bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of coastal vulnerability to flooding: comparison of two different methodologies adopted by the Emilia-Romagna region (Italy)
Authors: Perini L. , Calabrese L. , Salerno G. , Ciavola P. , Armaroli C.
Published: January 2016

Abstract. This paper aims at presenting and comparing two methodologies adopted by the Emilia-Romagna region, northern Italy, to evaluate coastal vulnerability and to produce hazard and risk maps for coastal floods, in the framework of the EU Floods Directive. The first approach was adopted before the directive had been issued. Three scenarios of damage were designed (1-, 10-, 100-year return periods), produced by the concurrent occurrence of a storm, high surge levels and high-water spring tidal levels. Wave heights were used to calculate run-up values along 187 equally spaced profiles, and these were added to the tidal and atmospheric water level contributions. The result is a list of 10 vulnerability typologies. To satisfy the requirements of the directive, the Geological, Seismic and Soil Service (SGSS) recently implemented a different methodology that considers three scenarios (10-, 100- and  >  100-year return periods) in terms of wave setup (not including run-up) plus the contribution of surge levels as well as the occurrence of high-water springs. The flooded area extension is determined by a series of computations that are part of a model built into ArcGIS®. The model uses as input a high-resolution lidar DEM that is then processed using a least-path cost analysis. Inundation maps are then overlapped with land use maps to produce risk maps. The qualitative validation and the comparison between the two methods are also presented, showing a positive agreement.
Estimation of insurance-related losses resulting from coastal flooding in France
Authors: Naulin J. P. , Moncoulon D. , Le Roy S. , Pedreros R. , Idier D. , Oliveros C.
Published: January 2016

Abstract. A model has been developed in order to estimate insurance-related losses caused by coastal flooding in France. The deterministic part of the model aims at identifying the potentially flood-impacted sectors and the subsequent insured losses a few days after the occurrence of a storm surge event on any part of the French coast. This deterministic component is a combination of three models: a hazard model, a vulnerability model, and a damage model. The first model uses the PREVIMER system to estimate the water level resulting from the simultaneous occurrence of a high tide and a surge caused by a meteorological event along the coast. A storage-cell flood model propagates these water levels over the land and thus determines the probable inundated areas. The vulnerability model, for its part, is derived from the insurance schedules and claims database, combining information such as risk type, class of business, and insured values. The outcome of the vulnerability and hazard models are then combined with the damage model to estimate the event damage and potential insured losses. This system shows satisfactory results in the estimation of the magnitude of the known losses related to the flood caused by the Xynthia storm. However, it also appears very sensitive to the water height estimated during the flood period, conditioned by the junction between seawater levels and coastal topography, the accuracy for which is still limited by the amount of information in the system.
PM10 measurements in urban settlements after lava fountain episodes at Mt. Etna, Italy: pilot test to assess volcanic ash hazard to human health
Authors: Andronico D. , Del Carlo P.
Published: January 2016

Abstract. We have carried out a preliminary study on the potential risks caused by the sub-10 µm fraction of volcanic ash (particulate matter, PM10) after the basaltic explosive eruptions from Mt. Etna volcano (Italy), which have dramatically increased in frequency over the last 20 years. We present results deriving from the study of the ash concentration in the air following the lava fountain episode from the New Southeast Crater of Etna on 15 November 2011, which caused tephra fallout over the eastern slope of the volcano. Short-duration tests of PM10 measurements were carried out at three different sites using a TSI® DustTrakTM aerosol monitor a few hours after the end of the eruption, and readouts of the air quality were repeated at the same sites a month later without volcanic activity. Furthermore, ash samples were characterized by grain size, componentry and morphological and petrochemical analyses. By comparing PM10 levels measured a few hours after the 15 November lava fountain and on 15 December, we found that relatively low amounts (500–1500 g m−2) of tephra fallout cause high levels of PM10 in the air. This is because the coarse particles, particularly basaltic ash, are readily broken up by traffic and hence remobilized into the air. We believe the impact from ash fallout in the Etnean territory should receive greater attention, especially regarding potential health problems. Simple but effective actions can be implemented to reduce eventual risks, first and foremost the prompt removal of the ash deposits from the urbanized areas.
Transport and bottom accumulation of fine river sediments under typhoon conditions and associated submarine landslides: case study of the Peinan River, Taiwan
Authors: Osadchiev A. A. , Korotenko K. A. , Zavialov P. O. , Chiang W.-S. , Liu C.-C.
Published: January 2016

Abstract. A combination of a three-dimensional Eulerian ocean circulation model (Princeton ocean model, POM) and a Lagrangian particle-tracking model (Surface-Trapped River Plume Evolution, STRiPE) is used to study the fate of fine river sediments discharged by the Peinan River at the southeastern coast of the island of Taiwan. The composite model is verified against in situ measurements and applied to simulate primary sediment deposition under freshet and typhoon discharge conditions of the Peinan River. It is shown that local wind plays a crucial role in sediment transport and settling in the coastal area through its influence on the river plume dynamics and turbulent mixing in the upper layer. Wind forcing conditions generally determine the location of the sediment deposit area, while its final pattern is defined by coastal circulation as modulated by the geometry of the coast and local bathymetry. In the study, region river-borne sediments are deposited to the sea floor, mainly in the shallow shelf areas. A significant portion of discharged fine sediments is moved offshore to the deeper ocean where it is further advected and dispersed by strong coastal circulation, mainly governed by the Kuroshio Current.The performed numerical experiments showed that sediment accumulation rate under typhoon conditions is about 2 orders of magnitude greater compared to freshet conditions. Based on the simulation results, we identified areas of continental shelf and continental slope adjacent to the Peinan River estuary which exhibit a high risk of formation of submarine landslides during and shortly after the typhoon events.
A detailed seismic zonation model for shallow earthquakes in the broader Aegean area
Authors: Vamvakaris D. A. , Papazachos C. B. , Papaioannou Ch. A. , Scordilis E. M. , Karakaisis G. F.
Published: January 2016

Abstract. In the present work we propose a new seismic zonation model of area type sources for the broader Aegean area, which can be readily used for seismic hazard assessment. The definition of this model is based not only on seismicity information but incorporates all available seismotectonic and neotectonic information for the study area, in an attempt to define zones which show not only a rather homogeneous seismicity release but also exhibit similar active faulting characteristics. For this reason, all available seismological information such as fault plane solutions and the corresponding kinematic axes have been incorporated in the analysis, as well as information about active tectonics, such as seismic and active faults. Moreover, various morphotectonic features (e.g. relief, coastline) were also considered. Finally, a revised seismic catalogue is employed and earthquake epicentres since historical times (550 BC–2008) are employed, in order to define areas of common seismotectonic characteristics, that could constitute a discrete seismic zone. A new revised model of 113 earthquake seismic zones of shallow earthquakes for the broader Aegean area is finally proposed. Using the proposed zonation model, a detailed study is performed for the catalogue completeness for the recent instrumental period.Using the defined completeness information, seismicity parameters (such as G–R values) for the 113 new seismic zones have been calculated, and their spatial distribution was also examined. The spatial variation of the obtained b values shows an excellent correlation with the geotectonic setting in the area, in good agreement with previous studies. Moreover, a quantitative estimation of seismicity is performed in terms of the mean return period, Tm, of large (M  ≥  6.0) earthquakes, as well as the most frequent maximum magnitude, Mt, for a typical time period (T  =  50 yr), revealing significant spatial variations of seismicity levels within the study area. The new proposed seismic zonation model and its parameters can be readily employed for seismic hazard assessment for the broader Aegean area.
3D-hydrodynamic modelling of flood impacts on a building and indoor flooding processes
Authors: Gems B. , Mazzorana B. , Hofer T. , Sturm M. , Gabl R. , Aufleger M.
Published: January 2016

Abstract. Given the current challenges in flood risk management and vulnerability assessment of buildings exposed to flood hazards, three-dimensional numerical modelling of torrential floods and its interaction with buildings are presented. By means of a case study application, the FLOW-3D software is applied to the lower reach of the Rio Vallarsa torrent in the village of Laives (Italy). A single-family house on the flood plain is thereby considered very detailed and exposed to a 300 yr flood hydrograph. Different building representation scenarios, amongst an entire impervious building envelope and the assumption of fully permeable doors, windows and cellar shafts, are analysed. The modelling results give insight into the flooding process of the building’s interior, the impacting hydrodynamic forces on the exterior and interior walls and, further, quantify the impact of flooding a building on the flow field on the adjacent flood plain. The presented study means a step towards the development of a comprehensive physical vulnerability assessment framework. For pure water floods, it shows possibilities and limits of advanced numerical modelling techniques within flood risk management and, thereby, the planning of local structural protection measures.
The fully nonlinear stratified geostrophic adjustment problem
Authors: Coutino A. , Stastna M.
Published: January 2016

Abstract. The study of adjustment to equilibrium is a classical problem in geophysical fluid dynamics. We consider the fully nonlinear, stratified adjustment problem from a numerical point of view. We present results of smooth dam break simulations based on experiments in the published literature. We focus on both the wave trains that propagate away from the nascent geostrophic state and the geostrophic state itself. For the Rossby number range considered the rank ordered solitary wave train of the non rotating adjustment problem breaks down into a leading packet-like disturbance and a trailing tail. We consider variations in Rossby number and demonstrate that the wave train emanates from the inertial oscillations of the geostrophic state itself, but that the precise phase of the oscillation that yields the wave train is Rossby number dependent. We quantify the strength of the inertial oscillations of the geostrophic state and find results that are in agreement with hydrostatic theory in the literature. We consider the effects of changes in the polarity of the initial perturbations and find that the leading wave packet never completely separates from the trailing tail in this case. Finally we demonstrate that both polarities yield a unique signature in the spectrum of the depth averaged kinetic energy. This signature is fundamentally different from that found in non-rotating cases, and allows for low rotation rates allows for the discrimination between the polarity of the initial perturbation.
Subvisible cirrus clouds – a dynamical system approach
Authors: Spreitzer E. J. , Marschalik M. P. , Spichtinger P.
Published: January 2016

Abstract. Ice clouds, so-called cirrus clouds, occur very frequently in the tropopause region. A special class are subvisible cirrus clouds with an optical depth lower than 0.03. Obviously, the ice crystal number concentration of these clouds is very low. The dominant pathway for these clouds is not known well. It is often assumed that heterogeneous nucleation at solid aerosol particles is the preferred mechanism although homogeneous freezing of aqueous solution droplets might be possible. For investigating subvisible cirrus clouds as formed by homogeneous freezing we develop a simple analytical cloud model from first principles; the model consists of a three dimensional set of ordinary differential equations, including the relevant processes as ice nucleation, diffusional growth and sedimentation, respectively. The model is integrated numerically and is investigated using theory of dynamical systems. We found two different states for the long-term behaviour of subvisible cirrus clouds, i.e. an attractor case and a limit cycle scenario. The transition between the states constitutes a Hopf bifurcation and is determined by environmental conditions as vertical updraughts and temperature. In both cases, the microphysical properties of the simulated clouds agree reasonably well with simulations using a complex model, with former analytical studies and with observations of subvisible cirrus. In addition, the model can also be used for explaining complex model simulations close to the bifurcation qualitatively. Finally, the results indicate that homogeneous nucleation might be a possible formation pathway for subvisible cirrus clouds.
Limiting amplitudes of fully nonlinear interfacial tides and solitons
Authors: Aguiar-González Borja , Gerkema Theo
Published: January 2016

Abstract. A new two-fluid layer model consisting of forced rotation-modified Boussinesq equations is derived for studying tidally-generated fully nonlinear, weakly nonhydrostatic dispersive interfacial waves. This set is a generalization of the Choi-Camassa equations, extended here with forcing terms and Coriolis effects. The forcing is represented by a horizontally oscillating sill, mimicking a barotropic tidal flow over topography. Solitons are generated by a disintegration of the interfacial tide. Because of strong non-linearity, solitons in some cases attain a limiting table-shaped form, in accordance with soliton theory. More generally, we use the model equations to investigate the role of the initial stages of the internal tide on the limiting amplitudes of solitons under fully nonlinear conditions. Numerical solutions reveal that the tide-generated solitons are primarily limited by the underlying quasi-nonlinear internal tide. We show the decisive factor is the generation of higher harmonics, which already limit the growth of the initial internal tide. As a consequence, and contrary to predictions by classical KdV theory alone, we find that tidally generated solitons are subjected to limiting amplitudes even under weakly nonlinear conditions. This implies that under strongly nonlinear conditions, amplitudes of solitons may be limited before attaining a table-shaped form.
Ocean–atmosphere–wave characterization of a wind jet (Ebro shelf, NW Mediterranean Sea)
Authors: Grifoll Manel , Navarro Jorge , Pallarès Elena , Ràfols Laura , Espino Manuel , Palomares Ana
Published: January 2016

Abstract. In this contribution the wind jet dynamics in the northern margin of the Ebro River shelf (NW Mediterranean Sea) are investigated using coupled numerical models. The study area is characterized by persistent and energetic offshore winds during autumn and winter. During these seasons, a seaward wind jet usually develops in a 50 km wide band offshore. The COAWST (Coupled Ocean–Atmosphere–Wave–Sediment Transport) modelling system was implemented in the region with a set of downscaling meshes to obtain high-resolution meteo-oceanographic outputs. Wind, wave and water current were compared with in situ observations and remote-sensing-derived products with an acceptable level of agreement. Focused on an intense offshore wind event, the modelled wind jet appears in a limited area offshore with a strong spatial variability. The wave climate during the wind jet is characterized by the developing of bimodal directional spectra, and the ocean circulation tends to present well-defined two-layer flow in the shallower region (i.e. inner shelf). The outer shelf tends to be dominated by mesoscale dynamics such as the slope current. Despite the limited fetch length, ocean bottom roughness considering sea state (wave-atmosphere coupling) modifies to a small extent the wind and significant wave height under severe cross-shelf wind events. However, the coupling effect in the wind resource assessment may be relevant due to the cubic relation between the wind intensity and power.
Diagnosing non-Gaussianity of forecast and analysis errors in a convective-scale model
Authors: Legrand R. , Michel Y. , Montmerle T.
Published: January 2016

Abstract. In numerical weather prediction, the problem of estimating initial conditions with a variational approach is usually based on a Bayesian framework associated with a Gaussianity assumption of the probability density functions of both observations and background errors. In practice, Gaussianity of errors is tied to linearity, in the sense that a nonlinear model will yield non-Gaussian probability density functions. In this context, standard methods relying on Gaussian assumption may perform poorly. This study aims to describe some aspects of non-Gaussianity of forecast and analysis errors in a convective-scale model using a Monte Carlo approach based on an ensemble of data assimilations. For this purpose, an ensemble of 90 members of cycled perturbed assimilations has been run over a highly precipitating case of interest. Non-Gaussianity is measured using the K2 statistics from the D'Agostino test, which is related to the sum of the squares of univariate skewness and kurtosis. Results confirm that specific humidity is the least Gaussian variable according to that measure and also that non-Gaussianity is generally more pronounced in the boundary layer and in cloudy areas. The dynamical control variables used in our data assimilation, namely vorticity and divergence, also show distinct non-Gaussian behaviour. It is shown that while non-Gaussianity increases with forecast lead time, it is efficiently reduced by the data assimilation step especially in areas well covered by observations. Our findings may have implication for the choice of the control variables.
Ocean modelling for aquaculture and fisheries in Irish waters
Authors: Dabrowski T. , Lyons K. , Cusack C. , Casal G. , Berry A. , Nolan G. D.
Published: January 2016

Abstract. The Marine Institute, Ireland, runs a suite of operational regional and coastal ocean models. Recent developments include several tailored products that focus on the key needs of the Irish aquaculture sector. In this article, an overview of the products and services derived from the models are presented. The authors give an overview of a shellfish model developed in-house and that was designed to predict the growth, the physiological interactions with the ecosystem, and the level of coliform contamination of the blue mussel. As such, this model is applicable in studies on the carrying capacity of embayments, assessment of the impacts of pollution on aquaculture grounds, and the determination of shellfish water classes. Further services include the assimilation of the model-predicted shelf water movement into a new harmful algal bloom alert system used to inform end users of potential toxic shellfish events and high biomass blooms that include fish-killing species. Models are also used to identify potential sites for offshore aquaculture, to inform studies of potential cross-contamination in farms from the dispersal of planktonic sea lice larvae and other pathogens that can infect finfish, and to provide modelled products that underpin the assessment and advisory services on the sustainable exploitation of the resources of marine fisheries. This paper demonstrates that ocean models can provide an invaluable contribution to the sustainable blue growth of aquaculture and fisheries.
Factors favouring phytoplankton blooms in the northern Adriatic: towards the northern Adriatic empirical ecological model
Authors: Kraus R. , Supić N. , Precali R.
Published: January 2016

Abstract. Influenced by one of the largest Mediterranean rivers, Po, the northern Adriatic (NA) production is highly variable seasonally and interannually. The changes are especially pronounced between winters and seemingly reflect on total Adriatic bioproduction of certain species (anchovy). We analysed the long-term changes in the phytoplankton production in the region, as derived from monthly oceanographic cruises, in relation to concomitant geostrophic currents distribution in the area and to Po River discharge rates in days preceding the cruises. In winter and early spring the phytoplankton abundances depended on existing circulation fields, in summer and autumn they were related to Po River discharge rates 1–15 days earlier and on concomitant circulation fields, while in late spring phytoplankton abundances increased 1–3 days after high Po River discharge rates regardless of the circulation fields. During the entire year the phytoplankton abundances were dependent on forcing of the previous 1–12 months of surface fluxes and/or Po River rates. The role of wind was uncertain but that was partly due to unmatched sampling time frames between meteorological and sea data. Low evaporation rates in November reflected significantly on the next February circulation pattern and, although with somewhat lower significance, on large phytoplankton blooms in the same month. We showed that the role of wind in evaporative flux enhancements is not straightforward as evaporative fluxes are highly dependent on other factors, e.g. air–sea temperature difference. Wind-induced vertical mixing was only sporadically related to phytoplankton abundances. From 1990 to 2004 a shift towards large winter bioproduction induced by circulation changes appeared. The investigations performed represent the preliminary actions in the construction of an empirical ecological model of the NA which can be used in the sustainable economy of the region, as well as for validation of the numerical ecological model of the region, which is currently being developed.
On the feasibility of the use of wind SAR to downscale waves on shallow water
Authors: Gutiérrez O. Q. , Filipponi F. , Taramelli A. , Valentini E. , Camus P. , Méndez F. J.
Published: January 2016

Abstract. In recent years, wave reanalyses have become popular as a powerful source of information for wave climate research and engineering applications. These wave reanalyses provide continuous time series of offshore wave parameters; nevertheless, in coastal areas or shallow water, waves are poorly described because spatial resolution is not detailed. By means of wave downscaling, it is possible to increase spatial resolution in high temporal coverage simulations, using forcing from wind and offshore wave databases. Meanwhile, the reanalysis wave databases are enough to describe the wave climate at the limit of simulations; wind reanalyses at an adequate spatial resolution to describe the wind structure near the coast are not frequently available. Remote sensing synthetic aperture radar (SAR) has the ability to detect sea surface signatures and estimate wind fields at high resolution (up to 300 m) and high frequency. In this work a wave downscaling is done on the northern Adriatic Sea, using a hybrid methodology and global wave and wind reanalysis as forcing. The wave fields produced were compared to wave fields produced with SAR winds that represent the two dominant wind regimes in the area: the bora (ENE direction) and sirocco (SE direction). Results show a good correlation between the waves forced with reanalysis wind and SAR wind. In addition, a validation of reanalysis is shown. This research demonstrates how Earth observation products, such as SAR wind fields, can be successfully up-taken into oceanographic modeling, producing similar downscaled wave fields when compared to waves forced with reanalysis wind.
Investigation of model capability in capturing vertical hydrodynamic coastal processes: a case study in the north Adriatic Sea
Authors: McKiver W. J. , Sannino G. , Braga F. , Bellafiore D.
Published: January 2016

Abstract. In this work we consider a numerical study of hydrodynamics in the coastal zone using two different models, SHYFEM (shallow water hydrodynamic finite element model) and MITgcm (Massachusetts Institute of Technology general circulation model), to assess their capability to capture the main processes. We focus on the north Adriatic Sea during a strong dense water event that occurred at the beginning of 2012. This serves as an interesting test case to examine both the models strengths and weaknesses, while giving an opportunity to understand how these events affect coastal processes, like upwelling and downwelling, and how they interact with estuarine dynamics. Using the models we examine the impact of setup, surface and lateral boundary treatment, resolution and mixing schemes, as well as assessing the importance of nonhydrostatic dynamics in coastal processes. Both models are able to capture the dense water event, though each displays biases in different regions. The models show large differences in the reproduction of surface patterns, identifying the choice of suitable bulk formulas as a central point for the correct simulation of the thermohaline structure of the coastal zone. Moreover, the different approaches in treating lateral freshwater sources affect the vertical coastal stratification. The results indicate the importance of having high horizontal resolution in the coastal zone, specifically in close proximity to river inputs, in order to reproduce the effect of the complex coastal morphology on the hydrodynamics. A lower resolution offshore is acceptable for the reproduction of the dense water event, even if specific vortical structures are missed. Finally, it is found that nonhydrostatic processes are of little importance for the reproduction of dense water formation in the shelf of the north Adriatic Sea.
DUACS DT2014 : the new multi-mission altimeter dataset reprocessed over 20 years
Authors: Pujol M.-I. , Faugère Y. , Taburet G. , Dupuy S. , Pelloquin C. , Ablain M. , Picot N.
Published: January 2016

Abstract. The new DUACS DT2014 reprocessed products are available since April 2014. Numerous and impacting evolutions have been implemented at each step of this new data processing. The main one is the use of a new 20-year altimeter reference period that changes the SLA and SLA gradient signature. Although all the DUACS products have been improved, this paper focuses on gridded products quality description over the global ocean. As part as this exercise, 21 years of data have been homogenized allowing us to retrieve accurate large scale climate signals such as global and regional MSL trend as well as interannual signals, but also refined mesoscale features. Extensive assessment has been performed on this dataset, which allowed us to establish a consolidated error budget. The errors at mesoscale are about 1.5cm2 in low variability areas and increase to 9cm2 in average in coastal regions, to reach more than 30cm2 in high mesoscale activity areas. The DT2014 products, compared to the previous version DT2010, presents additional signal for wavelengths lower than ~250km inducing SLA variance and mean EKE increase of respectively +5.1% and +15%. Comparison with independent measurements underlined the improved mesoscales restitution with this new dataset. The errors reduction at mesoscale reaches nearly 10% of the error observed with DT2010. The DT2014 also presents improved coastal signal with a 2 to 4% mean error reduction. High latitudes areas are also better represented in DT2014, with a better consistency between map spatial coverage and sea ice edge position. The budget error is finally discussed, in order to highlight the limitation of gridded products, notably in strong internal tide area.
Analyses of altimetry errors using Argo and GRACE data
Authors: Legeais J.-F. , Prandi P. , Ablain M. , Guinehut S.
Published: January 2016

Abstract. This study presents the evaluation of the performances of satellite altimeter missions by comparing the altimeter sea surface heights with in-situ dynamic heights derived from vertical temperature and salinity profiles measured by Argo floats. This external assessment method contributes to altimeter Calibration and Validation analyses that cover a wide range of activities. Among them, our approach focuses on the detection of altimeter drift and the estimation of the impact of new altimeter standards that requires an independent reference. The methodology and the Argo data used are first described and altimeter validation activities are then illustrated with some examples, separating the analyses of the long-term evolution of the mean sea level and its variability, at global and regional scales and results obtained via relative and absolute comparisons. The latter requires the use of the ocean mass contribution to the sea level derived from GRACE measurements. Our analyses are related to different subjects ranging from the estimation of the global mean sea level trend to the validation of multi-missions altimeter products as well as the assess ment of orbit solutions. Even if this approach contributes to the altimeter quality assessment, the differences between two versions of altimeter standards are getting smaller and smaller and it is thus more difficult to detect their impact. It is therefore essential to characterize the errors of the method, which is illustrated with the results of sensitivity analyses to different parameters. This provides an estimation of the robustness of the method and the characterization of associated errors. The results also allow us to draw some recommendations to the Argo community regarding the maintenance of the in-situ network.
Major improvement of altimetry sea level estimations using pressure derived corrections based on ERA-interim atmospheric reanalysis
Authors: Carrere L. , Faugère Y. , Ablain M.
Published: January 2016

Abstract. New Dynamic Atmospheric Correction (DAC) and Dry Tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed on the 1992-2013 altimeter period. Using these new corrections improves significantly sea-level estimations for short temporal signals (< 2 months); the impact is stronger if considering old altimeter missions (ERS-1, ERS-2, TP), for which DAC_ERA allows reducing the residual variance at crossovers by more than 10 cm2 in the Southern Ocean and in some shallow water regions. The impact of DT_ERA is also significant in the southern high latitudes for these missions. Using the ERA-interim forcing has the greatest positive impact on the first decade of altimetry, then this impact diminishes until giving similar results as the operational forcing from year 2002. Concerning more recent missions (Jason-1, Jason-2, and Envisat), results are very similar between ERA-Interim and ECMWF based corrections: on average on global ocean, the operational DAC becomes slightly better than DAC_ERA only from year 2006, likely due to the switch to a higher resolution of operational forcing. At regional scale, both DACs are similar in deep ocean but DAC_ERA raises the residual crossovers variance in some shallow water regions. On the second decade of altimetry, unexpectedly DT_ERA still gives better results compared to the operational DT. Concerning climate signals, both DAC_ERA and DT_ERA have a low impact on global MSL trend, but they can have a strong impact on long-term regional trends estimation, until several mm/yr locally.
Core operational Sentinel-3 marine data product services as part of the Copernicus Space Component
Authors: Bonekamp H. , Montagner F. , Santacesaria V. , Nogueira Loddo C. , Wannop S. , Tomazic I. , O' Carroll A. , Kwiatkowska E. , Scharroo R. , Wilson H.
Published: January 2016

Abstract. This paper describes the marine data available from the Marine Centre, part of the Sentinel-3 Payload Data Ground Segment, located at the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). The Marine Centre together with the existing EUMETSAT facilities provides a centralised operational service for operational oceanography. These descriptions of the marine data are produced with a focus on a user service perspective. They include the scientific and operational feedback mechanisms on the performance of the services as well as practical information and user support mechanisms.
Technical note: Common characteristics of directional spreading-steepness joint distribution in freak wave events
Authors: Liu S. H. , Yue X. Y.
Published: January 2016

Abstract. Seven freak wave incidents previously documented in the real ocean in combination with model hindcast simulations are used to study the variations associated with freak wave-related parameters, such as wave steepness, directional spreading, and frequency bandwidth. Unlike the strong correlations between the freak wave parameters and freak waves' occurrence which were obtained in experimental and physical research, the correlations are not clear in the freak waves occurred in the real ocean. Wave directional spreading-steepness joint distribution is introduced and common visual features were found in the joint distribution when freak waves occur among seven "freakish" sea states. The visual features show that freak wave incidents occur when the steepness is large and directional spreading is small. Besides the steepness is large and directional spreading is small, a long-duration relatively rough sea state is also necessary for the freak wave generation. The joint distribution is more informative than the sequential variation of any single statistical wave parameter. The continuous sea states of local large steepness and small directional spreading are supposed to be "freakish" sea states, and two-dimensional distribution visualization is found to be a useful tool for freak waves forecast. The common visual features of joint distributions supply an important cue for the theoretical and experimental research.
Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean
Authors: Jouanno J. , Capet X. , Madec G. , Roullet G. , Klein P. , Masson S.
Published: January 2016

Abstract. The aim of this study is to clarify the role of the Southern Ocean storms on interior mixing and meridional overturning circulation. A periodic and idealized numerical model has been designed to represent the key physical processes of a zonal portion of the Southern Ocean located between 70° S and 40° S. It incorporates physical ingredients deemed essential for Southern Ocean functioning: rough topography, seasonally varying air-sea fluxes, and high-latitude storms with analytical form. Level and distribution of mixing attributable to high frequency winds are quantified and compared to those generated by eddy-topography interactions and dissipation of the balanced flow. Results suggest that 1) the synoptic atmospheric variability alone can generate the levels of mid-depth dissipation frequently observed in the Southern Ocean (10–10–10–9 W kg−1) and 2) the storms strengthen the overturning, primarily through enhanced mixing in the upper 300 m, whereas deeper mixing has a minor effect. The sensitivity of the results to horizontal resolution (20, 5, 2 and 1 km), vertical resolution and numerical choices is evaluated. Challenging issues concerning how numerical models are able to represent interior mixing forced by high-frequency winds are exposed and discussed, particularly in the context of the overturning circulation. Overall, submesoscale-permitting ocean modelling exhibits important delicacies owing to a lack of convergence of key components of its energetics even when reaching Δx = 1 km.
Dilatant normal faulting in jointed cohesive rocks: a physical model study
Authors: Kettermann M. , von Hagke C. , van Gent H. W. , Grützner C. , Urai J. L.
Published: January 2016

Abstract. Dilatant faults often form in rocks containing pre-existing joints, but the effects of joints on fault segment linkage and fracture connectivity is not well understood. We present an analogue modeling study using cohesive powder with pre-formed joint sets in the upper layer, varying the angle between joints and a rigid basement fault. We analyze interpreted map-view photographs at maximum displacement for damage zone width, number of connected joints, number of secondary fractures, degree of segmentation and area fraction of massively dilatant fractures. Particle imaging velocimetry helps provide insights on deformation history of the experiments and illustrate the localization pattern of fault segments. Results show that with increasing angle between joint-set and basement-fault strike the number of secondary fractures and the number of connected joints increases, while the area fraction of massively dilatant fractures shows only a minor increase. Models without pre-existing joints show far lower area fractions of massively dilatant fractures while forming distinctly more secondary fractures.
Assessment of combating desertification strategies using the linear assignment method
Authors: Sadeghravesh M. H. , Khosravi H. , Ghasemian S.
Published: January 2016

Abstract. Select appropriate strategies according to all effective criteria in combating desertification process can be so useful in controlling and rehabilitation of degraded lands, and avoid degradation in vulnerable fields. This study provides systematic and optimal strategies of combating desertification by group decision-making model. To this end, in the framework of Multi Attribute Decision Making (MADM) and by using Delphi model (Delphi), the preferences of indexes were obtained. Then priorities of strategies were evaluated by using linear assignment (LA) method. According to the results, the strategies to prevent improper change of land use (A18), development and reclamation of plant cover (A23) and adjustment for harvesting from groundwater sources (A31), respectively were identified as the most important strategies for combating desertification in this study area. Therefore, it was suggested to consider ranking results in projects which controls and reduces the effects of desertification and rehabilitates degraded lands.
Effects of wood chip amendments on the revegetation performance of plant species on eroded marly terrains in a Mediterranean mountainous climate (Southern Alps, France)
Authors: Breton V. , Crosaz Y. , Rey F.
Published: January 2016

Abstract. The establishment of plant species can limit soil erosion dynamics in degraded lands. In marly areas in the Southern French Alps, both harsh water erosion and drought conditions in summer due to the Mediterranean mountainous climate prevent the natural implementation and rege neration of vegetation. Soil fertility improvement is sometimes necessary. With the purpose of revegetating such areas, we aimed to evaluate the effects of wood chip amendments on the revegetation performance of different native or sub-spontaneous plant species. We conducted two experiments on steep slopes over three growing seasons (2012–2014). The first consisted of planting seedlings (ten species), the second consisted of seeding (nine species including six used in the first experiment). First we noted that wood chips were able to remain in place even in steep slope conditions. The planting of seedlings showed both an impact of wood chip amendment and differences between species. A positive effect of wood chips was shown with overall improvement of plant survival (increasing by 11% on average, by up to 50% for some species). In the seeding experiment, no plants survived after three growing seasons. However, intermediate results for the 1st and 2nd years showed a positive effect of wood chips on seedling emergence: seeds of four species only sprouted on wood chips, and for the five other species the average emergence rate increased by 50%.
Basement structure of the Hontomín CO2 storage site (Spain) determined by integration of microgravity and 3D seismic data
Authors: Andres J. , Alcalde J. , Ayarza P. , Saura E. , Marzán I. , Martí D. , Martínez Catalán J. R. , Carbonell R. , Pérez-Estaún A. , García-Lobón J. L. , Rubio F. M.
Published: January 2016

Abstract. A multidisciplinary study has been carried out in Hontomín (Spain) to determine the basement structural setting/ geometry and that of the sedimentary succession of an area aimed to be the first Spanish pilot plant of CO2 injection. An integration of coincident 3D seismic results, borehole data and unpublished microgravity 5 maps aims to reproduce the deep structure of the basement and to quantify the thickness of the Triassic Keuper evaporites. All datasets manage to clearly identify two main fault systems compartmentalizing the main structural domains into three differentiated blocks. These have been interpreted to be reactivated normal faults that have led to the formation of 10 the Hontomín dome. The general structure is characterized by a half-graben setting filled with thick Keuper evaporites (up to 2000 m thick) forming an extensional forced fold.
Seismic structure beneath the Gulf of Aqaba and adjacent areas based on the tomographic inversion of regional earthquake data
Authors: El Khrepy Sami , Koulakov Ivan , Al-Arifi Nassir , Petrunin Alexey
Published: January 2016

Abstract. The Gulf of Aqaba is an elongated basin (~180 x 20 km) with depths reaching 1850 m. It represents the southern segment of the Dead Sea Transform (DST), which is one of the largest transform fault zones in the world. The opening of Gulf of Aqaba is thought to have originated from the relative displacement of the African and Arabian Plates. According to historical and recent earthquake records, it is seismically active. In this study, we present the first 3D model of seismic P and S velocities beneath the Gulf of Aqaba area based on the results of passive travel time tomography. The tomographic inversion was performed based on travel time data from ~9000 regional earthquakes provided by the Egyptian National Seismological Network (ENSN) and the International Seismological Center (ISC). The inversion results are generally consistent for P- and S-velocity patterns at all depths. At all depth intervals in the Red Sea, we observed strong high-velocity anomalies with abrupt limits that coincide with the coastal lines. This finding suggests that the oceanic nature of the crust in the northern Red Sea does not support the concept of gradual stretching of the continental crust. According to our results, in the middle and lower crust, the seismic anomalies seem to delineate a sinistral shift (~100 km) in the opposite flanks of the fault zone that is consistent with other estimates of the left-lateral displacement in the southern part of the DST. However, no displacement structures are visible in the upper-most lithospheric mantle.
Mechanisms of clay smear formation in unconsolidated sediments – insights from 3D observations of excavated normal faults
Authors: Kettermann Michael , Thronberens Sebastian , Juarez Oscar , Urai Janos Lajos , Ziegler Martin , Asmus Sven , Krüger Ulrich
Published: January 2016

Abstract. Clay smears in normal faults can form seals for hydrocarbons and groundwater, and their prediction in the subsurface is an important problem in applied and basic geoscience. However, neither their complex 3D structure, nor their processes of formation or destruction are well understood, and outcrop studies to date are mainly 2D. We present a 3D study of an excavated normal fault with clay smear, together with both source layers, in unlithified sand and clay of the Hambach open cast lignite mine in Germany. The faults formed at a depth of 150 m, and have Shale Gouge Ratios between 0.1 and 0.3. The fault zones are layered, with sheared sand, sheared clay and tectonically mixed sand-clay gouge. Thickness of clay smears in two excavated fault zones of 1.8 and 3.8 m2 is approximately log-normal, with values between 5 mm and 5 cm, without holes. The 3D thickness distribution is heterogeneous. We show that clay smears are strongly affected by R- and R'-shears, mostly at the footwall side. These shears can locally cross and offset clay smears, forming holes in the clay smear, while thinning of the clay smear by shearing in the fault core is less important. Thinnest parts of the clay smears are often located close to source layer cutoffs. Locally, the clay smear consists of overlapping patches of sheared clay, separated by sheared sand. More commonly, it is one amalgamated zone of shared sand and clay. Microscopic study of fault zone samples shows that grain-scale mixing can lead to thickening of the low permeability smears, which may lead to resealing of holes.
Effects of pumice mining on soil quality
Authors: Cruz-Ruíz A. , Cruz-Ruíz E. , Vaca R. , Del Aguila P. , Lugo J.
Published: January 2016

Abstract. Mexico is the world's fourth most important maize producer; hence, there is a need to maintain soil quality for sustainable production in the upcoming years. Pumice mining is a superficial operation that modifies large areas in central Mexico. The main aim was to assess the present state of agricultural soils differing in elapsed time since pumice mining (0–15 years) in a representative area of the Calimaya region in the State of Mexico. The study sites in 0, 1, 4, 10, and 15 year old reclaimed soils were compared with an adjacent undisturbed site. Our results indicate that gravimetric moisture content, water hold capacity, bulk density, available phosphorus, total nitrogen, soil organic carbon, microbial biomass carbon and phosphatase and urease activity were greatly impacted by disturbance. A general trend of recovery towards the undisturbed condition with reclamation age was found after disturbance, the recovery of soil total N being faster than soil organic C. The soil quality indicators were selected using principal component analysis (PCA), correlations and multiple linear regressions. The first three components gathered explain 76.4 % of the total variability. The obtained results revealed that the most appropriate indicators to diagnose the quality of the soils were urease, available phosphorus and bulk density and minor total nitrogen. According to linear score analysis and the additive index, the soils showed a recuperation starting from 4 years of pumice extraction.