bluuebunny/crossref_metadata_2025 huggingface dataset:
Manganese speciation in soils using X-ray absorption spectroscopy
Authors: Zahoransky Teresa , Mikutta Christian
Published: March 2020

Being one of Earth´s most redox-active elements, manganese participates in a great variety of environmental processes and is recognized as a key player controlling carbon turnover and oxidative transformation of organic and inorganic pollutants in soils. Moreover, Mn(III), Mn(IV) or mixed-valence Mn(III/IV) oxides and (oxy)hydroxides are highly effective sorbents for metal pollutants and nutrients in soils. Chemical reactivity, mobility, and bioavailability of Mn depend crucially on its speciation (chemical form). Yet, speciation studies on soil Mn are scarce. Therefore, we employed Mn K-edge (6,539 eV) X-ray absorption spectroscopy (XAS) to determine the oxidation states and local coordination environment (<5 Å) of Mn in oxic bulk soils (Cambisols, Luvisols, Stagnosol) from various field sites in Germany. Our XAS analyses cover 23 soil L, O, A, B, and C horizons exhibiting total Mn concentrations of between 200 and 2,300 mg/kg. For comparison, we also analyze a suite of 31 Mn reference compounds, including Mn carbonate, phosphate, oxides and (oxy)hydroxides, silicates, organic Mn compounds as well as clay and hydroxide minerals with adsorbed Mn(II). X-ray absorption near-edge structure (XANES) spectra are evaluated for the oxidation states of soil Mn using linear combination fit (LCF) analysis. In addition, the average local coordination environment of Mn in the soil samples is assessed by shell-fitting of extended X-ray absorption fine structure (EXAFS) spectra. Based on our XAS results, we will test the following hypotheses: (1) Soil L/O horizons comprise predominantly organically complexed Mn(II) and Mn(III), dominated by the former Mn species; (2) soil A horizons are dominated by Mn(III/IV) in Mn(III/IV)-oxide structures owing to high microbial activity, release of Mn(II) from primary silicates and/or plant residues, and its subsequent (a)biotic oxidation and precipitation as Mn(III/IV) oxides; (3) soil B horizons of different genesis differ in their bulk Mn speciation; Bt horizons of Luvisols are dominated by Mn(II) associated with phyllosilicates, whereas the Stagnosol Bg horizon is dominated by layer-type Mn(III/IV) oxides. In summary, our study will provide first comprehensive data on bulk Mn speciation in three major European soil types. This knowledge is a prerequisite for a better understanding of the biogeochemical Mn cycle in soils.
Direct Detection of Atmospheric Atomic Bromine Leading to Mercury and Ozone Depletion
Authors: Pratt Kerri , Wang Siyuan , McNamara Stephen , Moore Christopher , Obrist Daniel , Steffen Alexandra , Shepson Paul , Staebler Ralf , Raso Angela
Published: March 2020

Bromine atoms play a central role in atmospheric reactive halogen chemistry, depleting ozone and elemental mercury, thereby enhancing deposition of toxic mercury, particularly in the Arctic near-surface troposphere. Yet, direct bromine atom measurements have been missing to date, due to the lack of analytical capability with sufficient sensitivity for ambient measurements. Here we present direct atmospheric bromine atom measurements, conducted in the springtime Arctic near Utqiagvik, Alaska in March 2012. Measured bromine atom levels reached up to 14 ppt (4.2×108 atoms cm-3) and were up to 3-10 higher than estimates using previous indirect measurements not considering the critical role of molecular bromine. Observed ozone and elemental mercury depletion rates are quantitatively explained by the measured bromine atoms, providing field validation of highly uncertain mercury chemistry. Following complete ozone depletion, elevated bromine concentrations are sustained by photochemical snowpack emissions of molecular bromine and nitrogen oxides, resulting in continued atmospheric mercury depletion. This study shows that measured bromine atoms, resulting from photochemical snowpack production of molecular bromine, can quantitatively explain ozone and mercury loss in the near-surface polar atmosphere.
A microwave monitoring service for the study of the Stromboli volcano deformation
Authors: De Luca Claudio , Di Traglia Federico , De Novellis Vincenzo , Esposito Carmen , Nolesini Teresa , Manzo Mariarosaria , Tizzani Pietro , Natale Antonio , Berardino Paolo , Perna Stefano , Casagli Nicola , Lanari Riccardo , Casu Francesco
Published: March 2020

In this paper, we present the activities relevant to the microwave monitoring of the Stromboli volcano ground deformation, performed by IREA-CNR (Institute for the Electromagnetic Sensing of the Environment) and UNIFI (University of Florence) as Centres of Competence for the Italian Civil Protection Department.

The availability of Synthetic Aperture Radar (SAR) system provides, among several techniques, accurate information on the volcano morphology and deformation, thus allowing us to understand the on-going volcanic changes. In this work, we present the results of a back-analysis (from 2015) of the volcano behaviour in terms of ground deformation and an insight on the volcano crisis occurred from July 3 2019, by using Differential Interferometry SAR (DInSAR) measurements.

The generated DInSAR results are both satellite and ground based. In particular, we show the displacement time series obtained with Sentinel-1 data acquired from March 2015 to October 2019 over the whole island and from ascending and descending orbits, and the displacement estimated with a Ground-Based SAR placed for the Sciara del Fuoco and summit craters sensing.

Moreover, the combination of the deformation measurements retrieved with both monitoring systems, which are characterized by independent acquisition geometries, allowed us to partially reconstruct a 3D deformation field of Sciara del Fuoco area.

Finally, we show the preliminary result of a test about an operational monitoring service based on new methodologies for the processing of airborne SAR data, aimed at evaluating its relevance for Civil Protection purposes in volcanic risk context.

 

This work is supported by the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement, and by the 2019-2021 UNIFI and Italian Civil Protection Department agreement.
Comparing dissolved oxygen concentration outputs from two generations of the NorESM model
Authors: Torsvik Tomas , Heinze Christoph
Published: March 2020

A comparative study of dissolved oxygen concentration outputs from two generations of the NorESM model, NorESM-ME (CMIP5) and NorESM-LM (CMIP6), has been carried out as part of a general model development evaluation. Model output for dissolved oxygen consist of yearly averaged historical data over the period 1850-2000. The dimensionality of this data set was reduction by computing empirical orthogonal functions (EOFs), which are eigenvectors of the spatially weighted anomaly covariance matrix defined by the spatio-temporal dissolved oxygen field. EOF analysis of the two models show similar patterns of dissolved oxygen in the upper ocean (150m depth), with pronounced anoxic conditions in the western Pacific Ocean, Indian Ocean and southern Atlantic Ocean. At 500m depth the model outputs remain mostly in agreement for the Pacific Ocean, but the EOF patterns diverge significantly for both the Indian Ocean and Atlantic Ocean, and to some extent also for the Southern Ocean. For the Indian Ocean, the EOF shift seem to reflect a general reduction of oxygen levels in NorESM-LM compared to NorESM-ME. In the Atlantic Ocean situation is more complex, with NorESM-LM showing reduced oxygen levels near the equator, and enhanced oxygen levels at higher latitudes when compared to NorESM-ME. Further studies are currently in progress to investigate to what extent the similarities and discrepancies in dissolved oxygen concentration can be attributed to ocean temperature and stratification.
Lapse rate deviations from the moist adiabat in the tropical upper troposphere in climate models
Authors: Keil Paul , Schmidt Hauke , Stevens Bjorn
Published: March 2020

The tropospheric lapse rate in the tropics follows a moist adiabat quite closely and is mainly set by surface temperature and humidity in the convecting regions. Therefore, warming or biases at the surface are transferred via the moist adiabat to the upper troposphere. However, climate models show large discrepancies in the upper troposphere and recent observed upper tropospheric warming is around 0.5K weaker than predicted by the moist adiabat theory. Here we use the control simulations of the CMIP5 ensemble to show that large differences in the upper troposphere exist in the mean state that are unrelated to inter-model differences in the lower troposphere. In fact, CMIP5 models diverge (positively and negatively) from the moist pseudoadiabat by up to 2K at 300hPa. Precipitation weighted SSTs have recently been used to resolve the discrepancy between models and observations in upper tropospheric warming, but we show that they are not able to explain the differences in the mean state. While it is difficult to exactly depict the reasons for the inter-model spread, we demonstrate how the upper tropospheric lapse rate can deviate from the moist adiabat for the same lower tropospheric state with AMIP experiments. For this we use the ICON-A model, in which we tune convective and microphysical parameters. An improved understanding of the effect of different parameterisations on the models' lapse rates may help to better understand differences in the response to global warming.
Unraveling effects of reservoir operation on daily flow regime using distributed hydrologic model with global data: case study of the Chao Phraya Basin in Thailand
Authors: Wannasin Chanoknun , Brauer Claudia , Weerts Albrecht , van Verseveld Willem , Uijlenhoet Remko
Published: March 2020

Multipurpose reservoirs and dams have been a necessity for water management worldwide. Despite their benefit on water distribution and hydropower generation, dammed reservoirs remain controversial in many river basins due to their potentially negative impacts on streamflow and, consequently, the environment and society. Southeast Asia (SEA) is the region with the highest investment for large dammed reservoirs. Since SEA is highly exposed to hydrological hazards, particularly under climate change, the effects of reservoir operations on streamflow remain an important issue and should be thoroughly examined in specific contexts of this tropical region. Although many studies have revealed the reservoir effects on long-term (monthly-seasonal) streamflow, they are insufficient for improving the real-time prediction and control of floods and droughts. Therefore, by focusing on an SEA basin, this study aims to (i) quantify the effects of reservoir operations on the water balance and daily flow regime and (ii) distinguish effects of reservoir management and extreme weather on extreme flows. We investigated the Chao Phraya River Basin in Thailand that represents the highly regulated and hazard-prone river basins in SEA. The distributed (1km) wflow_sbm model was used to simulate the rainfall-runoff processes and streamflow in both naturalized (no reservoir) and regulated conditions. To overcome the lack of in-situ data often occurring in SEA basins, we drove the model with global meteorological data. To avoid overparameterization and long computational time, we applied high-resolution, seamless distributed parameter maps obtained with pedo-transfer functions. The model results were analyzed in comparison to daily observations for the 1989-2014 period. Our study revealed the significant effects of the multipurpose reservoirs on the water balance and daily flow regime, including flow rate, magnitude, duration, timing, fluctuation and frequency, during the regular and extreme conditions. The study also showed that the reservoir operations had larger effects on streamflow than extreme weather events. In addition, the operation rules are, in reality, very flexible to satisfy the water demand, which was difficult to represent by the monthly operation rules used in the simulations. The disparity led to the difficulty in the simulation of daily reservoir discharge. To apply the proposed model for the real-time forecasting and decision-making system, a more complex reservoir function with (sub)daily parameters should be tested.
Global Stability Properties of the Climate: Melancholia States, Invariant Measures, and Phase Transitions
Authors: Lucarini Valerio
Published: March 2020

For a wide range of values of the incoming solar radiation, the Earth features at least two attracting states, which correspond to competing climates. The warm climate is analogous to the present one; the snowball climate features global glaciation and conditions that can hardly support life forms. Paleoclimatic evidences suggest that in past our planet flipped between these two states. The main physical mechanism responsible for such instability is the ice-albedo feedback. Following an idea developed by Eckhardt and co. for the investigation of multistable turbulent flows, we study the global instability giving rise to the snowball/warm multistability in the climate system by identifying the climatic Melancholia state, a saddle embedded in the boundary between the two basins of attraction of the stable climates. We then introduce random perturbations as modulations to the intensity of the incoming solar radiation. We observe noise-induced transitions between the competing basins of attractions. In the weak noise limit, large deviation laws define the invariant measure and the statistics of escape times. By empirically constructing the instantons, we show that the Melancholia states are the gateways for the noise-induced transitions in the weak-noise limit. In the region of multistability, in the zero-noise limit, the measure is supported only on one of the competing attractors. For low (high) values of the solar irradiance, the limit measure is the snowball (warm) climate. The changeover between the two regimes corresponds to a first order phase transition in the system. The framework we propose seems of general relevance for the study of complex multistable systems. Finally, we propose a new method for constructing Melancholia states from direct numerical simulations, thus bypassing the need to use the edge-tracking algorithm.

Refs.

V. Lucarini, T. Bodai, Edge States in the Climate System: Exploring Global Instabilities and Critical Transitions, Nonlinearity 30, R32 (2017)

V. Lucarini, T. Bodai, Transitions across Melancholia States in a Climate Model: Reconciling the Deterministic and Stochastic Points of View, Phys. Rev. Lett. 122,158701 (2019)
Addressing geoscience diversity with innovative at-sea experiences for students and educators
Authors: Cooper Sharon , White Lisa , Lewis Jonanthan
Published: March 2020

Many countries face significant challenges in attracting, retaining and diversifying the workforce in the geosciences.  In the U.S. likely contributing factors include the homogeneity of the pool of mentors/role models available both within the workforce and in the professorate.  Another probable factor is “exposure gaps” among student populations; i.e., differing access to engaging facets of science, technology, engineering and mathematics (STEM). To address these challenges, the authors have created a set of NSF-funded programs. The STEMSEAS program recruits undergraduates from diverse backgrounds and institutions to sail on research vessels transits in the U.S. Academic Fleet – giving them relatively short, but transformative experiences at sea. Along with carefully selected mentors who are also from diverse backgrounds, these students spend 5-10 days at sea with a network of students from across the country experiencing a wide range of oceanography and Earth science research techniques and data collection methods.

For educators, the International Ocean Discovery Program (IODP) utilizes transits and tie-ups of the scientific ocean drilling vessel JOIDES Resolution to provide professional development for educators based on the science and technology of science drilling. School of Rock programs aim to address specific diversity goals, focusing on measures to broaden participation at all levels (i.e., pre-college, undergraduate and beyond) in innovative ways (e.g., from place-based curriculum to longitudinal peer mentoring through extracurricular STEM communities).  We seek to add rich international experiences to enhance educators’ motivation and morale, while fostering connections to establish new mechanisms for increased engagement, broader recruitment, enhanced support, and improved retention of students from underrepresented communities from the middle school level to the undergraduate and graduate levels and into the workplace. 

A sister program, Ambassadors for STEM Training to Enhance Participation (ASTEP) works with more upper-level undergraduate and graduate students to leverage both STEMSEAS and School of Rock.  In particular, ASTEP participants take part in both STEMSEAS and/or School of Rock programming, and then build on these experiences to create outreach materials and presentations to share with diverse communities afterwards. This presentation will share best practices and survey results from these programs and our participants that contribute to the conversations around diversity and inclusion, and replication of these models in international settings.
Soil-landscape patterns and fractal parameters of deforestation: a case study of Continental Ecuador Biosphere Reserves.
Authors: Urgilez-Clavijo Andrea , Tarquis Ana , Rivas-Tabares David , de la Riva Juan
Published: March 2020

The complex dynamics of changes in land use and land cover at different scales cause changes in the composition and configuration of the landscape. Deforestation, mainly caused by the transformation of forest to agricultural land, has been one of the most representative changes in recent years worldwide. In Ecuador, this transformation has occurred in different areas of the country, even in those areas declared by UNESCO as biosphere reserves (BRs), endangering the diversity of ecosystems and species existing within each of them. In this context, the identification of patterns, trajectories and magnitudes associated with the deforestation process in the BR areas is essential for the management, conservation and even evaluation of the protection effectiveness of these areas. We analyze the changes in land cover produced between 1990 and 2016 in the Sumaco and Bosque Seco BRs belonging to continental Ecuador, as well as the patterns associated with the deforestation process that occurred in that period. The quantification of land cover changes was performed using a cross-tabulation-table and their spatial location was done through a cross-classification image. The patterns were characterized using landscape ecology metrics and their nature described through multifractal analysis. In addition, the scales at which self-similarity characteristics are detected were identified by lacunarity analysis. The results show that there are three patterns associated with deforestation processes, (1) regrowth of preexisting patches without fusion of the adjacent patches, (2) Regrowth and fusion of preexisting patches and (3) the appearance of new deforested patches. In addition, the multifractal nature of the deforested structure was verified and characteristics of self-similarity at parroquia scale were identified.

ACKNOWLEDGEMENTS

This work was supported by the Program of University of Zaragoza-Santander for Ibero633 Americans in Doctorate studies. Second author acknowledges support from Project No. 634 PGC2018-093854-B-I00 of the Spanish Ministerio de Ciencia Innovación y Universidades of Spain and to the Comunidad de Madrid (Spain) and Structural Funds 2014–2020 (ERDF and ESF) project AGRISOST-CM S2018/BAA-4330. We are also grateful to University of Azuay and Ministry of Environment of Ecuador for providing data and resources for the development of this academic work.
Defining a multi-hazard index in territorial planning framework: application on the Coimbra municipality (western-central Portugal)
Authors: Dimuccio Luca , Cunha Lúcio , Figueiredo Rui
Published: March 2020

In order to support a more integrated approach in the early phases of Risk Management Process, a multi-hazard index was defined to assess the spatial and temporal interaction between natural hazards affecting the same area in a specific timeframe. The Coimbra municipality (western-central Portugal) was used as case study. This territory is an example of the persistent occurrence of potentially dangerous natural events: e.g., floods, landslides and forest fires. Using weighting methodologies, numerical values were assigned to each hazard-related factor (weights) and their categories (ratings). To minimize subjectivity/bias in weighting and rating-assignment processes, several quantitative methods were applied, including probabilistic frequency distribution, multi-criteria analysis and artificial neural networks. Monothematic hazard index quantification and subsequently multi-hazard assessment were implemented in a geographic information system. In few hotspots, the relationship between the observed multi-hazard manifestations and the predicted multi-hazard occurrences was recognized. A framework containing the main hazardous processes and most of the complex relationships/interconnections between them was established. The different degree of multi-hazard zones was mapped. This map can be used to support the implementation of actions to mitigate exposure and vulnerability to these hazards, as well as to promote the territorial management and the development of a resilient municipal system.
Visual and fluorescence characterisation of particulate aerosols in ice cores with imaging flow cytometry
Authors: Harris Matthew , Fogwill Chris , Power Ann , Turney Chris , Love John , Cage Alix , Law Antonia
Published: March 2020

Current efforts to examine and quantify so-called ‘biomarkers’ present in polar ice samples offer exciting potential as biological and biochemical proxies for past climate and ocean dynamics. Here we present a new rapid and easily replicable method to provide measurements of the microscopic particulate content of ice samples from polar environments. Using an Amnis® Imagestream® Imaging Flow Cytometer, melted snow and ice samples from Patriot Hills in the Ellsworth Mountains, Antarctica were analysed for their particulate (biological and non-biological) content. Selective use of a nucleic acid stain pre-treatment allows for a straightforward gating strategy that resolves both autofluorescent and non-autofluorescent biological material in sample replicates. In the Patriot Hills samples this method clearly identifies marine picoplankton, along with non-biological particulates such as tephra and minerogenic material. Crucially, the 60x Brightfield images provided by the Imagestream offer a significant additional capability above standard flow cytometry systems; each object identified by the machine can be visually differentiated (automatically or manually) from particulates with similar fluorescence properties. Back-trajectory analysis with the NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HySPLIT) model indicates that these ice-bound marine organisms originate from the Weddell and Amundsen-Bellingshausen Seas. This technique, when paired with established chemical and biochemical methods, shows considerable potential in providing valuable information about the nature and origin of aerosols and biomarker signals trapped in past ice layers.
Revealing the impact of deforestation on hydrology using remote sensing and land surface modeling
Authors: Maertens Michiel , De Lannoy Gabrielle , Apers Sebastian , Kumar Sujay
Published: March 2020

This study aims at better understanding the impact of deforestation on the local hydrology over the Argentinian Chaco, using land surface modeling and remote sensing data. The Chaco is an ecoregion characterized by unprecedented deforestation since the 1980s, mainly for cattle ranging and soybean production. More specifically, default climatological vegetation parameters (LAI, GVF) and static land cover in state-of-the-art land surface models (LSM), grouped within the NASA Land Information System (LIS), are updated using satellite-based dynamic vegetation parameters and yearly land use maps to feed the models with deforestation.

The presentation will show a spatio-temporal analysis of long-term water budget simulations using a range of LSMs (Noah, CLM, CLSM) in which dynamically updated vegetation and land cover parameters are included. Our simulations indicate that different LSMs result in a different partitioning of the total water budget, but all indicate an increase in soil moisture and percolation over the deforested areas.  Model output is evaluated using in situ soil moisture data, and various soil moisture retrieval products from SMOS (operational Level 2 and SMOS-IC) and SMAP (operational Level 2) and evapotranspiration data from GLEAM.
Crustal Anisotropy beneath Northern Iran calculated by harmonic decomposition of Receiver Functions.
Authors: Azqandi Mohsen , Abbassi Mohammad Reza , Mahmoodabadi Meysam , Sadidkhouy Ahmad
Published: March 2020

This study concerns crustal anisotropy at 16 permanent seismic stations to investigate preferentially aligned cracks or structures and their relation to the stress-state in the South Central Alborz (northern Iran). We consider plunging anisotropy and dipping interfaces of multiple layers using harmonic functions to correct the arrival time variations of Ps phases from different back-azimuths.

The dominant fast orientation of integrated crustal anisotropy strikes NE, almost parallel to the stress direction in the upper crust. The magnitude of crustal anisotropy is found to be in range of 0.1 s to 0.5 s. In some stations, intracrustal interface is observed, for which we analyzed harmonic decomposition of receiver functions to consider anisotropy in the upper crust. Upper crustal anisotropy strikes NE, close to the principal stress direction, indicating that stress in the upper crust plays a major role in producing anisotropy and deformation. In a few stations, crustal anisotropy display different directions rather than NE, which maybe controlled by cracks and fractures of dominant faults.

Keywords: Anisotropy, Receiver function, harmonic decomposition, Northern Iran.
Permian post-collisional basic magmatism from Corsica
Authors: Boscaini Andrea , Marzoli Andrea , Davies Joshua H.F.L. , Chiaradia Massimo , Bertrand Hervé
Published: March 2020

Post-Variscan early Permian magmatism is widespread in Corsica with mafic dykes emplaced during the extensional tectonic phase which followed the Variscan orogeny. This study focuses on a mafic dyke swarm intruded in the region of Ajaccio (Corsica, France). New U-Pb zircon geochronological data show that these intrusions were emplaced at ca. 282 Ma. Most Ajaccio dykes have a calc-alkaline affinity, while a few dykes show tholeiitic affinity resembling N-MORB basalts. Calc-alkaline to tholeiitic dykes are characterized by enriched to depleted Sr-Nd-Pb isotopic compositions, respectively. We interpret these data as evidence that an enriched mantle source, which was likely formed during Variscan subduction, sourced the calc-alkaline suite, while a depleted mantle component dominates the source of the tholeiitic suite. Notably, coeval Permian mafic intrusive bodies from throughout Corsica and from the Southern, Central and Western Alps display similar ages and geochemical features to the Ajaccio dyke swarm. This indicates that a widespread Permian magmatic province developed in a post-orogenic extensional tectonic setting at the margin of the former Variscan belt
Evaluating Arctic meteorology modelled with the Unified Model and Integrated Forecasting System
Authors: Young Gillian , Vüllers Jutta , Achtert Peggy , Field Paul , Day Jonathan , O'Connor Ewan , Brooks Ian , Tjernström Michael , Prytherch John , Neely III Ryan
Published: March 2020

State-of-the-art numerical models such as the UK Met Office Unified Model and European Centre for Medium-Range Weather Forecasting Integrated Forecasting System are crucial tools for forecasting future Arctic warming. However, their ability to reproduce clouds and boundary layer meteorology in the high Arctic has not been thoroughly evaluated following significant model developments over the last 10 years. Model evaluation is key to understanding where remaining process weaknesses lie, thus informing further parametrization developments to improve the simulated surface energy budget.

Here, we evaluate model performance with comparison to observations made during the Arctic Ocean 2018 expedition, where a suite of remote-sensing instrumentation was active aboard the Swedish icebreaker Oden measuring summertime Arctic cloud and boundary layer properties. We find that both models do not reproduce cloud fractions well at altitude (up to 8 km) and overestimate the occurrence of low (<1 km) clouds during the sea ice melt period of the expedition. Low cloud agreement with observations improves when the sea ice begins to refreeze; however, the underestimation of cloud aloft remains consistent regardless of sea ice conditions. In this presentation, we will indicate which model processes need to be improved to capture these summertime Arctic clouds more effectively.
Microbial activity in nuclear waste repository systems
Authors: Raff Johannes , Lopez-Fernandez Margarita , Hilpmann Stephan , Kluge Sindy , Steudtner Robin , Cherkouk Andrea
Published: March 2020

A multi-barrier system in which the radioactive waste is encapsulated in metal containers surrounded by a geotechnical barrier (e.g. compacted bentonite) deep underground in a stable geological formation is one of the internationally accepted options for the disposal of highly radioactive waste. Bentonites have good properties such as high swelling capacity and low hydraulic conductivity, which makes them favorable as backfilling material. However, indigenous microorganisms may affect these properties. Bentonite samples were collected from the Full-scale Engineered Barrier Experiment (FEBEX) - Dismantling Project [1] at the Grimsel Test Site (Switzerland) to study their microbial diversity. For that, total DNA was extracted directly from the cores and from enrichments of sulfate- and iron-reducing microorganisms as well as microorganisms were isolated from those enrichments. The microbial communities of the bentonites, the enrichments, as well as the isolates were analyzed by 16S rRNA gene sequencing. The results showed that Actinobacteria and Alphaproteobacteria dominated the FEBEX bentonite microbial population, while the dominant phylum in both enrichments was Firmicutes: concretely, Bacilli and Clostridia classes. In addition, bacteria from the genera Desulfitobacterium, Desulfosporosinus and Clostridium were isolated from the enrichments. Desulfosporosinus hippei DSM 8344 as a phylogenetic close relative was selected to study its interactions with uranium and especially its potential to reduce U(VI) to U(IV). This study revealed that microorganisms are present in bentonite samples after a long-term continuous heating. Sulfate- and iron-reducing microbes were enriched by using favorable conditions in specific media and the potential of the sulfate-reducing microorganisms on the reduction of uranium was verified. Therefore, it is important to characterize the microbial population of the bentonite, because microbes might compromise the safety of the deep geological repository of highly radioactive waste.

[1]http://www.grimsel.com/gts-phase-vi/febex-dp/febex-dp-introduction
Significant fluxes of methane over tropical wetlands and their associated δ13C isotopic source signatures
Authors: France James L. , Jones Anna , Lachlan-Cope Tom , Weiss Alex , Andrade Marcos , Moreno Isabel , Fisher Rebecca , Lowry Dave , Lanoiselle Mathias , Nisbet Euan , Lunt Mark
Published: March 2020

Tropical wetlands have been proposed as a potential driver for the recent rise in global atmospheric methane. However, direct access and quantification of emissions is difficult. In March 2019, a pilot study was given permission to overfly the Bolivian Llanos de Moxos wetlands to measure atmospheric mixing ratios of methane and collect spot samples for isotopic analysis. Combined with this was a short ground campaign to collect isotopic samples directly above the wetland edge to compare with the integrated atmospheric signature.

Atmospheric mixing ratios of methane reached a maximum of 2400 ppb (500 ppb above baseline concentrations) in the well mixed boundary layer flying at 400m above the wetland. Upwind and downwind transects were a maximum of 300 km, and methane mixing ratios increased roughly linearly with distance downwind. The isotopic data from the airborne surveys and ground surveys give a bulk isotopic signature for δ13CCH4 of ~-59 ‰ ± 4, which is less negative than Amazon floodplain work focusing on emission of methane through trees, but match well with bulk isotopic values from the Amazon Basin. Ground based wetland samples taken concurrently near Trinidad, Bolivia, gave a source signature of -56 ‰ ± 4 re-enforcing the likelihood that the atmospheric enhancements measured are related to the wetland emissions. For comparison, tropical wetlands measured at ground level during a recent Ugandan and Zambian campaign gave heavier δ13CCH4 isotopic source signatures of -50 to -54 ‰. Based on this snap shot study, flux estimations suggest that the Bolivian wetlands could be emitting ~10mg CH4 m-2 h-1. The observed mole fractions will be compared to model simulations to determine how well the Bolivian wetland methane fluxes are represented.
Seismic noise characterization of the Sos Enattos Mine (Sardinia), a candidate site for the next generation of terrestrial gravitational waves detectors
Authors: Giunchi Carlo , Di Giovanni Matteo , Saccorotti Gilberto , Naticchioni Luca
Published: March 2020

We present some preliminary results from ongoing seismic measurements aimed to assess the seismic noise levels in the Sos Enattos Mine (Sardina). Due to his geologic setting, low population density and lack of significant industrial activity, Sardinia is characterized by very low anthropogenic noise and very low seismic activity. These unique combinations of factors make Sardinia, and in particular the Sos Enattos site, suitable to host instruments that must be placed in particularly seismically quiet locations in order to meet their targeted sensitivity. This is certainly the case of gravitational waves detectors, whose next generation, called Einstein Telescope (ET), is planned to be able to measure a strain, induced by the passing wave on the interferometer’s arm, of the order of 2x10-25Hz-1/2. Three broadband seismometers has been installed since May 2019 both at surface and at different depths along the mine tunnels. We analyse the spectral distribution of the seismic noise with a special focus on the frequency bands that may affect the operation of a gravitational waves interferometer. We also study the correlation of seismic noise with the observed sea waves in the Mediterranean Sea. The results enlighten very low seismic noise levels at the surface and attenuation at the depths foreseen to build ET. Further, seismic noise levels appear to be strongly correlated with sea waves in NW Mediterranean Sea. We conclude that the selected site may meet the stringent seismic requirements needed to realize the ET infrastructure.
Evaluation of a multilayer snow scheme in NEMO-LIM3
Authors: Gilson Gaëlle , Fichefet Thierry , Lecomte Olivier , Barriat Pierre-Yves , Sterlin Jean , Massonnet François
Published: March 2020

Arctic sea ice is a major component of the Earth’s climate system and has been experiencing a drastic decline over the past decades, with important consequences regionally and globally. With the sustained warming of the Arctic, sea ice loss is expected to continue in the future. However, the estimation of its magnitude is model-dependent. As a result, the representation of sea ice in climate models requires further consideration. A major issue relates to the long-standing misrepresentation of snow properties on sea ice. However, the presence of snow strongly impacts sea ice growth and surface energy balance. Through its high albedo, snow reflects more solar radiation than bare sea ice does. When a snow cover is present, sea ice growth is reduced because snow is an effective insulator, with a thermal conductivity an order of magnitude lower than that of sea ice. Ocean circulation models usually use multiple layers to resolve sea ice thermodynamics but only one single layer for snow. Lecomte et al. (2013) developed a multilayer snow scheme for ocean circulation models and improved the snow depth distribution by considering the macroscopic effects of wind packing and redeposition. Since then, this snow scheme has been revisited and implemented in a more recent and much more robust NEMO-LIM version, using a simpler technical approach. In addition, new instrumental observations of snow thickness, distribution and density are available since these exploratory works. They are used in the current study to: 1) evaluate the performance of the multilayer snow scheme for sea ice in the NEMO-LIM3 model, and 2) investigate the climatic importance of this snow scheme. Here, we present results of simulations with a varying number of snow layers. By comparing these to the latest observational datasets, we recommend an optimum number of snow  layers to be used in ocean circulation models in both hemispheres. Finally, we explore the impact of a few specific parameterizations of snow thermophysical properties on the representation of sea ice in climate models.
Drivers of biases in the extratropical storm tracks in CMIP6
Authors: Priestley Matthew , Ackerley Duncan , Catto Jennifer , Hodges Kevin , McDonald Ruth , Lee Robert
Published: March 2020

Extratropical cyclones are the leading driver of the day-to-day weather variability and wintertime losses for Europe. In the latest generation of coupled climate models, CMIP6, it is hoped that with improved modelling capabilities come improvements in the structure of the storm track and the associated cyclones. Using an objective cyclone identification and tracking algorithm the mean state of the storm tracks in the CMIP6 models is assessed as well as the representation of explosively deepening cyclones. Any developments and improvements since the previous generation of models in CMIP5 are discussed, with focus on the impact of model resolution on storm track representation. Furthermore, large-scale drivers of any biases are investigated, with particular focus on the role of atmosphere-ocean coupling via associated AMIP simulations and also the influence of large-scale dynamical and thermodynamical features.
Estimating Vertical Land Motion in Northern Adriatic Sea with Coastal Altimetry and In Situ Observations
Authors: De Biasio Francesco , Vignudelli Stefano , Baldin Giorgio
Published: March 2020

The European Space Agency, in the framework of the Sea Level Climate Change Initiative (SL_CCI), is developing consistent and long-term satellite-based data-sets to study climate-scale variations of sea level globally and in the coastal zone. Two altimetry data-sets were recently produced. The first product is generated over a grid of 0.25x0.25 degrees, merging and homogenizing the various satellite altimetry missions. The second product that is still experimental is along track over a grid of 0.35 km. An operational production of climate-oriented altimeter sea level products has just started in the framework of the European Copernicus Climate Change Service (C3S) and a daily-mean product is now available over a grid of 0.125x0.125 degrees covering the global ocean since 1993 to present.

We made a comparison of the SL_CCI satellite altimetry dataset with sea level time series at selected tide gauges in the Mediterranean Sea, focusing on Venice and Trieste. There, the coast is densely covered by civil settlements and industrial areas with a strongly rooted seaside tourism, and tides and storm-related surges reach higher levels than in most of the Mediterranean Sea, causing damages and casualties as in the recent storm of November 12th, 2019: the second higher water registered in Venice since 1872. Moreover, in the Venice area the ground displacements exhibit clear negative trends which deepen the effects of the absolute sea level rise.

Several authors have pointed out the synergy between satellite altimetry and tide gauges to corroborate evidences of ground displacements. Our contribution aims at understanding the role played by subsidence, estimated by the diffence between coastal altimetry and in situ measurements, on the local sea level rise. A partial validation of these estimates has been made against GPS-derived values, in order to distinguish the contributions of subsidence and eustatism. This work will contribute to identify problems and challenges to extend the sea level climate record to the coastal zone with quality comparable to the open ocean, and also to assess the suitability of altimeter-derived absolute sea levels as a tool to estimate subsidence from tide gauge measurement in places where permanent GPS receivers are not available.
Improving the analysis of the soil-plant-atmosphere system thought earth observations in large monocrop cereal sequences
Authors: Rivas-Tabares David , Martín-Sotoca Juan J. , Saa-Requejo Antonio , Tarquis Ana María
Published: March 2020

Crop yields of rainfed cereal are highly dependent of the soil-plant-atmosphere system, especially referred to the weather conditions and soil properties. The study of this interaction is feasible through the earth observations of historical data. Remote sensing data and agricultural survey work together identifying and analyzing plots with monocrop cereal sequences. In this research, we investigate the relation of the Normalized Difference Vegetation Index (NDVI) residual time series behavior relative to soil classes from Self-Organizing Maps (SOM) and the precipitation residual time series.

The midlands of Eresma-Adaja watershed (Dueros’ River basin, Spain) is historically depicted to rainfed cereal agriculture, some evidence of monocropping sequences are worrisome the water availability in the area. Within this area, two contrasting soil properties sites were selected to assess plots with at least 20 years of rainfed monocropping sequences but under similar weather regime. This allows analyzing the effect and relationships of this practice by soil type in time. For this, we treat the NDVI and precipitation time residual series as signals. The use of the Generalized Structure Function applied to these residual time series and the Hurst exponent, serve to confirm the soil properties differences from SOM and to reinforce the scaling properties of soil-climate interaction in semiarid regions for cereals in monocrop. As a result, the NDVI and precipitation series present an antipersistence behavior supporting that precipitation regime is influencing as the same manner the NDVI residual time series among complimentary factors.

ACKNOWLEDGEMENTS

Finding for this work was partially provided by Boosting agricultural Insurance based on Earth Observation data - BEACON project under agreement Nº 821964, funded under H2020_EU, DT-SPACE-01-EO-2018-2020. The authors also acknowledge support from Project No. PGC2018-093854-B-I00 of the Spanish Ministerio de Ciencia Innovación y Universidades of Spain. The data provided by ITACyL and AEMET is greatly appreciated.

 
The new WMM2020 and IGRF-13 models, and a retrospective analysis of IGRF secular variation
Authors: Brown William , Beggan Ciarán , Cox Grace , Macmillan Susan
Published: March 2020

2020 marks the start of a new 5-year cycle and updated releases of the World Magnetic Model (WMM) and International Geomagnetic Reference Field (IGRF). These models provide a reference for the up-to-date internal geomagnetic field in 2020, and a prediction of its secular variation for the next 5 years, to 2025. While similar in some aspects, the two models have different specifications and many different users across diverse fields. They provide references to be used primarily for navigation (WMM) and geomagnetic coordinate systems (IGRF).

BGS produces the WMM in collaboration with the US’ NOAA/NCEI, while the IGRF is produced by an IAGA Div. V-MOD task force, this time consisting of fifteen teams across nine nations, including BGS. Here we present a summary of the production of the updated WMM2020 and IGRF-13, and BGS efforts to enable access to these models.

We also present a retrospective analysis of the predictive components of the candidate models for previous IGRF epoch’s secular variation. Recent epochs have seen notable geomagnetic jerks and the acceleration of the North magnetic dip pole, features not well represented by the constant SV format of models such as the IGRF. We assess the range of candidate models submitted for previous IGRF epochs, assess the accuracy of physically derived predictions versus mathematical extrapolations, and discuss the implications given the range of candidate models submitted for IGRF-13 secular variation over the next five years.
Investigation of strongly enhanced methane Part I: Chemical feedbacks and rapid adjustments.
Authors: Winterstein Franziska , Jöckel Patrick , Dameris Martin , Ponater Michael , Tanalski Fabian , Stecher Laura
Published: March 2020

Methane (CH4) is the second most important greenhouse gas, which atmospheric concentration is influenced by human activities and currently on a sharp rise. We present a study with numerical simulations using a Chemistry-Climate-Model (CCM), which are performed to assess possible consequences of strongly enhanced CH4 concentrations in the Earth's atmosphere for the climate.

Our analysis includes experiments with 2xCH4 and 5xCH4 present day (2010) lower boundary mixing ratios using the CCM EMAC. The simulations are conducted with prescribed oceanic conditions, mimicking present day tropospheric temperatures as its changes are largely suppressed. By doing so we are able to investigate the quasi-instantaneous chemical impact on the atmosphere. We find that the massive increase in CH4 strongly influences the tropospheric chemistry by reducing the OH abundance and thereby extending the tropospheric CH4 lifetime as well as the residence time of other chemical pollutants. The region above the tropopause is impacted by a substantial rise in stratospheric water vapor (SWV). The stratospheric ozone (O3) column increases overall, but SWV induced stratospheric cooling also leads to enhanced ozone depletion in the Antarctic lower stratosphere. Regional  patterns of ozone change are affected by modification of stratospheric dynamics, i.e. increased tropical up-welling and stronger meridional transport  towards the polar regions. We calculate the net radiative impact (RI) of the 2xCH4 experiment to be 0.69 W m-2 and for the 5xCH4 experiment to be 1.79 W m-2. A substantial part of the RI is contributed by chemically induced O3 and SWV changes, in line with previous radiative forcing estimates and is for the first time splitted and spatially asigned to its chemical contributors.

This numerical study using a CCM with prescibed oceanic conditions shows the rapid responses to significantly enhanced CH4 mixing ratios, which is the first step towards investigating the impact of possible strong future CH4 emissions on atmospheric chemistry and its feedback on climate.