bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of spectral properties of different Quaternary paleosols and parent materials
Authors: Szeberényi József , Barta Gabriella , Novothny Ágnes , Csonka Diána , Viczián István , Horváth Erzsébet , Végh Tamás
Published: March 2020

Diffuse Reflectance Spectroscopy (DRS) is a rapid method for analysing sediments and paleosols, which is a relatively new approach in Quaternary research. This method take into account the clay mineral content, the amount of Fe-bearing minerals and the grain size composition of samples at the same time.

Continuing our earlier research (Szeberényi et al. 2019), this paper reveals the relationship between the DRS curves of paleosols and their parent material. The basis of recent research was the most variable curve sections (between 400-1460 nm wavelength range) of entire measurement range (between 240-2000 nm). The goal of the actual study was to quantify the significant differences between original reflectance curves of paleosols and their parent materials in the case of different quaternary sediment successsions.

Different Quaternary sediment samples were chosen for characterization and comparison their reflectance curves, hereby detection and quantify the most important spectral properties of different paleosols and parent materials. Samples of different sediment types and paleosol variants were investigated from a loess-paleosol sequence at Malá nad Hronom (Slovakia) and a fluvial-aeolian sediment complex at Pilismarót (Hungary).

Five investigated curve sections were separated as the best indicators of reflectance properties of DRS curves. To compaire of spectral properties of samples was used the length of investigated curve sections. It could be explain by ΔR% value, which was shown the difference of reflectance intensity between end points of investigated curve sections.

This investigation showed the quantifiable differences between the units of pleistocene sediment successions, based on the reflectance properties. The influence of pedogenic processes were good detectable. Significant discrepancies were observed between reflectance curves of well-developed paleosols and parent material samples in the VIS-NIR range. Only in the visible range were observed differences between the weak developed paleosol layers and their parent materials. It could be separated from each other the fine sand, the sandy silt and the loess materials based on the intensity of entire reflectance curves.

 
Analysis of short large amplitude magnetic structures at the Kronian bow shock
Authors: Bebesi Zsofia , Erdos Geza , Dosa Melinda , Szego Karoly
Published: March 2020

            We present a comprehensive statistical analysis of Short Large Amplitude Magnetic Structures (SLAMS) upstream of the quasi-parallel bow shock of Saturn. During its mission Cassini extensive surveyed the quasi-parallel regime. For this study we used the measurements of the Cassini Plasma Spectrometer (CAPS) and the Magnetometer (MAG).

            The SLAM structures locally act as fast mode shock waves, and we observed possible ion beam reflection, multiple ion beams, deceleration and plasma heating of the solar wind protons. These features are in agreement with the near Earth observations. We also detected whistler precursor waves multiple times, which was also documented in studies of the Earth's foreshock region. Since the frequency of the upstream ULF waves detected at Saturn is lower than it is at Earth, it also has an effect on the spatial extension of the SLAM structures, which arise from these waves. With only one spacecraft's measurements it is not possible to study the SLAMS with the same efficiency as with the four-point measurements of the CLUSTER probes, but the basic observational features and the description of their evolutional characteristics are summarized.
Permafrost organic carbon transport and degradation on a transect from the Kolyma River to the East Siberian Shelf
Authors: Jong Dirk , Bröder Lisa , Keskitalo Kirsi , Kloostra Oscar , Tesi Tommaso , Zimov Nikita , Davydova Anya , Haghipour Negar , Eglinton Timothy , Vonk Jorien
Published: March 2020

Arctic rivers will be increasingly affected by the hydrological and biogeochemical effects of thawing permafrost. During transport, permafrost thaw-derived organic carbon (OC) can be degraded into greenhouse gases and potentially add to further climate warming, or transported to the shelf seas and buried in marine sediments, attenuating this ‘permafrost carbon feedback’. To assess the transport pathways and fate of permafrost-OC, we focus on the river-shelf continuum of the Kolyma River, the largest river on Earth completely underlain by continuous permafrost. Three pools of riverine OC were investigated: dissolved OC (DOC), suspended particulate OC (POC), and river sediment OC (SOC). Preliminary results of bulk carbon isotopes (δ13C, Δ14C) and molecular biomarkers (lignin phenols, leaf wax lipids) show contrasts in composition and degradation state for these carbon pools. Old permafrost-OC seems to be mostly associated with SOC, and less dominant in POC. However, while SOC shows the oldest Δ14C signal, lignin phenol results (e.g., acid to aldehyde ratios) suggest this material is the least degraded. In contrast, DOC shows more degraded signal, even at the outflow of an active permafrost thaw site. Our study serves as a terrestrial extension to earlier investigated marine sediments from the Kolyma paleoriver transect in the East Siberian Sea. It also highlights the value of connecting terrestrial and marine observations to gain insight into the complete pathway of permafrost-OC, from the moment of thaw, via aquatic transport and degradation, towards storage in marine sediments.
The seismic structure of the Galicia Interior Basin from new seismic images: Implications for the West Iberia margin formation
Authors: Cameselle Alejandra L. , Ranero César R. , Pinheiro Luis M. , Sallarès Valentí
Published: March 2020

The Galicia Interior Basin (GIB) off West Iberia, is considered an aborted rift formed in the context of opening of the North Atlantic rift system. Despite the Galicia Interior Basin being located in one of the best studied examples of magma-poor rifted margins (i.e., the West Iberia continental margin), its 3D structural variability and its role during continental rifting in the regional geodynamic context remains poorly understood. In this sense, Galicia Interior Basin represents the necessary link to understand the mechanisms of extension from the little extended shelf to the areas where continental breakup finally occurred.

Here we present new multichannel seismic data collected during FRAME cruise carried out onboard the Spanish “R/V Sarmiento de Gamboa” during summer 2018. The structure of the Galicia Interior Basin has been imaged using a 6-km-long solid-state digital multichannel streamer with 480 channels and two G-II gun arrays with a total volume of 3920 cu.in. fired every 37.5 m at 140 bar (2000 p.s.i.) pressure. The new post-stack time migrations of multichannel seismic profiles show the complex basement structure and deep sedimentary units across the region with an unprecedented detail. Additionally, we used state-of-the-art techniques to reprocessed a complementary set of vintage multichannel seismic profiles collected across the GIB. The integration of new and reprocessed seismic profiles provides the opportunity to study for the first time the 3D tectonic crustal-scale structure of the GIB.

Our images reveal syn- and post-rift sediment, tilted fault blocks, well-defined top-of-the-basement reflections, and also intra-basement and Moho reflections that offer new information about the variations in tectonic structural style during rifting. The data display an asymmetric structure and variations in the amount and distribution of crustal extension across the GIB. At the center of the basin – about 150 km landward from the continent-ocean transition – the continental basement has been thinned to 6-8 km associated with listric (in two-way travel time) normal faults without final breakup. Further offshore, the continental basement thickens again until ~20 km under the Galicia Bank, before entering the Deep Galicia Margin where continental basement thins laterally continuously to mantle exhumation and final breakup. The observed crustal structure and margin configuration represents a challenge to current models of rifting and continent-ocean transition structure, and allow to speculate on the possible causes for rift failure at the GIB in the context of the opening of the West Iberia margin.
Digital Water Approach for Smarter Water Management in Cities with Interconnected Infrastructure
Authors: Kapelan Zoran
Published: March 2020

Water management in cities has come a long way since the inception of early infrastructure long time ago. The modern water systems provide safe and reliable service via effective supply of clean water and collection, disposal and recycling of wastewater. However, the increasing pressures arising from the climate change, population growth and urbanisation are posing further challenges that need to be addressed in the urban environment. The advancement of new technologies such as latest artificial intelligence and machine learning methods, intelligent sensors and actuators linked via internet of things and fast 5G communication networks (to name the few) provide an opportunity to manage water in cities in a fundamentally different way that is more sustainable and resilient but also less impactful on other infrastructure systems.

The talk will start by defining what is meant by a smart water system in the context of a smart city. This will be followed by the presentation of several advanced type technologies and solutions that have been developed for the improved management of water and wastewater in urban environment. This includes new data analytics type technology for the automated detection and location of pipe bursts/leaks, equipment failures and other failure events in a water distribution system. This technology detects failure events in these system by processing pressure, flow and other data in near real-time by using artificial intelligence and other methods. In addition to saving water, energy and other resources this technology has the potential to reduce or, in some cases, prevent the negative impact of WDS failures on other infrastructure systems (e.g. impact on a transport system via major road closure following a pipe burst).

Another example that will be presented is the new technology for automated asset condition assessment of sewers. This technology, currently being commercialised,  processes standard CCTV data by using image processing and machine learning techniques to identify and classify structural and other faults in these pipes. The increased reliability and consistency of detection of these faults has the potential to reduce or remove the negative impact of related sewer failures on other critical urban infrastructure systems, e.g. impact on traffic or energy systems due to urban flooding and/or pollution that may occur as a result of non-detection.  A number of other smart water technologies and solutions will be presented. Most of these were developed in collaboration with various water utilities hence are of direct relevance to engineering practice. The talk will end with the key message that digital water approach has a huge potential to improve things in the water and other sectors.

 
Environmental and Hydrological Implications of Innovative Sprayable Biodegradable Polymer Membrane: First Results
Authors: Filipović Vilim , Filipović Lana , Wang Yusong , Braunack Michael V. , Adhikari Raju , Freischmidt George , Johnston Priscilla , Casey Phil S. , Bristow Keith L.
Published: March 2020

Agricultural management techniques like plastic mulch films are widely used to enhance crop production by conserving soil water and increasing temperature with the ability to suppress weeds. However, the use of plastic represents large environmental concern since the recovery of plastics from soils and its persistence in the environment is causing global problems. The EU in leading in policy with ban on single use plastics and it is a matter of time when conventional plastic mulch films will be banned as well. To solve the problem, researchers have turned their attention to biodegradable products while lately sprayable biodegradable polymer membrane (SBPM) technology was introduced. Here, we present first results of glasshouse study and in-field experiments with SBPM technology in Australia where with the use of subsurface drip irrigation we could improve water use efficiency of crops with reducing evaporation. First results indicate that SBPM technology could limit soil evaporation, reduce irrigation needs and prevent weed emergence while at the same time providing environmentally sustainable agricultural practice through its biodegradability, nontoxicity and sprayability nature. This innovative technology shows large potential even at this early development stage with the need for further improvement of SBPM formulation, management and properties.
Data-driven modelling of potential trajectories of the global water-energy-food nexus system
Authors: Masia Sara , Susnik Janez
Published: March 2020

There is increasing interest in the global water-energy-food (WEF) system and potential future system trajectories under global change, especially considering growing concerns over resource exploitation and sustainability. Previous studies investigating different aspects of this system have a number of shortcomings including not analysing all nexus sectors and/or not accounting for possible feedback between sectors, meaning it is difficult to identify system-wide tradeoffs, and makes comparison difficult. A global analysis of the WEF system linked to changes in potential gross domestic product (GDP) growth is presented, integrating the four sectors (water-energy-food-GDP) into a coherent analysis and modelling framework. GDP was included as previous related work demonstrates a link between GDP and each WEF sector. A system dynamics modelling approach quantifies previously qualitative descriptions of the global WEF-GDP system, while a Monte-Carlo sampling approach is adopted to characterise variability in resource use and growth at the global level. Correlative and causal analysis show links of varying strength between sectors. For example, the GDP-electricity consumption sectors are strongly correlated while food production and electricity consumption are weakly correlated. Causal analysis reveals that ‘correlation does not imply causation’. There are noticeable asymmetries in causality between certain sectors. Historical WEF-GDP values are well recreated with the exception of electricity production/consumption. Future scenarios were assessed using seven GDP growth estimates to 2100. Water withdrawals in 2100 and food production in 2050 are close to other literature estimations arrived at using very different means. Results suggest that humanity risks exceeding the ‘safe operating space’ for water withdrawal. Reducing water withdrawal while maintaining or increasing food production is critical, and should be decoupled from economic growth. Electricity production/consumption is also expected to grow, with the strength of growth linked to GDP pathways. Climate impacts of the production and consumption will depend greatly on the fuel source for the generation of power. This work provides a quantitative modelling framework to previously qualitative descriptions of the WEF-GDP system, offering a platform on which to build.
What can short temporal changes of stable isotope ratios and geochemical parameters of tap water at a single sampling site tell us?
Authors: Nagode Klara , Kanduč Tjaša , Zuliani Tea , Bračič Železnik Branka , Jamnik Brigita , Vreča Polona
Published: March 2020

Investigations of tap water and its source groundwater reflect combined features of regional hydrological processes and human activities including the changes in water supply system (WSS). In this context, multi-parameter characterization can present a reliable tool to propagate the geochemical “fingerprints” of water source from natural or artificial mixing. If the geochemical composition of different water source end members is significantly different, we can estimate the proportions of source water and their changes from particular source to tap.

To test this hypothesis, we performed a 24 hours sampling experiment of tap water in April 2019 at selected location in Ljubljana (i.e. at Jožef Stefan Institute), where groundwater from two different water fields and aquifers (i.e. from Kleče at Ljubljansko polje and Brest from Ljubljansko barje) is mixed. In-situ measurements of temperature, electrical conductivity and pH were performed and 25 water samples were collected hourly for determination of isotopic composition of oxygen (δ18O), hydrogen (δ2H) and dissolved inorganic carbon (δ13CDIC), 87Sr/86Sr isotope ratio and major (Ca, K, Mg and Na) and trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Tl, U, V and Zn).

The diurnal variations of parameters are not very large; however, temporal differences of some parameters (e.g. Ba, Mg) indicate that proportion of groundwater from Kleče and Brest water fields changed during the experiment. Based on observed temporal differences during the 24 hours experiment we could identify three different patterns: a.) higher values in the beginning and at the end and lower in between (i.e. δ18O, δ13CDIC, Ca, Na, B, Ba, Cr, Li, Sr); b.) lower values in the beginning and at the end and higher in between (i.e. K, Mg, As, Mn, V) and c.) higher values at the beginning of experiment (i.e. Cd, Co, Cu, Fe, Mo, Ni, Pb, Sb, Zn). The first and the second pattern (a and b) indicate the mixing of different groundwater from different water fields with different geochemical characteristics. The third pattern (c) however indicates the influence of release of elements due to corrosion of water supply system. Based on results of 24 hours experiment and additional information on functioning of water supply system changes in proportion of water from Kleče and Brest water fields will be estimated.
Rapid development and evaluation of fast process based models in Mobius
Authors: Norling Magnus
Published: March 2020

The open source Mobius framework allows for quick develoment of models based on ODE- and discrete-timestep equations. One can build and explore many model structures with only small modifications to the model code. Model run speed is fast, making it feasible to do extensive automated parameter space exploration, for instance using optimizers or MCMC algorithms. The framework can compile models to a format where they are accessible for interaction using the Python scripting language. Moreover, several calibration and uncertainty analysis tools in Python are already set up so that they can be used with any Mobius model. This can then be used to evaluate model structures using Bayesian methods. We show an example of evaluating a few DOC catchment models using this framework. Modelling frameworks are a good alternative to one-size-fits-all models, and we hope Mobius will be a useful tool for promoting more robust modelling.
Syros, blocks and matrix structure: evolution of a mélange along the subduction interface
Authors: Gyomlai Thomas , Agard Philippe , Jolivet Laurent
Published: March 2020

The nature and processes occurring at the subduction plate interface remain poorly constrained. In particular, the behavior of fluids and its impact on the rheology and the chemistry of the plate interface are mostly unknown. Based on detailed fieldwork, petrographic, geochemical analyses and thermodynamic modelling, the present study documents an example of a reacted “mélange” and metasomatism along the subduction interface: the Lia mélange zone on Syros island. Syros island is located in the Cycladic Archipelago in the centre of the Aegean domain which corresponds to the deepest exhumed parts of the Hellenides–Taurides belt. We show that this particular mélange zone is a disrupted yet still relatively coherent fragment of transitional lithosphere (i.e., OCT type from the Pindos Ocean), which has undergone dominant exhumation-related deformation with top to the east shearing. A large part of the “mélange” structure is inherited from the initial lithostratigraphic setting. Through detailed mapping and a statistical study of the nature of blocks and matrix we show that, as a first approximation, metasomatism occurs in contact between metavolcanite layers and serpentinite, with diffusion of Ca from the metavolcanites to the matrix and diffusion of Mg from matrix to metavolcanite. Most of the metavolcanite layers and blocks (mafic and carbonate) are mostly only partly digested but the ultramafic matrix has been largely metasomatised forming a tremolite-chlorite-talc schist, a “hybrid” rock, with an intermediate chemical composition. Geochemical data suggest that exhumation-related metasomatism is probably triggered and/or enhanced by the arrival of fluids from the dehydrating slab underneath. The Lia mélange zone shows that hybrid rocks can be formed by metasomatism along the subduction interface. Due to the absence of major tectonic mixing and of evidence of prograde reactions, this metasomatism may not be representative of deeper hybridization (as a potential source of arc volcanism). However, by changing the mineralogy of the matrix, the metasomatism changes the rheological properties of the mélange and thus could impact that of the subduction interface and the exhumation processes. This study highlights the significance of rock hybridization through metasomatism, largely in the context of a syn-convergent exhumation, along the slab interface and emphasizes its potential chemical and rheological impacts.
The emergence of community models in hydrology
Authors: Addor Nans , Clark Martyn P. , Henn Brian
Published: March 2020

Hydrological models (HMs) are essential tools to explore terrestrial water dynamics and to anticipate future hydrological events. Since their inception, HMs have been developed in parallel by different institutions. There is now a plethora of HMs, yet a relative absence of cross-model developments (code is almost never portable between models) and of guidance on model selection (modellers typically stick to the model they are most familiar with). Furthermore, traditional HMs, developed over the last decades by successive code additions, are rarely adapted to modern hydrological challenges, principally because they lack modularity. These HMs typically rely on a single model structure (most processes are simulated by a single set of equations), which make it difficult to i) understand differences between models, ii) run a large ensemble of models, iii) capture the spatial variability of hydrological processes and iv) develop and improve hydrological models in a coordinated fashion across the community.

These limitations can be overcome by modular modelling frameworks (MMFs), which are master templates for model generation. MMFs offer several options for each important modelling decision. They also allow users to add functionalities when they are required, by loading libraries developed and maintained by the community. This presentation uses FUSE (Framework for Understanding Structural Error) as an example of MMF for hydrology. FUSE enables the generation of a myriad of conceptual HMs by recombining elements from four commonly-used models. This presentation will summarize the development of FUSE version 2 (FUSE2), which was created with users in mind and significantly increases the usability and range of applicability of the original FUSE. In FUSE2, NetCDF output files contain a detailed description of the modelling decisions (e.g., selected modules, numerical scheme, parameter values), which improves reproducibility. FUSE2 also makes code re-usable, as modules can be used across the community and are not limited to a single model structure. After decades of siloed model development, we argue that MMFs are essential to develop and improve hydrological models in a coordinated fashion across the community.
Is Tuning of Auto-conversion Important for the Realistic Simulation of Indian Summer Monsoon Intraseasonal Oscillations and MJO in Coupled Climate Model?
Authors: Dutta Ushnanshu , Hazra Anupam , Chaudhari Hemantkumar , Saha Subodh Kumar , Pokhrel Samir
Published: March 2020

 

 
SWOT Mission Capabilities for the Prediction of Flow-Duration Curves: A Global Scale Assessment
Authors: Domeneghetti Alessio , Pugliese Alessio , Castellarin Attilio , Brath Armando
Published: March 2020

The Surface Water and Ocean Topography (SWOT) satellite mission will provide high-resolution estimates of riverine water surface characteristics, such as river surface width, elevation and slope. Those parameters will enable a global estimation of river discharges flowing into rivers wider than 100 m, with a temporal resolution varying from 3 to 10 days, in dependence of latitude. Although errors on streamflow estimates are expected to be highly dependent on flow regimes and geomorphic conditions, the mission potential on providing insights on the hydrological regime of inland rivers is still not fully investigated. To this end, in this study we propose a comparison of remotely sensed and empirical period-of-record flow-duration curves (FDCs) on worldwide basis. We used the Global Runoff Data Centre (GRDC) dataset, the world largest and freely available source of streamflow data. We filtered the original dataset by selecting only those sites that matched 2 criteria: river width larger than 100 m and streamflow time series longer than 10 years of continuous daily discharges. Such dataset query resulted in 1200 gauged river cross-sections readily available to be used for our purposes. To simulate SWOT observations, each record has been reduced following 4 different sampling scenarios, i.e. 3, 5, 7, and 10 days interval for a 3-year moving time-frame (i.e., SWOT mission lifetime). We then corrupted gauged data with random errors sampled from a gaussian distribution having zero mean and 30% standard deviation. For each site, we obtained a set of SWOT simulated FDCs to compare with their empirical counterparts. We found that tropical and temperate climates deliver good estimates throughout flow regimes, whereas, mostly arid climates may have higher uncertainties, especially for high- and low-flows.
TETGAR_C: a three-dimensional (3D) provenance plot and calculation tool for detrital garnets
Authors: Knierzinger Wolfgang , Wagreich Michael , Lee Eun Young
Published: March 2020

We present a new interactive MATLAB-based visualization and calculation tool (TETGAR_C) for assessing the provenance of detrital garnets in a four-component (tetrahedral) plot system (almandine–pyrope–grossular–spessartine). The chemistry of more than 2,600 garnet samples was evaluated and used to create various subfields in the tetrahedron that correspond to calc-silicate rocks, felsic igneous rocks (granites and pegmatites) as well as metasedimentary and metaigneous rocks of various metamorphic grades. These subfields act as reference structures facilitating assignments of garnet chemistries to source lithologies. An integrated function calculates whether a point is located in a subfield or not. Moreover, TETGAR_C determines the distance to the closest subfield. Compared with conventional ternary garnet discrimination diagrams, this provenance tool enables a more accurate assessment of potential source rocks by reducing the overlap of specific subfields and offering quantitative testing of garnet compositions. In particular, a much clearer distinction between garnets from greenschist-facies rocks, amphibolite-facies rocks, blueschist-facies rocks and felsic igneous rocks is achieved. Moreover, TETGAR_C enables a distinction between metaigenous and metasedimentary garnet grains. In general, metaigneous garnet tends to have higher grossular content than metasedimentary garnet formed under similar P–T conditions.
A boosting algorithm for Generalized Extreme Value distributions
Authors: Peter Madlen , Pasternack Alexander , Rust Henning
Published: March 2020

In weather and climate science statistical modeling is applied for manifold problems. Due to the increasing number of input variables, overfitting can easily deteriorate the performance for model predictions.  In order to avoid this, it is often meaningful to apply model selection approaches. Since conventional approaches can be very time-consuming especially for many predictors, we are using the boosting approach, which combines model selection and parameter estimation.  This iterative algorithm identifies and updates in each step only the most important coefficient, such that in the end most important predictor variables have non-zero coefficients and less relevant variables are ignored.
Boosting has been originally developed for classification problems but has also been extended and used for other applications; i.a. non-homogeneous gaussian regression. Based on the  non-homogeneous boosting proposed by Messner et al. (2016), which is used to model mean and variance of a forecast distribution simultaneously, we have developed a boosting algorithm for a non-stationary Generalized Extreme Value distribution (GEV). Thus, it is possible to identify the most relevant predictor variables for location, scale and shape parameter concurrently. We apply this algorithm to various toy model simulations to assess the effect of this novel approach.
Time dependent backward piping erosion 2D modeling with laminar flow transport equations
Authors: Aguilar-Lopez Juan Pablo , Wewer Manuel , Bogaard Thom , Kok Matthijs
Published: March 2020

Backward piping erosion (BEP) is a highly complex erosive process which occurs on granular soils when large head differences are exerted. This process represents a significant threat to dams and levees stability and therefore a large part of the design and reliability assessment of these water retaining structures is devoted to this single process. Several authors have achieved great accuracy in predicting the critical head difference that triggers the process but not so much has been studied regarding the time of occurrence and the duration of the erosive process.  In the present study we propose a 2D finite element model for which not only the critical head difference can be predicted but also the development of the erosive process in time. This was achieved by coupling the 2D Darcy partial differential equation with Exner’s 1D sediment transport mass conservation equation. Different laminar sediment transport rate empirical models were tested and used as inputs in the coupled model. To test the performance of the proposed model, the IJkdijk real scale experiment for piping erosion was simulated. The results show that the model is capable of predicting not only the critical head and its progression in time but also specific events of the process such as the instants of start of the erosion and the  complete seepage length development . An important conclusion of the study is that from several transport empirical formulas tested, the model from Yalin which is widely recognized by the sediment transport community performs the best.
Comparison of local amplification factors for fast forecast coastal tsunami amplitude modeling based on the extended Green’s law
Authors: Gailler Audrey , Giles Daniel
Published: March 2020

In the framework of operational conditions, the real time coastal modeling in near field is challenging to obtain accurate and reliable tsunami warning products for flooding hazard. Two main approaches are usually developed to generate maps of forecasting inundation and impacts for planning community response. One produces coastal predictions with run-up computation by solving numerically high-resolution forecast models in real time, taking into account all local effects. However, these runs depend on the availability of fine bathymetry/topography grids along the shore and are too time consuming in near field and operational context. The second approach is based on early prediction tools of the coastal wave amplitude calculated from empirical laws or transfer functions derived from these laws. Such tools are suitable in near field context (almost ten times faster than the high-resolution runs), but all local effects are not well taken into account and the assessment of run-up is missing. The linear approximations of coastal tsunami heights are provided very quickly, with global and conservative estimates.

Within the French Tsunami Warning Center (CENALT), a forecast method based on coastal amplification laws is being implemented. This fast prediction tool provides a coastal tsunami height distribution, calculated from the numerical simulation of the deep ocean tsunami amplitude and using a transfer function derived from the Green’s law. The method involves maps of regionalized values of the empirical correction factor function of the coastal configuration, as a way to amplify or attenuate specific local geometries. Due to a lack of tsunami observations in the NEAM basin, coastal amplification parameters are defined by trial and error regarding high resolution nested grids simulations on the basis of a set of historical and synthetic sources. A method to optimize these local amplification factors by minimizing a cost function is being developed at UCD. Comparisons are shown for several French coastal sites.

The local tsunami wave heights modeled from the extended Green’s law present a good agreement with the time-consuming high resolution models. The linear approximation is obtained within 1 min and provides estimates within a factor of two in amplitude. Although the resonance effects in harbors and bays are not reproduced and the horizontal inundation calculation needs to be studied further, this method is well suited for an early first estimate of the coastal tsunami threat forecast.
Summertime and wintertime atmospheric processes of secondary aerosol in Beijing
Authors: Duan Jing , Huang Rujin , Lin Chunshui , Ni Haiyan , Wang Meng
Published: March 2020

Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable studies in recent years. To elucidate the seasonal variations of fine particles composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) combined with other online instruments were used to characterize the submicron particulate matter (diameter < 1 μm, PM1) in Beijing during summer and winter 2015. Our results suggest that the photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueous-phase reaction became an important process for sulfate formation during winter. High concentration of nitrate (17% of the PM1 mass) was found during winter explained by enhanced gas-to-particle partitioning at low temperature, while high nitrate concentration (19%) was also observed under the conditions of high relative humidity (RH) during summer likely due to the hydrophilic property of NH4NO3 and hydrolysis of N2O5. As for SOA formation, photochemical oxidation perhaps played an important role for summertime oxygenated OA (OOA) formation and wintertime less oxidized OOA (LO-OOA) formation. The wintertime more oxidized OOA (MO-OOA) showed a good correlation with aerosol liquid water content (ALWC), indicating more important contribution of aqueous-phase processing than photochemical production to MO-OOA. Meanwhile, the dependence of LO-OOA and the mass ratio of LO-OOA to MO-OOA on atmospheric oxidative tracer (i.e., Ox) both degraded when RH were greater than 60%, suggesting that RH or aerosol liquid water may also affect the LO-OOA formation.
Macro-plastic weathering in a coastal environment: field experiment in Chesapeake Bay, Maryland
Authors: Rizzo Marzia , Lane Benjamin , Malkin Sairah , Vaccaro Carmela , Simeoni Umberto , Nardin William , Corbau Corinne
Published: March 2020

It is now widely recognized that marine plastics, which are strongly resistant to chemical and biological degradation, have become a widespread and massive pollutant in the world’s oceans. Despite this resistance, in the environment, larger plastic items fragment and degrade into secondary microplastics which are ingestible by some marine organisms and are therefore a potential threat to aquatic foodwebs. The present study aims to better understand factors that contribute to the weathering of plastics in a coastal marine environment, where most microplastics appear to be generated. 

Here we performed a field experiment to test the influence of different coastal conditions on macro-plastic weathering. Strips of commercial grade high-density polyethylene (HDPE) and polystyrene (PS) were mounted in replicate on racks (similar in appearance to keys on a glockenspiel, though all of the same length) and deployed at different treatment depths (subtidal versus intertidal) and different treatment hydrodynamic intensity zones (erosional versus depositional) in a sub-estuary of Chesapeake Bay (Maryland, USA). Strips were collected after environmental exposure of 4, 8 and 43 weeks and were analyzed for mass loss, surface chlorophyll accumulation, and surface appearance via SEM imaging.

We observed the PS strips degraded more quickly than the HDPE strips. The results show minor mass variation, in some samples even a slight mass increase, contrary to expectation. This was probably due to the deposition of clay and the presence of microorganisms into the microstructure of the strips, as observed by SEM. Moreover, the SEM images show different kind of fragmentation, with holes or with desquamations. The fragmentation was most marked for the PS strips located at intertidal depths caused by a more intense hydrodynamic energy. Finally, an increase over time was observed in the concentration of chlorophyll in both subtidal depositional PS strips and in subtidal erosional HDPE strips, associated with a lower hydrodynamic energy compared to the intertidal zones. This appears to confer a greater protection of the plastic which therefore undergoes less weathering.
Synchronization of traveling waves in coupled dispersive systems
Authors: Makarenko Nikolay , Makridin Zakhar
Published: March 2020

Сoupled KdV-type equations arise in multimodal dispersive models such as the Gear – Grimshaw system which describes weakly nonlinear internal waves in neighboring pycnoclines. Coupling occurs when two or more phase speeds of different modes are close together.  This phenomenon of kissing modes is known as the Eckart resonance providing energy transfer between pycnoclines in stratified fluid. Decoupled basic equations generate separated modes of traveling waves with different phase shifts. In this context, synchronization means the existence of coupled phase-shifted solutions which can be constructed from decoupled modes by appropriate perturbation procedure.  In the present paper, we consider analytic conditions which provide the existence of periodic solutions describing synchronized cnoidal-type wave trains. Application of the Lyapunov – Schmidt method reduces this problem to the nonlinear system of implicit bifurcation equations for unknown phase shift and wave amplitude. Asymptotic analysis of these equations results sufficient condition of synchronization, which involves the Poincare – Pontryagin function depending on coupling nonlinear terms. In addition, we illustrate two different limit cases which lead to the same existence condition.  First of them corresponds to a solitary-wave limit for cnoidal waves (i.e. a nonlinear long-wave limit), and the second one is adapted to a small-amplitude limit of coupled harmonic wave packets.

This paper was supported by RFBR (grant No 18-01-00648).
P wave anisotropy caused by partial eclogitization of descending crust demonstrated by modeling effective petrophysical properties
Authors: Zertani Sascha , Vrijmoed Johannes C. , Tilmann Frederik , John Timm , Andersen Torgeir B. , Labrousse Loic
Published: March 2020

Eclogitization occurs deep in subduction and collision zones inaccessible to direct observation. Field-based studies dealing with crustal material previously transformed at eclogite-facies conditions and exhumed to the surface provide information from the micro scale up to a few kilometers. On the other hand, geophysical methods aim at imaging the ongoing processes in-situ. However, these methods are limited by the achievable resolution and typically only sensitive to structures a few kilometers in size, leaving a large gap between the scales at which observations are interpreted. In this study we try to discern the implications of structures mapped in field-based studies to interpretations of geophysical imaging. We therefore calculated effective anisotropic P wave velocities for a suite of representative structural associations using the finite element method. The structural associations are directly extracted from observations of partially eclogitized assemblages on the island of Holsnøy in the Bergen Arcs of western Norway. Physical properties of the constituting lithologies are taken from laboratory measurements of the same rocks and the calculations are performed on a variety of scales, from the 20-m scale up to the kilometer scale to be able to predict how the effective seismic properties change with varying scale. Our results show that the P wave velocity of the effective medium is solely controlled by the volumetric fraction of the constituting lithologies and their elastic properties. We find that the structural relationship of the different lithologies has no significant influence on the resulting seismic velocities. P wave anisotropy, however, is controlled by the constituting lithology with the highest initial anisotropy and to a lesser extent by the modal abundance of the different lithologies. Further, our results show that seismic anisotropy is largely transferable across scales validating the assumptions often made when measuring seismic velocities on centimeter-sized sample volumes. On the kilometer scale, a scale that is potentially resolvable by geophysical methods, our results show that an eclogite-facies shear zone network such as the one exposed on Holsnøy would indeed produce a significant P wave anisotropy on a crustal scale. This anisotropy is produced by the eclogite-facies shear zones themselves even though eclogites are typically considered to be low-anisotropy rocks. Comparison of our results with active settings of continental collision and subduction zones reveals that eclogite-facies shear zones have the potential to produce a significant backazimuthal bias of the retrieved signal in geophysical imaging and underline the significance of seismic anisotropy as a tool to further increase the sensitivity of seismological methods to lithological variations.
Agriculture in Southern Mediterranean areas under climate change: Impacts on irrigated wheat grain yield and irrigation requirements
Authors: EL houssaine Bouras , Lionel Jarlan , Said Khabba , Salah Er-Raki , Alain Dezetter , Fathallah Sghir , Tramblay Yves
Published: March 2020

The southern Mediterranean regions are likely to face drastic climate changes (CC). Agricultural yields, particularly of cereals, could be severely affected, especially if significant changes occur at the key phenological stages. In addition, while agriculture is expected to meet around 83% of North African food demand by 2050, the increase in agricultural water requirements due to the intensification of practices, the extension of arable land and the expected warming could jeopardize the water supply of other key economic sectors. In this context, the present work aims to quantify the impact of CC on the grain yields of irrigated cereals and their water requirements in the Tensift-Haouz region of Morocco. The Med-CORDEX ensemble runs under scenarios RCP4.5 and RCP8.5 are first evaluated and disaggregated using the quantile-quantile approach. The impact of CC on the duration of the main wheat phenological stages based on the degree-day approach is then analysed by considering three typical sowing dates (early, around November 15th; intermediate, around December 15th; and late, around January, 15th). The results show that the rise in air temperature causes a shortening of the development cycle of up to 50 days (around 30%). The impacts of rising temperature, increasing atmospheric CO2 concentration and changes in precipitation on wheat yields are next evaluated, based on the AquaCrop model (previously calibrated on several plots of winter wheat in the region of study), both with and without taking into account the fertilizing effect of CO2. As expected, optimal wheat yields for all climate scenarios and time horizons will decrease on the order of 7 to 30% depending on the sowing date, if CO2 concentration rise is not considered. The results also show that the fertilizing effect of CO2 can counterbalance yield losses, since optimal yields could increase by 7% and 13% respectively at mid-century for the RCP4.5 and RCP8.5 scenarios. Finally, water requirements are expected to decrease by 13 to 42% depending on sowing date, scenario and horizon, mainly in response to the shortening of the cycle. This decrease is associated with a change in temporal patterns, with the requirement peak coming two months earlier than under current conditions. This study provides some quantitative elements for agricultural practices adaptation, in particular concerning the sowing date and also for water management in the south mediterranean region related to the temporal patterns of the crop water needs
K.ROOF II - Re-Watering after 5 Years of Repeated Summer Drought in Mature Beech and Spruce: Assessing Water Uptake and Allocation via Deuterium Labeling
Authors: Hesse Benjamin D. , Gebhardt Timo , Hafner Benjamin , Häberle Karl-Heinz , Grams Thorsten E. E.
Published: March 2020

Every drought period will eventually end and plants will have access to water again. This phase of “re-watering” is a critical point that will either ensure survival or collapse of ecosystems. The drought years 2018 and 2019 have laid bare how vulnerable Central European forest-systems are, even under short-term water scarcity. To understand the effects of repeated summer drought and its release on mature forest stands we investigated the recovery of a mixed forest stand. After 5 years of repeated experimental summer drought on roughly 100 trees (with n = 6 plots) the second phase of the Kranzberg Forest Roof (k.roof) experiment was started, which focuses on the re-watering with Deuterium labeled water (2H2O) of the mature stand composed of European beech (Fagus sylvatica (L.)) and Norway spruce (Picea abies (L.)H.Karst.). According to our hypotheses the water household of the more anisohydric beech will recover faster and “stronger” (higher resilience) than the more isohydric spruce, due to the differences in stomatal control (hypothetical hydraulic regulation in beech vs. hormonal (ABA) control in spruce). We simulated a rainfall event to end our experimental drought and labeled the throughfall-exclusion (TE) and control (CO) plots of the k.roof experiment with roughly 13000 L for TE and 2000 L for CO of 2H2O enriched water, i.e. δ2H 1500 and 400 ‰ respectively. We traced the 2H2O signal along the soil-plant-atmosphere continuum (SPAC) from the soil through the stems and branches up to the leaves with conventional and real-time techniques (xylem sensors connected to CRDS system). Additionally, we measured leaf water potential and pressure-volume (PV) curves to assess the release of the drought stress. The distribution of the “new” water within the soil happened within a few days and we could not find any differences between the beech, mix or spruce dominated sites. However, the water uptake of the trees was significantly delayed in spruce compared to beech, evident from both the deuterium tracer signal (in stems and leaves) and leaf water potential. However, release of osmotic adjust was not different in the two species. The data allow for estimating the drought resilience of the water household of a mature forest stand after five-years of repeated summer drought and subsequent re-watering. While both species recovered their water household after several months to the same level as the control trees, we found beech to react faster and stronger than spruce.