctic basin and undergoes cooling and significant freshening below the surface water atlantic water exiting through the intermediate and deep layers in fram strait follows different pathways in the arctic with trajectories being subject to topography constraints the travel time depends strongly on the pathway from 1 to 1000 years the intermediate outflow consists mainly of water entering the arctic at fram strait while half the deep outflow is composed of water from the barents sea we find that the barents sea branch which contributes to both the outflows at fram and davis straits is almost fully transformed after a year due to heat exchanges with the very cold atmosphere in the barents sea

structure and variability of the west greenland current in summer derived from 6 repeat standard sections abstract six historical sections across the west greenland current are examined three sections have been regularly occupied since the late 1950s while the three southern ones have been taken since 1984 significant variability is observed for the freshwater core of the coastal current on the shelf with salinity varying by over 3 units between years there is also significant variability in the shape and offshore position of the main shelf break front leading to large variability in eulerian velocities significant presence of irminger water is seen during the 1960s and the 2000s being found right across the sections in recent years maximum mean transport relative to the 34 8 isohaline of 5 5 3 9 sv relative to 700 db for 1984 2005 is observed at the cape desolation section transports decrease to the north with the majority of the exchange with the interior of the labrador sea occurring between cape desolation and fylla bank inter decadal transport variability is observed at fylla bank while a decline in transports since peaks in the early 1990s is seen at cape farewell and cape desolation freshwater transport is largest at cape desolation with a mean summer transport of 60 2 20 5 msv freshwater transport increases slightly between cape farewell and cape desolation and we suggest it is related to local discharge by glaciers into juliannehaab bight as well as the melting of sea ice we also find that years of high greenland ice cap melt are consistently associated with years of high freshwater transport at cape desolation suggesting a portion of the freshwater transport of the west greenland current may be associated with melt from the greenland ice sheet finally significantly enhanced freshwater transports 33 msv at cape desolation compared to the long term mean are seen in 2008 probably a signature of the record arctic ocean ice melt and export in 2007

major and trace element chemistry of gahnite as an exploration guide to broken hill type pb zn ag mineralization in the broken hill domain new south wales australia gahnite bearing rocks are common throughout the proterozoic broken hill domain new south wales australia where they are spatially associated with broken hill type pb zn ag mineralization including the supergiant broken hill deposit in the past such rocks have been utilized as exploration guides to ores of this type but their presence has had mixed success in discovering new occurrences of sulfide mineralization major element chemistry of gahnite has previously been used to define a compositional range associated with metamorphosed massive sulfides deposits including broken hill type deposits but it fails to distinguish sulfide rich from sulfide poor occurrences major and trace element data from la icp ms and electron microprobe analyses were obtained for gahnite from twelve broken hill type deposits to determine whether or not gahnite chemistry may be used to distinguish prospective exploration targets from nonprospective occurrences major and trace element data were discriminated using a principal component analysis and in a bivariate plot of zn fe versus ni cr v to distinguish gahnite associated with the broken hill deposit from that associated with sulfide poor lode pegmatite and sillimanite gneiss bivariate plots of zn fe versus trace element contents e g ga co mn co ni v cd suggest gahnite from the broken hill deposit has a relatively restricted compositional range that overlaps with some minor broken hill type occurrences based on the ore grade wt pb zn of rocks hosting gahnite at each locality gahnite in the highest grade mineralization from minor broken hill type deposits possess compositions that plot within the field for gahnite from the broken hill deposit which suggests that major and trace element chemistry e g zn fe 2 4 vs co 10 110 ppm ga 110 400 ppm mn 500 2 250 ppm and co 25 100 ppm vs ga 125 375 ppm may be used as an exploration guide to high grade ore

on the reduced sensitivity of the atlantic overturning to greenland ice sheet melting in projections a multi model assessment large uncertainties exist concerning the impact of greenland ice sheet melting on the atlantic meridional overturning circulation amoc in the future partly due to different sensitivity of the amoc to freshwater input in the north atlantic among climate models here we analyse five projections from different coupled ocean atmosphere models with an additional 0 1 sv 1 sv 106 m3 s of freshwater released around greenland between 2050 and 2089 we find on average a further weakening of the amoc at 26 n of 1 1 0 6 sv representing a 27 14 supplementary weakening in 2080 2089 as compared to the weakening relative to 2006 2015 due to the effect of the external forcing only this weakening is lower than what has been found with the same ensemble of models in an identical experimental set up but under recent historical climate conditions this lower sensitivity in a warmer world is explained by two main factors first a tendency of decoupling is detected between the surface and the deep ocean caused by an increased thermal stratification in the north atlantic under the effect of global warming this induces a shoaling of ocean deep ventilation through convection hence ventilating only intermediate levels the second important effect concerns the so called canary current freshwater leakage a process by which additionally released freshwater in the north atlantic leaks along the canary current and escapes the convection zones towards the subtropical area this leakage is increasing in a warming climate which is a consequence of decreasing gyres asymmetry due to changes in ekman pumping we suggest that these modifications are related with the northward shift of the jet stream in a warmer world for these two reasons the amoc is less susceptible to freshwater perturbations near the deep water formation sides in the north atlantic as compared to the recent historical climate conditions finally we propose a bilinear model that accounts for the two former processes to give a conceptual explanation about the decreasing amoc sensitivity due to freshwater input within the limit of this bilinear model we find that 62 8 of the reduction in sensitivity is related with the changes in gyre asymmetry and freshwater leakage and 38 8 is due to the reduction in deep ocean ventilation associated with the increased stratification in the north atlantic

the role of sea ice and other fresh water in the arctic circulation salinity stratification is critical to the vertical circulation of the high latitude ocean we here examine the control of the vertical circulation in the northern seas and the potential for altering it by considering the budgets and storage of fresh water in the arctic ocean and in the convective regions to the south we find that the present day greenland and iceland seas and probably also the labrador sea are rather delicately poised with respect to their ability to sustain convection small variations in the fresh water supplied to the convective gyres from the arctic ocean via the east greenland current can alter or stop the convection in what may be a modern analog to the halocline catastrophes proposed for the distant past the north atlantic salinity anomaly of the 1960s and 1970s is a recent example it must have had its origin in an increased fresh water discharge from the arctic ocean similarly the freshening and cooling of the deep north atlantic in recent years is a likely manifestation of the increased transfer of fresh water from the arctic ocean into the convective gyres finally we note that because of the temperature dependence of compressibility a slight salinity stratification in the convective gyres is required to efficiently ventilate the deep ocean

characteristics of meltwater export from jakobshavn isbrae and ilulissat icefjord jakobshavn isbrae which terminates in ilulissat icefjord has undergone rapid retreat and is currently the largest contributor to ice sheet mass loss among greenland s marine terminating glaciers accelerating mass loss is increasing fresh water discharge to the ocean which can feed back on ice melt impact marine ecosystems and potentially modify regional and larger scale ocean circulation here we present hydrographic observations including inert geochemical tracers that allow the first quantitative description of the glacially modified waters exported from the jakobshavn icefjord system observations within the fjord suggest a deep reaching overturning cell driven by glacial buoyancy forcing modified waters containing submarine meltwater up to 2 5 0 12 subglacial discharge up to 6 0 37 and large portions of entrained ocean waters are seen to exit the fjord and flow north the exported meltwaters form a buoyant coastal gravity current reaching to 100 m depth and extending 10 km offshore

last interglacial mis5e hydrographic shifts linked to meltwater discharges from the east greenland margin abstract proximal evidence of the surface ocean response to size reduction of the greenland ice sheet gis during the last interglacial mis5e and preceding glacial termination t2 remains largely elusive using a new sediment record from the western iceland sea the behavior of the northeastern gis and its relation to the subpolar north atlantic surface hydrography is examined extremely light oxygen isotopic 18o values are found off central east greenland during early mis5e and point to enhanced meltwater release potentially from the northeastern sector of the gis data from downstream the cold east greenland current egc and its eastward branches suggest a far reaching effect of this meltwater not only in the nordic seas but also in the se labrador sea in particular whereas an early mis5e warming at 128 5 126 5 ka in the two regions coincided with the relative reduction of meltwater input into the egc the subsequent cooling noted at 126 5 ka followed a renewed major freshwater event off central east greenland our data further indicate persistent freshwater influence from the east greenland margin over the entire mis5e interval and in addition also reveal a late mis5e meltwater event the latter event occurred just prior to the last glacial inception and emphasizes the importance of greenland meltwater as forcing factor on interglacial climates

seasonal variability of the warm atlantic water layer in the vicinity of the greenland shelf break the warmest water reaching the east and west coast of greenland is found between 200 m and 600 m whilst important for melting greenland s outlet glaciers limited winter observations of this layer prohibit determination of its seasonality to address this temperature data from argo profiling floats a range of sources within the world ocean database and unprecedented coverage from marine mammal borne sensors have been analysed for the period 2002 2011 a significant seasonal range in temperature 1 2 c is found in the warm layer in contrast to most of the surrounding ocean the phase of the seasonal cycle exhibits considerable spatial variability with the warmest water found near the eastern and southwestern shelf break towards the end of the calendar year high resolution ocean model trajectory analysis suggest the timing of the arrival of the year s warmest water is a function of advection time from the subduction site in the irminger basin

potential positive feedback between greenland ice sheet melt and baffin bay heat content on the west greenland shelf greenland ice sheet meltwater runoff has been increasing in recent decades especially in the southwest and the northeast to determine the impact of this accelerating meltwater flux on baffin bay we examine eight numerical experiments using an ocean sea ice model nucleus for european modelling of the ocean enhanced runoff causes shoreward increasing sea surface height and strengthens the stratification in baffin bay the changes in sea surface height reduces the southward transport through the canadian arctic archipelago and strengthens the gyre circulation within baffin bay the latter leads to further freshening of surface waters as it produces a larger northward surface freshwater transport across davis strait increasing the meltwater runoff leads to a warming and shallowing of the west greenland irminger water on the northwest greenland shelf these warmer waters can now more easily enter fjords on the greenland coast and thus provide additional heat to accelerate the melting of marine terminating glaciers

heat sources for glacial melt in a sub arctic fjord godthabsfjord in contact with the greenland ice sheet 1 recent warming of subpolar mode water off greenland has been suggested to accelerate the mass loss from tidal outlet glaciers of the greenland ice sheet we present a comprehensive analysis of water masses dynamics and interannual hydrographic variability in godthabsfjord a sill fjord in contact with tidal outlet glaciers on the west coast of greenland through seasonal observations we recognize an intermediate baroclinic circulation mode driven by tidal currents and an associated important local heat source for the fjord during summer this results in significant warming and freshening of the intermediate layer of the main fjord and the increase in heat content is equivalent to melting of 2 1 km3 of glacial ice this is comparable to 8 km3 glacial ice discharge estimated from the kangiata nun ta sermia calving front per year during winter the external heat source in the west greenland current enters the fjord as intermittent inflows of either cold 2 c dense water in pulses of 1 to 3 months duration four distinct circulation modes are observed in the fjord of which all can contribute to glacial ice melt an important aspect of the ice distribution in the fjord is that only a minor fraction is exported out of the fjord

ekman and eddy exchange of freshwater and oxygen across the labrador shelf break abstracttransport of freshwater from the labrador shelf into the interior labrador sea has the potential to impact deep convection via its influence on the salinity of surface waters to examine this transport the authors deployed two underwater gliders on a mission to traverse the continental shelf break multiple times between 5 july and 22 august 2014 the period when arctic meltwater has historically peaked in transport down the labrador shelf the field campaign yielded a unique dataset of temperature salinity and oxygen across the shelf break to a depth of 1000 m at unprecedented spatial resolution two mechanisms of cross shelf transport were examined ekman transport and transport due to mesoscale eddies ekman transport is quantified using satellite wind stress and near surface hydrographic properties and eddy induced transport is scaled using a parameterized eddy diffusivity and thickness gradients of layers of uniform potential density as well as the tracer gradients along those isopycnals

uav based remote sensing of the super sauze landslide evaluation and results unmanned aerial vehicles uavs equipped with digital compact cameras can be used to map landslides quickly and at a high ground resolution images taken by a radio controlled mini quad rotor uav of the super sauze france landslide have been used to produce a high resolution ortho mosaic of the entire landslide and digital terrain models dtms of several regions the uav capability for imaging fissures and displacements on the landslide surface has been evaluated and the subsequent image processing approaches for suitably georectifying the data have been assessed for super sauze horizontal displacements of 7 to 55 m between a high resolution airborne ortho photo of may 2007 and a uav based ortho mosaic of october 2008 have been measured fixed areas of persistent deformation have been identified producing fissures of different distributions and orientations comparable to glacial crevasses and relating directly to the bedrock topography the uav has demonstrated its capability for producing valuable landslide data but improvements are required to reduce data processing time for the efficient generation of ortho mosaics based on photogrammetric dtms in order to minimise georeferencing errors

the potential of 3d gully monitoring with gis using high resolution aerial photography and a digital photogrammetry system although gully erosion is generally considered a major process of land degradation its contribution to total soil loss by erosion has recently been a subject of much discussion the lack of adequate methods for the documentation and monitoring of gullies resulted in the shortage of quantitative data therefore a high resolution remote sensing system for aerial surveys by blimp or kite has been developed which meets spatial and temporal image resolutions required for short term gully monitoring the objective of this paper is to examine the potential of a method using non metric digital photogrammetry and gis for gully surface modelling and monitoring two bank gullies representing different morphological types of gullies v shaped and u shaped were chosen from a dataset of gully systems in semi arid spain the considerable relief energy and complex topography of the gullies in a natural vegetated landscape were found to be a challenge to digital photogrammetric techniques introducing errors which inhibit fully automated dem generation using a hybrid method combining stereomatching for mass point extraction with manual 3d editing and digitizing high resolution dems 5 and 7 5 cm pixel size were created for the study sites gis analysis of the dems for different monitoring periods 2 to 4 years allowed the computation of gully area and volume as well as their changes with an accuracy and detail sufficient to represent the geomorphological forms and processes involved furthermore the spatially continuous survey of the entire form offered the possibility of distinguishing different zones of activity both at the gully rim and within the gully interior identifying patterns of erosion and deposition which indicate the limited use of headcut retreat rates for the assessment of sediment production on a short term basis

volume and freshwater transports through the canadian arctic archipelago baffin bay system 1 baffin bay connects the arctic ocean and the labrador sea it receives polar water through the canadian arctic archipelago and by the west greenland current the polar water is after transformation exported through davis strait with control sections both upstream and downstream baffin bay invites the use of an idealized geostrophic approach to estimate transports the baroclinic transports driven by the density differences between the arctic ocean and baffin bay are first determined the density and upper layer depth are assumed the same in lancaster sound nares strait and the west greenland current once the baroclinic transports are estimated the sea level difference between the arctic ocean and baffin bay is computed next the upper layer depth in nares strait and the west greenland current is reduced while the sea level difference is kept constant this allows for deep inflows through nares strait and the west greenland current to establish a deep outflow through davis strait a barotropic sea level slope between the arctic ocean and the labrador sea is estimated from two ideal water columns the transports are computed for different salinities in the polar water and the salinity giving mass balance in the deeper layers is determined the effects of possible increased melting of the greenland icecap are examined if the meltwater is added directly to baffin bay the effects are small but if it is incorporated in the east and west greenland current a significant reduction of the outflow through the archipelago might occur

acceleration of jakobshavn isbrae triggered by warm subsurface ocean waters observations over past decades show a sudden switch of jakobshavn isbrae a large outlet glacier feeding a deep ocean fjord on greenland s west coast from slow thickening to rapid thinning in 1997 this switch is associated with a doubling in glacier velocity hydrographic data show a concurrent sudden increase in subsurface ocean temperatures along the entire west coast of greenland suggesting that the changes in jakobshavn isbrae were triggered by the arrival of relatively warm water originating from the irminger sea observations over the past decades show a rapid acceleration of several outlet glaciers in greenland and antarctica1 one of the largest changes is a sudden switch of jakobshavn isbrae a large outlet glacier feeding a deep ocean fjord on greenland s west coast from slow thickening to rapid thinning2 in 1997 associated with a doubling in glacier velocity3 suggested explanations for the speed up of jakobshavn isbrae include increased lubrication of the ice bedrock interface as more meltwater has drained to the glacier bed during recent warmer summers4 and weakening and break up of the floating ice tongue that buttressed the glacier5 here we present hydrographic data that show a sudden increase in subsurface ocean temperature in 1997 along the entire west coast of greenland suggesting that the changes in jakobshavn isbrae were instead triggered by the arrival of relatively warm water originating from the irminger sea near iceland we trace these oceanic changes back to changes in the atmospheric circulation in the north atlantic region we conclude that the prediction of future rapid dynamic responses of other outlet glaciers to climate change will require an improved understanding of the effect of changes in regional ocean and atmosphere circulation on the delivery of warm subsurface waters to the periphery of the ice sheets

wind forcing of volume transport through lancaster sound 1 volume and freshwater transport through lancaster sound are estimated from mooring measurements collected in eastern barrow strait for 13 years between 1998 and 2011 estimates from 2006 to 2011 confirm the relationship between surface wind and volume transport derived from data collected between 1998 and 2006 volume transport through barrow strait along the northwest passage is significantly correlated with northeastward winds in the beaufort sea parallel to the western coasts of the canadian arctic archipelago at monthly to interannual time scales the location and wind direction for which there is maximum correlation are consistent with the flow being driven by a sea level difference between opposite ends of the passage and the difference being determined by setup caused by alongshore winds in the beaufort sea monthly alongshore wind anomalies account for 43 of the variance of the transport anomalies p 0 05 the annual cycles of the total volume transport and its part attributed to the beaufort sea wind both have peaks in the summer and are lowest in the autumn correlations of the volume transport anomaly with ice velocity anomalies are lower than with surface wind anomalies

oceanic transport of surface meltwater from the southern greenland ice sheet meltwater runoff from the greenland ice sheet alters ocean surface salinity numerical simulations show that meltwater from southeastern greenland is transported to the labrador sea more efficiently than that from southwestern greenland

evaluation and control mechanisms of volume and freshwater export through the canadian arctic archipelago in a high resolution pan arctic ice ocean model 1 this study examined the 1979 2004 volume and freshwater fluxes through the canadian arctic archipelago caa and into the labrador sea using a high resolution 9 km coupled ice ocean model of the pan arctic region to provide a reference compare with limited observational estimates and investigate control mechanisms of this exchange the 26 year mean volume and freshwater fluxes through nares strait were 0 77 sv 0 17 sv and 10 38 msv 1 67 msv respectively while those through lancaster sound amounted to 0 76 sv 0 12 sv and 48 45 msv 7 83 msv respectively the 26 year mean volume and freshwater fluxes through davis strait were 1 55 sv 0 29 sv and 62 66 msv 11 67 msv while the modeled fram strait branch provided very little 2 freshwater into the labrador sea compared to the total caa input compared to available observations the model provides reasonable volume and freshwater fluxes as well as sea ice thickness and concentration in the caa in nares strait and lancaster sound volume flux anomalies were controlled by the sea surface height ssh gradient anomalies along the straits and freshwater anomalies were highly correlated with the volume anomalies at least half of the variance in the time series of ssh gradient anomaly was due to ssh anomalies in northern baffin bay the west greenland current wgc exhibits seasonality with cross shelf flow into the labrador sea peaking in january february march while reducing the northward flow across eastern davis strait we hypothesize that the eddy reduced northward flow of wgc results in the lower volume and ssh in baffin bay this maximizes the ssh gradients between the arctic ocean and baffin bay leading to maximum winter volume fluxes through nares strait and lancaster sound model limitations include the insufficient spatial resolution of atmospheric forcing especially to account for the effects of local topography the representation of river runoff into hudson bay and coastal buoyancy currents low mobility of modeled ice and incomplete depiction of ice arching many of these issues are expected to be resolved with increased model grid cell resolution improved sea ice and ocean models and more realistic atmospheric forcing

composition and fluxes of freshwater through davis strait using multiple chemical tracers 1 freshwater transport through davis strait can supply additional buoyancy to the deep convection region of the labrador sea which influences the strength of the meridional overturning circulation and consequently the global climate the freshwater contribution from local sea ice meltwater meteoric water fluvial glaciofluvial and precipitation and the arctic outflow were quantified using oxygen isotope composition 18o salinity and nutrient relationships in september october 2004 freshwater transported by the arctic outflow was isolated using a modified nutrient relationship method and further deconvoluted into sea ice meltwater meteoric water and pacific water for the first time fluxes of individual freshwater components were estimated using observations of the velocity field derived from mooring arrays and geostrophic currents from hydrography the arctic outflow dominated in western davis strait 60 and its influence extended eastward close to the greenland slope the sea ice meltwater fraction was small 6 and attributed to glacial meltwater the freshwater inventory of the 0 100 m layer was equivalent to 7 4 m in western davis strait 8 m from the arctic outflow and 0 6 m from brine rejection in eastern davis strait the freshwater inventory was 4 m 3 m from meteoric water and 1 m from sea ice meltwater the arctic outflow contributed 82 99 msv to the southward freshwater transport about 67 81 of the total glacial meltwater contributed the largest northward transport of 10 30 msv

radiocarbon evidence for the timing and rate of island development beach rock formation and phosphatization at lady elliot island queensland australia abstract lady elliot island great barrier reef is a coral cay constructed from near concentric shingle ridges composed of coral tridacna shells and bioclastic sand bound by guano derived phosphatic cement radiocarbon dating of individual tridacna samples is used to investigate the evolution of the island and place constraints on the variations in storminess of the last 3200 years a shallow platform reef existed at lady elliot since at least 6500 yrs b p shortly before 3200 yrs b p island growth by shingle progradation commenced and proceeded to the present at a rather uniform lateral rate 60 m ka 1 to leeward and 90 m ka 1 windward phosphatization may have occurred continuously or episodically at any time throughout the last 3200 years the youngest cemented ridge top is less than 770 years whereas at the base of uncemented ridges phosphatization is a modern 1950 a d process similarly low level beach rock has continued to form within the last 25 years a significant period of instability occurred less than 500 years ago during which marine erosion truncated the southwestern extremity of lady elliot island formed an eastern spit and stranded high level beach rock however the radiocarbon ages of tridacna samples from shingle ridges from lady elliot and curacoa islands are uniformly distributed kolmogorov smirnov test throughout the last 4000 years we interpret this to indicate no significant variation in ridge forming processes or fluctuation in average storminess during this interval

antarctic ice sheet loss driven by basal melting of ice shelves accurate prediction of global sea level rise requires that we understand the cause of recent widespread and intensifying glacier acceleration along antarctic ice sheet coastal margins atmospheric and oceanic forcing have the potential to reduce the thickness and extent of floating ice shelves potentially limiting their ability to buttress the flow of grounded tributary glaciers indeed recent ice shelf collapse led to retreat and acceleration of several glaciers on the antarctic peninsula but the extent and magnitude of ice shelf thickness change the underlying causes of such change and its link to glacier flow rate are so poorly understood that its future impact on the ice sheets cannot yet be predicted here we use satellite laser altimetry and modelling of the surface firn layer to reveal the circum antarctic pattern of ice shelf thinning through increased basal melt we deduce that this increased melt is the primary control of antarctic ice sheet loss through a reduction in buttressing of the adjacent ice sheet leading to accelerated glacier flow the highest thinning rates occur where warm water at depth can access thick ice shelves via submarine troughs crossing the continental shelf wind forcing could explain the dominant patterns of both basal melting and the surface melting and collapse of antarctic ice shelves through ocean upwelling in the amundsen and bellingshausen seas and atmospheric warming on the antarctic peninsula this implies that climate forcing through changing winds influences antarctic ice sheet mass balance and hence global sea level on annual to decadal timescales

linking pattern to process in reef sediment dynamics at lady musgrave island southern great barrier reef linking surficial sediment patterns in reef environments to the processes that underlie their depositional dynamics enables predictions to be made of how environmental changes will influence reef associated sedimentary landforms such as islands and beaches geomorphic linkages between sediment deposition patterns and the biophysical processes that drive them are often poorly resolved particularly at broad landscape scales where tangible statements can be made about structural changes to landforms the present study applies geospatial techniques to link patterns in reef sediment dynamics at lady musgrave island to the underlying processes driving them in situ calcification is characterized by developing a high resolution map of the surficial calcium carbonate producing communities inhabiting the reef platform and associated sediments across the reef flat are analysed for grain size kurtosis sorting and threshold bed shear stress to explore transport pathways across the reef flat and lagoon wave energy is modelled across the entire reef platform as a potential driver of sediment dynamics and morphometric linkages are empirically defined between wave energy and grain size findings indicate that carbonate sediments are primarily sourced from calcifying communities colonizing the outer periphery of the reef platform and that sediment grain size can be reliably linked to wave energy by virtue of a linear model

kinematics of the pacific equatorial undercurrent an eulerian and lagrangian approach from gcm results abstract three dimensional monthly velocity fields from an ocean general circulation model are used to study the annual mean mass balance of the pacific equatorial undercurrent euc eulerian diagnostics are used to evaluate the various meridional vertical and zonal mass fluxes related to the euc there are several distinct regimes along the equator showing clear asymmetries between the western and eastern parts of the basin and between the northern and southern edges of the euc meridional fluxes are decomposed into pure ekman divergence and geostrophic convergence and it is shown that the asymmetries are mainly related to the spatial structure of the ekman divergence and thus to that of the trade winds lagrangian calculations are used to evaluate accurately the mass transfers between various sections of the euc and between the euc domain and the tropics the authors show that geostrophic convergence only ventilates the upper layers of the euc and that the euc really is a tongue of water flowing

retroflection of part of the east greenland current at cape farewell the east greenland current egc and the smaller east greenland coastal current egcc provide the major conduit for cold fresh polar water to enter the lower latitudes of the north atlantic they flow equatorward through the western irminger basin and around cape farewell into the labrador sea the surface circulation and transport of the cape farewell boundary current region in summer 2005 is described the egcc merges with arctic waters of the egc to the south of cape farewell forming the west greenland current the egc transport decreases from 15 5 sv south of cape farewell to 11 7 sv in the eastern labrador sea where the water becomes known as irminger sea water the decrease in egc transport is balanced by the retroflection of a substantial proportion of the boundary current 5 1 sv into the central irminger basin a new pathway for fresh water into the interior of the subpolar gyre

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

warming and freshening of baffin bay 1916 2003 1 regression analysis of historical hydrographic data is used to determine changes in temperature and salinity in baffin bay for the time period from 1916 to 2003 we find two distinct sets of changes in the baffin first areas affected by the atlantic inflow to baffin bay show substantial and statistically significant warming trends in the more than 2000 m deep basin the warming peaks at 0 11 0 06 c decade at 700 m depth below the 640 m sill depth of davis strait connecting baffin bay to the north atlantic ocean a vertical heat flux divergence of 0 25 w m2 is required to warm baffin bay below 900 m by the amount observed the required heat appears to be advected from the shelf and slope regions of the eastern labrador sea via davis strait along the west greenland shelf break and diffuses vertically and horizontally into the deep central basin the north atlantic oscillation index accounts for about 30 of the interannual variance of temperature fluctuations below the davis strait sill depth second areas affected by arctic inflow to baffin bay show a marginally significant freshening of up to about 0 086 0 039 psu decade this freshening trend extends along the western margin of baffin island to davis strait and into the labrador sea the freshening in the northern reaches of baffin bay is similar in size to that at its southern reaches temporal variability of annual composites between these locations appears to be in phase suggesting a swift transition of arctic waters at 76 n to labrador sea waters at 62 n

origin formation and variability of the subpolar mode water located over the reykjanes ridge the origin and formation of the subpolar mode water spmw located over the reykjanes ridge in the north atlantic ocean and the variability of its properties over the period 1966 2004 are investigated through the use of a global eddy permitting 1 4 degrees ocean sea ice model and a lagrangian analysis tool the spmw is fed by subtropical and subpolar waters advected by the branches of the north atlantic current the spmw acquires its properties when its source waters enter the winter mixed layer in the iceland basin the spmw temperature variability is mainly explained by variations of the relative contributions of the subtropical and subpolar water transports to the total transport compared to the 1966 2004 mean lower higher subtropical water relative transport contribution leads to colder warmer spmw in the early 1990s in the late 1960s and late 1990s the intensity of the winter convection in the iceland basin also influences the spmw temperature through the amount of relatively cold intermediate waters of subtropical origin integrated in the spmw layer strong convection partly explains the cold spmw of the early 1990s the large increase in the spmw temperature in the late 1990s is due to both a decrease in the winter convection and an increase in the relative transport of the subtropical waters

externally forced fluctuations in ocean temperature at greenland glaciers in non summer months the factors that control the submarine melt rate at greenland s glaciers are uncertain and largely inferred from brief summer surveys in the fjords where glaciers terminate continuous records of water properties and velocity for the months september to may from two large greenland fjords reveal strong variability on 3 to 10 day timescales as a result of pulses of water that are propagated from the shelf ocean

meltwater pathways from marine terminating glaciers of the greenland ice sheet the greenland ice sheet gris stores the largest amount of freshwater in the northern hemisphere and has been recently losing mass at an increasing rate an eddy permitting ocean general circulation model is forced with realistic estimates of freshwater flux from the gris two approaches are used to track the meltwater and its trajectory in the ocean we show that freshwater from western and eastern gris have markedly different fates on a decadal timescale freshwater from west greenland predominantly accumulates in baffin bay before being exported south down the labrador shelf meanwhile gris freshwater entering the interior of the labrador sea where deep convection occurs comes predominantly 80 from east greenland therefore hosing experiments which generally assume a uniform freshwater flux spatially will not capture the true hydrographic response and regional impacts in addition narrow boundary currents are important for freshwater transport and distribution requiring simulations with eddy resolving resolution

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

the circulation water masses and sea ice of baffin bay abstract the oceanographic meteorological and sea ice conditions in baffin bay are studied using historical hydrographic satellite and meteorological data and a set of current meter data from a mooring program of the bedford institute of oceanography baffin bay is partially covered by sea ice all year except august and september the interannual variation of the ice extent is shown to be correlated with winter air temperature available hydrographic data were used to study the water masses and the horizontal and vertical distribution of temperature salinity three water masses can be identified arctic water in the upper 100 300 m of all regions except the southeast west greenland intermediate water at 300 800 m in most of the interior of baffin bay and deep baffin bay water in all regions below 1200 m the temperature and salinity in baffin bay have limited seasonal variability except in the upper 300 m of eastern davis strait northern baffin bay and the mouth of lancaster sound summer data have a temperature minimum at 100 m which suggests winter convection does not penetrate deeper than this depth current meter data and results of a circulation model indicate that the mean circulation is cyclonic the seasonal variation of the currents is complex overall summer and fall tend to have stronger currents than winter and spring at all depths among the different regions the largest seasonal variation occurs at the mouth of lancaster sound and the baffin island slope model generated velocity fields show a basic agreement with the observed currents and indicate strong topographic control in the vicinity of davis strait and on the greenland shelves the model also produces a southward counter current on the greenland slope which may explain the observed high horizontal shears over the greenland slope estimates of the volume and fresh water transports through lancaster jones and smith sounds are reviewed transports through davis strait are computed from the current meter data the balance of freshwater budget and sensitivity of the thermohaline circulation to freshwater transport are discussed

long term variability of supratidal coastal boulder activation in brittany france abstract high energy supratidal coastal boulder deposit scbd dynamics were investigated on vierge island and pors carn point north and south of western brittany france respectively morphological changes induced by boulder transport and quarrying were quantified using high resolution topographic survey data taken between 2012 and 2017 additional in situ wave parameters and water levels were also recorded over this period 2014 2017 in order to compute the maximum water levels and assess the relationship between scbd morphological changes and specific hydrodynamic conditions during extreme water levels for maximum water levels exceeding a one in ten year event scbds were broadly reworked up to 40 of the total volume during lower intensity events for which maximum water levels were still very high morphological changes represented 1 to 5 of the total volume these morphological and hydrodynamic observations were then used to calibrate a chronology of scbd activation events based on 70 years of hindcast winter maximum water levels these long term time series showed great interannual variability in scbd activation but no significant long term trend winter frequency scbd activation was better correlated to the wepa index r 0 46 than the nao index r 0 1 therefore the wepa index can be considered to be a more significant climate proxy for assessing storm related geomorphic changes in the temperate latitudes of the n e atlantic basin 36 52 n including the brittany coast the potential of scbds as a morphological storm proxy for macrotidal high energy rocky coasts is addressed