bluuebunny/crossref_metadata_2025 huggingface dataset:
Isotope insights into sulfate loads and sulfur cycling in a heavily polluted river network
Authors: Goldhammer Tobias , Lenz Juliane
Published: March 2020

Sulfate isotopes in a heavily polluted river network

Tobias Goldhammer1, Juliane Lenz2

1Leibniz-Institute for Freshwater Ecology and Inland Fisheries, Department of Chemical Analytics and Biogeochemistry, Berlin, Germany

2University of Bremen, Department of Geosciences, Germany

The Spree is the major river system in NE Germany, with about 380km in length and a catchment of more than 10,000 km2. While intensive open pit lignite mining in the upper catchment has significantly altered the hydrology and hydrochemistry over the last century, River Spree is at the same time a critical supplier of drinking water to the city of Berlin. Acid mine drainage is the major contributor to the river water sulfate load, which frequently exceeds the drinking water limit of 250mg L-1. Increasing summer drought and low-flow regimes are projected to intensify this situation in the future. The sulfate pollution in River Spree has induced a significant shift in biogeochemical regimes, in particular in those compartments of the river network where low flow velocity is supportive to sediment accumulation and bacterial sulfate reduction. Secondary effects include the mobility of iron and phosphorus, and entail critical consequences for the aquatic ecosystem.

In this contribution, we discuss the results of an integrated study of hydrochemistry and sulfate and water isotopes in the Spree river network. We put particular emphasis on

(1) Differentiating major geographic and functional sulfate sources and sinks in the Spree river network based on sulfur and oxygen isotopes in river sulfate

(2) Quantifying these sources and sinks by simple endmember models, and identifying limitations of this approach

(3) The role of biogeochemical sulfur cycling (reduction/reoxidation cycles and intermediates) in retention spaces of the river network and the consequence for prevailing isotope signatures.
Setting up the NEMO (Nucleus for European Modeling of the Ocean) for Baltic Sea region - open boundary conditions
Authors: Andrzejewski Jan , Jakacki Jaromir , Muzyka Maciej , Przyborska Anna
Published: March 2020

The Baltic Sea is inland, Shelf Sea in northern part of Europe. It is shallow with average depth of 52 meters and deepest point 459 meters located at Landsort Deep. Baltic Sea is connected with North Sea via the Danish Straits (comprising of Great Belt, Little Belt and Øresund). These systems ensure only limited exchange between oceanic waters and seawaters, which affect the low salinity in Baltic reservoir. Runoff from surrounding lands (approximately 200 rivers) and positive difference of precipitation minus evaporation additionally refreshes water and makes Baltic a brackish sea. The only charge of salt comes from the North Sea with so-called inflows or less frequent occurring Major Baltic Inflows (MBI). This exchange between Danish Straits is the key for properly working simulation. In this work the tool, well known as NEMO, was used to perform the numerical simulation for the Baltic Sea area. This presentation is focused on the first stage of validation of the model results for the Baltic Sea region where influence of open boundary conditions is noticeable as soon as possible. The main change in the model is the assimilation of sea surface height in Kattegat area. Also water outflow mass controlling from the Baltic Sea has been introduced. The properly working open boundary conditions affect the water exchange between Baltic Sea and North Sea, thus the MBI and minor salty inflows are well represented. This is very important part in modeling the Baltic
Sea, where narrow Danish Straits limits the water exchange which controls the salt budget, adding the salt with inflows and receiving brackish outflow out to the Ocean. This work presents comparison between model output with results measured in situ and from other validated model, the period which is compared is the Major Baltic Inflow in the beginning of 1993.
The FDR4ATMOS Project
Authors: Lichtenberg Günter , Slijkhuis Sander , Hamidouche Mourad , Coldewey-Egbers Melanie , Aberle Bernd , Noël Stefan , Bramstedt Klaus , Hilbig Tina , Bösch Tim , Lambert Jean-Christopher , van Gent Jeroen , Hubert Daan , Green Paul , Hunt Sam , Krijger Matthijs , Dehn Angelika , Brizzi Gabriele
Published: March 2020

The Fundamental Data Record for ATMOSpheric Composition (FDR4ATMOS) project is part of the ESA Long Term Data Preservation (LTDP) programme aimed at the preservation and valorization of data assets from ESA’s Earth Observation (EO) Heritage Missions. It has two objectives. The first one is to update the SCIAMACHY processing chain for better Ozone total column data. After the full re-processing of the SCIAMACHY mission with the updated processor versions 9 (Level 1) and version 7 (Level 2), ground-based validation showed that the total Ozone column drifted downward by nearly 2% over the mission lifetime. This drift is likely caused by changes in the degradation correction in the Level 1 processor, that led to subtle changes in the spectral structures. These are misinterpreted as an atmospheric signature. FDR4ATMOS will update the Level 0-1 processor accordingly with the final aim of a mission re-processing.

The main objective of the FDR4ATMOS project is to develop a cross-instrument Level 1 product for GOME-1 and SCIAMACHY for the UV, VIS and NIR spectral range, with focus on the spectral windows used for O3, SO2, NO2 total column retrieval and the determination of cloud properties. Contrary to other projects, FDR4ATMOS does not aim to build harmonised time series based on Level 2 products (geophysical parameters) but to build a Fundamental Data Record (FDR) of Level 1 products, i.e. radiances and reflectances. The GOME-1 and SCIAMACHY instruments together span 17 years of spectrally highly resolved data essential for air quality, climate, ozone trend and UV radiation applications. The goal of the FDR4ATMOS project is to generate harmonised data sets that allow the user to use it directly in long-term trend analysis, independently of the instrument. Since this was never done for highly resolved spectrometers, new methods have to be developed that e.g. take into account the different observation geometries and observation times of the instrument without impacting the spectral structures that are used for the retrieval of the atmospheric species. The resulting algorithms and the processor should also be as generic as possible to be able to easily transfer the methodology to other instruments (e.g. GOME-2 and Sentinel-5p) for a future extension of the time series. The project will support new applications and services and will enhance traceability of satellite-derived data with improved uncertainty estimates based on rigorous metrological principles.

FDR4ATMOS started in October 2019 and is currently in phase 1. We will present the motivation, goals and first results of the project.
Development and testing of an innovative energy wall system in Torino (Italy)
Authors: Baralis Matteo , Barla Marco
Published: March 2020

Shallow geothermal energy (SGE) is increasingly being regarded as a valuable solution for space heating and conditioning because of high efficiency, diffuse availability and low environmental impact. Significant growth in the number of installations is envisaged as a result of energy policies and European Directives. Indeed, the obligations in the construction sector about the share of energy supply from renewable sources is increasingly pushing the design of new and renovated buildings. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation costs related to drilling of traditional installations represent an hampering factor. Thermally activating geostructures such as piles, diaphragm wall, tunnels and anchors can allow to include these costs in the construction of the structural elements. Moreover, a large availability of operational surface is represented by new and/or existing building heritage in urban areas as most of them  have underground levels that can be equipped with heat exchangers.

This contribution introduces a novel modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system concept allows its application not only to new structures and buildings but also to existing ones. While the low depths interested may penalize the heat exchange rates, on the contrary, extremely low installation costs make the cost-benefit ratio of this new technology extremely interesting and promising.

A first prototype consisting of three modules was designed by the authors and installed in an office building in Torino (Italy). External deployment of pipes to the basement wall in two different arrangements was realized in order to test system efficiency. Due to the experimental nature of the tests, a large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partially saturated ground volume involved in heat exchange.

Preliminary thermal performance tests were performed together with numerical modelling re-interpretation. On the basis of the first tests and interpretation carried out, it was demonstrated that remarkable heat exchange rates of up to 20 and 27 W/m2 could be injected/extracted from the ground in summer and winter respectively. Furthermore, the monitoring records suggest that extremely low affection of ground thermal status is operated by the system with respect to analogous non thermo-active walls. This evidence is extremely promising in the perspective of wide and dense diffusion of this new shallow geothermal energy system in urban areas where thermal interferences should be limited or avoided.
Estimating the unimodal and bimodal van Genuchten model parameters using the simplified evaporation and dewpoint methods
Authors: Acevedo Sara , Contreras Cristina , Martinez Sofia , Bonilla Carlos
Published: March 2020

The pressure plate method has been widely used for describing the soil water retention curve (SWRC). However, the simplified evaporation method (SEM) appears as an alternative because of its high resolution and automatization. On the other hand, the unimodal and bimodal van Genuchten models (VGM) have been used for describing the SWRC by computing the shape parameters. However, parametric pedotransfer functions (PTFs) have been developed based on the pressure plates method, focusing on the unimodal VGM. Therefore, the objectives of this study were: (1) to measure the SWRC with the simplified evaporation method (SEM) coupled to the dewpoint potentiometer (DP) in soils with different land use and soil texture, (2) to adjust and compare the VG unimodal and bimodal parameters, and (3) to estimate the VG unimodal and bimodal parameters through regression techniques including a linear approach and random forest. Thirty topsoils (disturbed and undisturbed cores) were sampled across a climate gradient and measured by duplicated. Preliminary results showed that the high resolution of the SWRC data obtained with the SEM + DP leads to a better fit when using the bimodal VGM.
Groundwater changes affect crustal deformation, elastic properties and seismicity rates in the Southern Alps (Italy)
Authors: Pintori Francesco , Serpelloni Enrico , Longuevergne Laurent , Almagro-Vidal Carlos , Zaccarelli Lucia , Garcia-Aristizabal Alexander , Faenza Licia , Belardinelli Maria Elina , Bragato Pier Luigi
Published: March 2020

We show the results of a multidisciplinary study on hydrologically-induced deformation in the Southern Alps (Italy) developed integrating geodetic, seismological and hydrological observations. The study region, located across the Belluno Valley and the Montello Hill, is part of the Adria-Eurasia boundary, where ~1 mm/yr of N-S shortening is accommodated across a S-verging fold-and-thrust belt. GNSS time-series show the occurrence of non-seasonal horizontal transient displacements, characterized by a sequence of extensional and contractional deformation episodes oriented along the direction of the tectonic shortening. This signal is temporally correlated with water storage changes that are estimated using a lumped hydrological model based on precipitation, temperature, potential evapotranspiration and Piave river flow measurements. Geodetic and hydrological information are integrated in a 2D mechanical model with the goal of defining possible geological structures responsible for the measured subcentimetric geodetic displacements. Our interpretation implies that precipitation water rapidly penetrates the epikarst developed at the hinge of the anticline associated with the Bassano-Valdobbiadene thrust, converging toward a sub-vertical, deeply rooted hydrologically-active fracture (associated with its back-thrust), which tend to focus groundwater fluxes and pressure changes, generating ground displacements. Accordingly, seismic velocity changes computed from the analysis of ambient seismic noise cross-correlation show a temporal (anti) correlation with the evolution of water storage changes, suggesting that fluid increase in the aquifer perturb the Earth crust at depth by decreasing the seismic velocity (and vice-versa, during water storage decrease phases). Finally, by analyzing the seismicity recorded between 2012 and 2017 by a local network using a covariate model, we found that seismicity rates from a cluster of background seismicity correlate with changes in water storage. Although a spatial correlation between these seismic events and Coulomb stress changes associated with transient deformation episodes is not clear, it is worth noting that our model suggests stress perturbations of the order of 5-10 KPa down to 5-10 km of depth.
Temporal Variations of Near-surface seismic structure of Taiwan revealed by coda interferometry
Authors: Cai Sheng-Jyun , Chen Li-Wei , Lee Hsin-Yu , Chen Ying-Nien , Gung Yuan-Cheng
Published: March 2020

We report the temporal change of the near-surface(<400m) seismic structure of Taiwan revealed by coda interferometry. Following our earlier work (Chen et al., 2017), the Empirical Green’s Functions (EGF) of shear waves extracted from the earthquake coda recorded by the vertical pairs of borehole array, deployed by the Central Weather Bureau, are used to examine the temporal variations of vs and Vs azimuthal anisotropy at the borehole sites. In total, about 700 local events, from 2013 to 2018, are used in this study. The band-passed (3 – 8 hz) EGF extracted from each single event are stacked over variable time period to ensure the reliability of measurements and the desired temporal resolution. The averaged Vs and patterns of Vs azimuthal anisotropy are in good agreement with the site geology, the ambient stress and those reported in our early work. Apparent drop in the Vs isotropic velocities and perturbations in Vs azimuthal anisotropy are observed in few representative borehole sites, and we also noticed that such variations are tightly correlated with the occurrence of major earthquakes in Taiwan. We present the preliminary results and discuss the triggering mechanisms, the healing revolution, and their relationship with the site geology.
Evaluation of MM5 and HadGEM3-RA hindcast in the CORDEX East Asia Phase Ⅱ: near-surface air temperature
Authors: Shin Seok-Woo , Cha Dong-Hyun , Kim Taehyung , Kim Gayoung , Park Changyoung , Lee Minkyu , Byun Young-Hwa , Kang Hyun-Suk
Published: March 2020

Extreme temperature can have a devastating impact on the ecological environment (i.e., human health and crops) and the socioeconomic system. To adapt to and cope with the rapidly changing climate, it is essential to understand the present climate and to estimate the future change in terms of temperature. In this study, we evaluate the characteristics of near-surface air temperature (SAT) simulated by two regional climate models (i.e., MM5 and HadGEM3-RA) over East Asia, focusing on the mean and extreme values. To analyze extreme climate, we used the indices for daily maximum (Tmax) and minimum (Tmin) temperatures among the developed Expert Team on Climate Change Detection and Indices (ETCCDI) indices. In the results of the CORDEX-East Asia phase Ⅰ, the mean and extreme values of SAT for DJF (JJA) tend to be colder (warmer) than observation data over the East Asian region. In those of CORDEX-East Asia phase Ⅱ, the mean and extreme values of SAT for DJF and JJA have warmer than those of the CORDEX-East Asia phase Ⅰ except for those of HadGEM3-RA for DJF. Furthermore, the Extreme Temperature Range (ETR, maximum value of Tmax - minimum value of Tmin) of CORDEX-East Asia phase Ⅰ data, which are significantly different from those of observation data, are reduced in that of CORDEX-East Asia phase Ⅱ. Consequently, the high-resolution regional climate models play a role in the improvement of the cold bias having the relatively low-resolution ones. To understand the reasons for the improved and weak points of regional climate models, we investigated the atmospheric field (i.e., flow, air mass, precipitation, and radiation) influencing near-surface air temperature. Model performances for SAT over East Asia were influenced by the expansion of the western North Pacific subtropical high and the location of convective precipitation in JJA and by the contraction of the Siberian high, the spatial distribution of snowfall and associated upwelling longwave radiation in DJF.
Stochastic Resonance could explain Recurrence of Grand Minima
Authors: Albert Carlo , Ulzega Simone
Published: March 2020

Proxies of solar activity have revealed repeated Grand Minima that occur with a certain regularity associated with the well-known Gleissberg and Süss/deVries cycles. These and other prominent cycles in the spectrum of solar activity are also seen in the spectrum of the planetary torque exerted on the solar tachocline, which has revived the hypothesis of a planetary influence on solar activity. It is not clear, however, how the extremely weak planetary forcing could influence the solar magnetic activity. Here, we suggest that stochastic resonance could explain the necessary amplification of the forcing and provide numerical evidence from stochastic time-delayed dynamo models. If the intrinsic noise of the solar dynamo allows for a frequent switching between active and quiescent stable states, tiny periodic forcings can be greatly amplified, provided the dynamo is poised close to a critical point. Such a forcing could be caused by a tidal modulation of the minimal magnetic field required for flux-tube buoyancy.
Monitoring of temporal seismic velocity changes in the North Anatolian Fault zone using data derived scattering properties
Authors: van Dinther Chantal , Campillo Michel , Margerin Ludovic , Lecointre Albanne
Published: March 2020

Monitoring of temporal seismic velocity changes can provide us with information on the mechanical state of the Earth’s crust due to processes of stress build-up and release. 

In current work, we use the Dense Array of North Anatolia [1], which has been continuously recording from May 2012 until October 2013, to analyse the spatio-temporal variations of seismic velocity changes in the North Anatolian Fault zone (NAF). We compute daily ambient-noise cross-correlation functions for all 63 three-component stations in the frequency band between 0.1 – 1 Hz.

To retrieve spatial distribution of seismic velocity changes in such an inhomogeneous fault zone, we go beyond the simple linear travel-time shifts approximation and homogeneous sensitivity kernel. We therefore invert for the travel-time shifts at different lag-times. Furthermore, we use sensitivity kernels for media with inhomogeneous scattering properties. The scattering properties for the sensitivity kernels are derived from the data: a scattering mean free path inside the fault zone (northern strand of NAF) of ∼ 10 km and ∼ 150 km outside the fault zone, the attenuation coefficient inside and outside the fault zone are 80 and 100 respectively. 

 

[1] DANA. Dense array for north anatolia. International Federation of Digital Seismograph Networks doi:10.7914/SN/YH2012, 2012.
Plants, plastic and rivers: Do water hyacinths play a role in riverine macroplastic transport?
Authors: Castrop Evelien , van Emmerik Tim , van den Berg Sanne , Kosten Sarian , Strady Emilie , Kieu-Le Thuy-Chung
Published: March 2020

Excess of plastic debris in the environment is a worldwide problem. The origin of the plastic sources is partly land-based, the function of rivers as transportation pathways for plastics is an emerging research field. However, the transportation dynamics of macroplastic in river systems are still poorly understood(Blettler et al., 2018; Schmidt et al., 2017). By studying the interaction of riverine plastic transport and water plants, the transport dynamics can be better understood, which might help with the mitigation of the environmental plastic debris problem. 

A field study based in the Saigon river, Vietnam, found a correlation between macroplastic(>5 cm) abundance and organic material, where no other correlations were found(van Emmerik et al., 2019). We hypothesize that water hyacinths have an important role in the spatiotemporal dynamics of riverine macroplastic transport. The organic material in this river was predominantly identified as water hyacinths, an invasive plant common in Southeast Asia. In this study, we developed a method using image analysis, to detect macro plastics and floating vegetation(lab-grown water hyacinths). Image analysis in combination with drone technology creates opportunities to collect field data, with already promising results(Geraeds et al., 2019). We analyzed the images, to obtain an approximation of the amount of plastic and vegetation, visible from the surface. We subsequently use this data to evaluate the relationship between plastic abundance and vegetation in rivers. The method developed in this study can be used to collect data in the field. Targeted observations of plastic entrapment in water hyacinths may shed additional light on the potential of using water hyacinths as a proxy for riverine macroplastic transport dynamics. 

References

M. C. Blettler, E. Abrial, F. R. Khan, N. Sivri, and L. A. Espinola. Freshwater plastic pollution:Recognizing research biases and identifying knowledge gaps. Water research, 143:416-424, 2018.

M. Geraeds, T. van Emmerik, R. de Vries, and M. S. bin Ab Razak. Riverine plastic litter monitoring using unmanned aerial vehicles (uavs). Remote Sensing, 11(17):2045, 2019.

C. Schmidt, T. Krauth, and S.Wagner. Export of plastic debris by rivers into the sea. Environmental science & technology, 51(21):12246-12253, 2017.

T. van Emmerik, E. Strady, T.-C. Kieu-Le, L. Nguyen, and N. Gratoit. Seasonality of riverine macroplastic transport. Nature Scientific Reports, 2019.
New insights into the magmatic system southeast of El Hierro from high-resolution 2D seismic data
Authors: Lenz Kai-Frederik , Gross Felix , Klügel Andreas , Barrett Rachel , Held Philipp , Lindhorst Katja , Wintersteller Paul , Krastel Sebastian
Published: March 2020

A new high-resolution seismic dataset is used to investigate the distribution and influence of different phases of magmatic activity in the southeast of El Hierro, Canary Islands. The Canary Archipelago off NW-Africa has largely been formed over the past 20 Myr, but older volcanic edifices exist. One of those older edifices is Henry Seamount, an extinct 126 Ma volcano located 40 km southeast of El Hierro, the youngest (1.1 Ma) and westernmost of the Canary Islands. Hence, the area southeast of El Hierro is influenced by both older and younger magmatic activity. We also found evidence for comparatively young volcanic activity at Henry Seamount, probably contemporaneous to El Hierro. Therefore, a complex magmatic system is assumed to have resulted in the different phases of magmatic activity.

A detailed high-resolution 2D seismic reflection dataset was collected in an area between El Hierro and Henry Seamount during RV Meteor expedition M146 in 2018 to image the expressions of this magmatic system in the upper sub-surface. Several acoustic blanking zones were discovered and identified as the most prominent features in this seismic dataset. We classify these blanking zones into three different types. Type 1 blanking zones are related to volcanic edifices, which crop out at the seafloor and cut through all imaged sedimentary units. Type 2 blanking zones are characterised by upward bending of adjacent reflectors and are most likely caused by hydrothermal doming resulting from saucer-shaped sill intrusions. Type 3 blanking zones cut clearly through adjacent reflectors, and are probably related to fluids or gases that were mobilized by the sill intrusions. The type 1 and 2 blanking zones cluster in the central part of the working area, whereas the blanking zones of type 3 are located on the outskirts. This specific distribution and the occurrence of the varying blanking zone types are combined to make a conceptual model of this complex magmatic system. Our model takes sill intrusions, hydrothermal doming, as well as volcanic out-crops and mobilized fluids into account. Therefore, this study provides new insights into the magmatic evolution of the youngest Canary Island, which can help to achieve a better understanding of the whole system.
Contribution of turbulent heat fluxes to surface ablation on the Greenland ice sheet.
Authors: Van Tiggelen Maurice , Smeets Paul , Reijmer Carleen , Noël Brice , Steiner Jakob , Nieuwstraten Emile , Immerzeel Walter , van den Broeke Michiel
Published: March 2020

Over ice sheets and glaciers, the turbulent heat fluxes are, next to the radiative fluxes, the second largest source of energy driving the ablation. In general, most (climate) models use a bulk turbulence parametrization for the estimation of these energy fluxes. Recent work suggest that the turbulent heat fluxes might be greatly underestimated by such models. Unfortunately, only a few direct and long-term observations of turbulent fluxes are available over ice sheets to evaluate their inclusion in models. 

In this study, we developed a vertical propeller eddy-covariance method to continuously monitor the sensible heat fluxes over the Greenland ice sheet (GrIS). We quantify its contribution to surface ablation using three years of data from the K-transect, located in the western ablation area of the GrIS. The direct flux measurements are also compared to those from several bulk turbulence models, and to a high-resolution regional climate model (RACMO2), in order to quantify modelling uncertainty.

The differences between observations and models highlight the need for upgrading the bulk turbulence parameterizations and especially the model parameters, such as the surface roughness lengths. We also find that during short but extreme warm events, the turbulent heat fluxes become the largest source for surface ablation. Typical for such intense events on the K-transect are fast changes in wind direction, which cause changes in the surface roughness parameters due to the anisotropic feature of the ice hummocks. These parameters are critical for modelling the turbulent fluxes in bulk parameterizations, but are often variable and unknown. We conclude with drone topography measurements to better constrain the surface roughness locally, and discuss methods to improve the modelling of turbulent surface fluxes on the whole GrIS.
Coupled modelling of daily stream concentrations of carbon, nitrogen and phosphorus in a small agricultural watershed
Authors: Strohmenger Laurent , Hrachowitz Markus , Fovet Ophélie , Gascuel-Odoux Chantal
Published: March 2020

Hillslope, groundwater, near- and in-stream interactions are key processes to understand in order to reduce the impact of agriculture on natural ecosystem. Indeed, hydrologic connectivity controls the fate of the nutrients within a catchment. The dynamics of nutrients (Nitrates NO3 and Phosphates PO4) and dissolved organic carbon (DOC) at the outlet are the product of past agricultural practices and local climate conditions. DOC, NO3 and PO4 are usually studied and modelled separately and originate from wetlands, groundwater and surface flows respectively. The simultaneous modelling of these elements is an opportunity to better understand the hydrologic connectivity because of their specific spatial origin, reactivity and mobilization processes. We developed a parsimonious rainfall-runoff model coupled with solutes reactivity and transport module in an agricultural research catchment (Kervidy-Naizin, 5km²). We used a three boxes lumped model (soil, groundwater and wetland) and StorAge-Selection function (SAS-function), agricultural surplus and daily climatic variables (precipitations, temperature, evapotranspiration) in order to simulate the daily discharge and stream concentrations at the outlet. Model tests confirmed that adding constraints such as solutes concentrations to a hydrological model helped to avoid unlikely sets of parameters. Simulations also showed that air temperature and agricultural practices are the major drivers of the supply of elements available within the catchment by controlling their biogeochemical reactivity; and that water table levels and precipitations are the major drivers of the variability of the concentrations in the stream by controlling the hydrological connectivity and the mixing between sources areas.
Assessing the Atlantic Water Pathways To The Arctic In a High-Resolution NEMO Model
Authors: Roach Christopher , Herbaut Christophe , Houssais Marie-Noëlle
Published: March 2020

Most Atlantic Water (AW) enters the Arctic Ocean through the West Spitzbergen Current, passing north of Svalbard, either moving along the upper slope or passing over and around the Yermak Plateau. Recent model studies (Koenig et al. 2017 and Crews et al. 2019) have improved our understanding of these pathways but were limited to periods of 1-5 years. This is insufficient for examining the contributions of AW inflow to climate-scale problems such as the ‘Atlantification’ of the Arctic.

In this study we use 23 years (1995-2018) of high resolution (~1/24°) velocity fields from a NEMO 3.6 model (DOI: 10.5281/zenodo.2682406) allowing us to examine the geographic distributions and strengths of AW inflow pathways using a Lagrangian particle tracking approach. Virtual particles were released on a section at 30° E and tracked backwards in time using the PARCELS 2.0 particle tracking system (Delandmeter and van Sebille 2019).

For the present analysis, we focus on trajectories of particles which are contained in AW layer at the release line (SA>34.9 and CT>2°C) and could be tracked backwards to the Nowegian Sea (here taken as south of 75° N). A control line was selected across the Yermak Plateau to allow us to separate particles passing through the Svalbard and Yermak branches. Using these particle trajectories, we created a time-series of transport of AW reaching the southern rim of the western Nansen Basin. The transport was found to vary between 0.5 Sv and 3.75 Sv, comparable to previous studies (e.g. Beszczynska-Möller et al. 2012), and to be dominated, on average, by the Yermak Branch.
A stable isotope assay for determining microbial degradation rates of plastics in the marine environment
Authors: Goudriaan Maaike , Hernando Morales Victor , van Bommel Ronald , van der Meer Marcel , Rachel Ndhlovu Rachel , van Heerwaarden Johan , Hinrichs Kai-Uwe , Niemann Helge
Published: March 2020

The popularity of plastic as a cheap and easy to use, moldable material has been growing exponentially, leading to a likewise increase in plastic waste. As a result, plastic pollution has been surging in the marine realm, and the effects and fates of these modern, man-made compounds in our oceans are unresolved. Pathways of plastic degradation (physicochemical and biological) in the marine environment are not well constrained; yet, microbial plastic degradation is a potential plastic sink in the ocean. However, there is a lack of methods to determine this process, particular if the overall turnover is in the sub-percent range.  We developed a novel method based on incubations with isotopically labelled polymers for investigating microbial plastic degradation in marine environments. We tested our method with a Rhodococcus Ruber strain (C-208), a known plastic degrader, as a model organism. In our experiments we used granular polyethylene (PE) that was almost completely labelled with the stable isotope 13C (99%) as a sole carbon source. We monitored CO2 concentration and stable carbon isotope ratios over time in the headspace during 35-day incubations at atmospheric oxygen concentrations and found an excess production of 13C-CO2. This result provides direct evidence for the microbially mediated mineralization of carbon that was ultimately derived from the polymer. After terminating the incubation, we measured the dissolved inorganic carbon (DIC), and pH, allowing us to determine the total excess production of 13C-CO2 and DIC, and thus the rate of plastic degradation. Of the 2000 μg PE added, ~0.1% was degraded over a time course of 35 days at a rate of ~1.5 μg month-1, providing a first characterization of the mineralization kinetics of PE by R. Ruber. The results show that isotopically labelled polymers can be used to determine plastic degradation rates. The method shows promise for being more accurate than the classic gravimetrical methods.
Role of paleogeography in preconditioning the Late Cretaceous Oceanic Event (OAE2) in a full global circulation Earth System model
Authors: Manning Alexander , Valdes Paul , Monteiro Fanny , Williams Jonny
Published: March 2020

Ocean anoxic event 2 (OAE2) was a large perturbation in the Earth's ocean carbon system, occurring at approximately 93.5 Ma, and is characterised by widespread black shales deposition in sediment records. This record has been interpreted as evidence of large anoxia in the global ocean for a long period, resulting in large scale extinction of marine life. However, the exact causes of OAE2, and how it initially developed, are not fully understood. We modelled the period leading up to OAE2 using the HadCM3L global climate model with full ocean (HADOCC) and terrestrial carbon cycle (TRIFFID) modules. We compared our results to equivalent simulations using late Cretaceous (Maastrichtian) paleogeographies. This allowed us to analyse the effects of continental configuration on the development to the OAE. Our results show that restricted ocean circulation, caused by the paleobathymetry, is necessary for anoxic conditions to develop but is not sufficient alone. This suggests that continental configuration is highly important in determining the ability of the oceans to develop an OAE and may explain why they only occur during some times during Earth history.
Evaluation of a new snow albedo scheme in RACMO2 for the Greenland ice sheet
Authors: van Dalum Christiaan , van de Berg Willem Jan , Lhermitte Stef , van den Broeke Michiel
Published: March 2020

Snow and ice albedo schemes in present day climate models often lack a sophisticated radiation penetration scheme and are limited to a broadband albedo. In this study, we evaluate a new snow albedo scheme in the regional climate model RACMO2 that uses the two-stream radiative transfer in snow model TARTES and the spectral-to-narrowband albedo module SNOWBAL for the Greenland ice sheet. Additionally, the bare ice albedo parameterization has been updated. The snow and ice albedo output of the updated version of RACMO2, referred to as RACMO2.3p3, is evaluated using PROMICE and K-transect in-situ data and MODIS remote-sensing observations. Generally, the RACMO2.3p3 albedo is in very good agreement with satellite observations, leading to a domain-averaged bias of only -0.012. Some discrepancies are, however, observed for regions close to the ice margin. Compared to the previous iteration RACMO2.3p2, the albedo of RACMO2.3p3 is considerably higher in the bare ice zone during the ablation season, as atmospheric conditions now alter the bare ice albedo. For most other regions, however, the albedo of RACMO2.3p3 is lower due to spectral effects, radiation penetration, snow metamorphism or a delayed firn-ice transition. Furthermore, a white-out effect during cloudy conditions is captured and the snow albedo shows a low sensitivity to low soot concentrations. The surface mass balance of RACMO2.3p3 compares well with observations. Subsurface heating, however, now leads to increased melt and refreezing in south Greenland, changing the snow structure.
Site Characterization and Multipath Maps Using Zernike Polynomials
Authors: Gatti Andrea , Tagliaferro Giulio , Realini Eugenio
Published: March 2020

Receiver antenna calibration plays an important role in precise point positioning (PPP). The correct management of the phase center offset and variations (PCV) and multipath effects can drastically improve the estimation of tropospheric parameters and the stability of the position over short measurement sessions. Correction parameters, to compensate for PCV, are usually computed in laboratory on all the geodetic grade antennas, but they are not available for low-cost apparatus; multipath can be partially mitigated by a robot calibration on site but this is an expensive procedure that is rarely adopted. Multipath staking maps (MPS) using carrier phase observation residuals are a cheap and powerful tool to generate site-specific corrections, effective for reducing both near-field and far-field effects. These maps can be generated by gridding multiple residuals falling in a cell of a pre-determined size. In this work, we propose to compute a set of polynomial coefficients of a Zernike expansion from the residuals of a PPP uncombined least-squares adjustment performed by the open-source goGPS processing software; these coefficients can be later used to synthesize corrections of the observations for the next processing of the target station. In contrast with gridding techniques, this approach allows a to generate smoother corrections and allows a limited automatic extrapolation of the correction values in areas of the sky that were not covered by observations in the set of data used in the calibration phase. The results show that the technique is effective in the modelling of multipath and residual phase center variations allowing a drastic reduction of the undifferenced residuals. Zernike polynomials are a sequence of polynomials orthogonal on the unit disk, vastly used in optics but, to our knowledge, never considered for GNSS applications, their symmetric properties and the circular support area makes them an interesting object of investigation for other possible usages in GNSS processing.
Remote Benthic Habitat Mapping Using Sunglint corrected multispectral Imagery in Bahrain waters
Authors: Alkhuzaei Manaf , Brolly Matthew , Burnside Niall , Carey Chris , Maniatis Georgios
Published: March 2020

The marine area of Bahrain comprises 91% of the total area of the country, the management of which is crucial for decision-makers, as it contains the country’s most valuable resources. It is also ecologically important supporting such fauna as, sea dugong, dolphins, green turtles, and 70+ species of fish, and such flora as seagrass beds and algae which provide essential ecosystem services. Providing current benthic habitat maps using remote methods is vital for efficient management and monitoring of these dynamic resources. In this threefold study, remotely sensed Landsat 8/OLI and Sentinel-2 imagery, combined with field survey (176 points), are used to investigate, classify, and map benthic habitats in light of varying spatial and spectral image resolutions while also assessing the role sunglint correction methods perform. Two widely applied methodologies proposed by Hedley et al. (2005) and Lyzenga (2006) for sunglint correction in the water column are examined to assess their role in creating accurate classification maps in this region. Sunglint is an issue in Bahrain due to its shallow waters, long summer and clear skies. The results using unsupervised classification indicate the effectiveness of both correction methods, demonstrating comparable results of high classification accuracy using either 3 (Blue, Green and Red) or 4 (Coastal Aerosol, Blue, Green and Red) spectral band combinations. Maximum accuracy using Hedley was 74% (4 bands) for Landsat 8 and 80% (3 bands) for Sentinel-2 while for Lyzenga 74% (4 bands) for Landsat 8 and 80% (3 bands) for Sentinel 2. The outputs generated were all >68%, with the introduction of more spectral bands associated with higher accuracy for Landsat 8 but inversely for Sentinel 2.
Multi-source data driven spatial changes of FFCO2 emissions balance and mitigation potential of different land use in China
Authors: Zhao Jing , Li Guoqing , Cohen Jason Blake
Published: March 2020

Estimates of fossil-fuel carbon dioxide (FFCO2) emissions in China are contingent on large uncertainty, and currently have enormous discrepancies among different inventories/datasets. The uncertainty is most attributed to underlying causes: only a few actual measurements and consumption data, and the statistical methods to confine the spatial resolution of FFCO2. In this study, an attempt is made to assess the heterogeneities and uncertainty associated with spatial distributions of emissions in six gridded FFCO2 inventories/datasets, which are compared at a 0.25 × 0.25 degree resolution.

We extract signals of urban CO2 emissions with a Deep Learning (DL) & Deep Reinforcement Learning (DRL) modeling framework from the existing new generation of satellite (OCO-2/GOSAT-2/TROPOMI) observations of atmospheric column CO2 (XCO2). We then use the results as a proxy to further estimate of the FFCO2 uncertainty. Subsequently, the estimated FFCO2 uncertainty is included in an up-to-date multivariate spatial statistic to analyze China’s spatiotemporal FFCO2 emissions balance, with a specific consideration made for the mitigation potential of different land-use types.

We find an interconnected system between the spatial FFCO2 emissions distribution and two diverse factors being the most important: urbanization and either croplands (rainfed, irrigated, and post-flooding) or native vegetation. We have determined that wettability in croplands or the increase in native vegetation have an association with the decrease of FFCO2 emissions. Ongoing work addresses the potential impacts of this FFCO2 uncertainty on flux inversions.
Species-dependent variation in geotechnical properties and erodibility of salt marsh sediments
Authors: Evans Ben , Brooks Helen , Carr Simon , Chirol Clementine , Christie Elizabeth , Kirkham Matthew , Moeller Iris , Royse Katherine , Shears Olivia , Spencer Kate , Spencer Thomas
Published: March 2020

Salt marshes provide diverse ecosystem services including coastal protection, habitat provision and carbon sequestration. The loss of salt marshes is a phenomenon that is observable on a global scale and is of great socioeconomic concern due to the substantial benefits these environments provide. The causes of spatial variability in rates of marsh loss are inadequately understood for the purposes of predicting future ecosystem functions and distributions in the context of global environmental change.

We investigate the relationship between vegetation of different genera and the mechanical properties of the substrate. We couple in-situ and laboratory tests of substrate geotechnical properties with micro-CT imaging of undisturbed root network structures to assess the contribution of three halophytes to sediment stability. We investigate the role of Puccinellia spp., Spartina spp. and Salicornia spp. in the modification of geotechnical parameters such as critical shear strength and cohesion when compared to un-vegetated sediments. We then compare these effects between clay-rich and sandy contexts on the East and West coasts of the United Kingdom respectively.

We find that the three genera are characterised by different root network morphologies which, in part, explain the differences that we observe between the geotechnical properties of sediments colonised by these contrasting vegetation types. The presence of roots within the sediment structure increases the cohesion, as measured using a laboratory shear box test, when compared to bare sediment, with the magnitude of this effect varying by root morphology and sedimentology. In-situ shear vane tests reveal a localised spatial variability in sediment shear strength that is related to halophyte species distributions. This allows multispectral UAV imagery to be used to map species distributions and thereby infer a component of the sediment’s vulnerability to erosion that supports the prediction of future marsh distributions and, ultimately, ecosystem service provision.
Soil organic carbon stock development in chernozemic soils following agricultural abandonment
Authors: Novák Tibor József , Márta László , Balogh Szabolcs
Published: March 2020

Post agricultural development of traditionally intensively cultivated high fertility soils is a relevant question in surroundings of towns affected by urban sprawl, where extent areas of former cultivated soils are converted into residential, industrial or infrastructural surfaces. Part of these areas will covered by artificially sealed soils, but always extent areas remain for green areas, managed with different intensity, which allows recharge of soil organic carbon stocks and soil regeneration processes. In our study agricultural and post agricultural soils were sampled in a Chernozemic landscape affected by urbanization processes. Besides of other regeneration processes, concerning to the improvement of soil structure, we found that soil organic carbon stocks in the 0-30 cm soil layer are significantly higher in post agricultural soils (9.4±0.5 kg·m-2) as in ploughed (6.4±0.8 kg·m-2) or in ploughed plus irrigated (5.6±0.7 kg·m-2) profiles. The difference was found to be significant not only until the depth of the cultivated layer (30 cm), but until the sampled 70 cm depth throughout (17.8±0.9; 10.8±3.3 and 10.6±2.7 kg·m-2 respectively). Our results point on the high carbon recovery potential of suburban areas converted from fertile cultivated soils.
Met.3D: Interactive 3D ensemble visualization for rapid exploration of atmospheric simulation data
Authors: Rautenhaus Marc
Published: March 2020

Visualization is an important and ubiquitous tool in the daily work of atmospheric researchers and weather forecasters to analyse data from simulations and observations. Visualization research has made much progress in recent years, in particular with respect to techniques for ensemble data, interactivity, 3D depiction, and feature-detection. Transfer of new techniques into the atmospheric sciences, however, is slow.

Met.3D (https://met3d.wavestoweather.de) is an open-source research software aiming at making novel interactive 3D and ensemble visualization techniques accessible to the atmospheric community. Since its first public release in 2015, Met.3D has been used in multiple visualization research projects targeted at atmospheric science applications, and also has evolved into a feature-rich visual analysis tool facilitating rapid exploration of atmospheric simulation data. The software is based on the concept of “building a bridge” between “traditional” 2D visual analysis techniques and interactive 3D techniques and allows users to analyse their data using combinations of 2D maps and cross-sections, meteorological diagrams and 3D techniques including direct volume rendering, isosurfaces and trajectories, all combined in an interactive 3D context.

This PICO will provide an overview of the Met.3D project and highlight recent additions and improvements to the software. We will show several examples of how the combination of 2D and 3D visualization elements in an interactive context can be used to explore atmospheric simulation data, including the analysis of forecast errors, analysis of synoptic-scale features including jet-streams and fronts, and analysis of forecast uncertainty in ensemble forecasts.