bluuebunny/crossref_metadata_2025 huggingface dataset:
Routes to stability for spatially periodic breather solutions of a damped NLS equation.
Authors: Schober Constance
Published: March 2020

 The spatially periodic breather solutions (SPBs) of the nonlinear Schrödinger (NLS) equation, i.e. the heteroclinic orbits of unstable Stokes waves, are typically unstable. In this talk  we examine  the effects of dissipation on the  one- mode SPBs  U(j)(x,t) as well as multi-mode SPBs U(j,k)(x,t) using a damped  NLS equation which incorporates both uniform linear damping and nonlinear damping  of the mean flow,
for a range of parameters typically encountered in experiments. The damped wave dynamics is viewed as near integrable, allowing one to use the spectral theory of the NLS equation to interpret the perturbed flow. A broad categorization of how the route to stability for the SPBs  depends on the mode structure of the SPB and whether the damping is linear or nonlinear is obtained 
as well as the distinguishing features of the stabilized state.  Time permitting, a reduced, finite dimensional dynamical system that goverms the linearly damped SPBs will be presented 
The Daytime and Nighttime Mapped Whistler Plasmapause Observed by DEMETER
Authors: Chen Chao-Yen , Liu Jann-Yenq
Published: March 2020

This paper investigates the plasmapause positions in the ionosphere by measurement of the whistler count probed by DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite in the daytime at 1030 LT (local time) and the nighttime at 2230 LT during 2005-2010.  The whistler finds the plasmapause position which can be clearly allocated in both daytime and nighttime.  We examine the nighttime/daytime plasmapause in various longitudes, solar activities, seasons, and geomagnetic actives.  Results show that the daytime plasmapause appears in the equatorward side of the nighttime one.  Both the daytime and nighttime plasmapause are sensitive to solar activity, which move equatorward form the low to high solar activity in the study period.  The seasonal variation of the plasmapause are rather random and insignificant.  During magnetic disturbed condition, the plasmapause tend to move equatorward.
Probabilistic modeling of the water availability in a large surface reservoir in the Netherlands
Authors: Hurkmans Ruud , Geerse Chris , Kuijper Bastiaan , Klopstra Durk , de Jong Bas , Berger Herbert , van Twuiver Hans
Published: March 2020

During dry spells, a large part of the Netherlands depends on water from the IJssel lake, a large surface water reservoir. Water is extracted for a number of purposes, such as irrigation, water quality, shipping and drinking water. Besides local precipitation, the main source of water flowing into the lake is the river IJssel; a distributary of the Rhine. During periods of low discharge and low precipitation, water shortages may occur, as the recent summer of 2018 showed. ​We develop a probabilistic model to simulate water availability in the lake during dry spells. We derive marginal distributions of precipitation, open water evaporation, river discharge and water intake from the surrounding region, based on a 101-year simulation of the deterministic Dutch national water model. We assess the plausibility of the resulting extreme tail of the distributions by comparing them to values based on the ECWMF seasonal reforecasting archive, which, when all ensemble members, years and lead times are combined, contains over 4,000 years of data. All correlations between the four terms are modeled using a four-dimensional copula. The resulting distributions of water availability show aggregated water shortages up to extremely dry (return periods in excess of 10,000 years) conditions. Lake level dynamics are, during dry conditions, dominated by high water demand from the surrounding region (caused by lack of local precipitation) and low IJssel river discharges. A coincidence of these two terms causes the most extreme shortages. Because model is conceptually relatively simple, it is able to run a large number of realizations and is potentially highly suitable for, for example, assessment of measure effectiveness.

 
Composting winery wastes with clinoptilolite. Suitability for land application.
Authors: Kolovos Chronis , Doula Maria , Kavasilis Stamatios , Zagklis Georgios , Tsitselis Gerasimos , Kostopoulos Panagiotis
Published: March 2020

Soil application of raw winery wastes is a procedure of doubtful appropriateness, mainly because of waste properties, i.e. very acidic pH; high electrical conductivity; and high content of polyphenols. The disposal of winery waste on soils may cause various environmental and health hazards as for example soil overloading with polyphenols and salts, phytotoxicity to plants, odor nuisance etc. Pathogens, which may still be present in the decomposed material could spread plants and soil diseases, while waste piles attract insects, pests, domestic rodents and wildlife which may threaten public and animal health. Despite these facts, many wine producers discharge winery waste to the nearby agricultural or forest ecosystems, without treatment although this type of agricultural waste could be a significant source of organic matter and nutrients.

 

In general, degradation of winery waste is a slow procedure which becomes even slower under the xerothermic climatic conditions in Greece, which may slow down the microbially mediated decomposition of organic matter and nutrients cycling; degradation of winery waste piles takes more than 5 years to be completed naturally. However, the final products are of doubtful appropriateness for fertilization use, mainly because of low quality organic matter and low nutrients content (lost mainly due to the exposure of piles to uncontrolled environmental conditions for years).

 

This study aims to highlight the advantages of composting winery wastes by using also other agricultural wastes and additives as feedstock to produce a safe and environment friendly compost, appropriate for application to agricultural ecosystems. For this a 41 hectares vineyard in North Greece of about 400 tn grapes yield annually and generation of approximately 100 tn of waste was selected. Winery waste was collected after harvesting and wine-making period of 2018 and composted with cow manure, wheat straw and clinoptilolite up to 5%.

 

Composting phase lasted 5 months, and during this period the pile was monitored as regard temperature, moisture and oxygen content. After composting completion, the final product was fully characterized in terms of its physical and chemical properties, considering national legislation organic materials reuse on soils. The outcomes of this study show a great potential for managing such waste types by composting using clinoptilolite in the feedstock materials since the final product has suitable physical and chemical properties for many crops, i.e. slight alkaline pH, low electrical conductivity, low polyphenol content and high content of available nutrient, therefore can be used as soil amendment or organic fertilizer.
Assessment of decadal prediction skills and sensitivity to sea-ice thickness initialization in the Arctic when seasonal ice becomes dominant in the Arctic
Authors: Tian Tian , Yang Shuting , Karami Pasha , Massonnet François , Kruschke Tim , Koenigk Torben
Published: March 2020

The Arctic has lost more than 50% multiyear sea ice (MYI) area during 1999-2017. Observation analysis suggests that if the decline of the MYI coverage continues, changes in the Arctic ice cover (i.e. area and volume) will be more controlled by seasonal ice than the effect of global warming. To investigate how large and where the source of Arctic prediction skill is given a large losses of thick MYI during the last two decades, we explore the decadal prediction skills and sensitivity to sea ice thickness (SIT) initialization from the EC-Earth3 Climate Prediction System with Anomaly Initialization (EC-Earth3-CPSAI). Three sets of ensemble hind-cast experiments following the protocol for the CMIP6 Decadal Climate Prediction Project (DCPP) are carried out in which the predictions start from: 1) a baseline system with ocean only initialization; 2) with ocean and sea ice concentration (SIC) initialization; 3) with ocean, SIC and SIT initialization. The hind-cast experiments are initialized and validated based on the ERA-Interim-reanalysis for the atmosphere and ORAS5 for ocean and sea-ice, with a focus period 1997-2016. All initialized experiments show better agreement with ORAS5 than the CMIP6 historical run (i.e. the Free run) for the first winter sea ice forecast. The SIT initialized experiments show the best skill in predicting SIT (or volume) and the added value by greatly reducing errors of near surface air temperature over the Greenland and its surrounding waters. In the Central Arctic, the Beaufort and East Siberian Seas, there are only minor differences in prediction skills on seasonal to decadal time scales between the ocean-only initialized and the SIT initialized experiments, indicating that the source of predictability in these regions are mainly from the ocean; while the ocean-only initialization degrades skill with larger RMSE than the Free run, e.g. during the ice-freezing season in the GIN and Barents Seas, or at  the summer minimum in the Kara Sea, the added value from the SIT initialized experiment is present, and it may have long-term effect (>4 years) probably associated with sea-ice recirculation. In all cases, the improvement from the ocean-only initialization to also including SIC initialization is found negligible, even somehow degrading the skills. This highlights the important use of SIT in predicting changes in the Arctic sea ice cover at various time scales during the study period. Therefore, the sea-ice initialization with constraint on SIT is recommended as the most effective initialization strategy in our EC-Earth3-CPSAI for present climate prediction from seasonal to decadal time scales.
Towards publishing soil and agricultural research data: the BonaRes DOI
Authors: Svoboda Nikolai , Specka Xenia , Hoffmann Carsten , Heinrich Uwe
Published: March 2020

The German research initiative BonaRes (“Soil as a sustainable resource for the bioeconomy”, financed by the Federal Ministry of Education and Research, BMBF) was launched in 2015 with a duration of 9 years and perpetuation envisaged. BonaRes includes 10 collaborative soil research projects and, additionally, the BonaRes Centre.

Within the BonaRes Data Centre (important infrastructure in the planned NFDI4Agri), diverse research data with mostly agricultural and soil background are collected from BonaRes collaborative projects and external scientists.  After a possible embargo expires, all data are made available in a standardized form for free reuse via the BonaRes Repository. Once the administrative and technical infrastructure has been established, the Data Centre provides services for scientists in all terms of data management. The focus here is on the publication of research data (e.g. long-term experiments, field trials, model results) to ensure availability and citeability and thus foster scientific reuse. Available data can be accessed via the BonaRes Repository. For instance: https://doi.org/10.20387/BonaRes-BSVY-R418.

Due to the high diversity of agricultural data provided via our repository, we have developed individually tailored strategies to make them citable for 1.) finalized data, 2.) regularly updating and 3.) data collections with related tables. The challenge is that the author's rights (license CC-BY) must be preserved and yet a user-friendly citation of even large amounts of data must be ensured. We will present our BonaRes DOI concept by means of use cases and will be looking forward to discuss it with the professional community.
Comparison of noble gas temperature with recent mean annual air and soil temperature in different regions of Hungary
Authors: Puskás-Preszner Anita , Fekete Carmen , László Elemér , Kompár László , Hajnakl Andor , Palcsu László
Published: March 2020

This paper describes the relation of noble gas temperature (NGT) and mean annual air (MAAT) and soil (MAST) temperature through studying water samples and meteorological data from six Hungarian regions. Alluvial plains, hilly and mountainous regions were studied to investigate the effects of geomorphological, hydrogeological and micro-climatic conditions. Water samples were collected from springs and wells fed from different aquifers. Comparing NGTs derived from these water samples with the MAAT and MAST values of the given region, we identified differences between the sampled areas. In case of the Geresd Hills, Mezőföld, Danube-Tisza Interfluves and Nyírség, the NGTs (13.0 ± 0.9 °C, 12.1 ± 1.1 °C, 12.1 ± 0.6 °C and 12.7 ± 1.6 °C, respectively)  generally reflect MAST, however in karstic Bükk Mts. (6.8 ± 0.6 °C) and Mecsek Mts. (10.7 ± 1.9 °C) they are closer to MAAT. Consequently, it can be concluded that the direct relationship between noble gas temperature and mean annual air temperature is not always as well-defined as it is often assumed. It is shown that MAAT and MAST should be distinguished, especially when using NGT as a paleoclimate proxy.
The first definition of paleointensity in the Early Cretaceous basalts from the Franz Josef Land
Authors: Vinogradov Evgeniy , Eliseev Andrey , Metelkin Dmitriy , Abashev Victor , Vernikovsky Valery , Mikhaltsov Nikolay
Published: March 2020

We present the first definition of paleointesity of the Earth’s magnetic field that were obtained in the Early Cretaceous igneous rocks from the Franz Josef Land archipelago (Hooker and Scott Kelty Islands). The age of magmatism was determined by U-Pb method as the Early Cretaceous, about 125 Ma. A mean paleomagnetic direction for these rocks was calculated as D=40.2 deg, I=75.5 deg, a95=2.1 deg, k=89.3, N=52. A corresponding paleomagnetic pole is now located at Plat=69.0 deg; Plon=180.3 deg, A95=3.7 deg. An assessment of the domain structure of ferrimagnets using the Day plot diagram shows that the carriers of the natural remanent magnetization are pseudo-single-domain grains of titanomagnetites with varying Ti-content. Magnetic remanence was unblocked in temperatures of 350-400 °C. Some samples are characterized by unblocking temperatures of 560 °C. The determinations of the absolute values of paleointensity were obtained by the Thellier-Coe method with the implementation of the procedure "check-points". The values of Banc vary within 8.4–16 µT, which is noticeably lower than the current magnetic field at the sampling point ≈55 µT. The corresponding VDMs of 1.13–2.25 × 1022 Am2, with the current value of VDM ≈8 × 1022 Am2. Numerous basalt flows are well studied by paleomagnetic and rockmagnetic methods, together with a large number of geochronological definitions, this makes basalts from the Franz Josef Land promising for obtaining new qualitative determinations of paleointensity in the Early Cretaceous time.

This work was supported by the RSF (project no. 19-17-00091) and the RFBR (project nos. 18-35-00273, 18-05-70035).
A multi-dimensional Sentinel-based Soil Monitoring Scheme (S2MoS) for soil clay content estimation
Authors: Tziolas Nikolaos , Tsakiridis Nikolaos , Ben Dor Eyal , Theocharis John , Zalidis George
Published: March 2020

Earth Observation (EO) has an immense potential as an enabling tool for mapping the spatial variation of the topsoil layer. Additionally, machine learning based algorithms deployed on cloud computing infrastructures have a great potential to revolutionize the processing of EO data. This paper aims to present a multi-dimensional Sentinel-based Soil Monitoring Scheme (S2MoS) based on open-access Copernicus Sentinel data and the Google Earth Engine platform to map soil properties. Building on key results from existing data mining approaches to extract bare soil reflectance values the current study presents i) preliminary insights on the synergistic use of open access SAR and optical images obtained from Sentinel-1 and Sentinel-2 sensors; and ii) evaluate the efficiency of machine learning algorithms to predict soil attributes based on multi-temporal analysis. In that regard, this study evaluated, based on Sentinel images extending over a 3 years period (2017-2019), the performance of two state of the art machine learning approaches, namely random forest and neural networks. Spatial thresholds values of 0.25 and 0.075 for Normalized Difference Vegetation Index and Normalized Burn Ratio 2 indices respectively were applied to mask bare soil pixels. In this study, we used 5000 soil data belonging to cropland land use from the European LUCAS topsoil database. We calibrated the models based on 4000 soil samples and then validated this approach with the rest 1000 samples  predict soil clay content. A higher prediction performance (R2=0.53) was achieved by the inclusion of both types (SAR and optical) of observations using the neural network model, demonstrating an improvement of about 5% in overall accuracy compared to the R2 using the multi-year median optical composite.
On the impact of the hydrological model and catchment hydrology on the design flood estimation in a small catchment in Central Italy affected by the recent 2016 earthquake events
Authors: Azimi Shima , Barbetta Silvia , Moramarco Tommaso , Tarpanelli Angelica , Camici Stefania , Formetta Giuseppe , Rigon Riccardo , Massari Christian
Published: March 2020

Flood is one of the most frequent disasters which dangerously impacts societies and economies worldwide. Floodplain management and hydraulic risk analysis based on design flood estimation are essential tools to reduce damages and save human lives. Flood Frequency Analysis (FFA) has been classically used to derive design river discharge estimates, however, the scarce availability of discharge observations, especially in small catchments (<150 km2), makes its application not always possible. In addition, with the projections foreseen by the International Panel on Climate Change (IPCC) the use of FFA might lead to incorrect estimates of design river discharge as FFA is based on the concept of stationarity. Generally, long rainfall and temperature time series are much more available than discharge observations but their temporal coverage is often not sufficient for carrying out FFA via a hydrological simulation.

To handle these drawbacks, the combination of a stochastic generation of rainfall and temperature time series, Regional Circulation Model (RCM) projections and continuous hydrological models provides a reliable tool for obtaining long river discharge time series to implement FFA. However, design flood estimations can be significantly uncertain due to several factors such as 1) the specific model structure, parameterizations and processes representation, 2) the catchment hydrology and 3) the specific climate change scenario.

The primary objective of this study is to explore the sensitivity of the design river discharge estimates to the hydrological model complexity and parameterization. For this, three continuous hydrological distributed models named the Modello Idrologico SemiDistribuito in continuo (MISDc), the Soil & Water Assessment Tool (SWAT) and GEOFrame NewAGE model are forced with long timeseries of rainfall and temperature obtained via the Neyman-Scott rectangular pulse model (NSRP) for stochastic rainfall generation, and the fractionally differenced ARIMA model (FARIMA) for stochastic temperature generation. A secondary objective is to understand the impact of climate change and the catchment hydrology on the design river discharge estimates via the use of different RCM projections.

The study is carried in the Upper Nera catchment in Central Italy which was impacted by the recent 2016 earthquake and for which is necessary to identify hydraulic risk mitigation measures and adaptation for a forward planning in the floodplain areas where new settlements will be rebuilt.

Preliminary results suggest the high dependency of the design river discharge estimates to the chosen hydrological model and a different response of the sub-catchments to the climate change scenario.
To what extent can the synoptic weather explain high PM2.5 pollution in Seoul?
Authors: chang limseok , hong hyunkee , kim cheolhee
Published: March 2020

The change in PM level is the combined result of meteorological change and emission control. Meteorological change can strengthen or weaken the effectiveness of emission control. We applied an empirical and a statistical method to understand the effect of the meteorological variables on high PM2.5 event. A major meteorological mode associated with synoptic weather pattern that governs the high PM2.5 concentration in Seoul was identified through the empirical synoptic weather pattern classification and principal component analysis and regression. We used 2016-2018 PM2.5 observations from ~110 sites and 1 surface meteorological observation and 1 radiosonde observation within Seoul Metropolitan Area (SMA). Fifty cases with high PM2.5 concentration in SMA were selected in 2016 for the empirical weather pattern classification, and observed PM2.5 and meteorological data during 2017 ~ 2018 for the principal component analysis and regression.

As a result, a total of six synoptic weather patterns were derived, which was in agreement with the dominant meteorological mode of principal component analysis and regression. The dominant meteorological consists of high temperature at 850hPa, high geopotential height at 500hPa, high surface temperature, low wind speed at both surface and 850 hPa. The meteorological modes associated with the six patterns account for more than 90% of all high PM2.5 pollution days. Our results suggest that major synoptic weather modes can be used to easily predict high dust concentration potentials compared to WRF-SMOKE-CMAQ based air quality forecasting models.
Coastal risk assessments due to hybrid disasters in Korea
Authors: Kang Tae-Soon , Oh Hyeong-Min , Hwang Soon-Mi , Kim Ho-Kyun , Jeong Kwang-Young
Published: March 2020

Korean coasts are exposed to high risks such as storm surge, storm-induced high waves and wave overtopping. Also, localized heavy rainfall events have occurred frequently due to climate change, too. Especially, since coastal urban areas depend heavily on pump and pipe systems, extreme rainfalls that exceed the design capacity of drainage facility result in increasing inland flood damage. Nevertheless, the population in Korea is concentrated in the coastal areas and the value and density of coastal utilization are increasing. In this study, the risk of hybrid disasters in the coastal areas was assessed for safe utilization and value enhancement of coastal areas. The framework of the coastal risk assessment has been adopted from the concept of climate change vulnerability of the IPCC(2001). Coastal Risk Index(CRI) in this study was defined as a function of Exposure and Sensitivity exclude Adaptive Capacity using GIS-based DBs. Indicators of Exposure consisted of a storm surge, storm-induced high waves, wave overtopping and rainfalls. Indicators of Sensitivity consisted of human(population density), property(buildings and roads), and geography(inundation area). All these indicators were gathered from government agencies, numerical model experiments(ADCIRC, unSWAN, FLOW3D and XP-SWMM model), and field surveys(Drone & Lidar survey). And then spatial analysis was performed by using a GIS program after passing the quality control and analyzed data were standardized and classified 4 grades; Attention(blue color), Caution(yellow color), Warning(orange color) and Danger(red color). This frame of risk assessment was first applied to Marine City, Haeundae in Busan, Korea which was heavily damaged by the typhoon CHABA in 2018. According to the assessment results, it was confirmed that the results were in good agreement with the observation data and damage range. At present, the study area of risk assessment is expanding to other areas. The results of coastal risk assessment are used as reference indicators to identify and prevent the cause of coastal disasters, establish countermeasures, determine the development or management of coastal areas based on GIS, thus will contribute to effective and safe coastal management.
Dominica: transcrustal magmatic system and eruptive halogen budgets
Authors: d'Augustin Thiebaut , Balcone-Boissard Hélène , Boudon Georges , Martel Caroline , Deloule Etienne , Bürckel Pierre
Published: March 2020

Dominica island experienced the largest explosive eruptions (ignimbrites) of the Lesser Antilles arc. The recent revised chronostratigraphy of the Morne Trois Pitons – Micotrin eruptive activity evidenced a series of plinian eruptions that occurred between 18 ka and 9 ka BP. Here we focus on these recent eruptions in order to determine the magma storage conditions at depth and volatile degassing budget. Volatile concentrations (H2O, CO2) in melt inclusions indicate storage conditions of 200 MPa (~6-8 km deep) and 860-880°C in agreement with experimental constraints from phase-equilibrium data. The magmas were thus stored shallower than those involved during the ignimbritic eruptions (~16 km deep). Magma composition and halogen ratios suggest a common magma origin for all eruptions of Morne Trois Pitons Micotrin volcano in the last 60 kyrs. In addition, for the first time, a complete degassing budget including H2O, CO2, SO2, F, Cl, and Br has been established for all these explosive eruptions. The estimation of their eruptive fluxes towards the atmosphere supports the potential important role of halogen elements in the modification of atmosphere chemistry. Br degassing budget was the same order of magnitude as S whereas F and Cl budgets were 1 and 2 orders of magnitude higher than these two species.
Slab-derived fluid evolution induced from oxygen and hydrogen isotopes compositions of blueschist-facies phengites
Authors: Tsujimori Tatsuki , Pastor-Galán Daniel , Álvarez-Valero Antonio
Published: March 2020

Phengite is the most common metamorphic mineral in HP-UHP metasedimentary rocks, which can convey H2O, LILEs (especially K, Ba, Cs and Rb), Li, B and N in their structure formed at depths up to 300 km. The breakdown of phengite in a downgoing oceanic slab would cause fluid-induced element transport into the overlying mantle wedge. We have investigated the 2H/1H (D/H) and 18O/16O ratios of twenty-four phengite separates from pelitic schists of the Devonian–Carboniferous Renge Belt (SW Japan), Permian Shaiginsky Complex (Far East Russia) and Cretaceous Sambagawa Belt (SW Japan).

We found the presence of the very light hydrogen isotope (δD < –95‰) in blueschist-facies phengites in the three different metamorphic belts. For example, phengite from the lawsonite- and epidote-grade metasedimentary schists of the Osayama Serpentinite Mélange (OSM) of the Renge Belt are characterized by negative hydrogen isotope compositions (δD values relative to VSMOW) ranging from –113 to –93.9‰ and oxygen isotope compositions (δ18O values relative to VSMOW) ranging from +12.9 to +14.6‰.

High-Si features and K–Ar ages of the investigated phengites deny the possibility of meteoric-hydrothermal alteration to have caused the low δD values. The light values might be attributed to isotopic fractionation during progressive metamorphic dehydration.Assuming a meamorphic temperatures range of 250–350°C for the OSM schists, the inferred metamorphic fluid compositions in blueschist-facies depth for that fossil slab had a range of δD = ~–40 to –75‰ and δ18O = ~+13 to +15‰. These values are significantly lighter than the slab-fluid induced from the Arima hot spring water in a forearc region of modern SW Japan subduction zone. Our study suggests that slab-derived fluids in ancient Pacific-type subduction zone are characterized by light hydrogen isotope and that the phengite breakdown can affect hydrogen isotope of nominally anhydrous minerals (NAMs) in the deep mantle.
Flocculation of microplastic and cohesive sediment in natural seawater
Authors: Andersen Thorbjørn Joest , Rominikan Stiffani , Laursen Ida Stuhr , Skinnebach Kristoffer Hofer , Grube Nynne Zaza , Jedal Soeren Roger , Laursen Simon Nyboe , Fruergaard Mikkel
Published: March 2020

The flocculation of combinations of microplastic particles (MP) and natural cohesive sediment has been investigated in a laboratory setup using unfiltered seawater. The experiments were conducted in order to test the hypothesis that MP may flocculate in estuarine and marine environments with natural organic and inorganic particles. MP particles in the size-range 63 – 125 µm were incubated with suspensions of local untreated seawater and untreated fine-grained sediment (< 20µm) collected from a tidal mudflat. Settling experiments were carried out with both a floc-camera video equipment (PCam) and conventional settling tubes.

Flocculation and sedimentation of MP-particles of PVC have been investigated as well as particles from high density polypropylene which is used in certain fishing gear. The studies have generally confirmed our hypothesis that microplastics are incorporated into aggregates along with other natural particles, thus settling faster than they would as single particles. The exact aggregation mechanisms still remains to be revealed but the general cohesiveness of fine-grained natural particles, organic particles as well as particulate and dissolved organic polymers are believed to be responsible for the flocculation. A strong effect of salt ions was also observed, confirming the classical concept of increased flocculation of fine-grained particles as they are transported from fresh-water to estuarine and marine waters.

The implication of the aggregation is that primary MP from land-based sources are likely to flocculate with other suspended particles, especially as they enter saline waters. The particles are therefore expected to deposit close to the sources, typically rivers. This applies to both micro-plastic particles that are denser than seawater but also to low-density plastic types which should otherwise float. However, secondary MP may be formed by disintegration of plastic anywhere and these MP particles could therefore settle wherever there is plastic present at the sea surface, for example under the ocean gyres where plastic is known to accumulate. Here, too, interaction with other particles in the water column is expected, but the concentration of natural particles is much lower than in coastal waters and it may be that the transport of natural organic and inorganic particles will start to be modified if the concentration of plastic in the marine environment continues to rise.
Isotopic characterisation of methane emissions from oil and gas operation in Romania
Authors: Menoud Malika , van der Veen Carina , Maazallahi Hossein , Fernandez Julianne , Korben Piotr , Calcan Andreea , France James , Lowry David , Schmidt Martina , Röckmann Thomas
Published: March 2020

Reducing methane emissions is an important goal of climate change mitigation policies. Recent studies focused on emissions from oil and gas industry, because fixing gas leaks presents a "no-regret" mitigation solution. Yet, uncertainties regarding the fossil fuel emission rates and locations, as well as temporal and spatial variability, are still large for individual source processes, in particular in regions without regular measurements. The Romanian Methane Emissions from Oil and gas (ROMEO) project brought 13 research teams to Romania in order to quantify emissions from this sector. Methane stable isotopes are widely used for source characterisation, but measurement data is lacking from many important geographical locations, such as Eastern Europe. 

A total of 380 air samples were collected in urban areas and around oil and gas extraction sites, from ground level vehicles and from an aircraft. There were measured for δ13C-CH4 and δD-CH4 using a continuous flow isotope ratio mass spectrometry (CF-IRMS) system. The results were analysed using the Keeling plot approach to derive source signatures at each sampled site. The source signatures obtained for 76 individual oil and gas operation sites range from -70.5 to -22.4 ‰ V-PDB, and from -252 to -144‰ V-SMOW, for δ13C and δD respectively. They show a large heterogeneity in δ13C, and more regularity in δD values. Variations are affected by the maturity of hydrocarbon deposits, and by different contributions from microbial and thermogenic gas. We will present how the signatures measured at the surface relate to the signatures found for larger plumes sampled from the aircraft. The results of the campaign in Bucharest city reveal a larger contribution from the waste system than fossil fuel fugitive emissions. 

The isotopic characterisation of methane emissions in this region will help to constrain the methane budget on a regional scale, and to improve national inventories.
Combining time series of Sentinel-1 and -2 with in-situ data for estimating soil moisture at crop field scale
Authors: Padilla Marc , Pérez Ana , Pinilla Mirta
Published: March 2020

Soil moisture is one of the key variables for crop modeling and scheduling farm operations. Current available soil moisture products are generated at global or regional scales and its spatial resolution (~1km2) is usually too coarse for common small farms. Within the framework of the EU Horizon2020 funded TWIGA project, we intended to provide improved soil moisture estimates at crop field scale. The advantage of focusing at the scale of a single crop is that the algorithm selection can be based more on the retrieval accuracy rather than on the computing performance.

Time series of Sentinel-1 SAR backscatter (at VH and VV polarizations) and Sentinel-2 NDVI observations, on each crop field, were assimilated with a semiempirical polarimetric backscattering model for bare soil surfaces (Oh) coupled with a Water Cloud model (WCM). Some of the model parameters are the actual variables of interest to be estimated, in our case the daily surface soil moistures. They were estimated by a Bayesian inversion approach. The key advantage of using WCM, is that the effects of vegetation on backscatter can be taken into account, and therefore soil moisture estimates are available even when vegetation is present. The empirical model parameters (surface roughness, and A and B parameters of WCM) were calibrated with in-situ data from four stations in Ghana, with observations every 30 minutes from May to October 2019 at 10 cm depth. The calibration was based on a hierarchical Bayesian regression, to take into account that model parameter distributions might vary across land cover types and across in-situ stations themselves. The validation was based on the comparison between the soil moisture observations of one in-situ station and estimates from the model couple calibrated with the data from the other three in-situ stations. That procedure was repeated for each station. Correlation coefficients were above 0.64 and root mean square error bellow 0.065 m3/m3 in two out of the four stations. Accuracy tended to be dependent on field size, due to the well known SAR speckle noise. The station with the lowest accuracy was locate on a 30x30m2 field. Accuracy was additionally affected by likely sudden changes on the surface soil or vegetation during the analysis time windows. Correlation coefficients were higher (~0.85) on the time periods without such sudden changes.

Given the results of the current study, we would recommend that the location of eventual future in-situ stations should be preferably placed on larger fields, larger than 30x30m2. Further research would be needed to improve the model and understand better its limitations for an eventual operational implementation.

 
Factors Controlling the Thickness of the Jovian Current Sheet
Authors: Khurana Krishan , Paranicas Chris , Hospodarsky George
Published: March 2020

The Jovian current sheet is the main repository of Jupiter’s magnetospheric plasma. Spatial variations in its thickness and therefore its plasma content are poorly understood because thickness determination requires a knowledge of the motion of the current sheet relative to the observing spacecraft which is hard to get. Recently, we have developed a new technique that uses the timings of any three consecutive current sheet crossings to determine the instantaneous motion of Jupiter’s current sheet relative to the spacecraft. Next by using this technique and modeling the magnetic field and electron density dataset in terms of Harris current sheet type equilibria we can estimate the thickness and plasma content of the Jovian current sheet over all local times and radial distances. Our modeling of Juno and Galileo magnetic field data shows that in all local times the current sheet thickness increases with radial distance. We also find that the Jovian current sheet is highly asymmetric in local time, being at its thinnest in the dawn sector and the thickest in the dusk sector. The current sheet thickness on the dayside is comparable to that in the dusk sector. The nightside current sheet is intermediate in its thickness to the dawn and the dusk sectors.

We show that the increase in the thickness of the current sheet with radial distance can be explained in terms of the increasing temperature and therefore the plasma beta of the current sheet with radial distance. However what causes the sharp local time variations of the current sheet is not yet fully understood. We will discuss several models of plasma transport and redistribution in Jupiter’s magnetosphere that can create local time differences in the plasma content and therefore the current sheet thickness. These models have testable implications for the structure of the magnetosphere (open versus closed, convective versus diffusive transport of plasma etc.).
The sea-level signal in Pleistocene shallow-marine records – examples from carbonate and siliciclastic sequences
Authors: Mauz Barbara , Shen Zhixiong , Barlow Natasha , Hodgson David , Woodroffe Colin
Published: March 2020

It is generally accepted that sea-level change represents the most important boundary condition that controls stratigraphic architecture in the shallow-marine area and further downdip. The shallow-marine stratigraphic body is then a result of the changing ratio between sediment supply and accommodation space with a range of local (autogenic) processes interplaying with the eustatic (allogenic) sea level. Extracting the sea-level signal from this interplay is typically approached through rigorous interpretation of the indicative meaning of relevant sea-level markers and through comparison with the most appropriate glacio-isostatic adjustment (GIA) model. The latter comparison is insightful for the last glacial period, but for the Pleistocene it suffers from the dilemma that the GIA contribution to sea-level change cannot be predicted for a specific location unless the ice history is known but this is what the shallow-marine record is trying to reconstruct.

Here we aim for Pleistocene sea-level reconstructions that are largely independent of GIA predictions. For this we present Pleistocene shallow-marine records from high-, mid- and low-latitudinal settings. The presentation focuses on four aspects: type and quality of the data (e.g. outcrop, borehole, etc), preservation of the record, separation of allogenic versus autogenic signal and completeness of the eustatic cycle.

We show that in siliciclastic systems the preservation depends on sediment supply and on the coastal energy with which ravinement and regression surfaces obliterate the stratigraphic record. Separating autogenic from allogenic signals depends very much on data quality and the ability to reconstruct the antecedent topography. None of our records show a complete eustatic cycle from lowstand to highstand and back to lowstand where the missing part of the cycle seems to be indicative for the type of shallow-marine record and its location on earth.

We discuss reasons and implications of our findings and emphasise the need for far greater consideration of stratigraphic architecture, carbonate facies and facies correlation.
Comparison of natural and urban drainage network characteristics based on Gibbs’ Model
Authors: Kim Kyungjae , Seo Yongwon
Published: March 2020

Natural catchments have formed efficient river networks for a long time. similarly, urban drainage networks have been developed with the purpose of efficiently draining rainfall from catchments to flood mitigation. In this study, we analyzes and compares the characteristics between the naturally formed river networks for a long time and the artificially formed drainage networks using Gibbs’ Model. Gibbs’ Model is a stochastic stream network model, which can generate multiple realizations of stochastic networks based on a single parameter value of . Gibbs‘ Model was applied to a total number of 239 urban catchments in Seoul, South Korea and 70 natural catchments in the Midwestern areas of US. Topographic characteristics of catchments are analyzed along with the efficiency of drainage networks, which are presented by for both natural and urban catchments. The result of this study demonstrates the difference between natural and artificial drainage network characteristics and suggests a new alternative measures to mitigate flood risks in urban catchments facing extreme hydrologic events with climate change.
Towards a unified framework for maximum wave computation from numerical models: outcomes from the LATEMAR project.
Authors: Benetazzo Alvise , Barbariol Francesco , Pezzutto Paolo , Bertotti Luciana , Cavaleri Luigi , Davison Silvio , Sclavo Mauro
Published: March 2020

Reliable prediction of oceanic waves during severe marine storms has always been foremost for offshore platform design, coastal activities, and navigation safety. Indeed, many damaging accidents and casualties during storms were ascribed to the impact with abnormal and unexpected waves. However, predicting extreme wave occurrence is a challenging task, at first, because of their inherent randomness, and because the observation of large ocean waves, of primary importance to assess theoretical and numerical models, is limited by the costs and risks of deployment during severe open-ocean sea-state conditions.

In the context of the EU-based Copernicus Marine Environment Monitoring Service (CMEMS) evolution, the LATEMAR project (https://www.mercator-ocean.fr/en/portfolio/latemar/) aimed at improving the modelling of large wave events during marine storms. Indeed, at present, operational systems only provide average and peak wave parameters, with no information on individual waves whatsoever. However, developments of the state-of-the-art third-generation wave models demonstrated that using the directional wave spectrum moments into theoretical statistical models for wave extremes, forecasters are able to accurately infer the expected shape and likelihood of the maximum waves during storms.

The main purpose of the activity is therefore to provide the wave models WAM and WAVEWATCH III with common procedures to explicitly estimate the maximum wave heights for each sea state. LATEMAR achieved this goal by: performing an extensive assessment of the model maximum waves using field observations collected from an oceanographic tower; comparing WAM and WAVEWATCH III maximum wave estimates in the Mediterranean Sea; investigating the sensitivity of the maximum waves on the main sea state parameters. All model developments and evaluations resulting from this research project will be directly applicable to the wave model forecasting systems to expand their catalogue.
Modelling of impacts of erosion processes on agricultural landscapes due to intensive rainfall events
Authors: Kohnová Silvia , Németová Zuzana
Published: March 2020

At present, the occurrence of extreme precipitation events is becoming more and more frequent and therefore it is important to quantify their impact on the landscape and soil degradation processes. Until now a wide range of soil erosion models have been developed and many significant studies performed to evaluate soil erosion processes at local and regional level, but there are still many modeling principles that suffer from a range of problems. The general problem in soil erosion modelling lies in the validation and verification of the methodologies used. The validation of erosion models is a very complicated and complex process due to lack of suitable sites, financial demands and due to the high temporal and spatial variability. The paper points to validate the physically and event-based Erosion-3D model predominantly developed to calculate the amounts of soil loss, surface runoff, and depositions resulting from natural and design rainfall events. In the study two different erosion assessment methods were chosen in order to compare diverse evaluation approaches. Both water erosion assessment methods used have certain advantages and disadvantages, but nowadays the use of physically-based models, which are a younger generation of models, are regarded to be a more innovative and effective technique for the evaluation of complex runoff-erosion processes, deposition and transport processes. The significant contribution of physically-based models is seen in their more precise representation of the erosion and deposition processes, a more proper calculation of the erosion, deposition and sediment yields and the application of more complicated characteristics, including fluctuating soil conditions and surface properties in comparison with empirical models. The validation of the models was performed based on the continuous rainfall events for the period selected (2015, 2016 and 2017). The extreme rainfall events occurring during the period were chosen and their serious impact on the agricultural land was modeled. The modelled sediment data were compared with the measured sediment deposition data obtained by a bathymetry survey of the Svacenicky Creek polder. The polder is situated in the middle of the Myjava hill lands in the western part of Slovakia and the bathymetry measurement were conducted using a hydrographical survey using the EcoMapper Autonomous Underwater Vehicle (AUV) device. The results of the study include a comparison between the modelled and measured data and an assessment of the impact of the intensive rainfall events on the investigated territory.

Key words: intensive rainfall events, agricultural land, soil degradation processes, hydrological extremes, physically-based model