bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic characterization of ghost rocks from the Sterkfontein cave (South Africa): are iron oxides linked to biological activity?
Authors: Isambert Aude , Watkinson Maud , Pisapia Céline , Gérard Emmanuelle , Menez Bénédicte , Maire Richard , Bruxelles Laurent
Published: March 2020

The Sterkfontein caves system in the Cradle of Humankind (South Africa) is a karstic environment resulting from a ghost-rock karstification process that developed in the Malmani dolomite formation presenting interlayered more resistant chert layers (Bruxelles, 2017). This process of karstification occurs under low hydrodynamic conditions leaving in place a residual highly porous altered rock, which preserves the structure of the initial bedrock, and which is called “ghost rock”. Due to its high porosity and in the presence of water, ghost-rocks can represent a potential habitat for microorganisms, ubiquitous on and in Earth, with metabolisms mainly relying on dissolution or precipitation processes of minerals. Thus some secondary mineralizations of manganese and iron oxides, found associated to microorganisms in cave systems, could have a biological origin (Banerjee and Joshi, 2012). To better characterize the alteration phases and understand the process of karstification and the potential role of microorganisms and biofilms, samples including dolomitic bedrock, cherts and ghost-rocks were collected at the Sterkfontein cave system. We report here magnetic properties of powdered samples (low-field susceptibility, hysteresis parameters, saturation magnetization and MPMS measurements). In parallel to these magnetic measurements, XRD analyses, FTIR spectroscopic analyses and microscopic observations (SEM) have been realized in order to better characterize the mineralogy of bedrock and secondary phases and to better constrain the alteration processes. We observe that the ghost-rock is mostly composed of quartz and oxides. The magnetic phases detected are mainly hematite and goethite, precipitated on the quartz grain boundaries. These first observations could be explained by a total dissolution of the main bedrock (dolomite) and a partial chemical alteration and mechanical erosion of cherts. To go further, an additional microbial ecology study in the cave system is needed to better constrain the role of microorganisms in the precipitation of oxides detected.

 

Banerjee, S., Joshi, S.R., 2013. Insights into Cave Architecture and the Role of Bacterial Biofilm. PNAS, India Section B: Biological Sciences 83, 277–290.

Bruxelles L., 2017. Des fantômes et des hommes. Le rôle de la fantômisation dans la formation des karsts à homininés d’Afrique du Sud. Karstologia 69, 1–8.
Study of sea water chemistry changes due to thawing permafrost
Authors: Pogojeva Maria , Yakushev Evgeniy , Petrov Ilya , Yaeski Evgeniy , Polukhin Alexander
Published: March 2020

Influence of thawing permafrost on the chemical properties of the sea water was studied in 2 experiments organized in Svalbard in 2017 and 2018. Permafrost samples were collected at an abrasive cliff 10 km west of Longyearbyen. Experiments were focused on identifying the possible changes in concentrations of nutrients, carbonate system parameters and pollutant composition related to permafrost thawing. During the experiment, the samples of permafrost were added to the seawater. The solution was exposed to natural conditions for 24 hours in 2017 and 5 days in 2018 while water samples from the solution were taken at specified time intervals. The results of the experiment show that the sea water composition changes are connected to the permafrost thawing. Data from this experiment allowed us to estimate the total annual supply of nutrients to the Arctic from permafrost thawing by multiplying the change in concentration from this study by the annual eroded permafrost total volume in Siberia.

 

 

 
Spatial variations of long-period waves and harbor oscillations around Taiping Island in the South China Sea
Authors: Su Shih-Feng , Weng Wen-Kai
Published: March 2020

Most coral reef islands in the South China Sea are primary influenced by monsoons from the northeast in winter to the southwest in summer. Because the length scale of the islands ranges between O(100 m) and O(1000 m), nearshore waves and currents on the windward and leeward sides are modulated by seasonal wave directions as well as reef morphology. It is well known that long-period swell and infragravity waves play a vital role in dominating hydrodynamics and sediment dynamics on fringing reefs. However, spatial characteristics of long waves on the entire islands have not been well studied. In the present study, a phase-resolving Boussinesq-type wave model, is employed to investigate wave distributions around Taiping Island in the South China Sea during the monsoon. Wave transformations of refraction, diffraction, reflection and nonlinear wave interactions on the complex reef geometry are simulated using a high resolution grid. Model results will display spatial variability of significant wave height, infragravity waves and nearshore currents around the reef platform. The importance of long wave diffraction and resulting wave frequency components at the leeward side of the island will be examined. A small harbor located at the southern island often experiences harbor oscillations during the winter monsoon, even it located at the leeward side. Harbor oscillations forced by periods of wind-wave, swell and infragravity waves will be explored to provide critical indicators for the harbor management.
Evolution of plant terpenoids on a ‘biotic ferry’
Authors: Dutta Suryendu
Published: March 2020

Palaeogegraphic model suggests that the Indian plate was separated from Gondwana during Late Jurassic and started moving towards the northern hemisphere during the Early Cretaceous and remained as an island continent during the entire Cretaceous until it collided with Asia in Early Eocene at ca. 50 Ma.  It is believed that many vertebrate groups may have originated in India or other Gondwanan land masses and were carried on the rafting Indian plate and finally dispersed ‘out of India’ following the collision between India and Asia. However, the evolution of plants on the rafting continent is poorly documented.

 

A brief outline on evolution of plant terpenoids from Permian to Eocene on the Indian continent will be discussed during the presentation. The Permian coals are characterized by tricyclic and teracyclic diterpenoids. The possible source of these compounds is extinct seed ferns.

The molecular composition of Jurassic and early Cretaceous coals and sediments suggests that the vegetation was contributed by conifers (e.g. Arucariaceace, Podocarpaceae) during the period. Aromatic triterpenoids derived from angiosperms are detected in the sediments of Late Maastrichtian age. Drastic reduction of coniferous vegetation and proliferation of angiosperms in early Palaeogene are observed in the present study. The terpenoid signatures of early Palaeogene lignites suggest that the western India was covered by widespread thick closed rain forests dominated by family Dipterocarpaceae thriving under the influence of tropical climate.
The oxidizing power of the dark side: Rapid nocturnal aging of biomass burning as an overlooked source of oxidized organic aerosol
Authors: Kodros John , Papanastasiou Dimitris , Paglione Marco , Masiol Mauro , Squizzato Stefania , Florou Kalliopi , Kołodziejczyk Agata , Skyllakou Ksakousti , Nenes Athanasios , Pandis Spyros
Published: March 2020

Oxidized organic aerosol (OOA) is a major component of ambient particulate matter, substantially affecting both climate and human health. A considerable body of evidence has established that OOA is readily produced in the presence of daylight, thus leading to the association of high concentrations of OOA in the summer or mid-afternoon. However, this current mechanistic understanding fails to explain elevated OOA concentrations during night or wintertime periods of low photochemical activity, thus leading atmospheric models to under predict OOA concentrations by a factor of 3-5. Here we show that fresh emissions from biomass burning rapidly forms OOA in the laboratory over a few hours and without any sunlight. The resulting OOA chemical composition is consistent with the observed OOA in field studies in major urban areas. To estimate the contribution of nocturnally aged OOA in the ambient atmosphere, we incorporate this nighttime-aging mechanism into a chemical-transport model and find that over much of the United States greater than 75% of the OOA formed from fresh biomass burning emissions underwent nighttime aging processes. Thus, the conceptual framework that OOA is predominantly formed in the presence of daylight fails to account for a substantial and rapid oxidation process occurring in the dark.
The kinematic vorticity analysis of ductile shear zones of Ambaji Granulite, NW India and its tectonic implications
Authors: Tiwari Sudheer Kumar , Beniest Anouk , Biswal Tapas Kumar
Published: March 2020

The Neoproterozoic (834 – 778 Ma) Ambaji granulite witnessed four deformation phases (D1- D4), of which the D2 deformation phase was most significant for the exhumation of granulites in the ductile regime. We performed a field study to investigate the tectonic evolution of the D2 deformation phase and investigated the deformation evolution of the ductile extrusion of the Ambaji granulite by estimating the vorticity of flow (Wm) with the Rigid Grain Net and strain ratio/orientation techniques.

During the D2 deformation phase, the S1 fabric was folded by F2 folds that are coaxial with the F1 folds. The F2 folds were produced in response to NW-SE compression. Because the large shear zones are oriented parallel to the axial plane of the F2 folds, they likely formed simultaneously during the D2 deformation phase. Compression during the D2 deformation phase accommodated most of the exhumation of the granulite along the shear zones. D2 shearing was constrained between 834 ± 7 to 778 ± 8 Ma (Monazite ages).

The shear zones evolved from a high temperature (>700 °C) thrust-slip shearing event in the lower-middle crust to a low temperature (450 °C) retrograde sinistral shearing event at the brittle-ductile-transition (BDT). The Wm estimates of 0.32–0.40 and 0.60 coincide with the high temperature event and suggests pure shear dominated deformation. The low temperature phase coincides with Wm estimates of 0.64–0.87 and ~1.0, implying two flow regimes. The shear zone was first affected by general non-coaxial deformation and gradually became dominated by simple shearing.

We interpreted that the high temperature event happened in a compressive tectonic regime, which led to horizontal shortening and vertical displacement of the granulite to the BDT. The low temperature event occurred in a transpressive tectonic setting that caused the lateral displacement of the granulite body at BDT depth. The Wm values indicate a non-steady strain during the exhumation of granulite. From the BDT to surface, the Ambaji granulite exhumed through the NW-SE directed extension for normal faults via brittle exhumation through crustal extension and thinning.
REPRO: Through Diffusion Experiment (TDE) - Diffusion and Porosity Properties of Rock Matrix in Stress Field of Repository Level
Authors: Rahkola Kalle , Poteri Antti , Koskinen Lasse , Andersson Peter , Nilsson Kersti , Byegård Johan , Siitari-Kauppi Marja , Helariutta Kerttuli
Published: March 2020

Radionuclides usually migrate slower than the flowing water due to sorption and matrix diffusion. The performance assessment assumes that retention takes place mostly in the vicinity of the deposition holes. REPRO (REtention Properties of ROck matrix) experiments analyzed the matrix retention properties of the rock matrix under realistic conditions deep in the bedrock in ONKALO underground characterization facility at Olkiluoto, Finland. The objective was to investigate tracer transport in the rock matrix, which was representative to the near-field of the final disposal repository of the spent nuclear fuel, and to demonstrate that the assumptions made in the safety case of the deep geological spent fuel repository were in line with site evidence.

REPRO is composed of several supporting laboratory and in-situ experiments which investigate the retention properties under different experimental configurations. The first in-situ experiments were water phase diffusion experiments performed 2012-2013. Through Diffusion Experiment (TDE) studies diffusion and porosity properties of rock matrix in stress field of repository level and sorption properties of nuclides in intact rock circumstances.

The TDE experiment has been performed in three parallel drillholes drilled near to each other. Breakthrough of the radioactive tracer is monitored with on-line measurements and samplings along and perpendicular to the foliation. The non-sorbing radioactive isotope traces of HTO and 36Cl, as well as slightly sorbing 22Na and strongly sorbing 133Ba and 134Cs were used. TDE was designed to control advective flow, as it had caused problems in previous in-situ tests.

Supporting laboratory studies were performed for drillcore samples sampled from the experimental drillholes. In these laboratory experiments, i.e. porosity, permeability and diffusion coefficients of the drillcores were determined using different methods.

The TDE experiment was carried out from 2016 to 2019. A breakthrough was seen in the timeframe predicted by scoping calculations carried out. REPRO has produced data and knowledge to the safety case and the performance assessment. According to the preliminary results, values measured in the laboratory are applicable also in larger scale and in-situ conditions.
Diagnostic of a regional distributed hydrological model through hydrological signatures
Authors: Branger Flora , Horner Ivan , Marçais Jean , Caballero Yvan , Braud Isabelle
Published: March 2020

Distributed models are useful tools for the assessment of water resources in a context of global change. However, due to the high spatial heterogeneity of the corresponding catchments, these models end up being quite complex with a high number of parameters. In particular, it is not easy to obtain good performances and physically sounded parameter values at all points in the catchment. In order to complement the traditional evaluation approach based on performance criteria, we developed a diagnostic approach based on hydrological signatures. A set of hydrological signatures based on precipitation and runoff data was defined and applied to a regional model of the Rhône basin (100 000 km2) in France. The comparison of simulated and observed signatures for 45 contrasted sub-basins of various sizes, climates, geologies and land uses, show that performance and ability to reproduce signatures are not always correlated. The analysis of signature results, combined with additional hydrogeology expertise, provided directions to improve the model parameterization, especially in the groundwater compartment. The study also provided feedback on the degree of information contained in the signatures and allows us to make recommendations for future studies.
Dynamic environmental response to the Younger Dryas cooling in the sediment record of Lake Gościąż
Authors: Müller Daniela , Tjallingii Rik , Plessen Birgit , Płóciennik Mateusz , Ramisch Arne , Neugebauer Ina , Schwab Markus J. , Słowiński Michał , Błaszkiewicz Mirosław , Brauer Achim
Published: March 2020

The last deglaciation in the northern hemisphere was interrupted by several short cold setbacks of which the Younger Dryas (YD) was the last and most pronounced. This abrupt and extreme cold period provides valuable insights into regional climate and environmental responses. To decipher the rate of such rapid changes continuous climate archives of annually laminated (varved) sediments are crucial.

Lake Gościąż (central Poland) exhibits an iconic varved lake sediment record that is one of the few European lake records preserving varves throughout the complete YD. To re-investigate this archive, 10 new sediment cores have been obtained along a N-S transect through the deepest part of the lake basin. We used a combination of continuous microfacies analyses, XRF element core scanning, µ-XRF mapping, and high-resolution chironomid-inferred mean July air temperature as well as analyses of stable oxygen and carbon isotopes.

Lacustrine sedimentation begins in the late Allerød, is briefly interrupted by a slump during the early YD and proceeds continuously afterwards. Here, we present a first continuous microfacies investigation of the complete YD in Lake Gościąż. Varve composition during the YD is the most complex and variable one, featuring primarily diatom frustules, calcite, re-worked and re-suspended material. Contrastingly, the simpler structured varves during the early Preboreal and late Allerød are characterized predominantly by calcite, rhodochrosite and dissolved organic matter. The change in microfacies at both YD transitions occurs not simultaneously with the other proxy responses.

Causes of and differences in proxy responses in regard to the dynamics of environmental change during a major change in climate are discussed. Further, we conduct a proxy comparison at both YD transitions and provide a detailed documentation of the transitions through µ-XRF mapping.

This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution Analysis (ICLEA) of the Helmholtz Association (grant number VH-VI-415). It is further a contribution to a scientific project financed by the National Science Centre, Poland – No. UMO-2015/19/B/ST10/03039.
The last traces. Historical images and the reconstruction of lost archaeological landscapes
Authors: Strupler Nehemie
Published: March 2020

Since one century, aerial photography has a successful track record of detecting and mapping archaeological traces of human activity in the landscape. The tools and procedures evolved gradually, following technological and methodological advancements of earth remote sensing. It started with the use of crop marks and other proxies such as soil, shadow or snow to distinguish observable differences caused by subsurface archaeological remains, locating buried archaeological features.  Beside theses data gathered by archaeologists, the declassification at the end of the last century of millions of photographs (such as the CORONA, ARGON or LANYARD US satellite programs as well as other non-US military programs) has resulted in a vast archive.

Historical images represent a fundamental tool in archaeological research, particularly for Western Asia.  They document nowadays inaccessible landscapes that has been recovered by modern human infrastructure (i.e.  building, roads) or heavily modified (notably by the increasing use of mechanized agricultural methods), erasing fragile traces from thousands of years ago.  Only through the detailed analysis of archives from the 20th century, is it possible to recover archaeological evidences and paleo-environmental features.  

The traditional workflow uses historical images as a first step prior to archaeological fieldwork, asserting and dating detected features. One main problem arises when ground truthing of these detected features is not possible anymore. How trustful are the detections and how to date them? My poster/talk will present sources as well as state-of-the-art analysis of historical aerial images based on the Scaling Territories Project (SCATTER).  The combined use of historical maps, aerial images and ground acquired archaeological data from nearby field-walking prospections enables to reconstruct the paleo-landscapes and the location of (presumed and know lost) settlements in Central Anatolia.  
Unsolved problems in hydrology: societal responses to unprecedented events
Authors: Rusca Maria , Di Baldassarre Giuliano , Messori Gabriele
Published: March 2020

Understanding how different societal groups respond to drought or flood events is one of the unsolved problems in hydrology (UPH), concerning the interfaces with society. More specifically, there is a need to decipher the relationship between potential impacts of unprecedented events, distribution of sociohydrological risk as well as future adaptation and recovery trajectories. In this presentation, we introduce a new analytical approach to answer the question of how contemporary societies might adapt to and recover from unprecedented drought and flood events in an inclusive and sustainable fashion. In doing so, this presentation deepens our understandings of the interface between hydrological extremes and society. Addressing this question requires creating new forms of knowledge that integrate analyses of the past, i.e. historical and political processes of risk and adaptation and the underlying power relations, with hydroclimatic projections of unprecedented events. We thus combine three aspects which have been studied individually, but never integrated: a. scenarios based on social science theories on disaster management; b. case studies of past hydroclimatic events which were unprecedented at the time of their occurrence; c. conceptual transfer across case studies - that is, learning something about potential future unprecedented events at one location by leveraging events which occurred elsewhere. Some of the scenarios developed may already be emerging in current times, whilst others are plausible hypotheses in humanity’s future space. This approach, at the nexus between social and hydrological sciences, has the concrete advantage of providing an impacts-focussed vision of future risk, beyond what is achievable within conventional disciplinary boundaries. 
Comparing runoff statistics simulated with a hydrological model utilizing stochastically generated lumped catchment rainfall and multiple point rainfall
Authors: Thiele Luisa-Bianca , Pidoto Ross , Haberlandt Uwe
Published: March 2020

For derived flood frequency analyses, stochastic rainfall models can be linked with rainfall-runoff models to improve the accuracy of design flood estimations when the length of observed rainfall and runoff data is not sufficient. In the past, when using stochastic rainfall time series for hydrological modelling purposes, catchment rainfall for use in hydrological modelling was calculated from the multiple point rainfall time series. As an alternative to this approach, it will be tested whether catchment rainfall can be modelled directly, negating the drawbacks (and need) encountered in generating spatially consistent time series. An Alternating Renewal rainfall model (ARM) will be used to generate multiple point and lumped catchment rainfall time series in hourly resolution. The generated rainfall time series will be used to drive the rainfall-runoff model HBV-IWW with an hourly time step for mesoscale catchments in Germany. Validation will be performed by comparing modelled runoff regarding runoff and flood statistics using stochastically generated lumped catchment rainfall versus multiple point rainfall. It would be advantageous if the results based on catchment rainfall are comparable to those using multiple point rainfall, so catchment rainfall could be generated directly with the stochastic rainfall models. Extremes at the catchment scale may also be better represented if catchment rainfall is generated directly.
Development and application of Phyto-VFP model (Variable Fluorescence Phytoplankton Production) to estimate primary production in highly vulnerable marine pelagic ecosystems
Authors: Bonamano Simone , Madonia Alice , De Luca Antonio , Lazzara Luigi , Becagli Silvia , Piermattei Viviana , Marcelli Marco
Published: March 2020

Marine phytoplankton production (PP) represents an influential force on the carbon cycle and the climatic processes on a global scale, being responsible for up to 40% of the biological fixation of atmospheric CO2.
Understanding and predicting the effects of climate change on marine phytoplankton is crucial within the analysis of climate change scenarios as it affects the ecological responses of the higher trophic levels. In this context, the development of predictive models for the estimation of PP provides useful scientific responses to address the issues of sustainability in a climatically changing world. The need to estimate PP more accurately allows to face the impacts of global change on highly vulnerable areas such as such as regional seas and polar regions.
In this work we present the Phyto-VFP (Variable Fluorescence Phytoplankton Production), a new bio-optical model which enables to compute PP by integrating the effects of the photo-acclimation processes of phytoplankton with the dynamic conditions of the water column.
To parametrise the photo-physiological behavour of phytoplankton cells a series of laboratory experiments based on in vivo variable fluorescence measures were conducted on culture species selected according to the ecological features of the investigated areas.
The performance of Phyto-VFP was evaluated with concurrent estimates of radiocarbon (14C) uptakes and the results obtained with the use of the Morel bio-optical model, under different dynamic and optical conditions, during two oceanographic cruises in the Mediterranean Sea.
Here we present the results of the model validation as well as the application of Phyto-VFP model to different highly vulnerable regions to climate change. 
Environmental changes in the Wehntal Valley in Northern Switzerland
Authors: Miocic Johannes , Drescher-Schneider Ruth , Graf Hans Rudolf , Kühn Marlu , Preusser Frank , Schoch Werner H. , Thew Nigel , Wick Lucia , Furrer Heinz
Published: March 2020

Quaternary deposits within the glacially overdeepened trough of the Wehntal Valley in Northern Switzerland, record glacial and interglacial conditions from the Beringen Glaciation (MIS 6) through to the Holocene. The area is well known for the Niederweningen site, with its rich Late Pleistocene mammal remains found in a buried peat deposit. In addition to this famous “mammoth peat”, more deeply buried peat layers, part of which have previously been attributed to the final part of the Last Interglacial, also include a wealth of environmental data.

Here, we present the first results of an investigation, including sedimentology, geochemistry, palaeobotany (pollen, wood and plant macroremains), malacology, and luminescence dating, of two 16 meter drill cores taken close to the Niederweningen site. The analysed sedimentary successions in both cores show a transition from a series of laminated silts typical of a lake environment to a several meter-thick succession of well-developed organic silts, tufaceous silts and peat layers characteristic of near shore and shore conditions. The presence of dropstones and a lack of organic material in the lower part of the lake sediments indicate glacial conditions, while the peat-rich succession formed during a relatively warm period followed by a time of fluctuating climate. Preliminary results indicate that the organic-rich units represent the Last Interglacial, followed by warm interstadials during the early part of the Last Glacial period. The "mammoth peat" appears to be missing from the studied cores. Erosive surfaces within the peaty succession impede a straightforward interpretation.
The Potential Role of Citizen Science for Addressing Global Challenges and Achieving the UN Sustainable Development Goals
Authors: Fraisl Dilek , Campbell Jillian , See Linda , Wehn Uta , Wardlaw Jessica , Gold Margaret , Moorthy Inian , Arias Rosa , Piera Jaume , L. Oliver Jessica , Maso Joan , Penker Marianne , Fritz Steffen
Published: March 2020

The contribution of citizen science to addressing societal challenges has long been recognized. The United Nations (UN) Sustainable Development Goals (SDGs), as an overarching policy framework and a roadmap to guide global development efforts until 2030 for achieving a better future for all, could benefit from the potential that citizen science offers. However, there is a lack of knowledge on the value of citizen science, particularly in addressing the data needs for SDG monitoring, among the UN agencies, national statistical offices, policy makers and the citizen science community itself. To address this challenge, we launched a Community of Practice on Citizen Science and the SDGs (SDGs CoP) in November 2018 as part of the EU Horizon 2020 funded WeObserve project.

The SDGs CoP brings together citizen science researchers, practitioners, UN custodian agencies, broader data communities and other key actors to develop an understanding on how to demonstrate the value of citizen science for SDG achievement. The initial focus and the main objective of the SDGs CoP has been to conduct a research study to understand the contribution of citizen science to SDG monitoring and implementation. In this talk, we will present the work of the SDGs CoP. We will first discuss existing data gaps and needs for measuring progress on the SDGs, and then provide an overview on the results of a systematic review that we undertook within the CoP, showing where citizen science is already contributing and could contribute data to the SDG framework. We will provide concrete examples of our findings to demonstrate how citizen science data could inform the SDGs. We will also touch on the challenges for and barriers to the uptake of citizen science data for the SDG monitoring processes, and how to bring this source of data into the scope of official statistics.
Long-term assessment of surface dynamics in the Tyrrhenian Sea
Authors: Zambianchi Enrico , Krauzig Naomi , Falco Pierpaolo
Published: March 2020

The variability of surface dynamics has been investigated extensively in the Mediterranean Sea for different temporal and spatial coverage, whereas a specific evaluation for the area of the Tyrrhenian Sea does not exist. Thus, this study is focused on the Tyrrhenian basin, a subbasin of the western Mediterranean, which is considered sensitive to climatic variations due to its small size and isolated nature. The main scope is to provide a comprehensive and up-to-date assessment of the sea surface warming, the sea level changes and the general surface circulation in the Tyrrhenian Sea, as well as to improve the understanding of the relation to large-scale teleconnection patterns and to regional air-sea interaction. The long-term spatio-temporal variability and trends were investigated using satellite-derived, in-situ and reanalysis-based datasets up to the end of 2018. Further, the possible linkage with the occurrence of extreme weather events was assessed using observations from the European Severe Weather Database. The different datasets cover multiple temporal and spatial scales and enable the investigation of the potential physical processes related to the non-homogeneous, time-depended spatial variability. The results indicate a significant increase in sea level and sea surface temperature which appears to be linked with the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO), respectively. Moreover, analysis of the basin’s surface circulation together with local air-sea exchanges of heat, freshwater and momentum indicated a significant influence of the wind-driven Ekman pumping variability.
The specificity of thermal denudation feature distribution on Yamal and Gydan peninsulas, Russia
Authors: Nesterova Nina , Khomutov Artem , Kalyukina Arina , Leibman Marina
Published: March 2020

Thermal denudation is a combination of the processes responsible for the formation of retrogressive thaw slumps (cryogenic earth flows) and thermocirques. Thermocirques are the depressions with a semi-circle shape resulting from tabular ground ice thaw. Environments characteristic of Сentral parts of Yamal and Gydan peninsulas forming the so called  Kara sub-latitudinal transect, are favorable to activation of thermal denudation. The key factors are continuous permafrost distribution and shallow occurrence of tabular ground ice.

An increase in ground temperature and active layer thickness in 2012-2013 cause the intensification of thermal denudation along Kara sub-latitudinal transect. Field studies in the area of “Vaskiny Dachi” research station as well as remote sensing of 2018 data demonstrates the presence of both active and stabilized thermocirques during.

This research presents preliminary results of collecting and analyzing the distribution of more than 400 landforms caused by thermal denudation identified in central Yamal and central Gydan peninsulas. Coastal thermodenudation landforms were not taken into account to exclude the influence of wave erosion in this study. Such work became possible due to free of charge satellite images with a very high spatial resolution available at the service Yandex.Maps (https://yandex.ru/maps/).

In Yamal peninsula, we identified 63 active and 53 stabilized thermodenudation landforms, in Gydan peninsula, 169 active and 166 stabilized, respectively. Active thermodenudation features concentrate in the western and southern parts of central Yamal, while stabilized dominate in western and central parts. In central Gydan both active and stabilized features of thermal denudation are located at northwestern part and are distributed more evenly compared to Yamal. Northern border of all identified thermodenudation features for both Yamal and Gydan peninsulas is located at 71 degrees North, and the southern border at 69 degrees North. Despite the difficulties of visual interpretation of thermal denudation features, we defined the majority of them as thermocirques, most of which are located along lake coastlines. Such indication was also confirmed by in-situ data collected during multiyear field campaigns in the study area. These results reveal a prevalence of thermal denudation features in the study area and the collected data gives us an opportunity for spatial analysis of their distribution.

The reported study was partially funded by RFBR according to the research project #18-05-60222 
A spatio-temporal view of variability in pollen records during the last Glacial
Authors: Weitzel Nils , Adam Moritz , Sommani Anna , Rehfeld Kira
Published: March 2020

Climate variability influences the probability of extreme events and is therefore of great importance for risk management. Nevertheless, changes in climate variability over time are far less studied than changes in the mean state of the climate system. Proxy records can be used to estimate the dependency of climate variability on the state and timescale, but their climate signal is perturbed by non-climatic processes and dating uncertainties. Analyzing ice cores and marine sediments, it was shown that temperature variability during the Last Glacial Maximum was larger than in the Holocene and that the magnitude of variability change depends on latitude.

We estimate millennial and orbital scale variability in pollen records during the last Glacial. We draw on a global network of published pollen records, which are influenced by local temperature and moisture availability, and compare these estimates with temperature, precipitation, and vegetation variability in climate simulations of the last Glacial cycle. We discuss the regional consistency of timescale dependent estimates. Differences between Marine Isotope Stages 2, 3, and 4 are examined by comparing spatial patterns during those three periods. Then, we use spectral methods to study the scaling behavior of the pollen records. This provides additional information on the continuum of variability from centennial to orbital scales. Finally, we quantify the co-occurrence of millennial and orbital scale fluctuations across different pollen records with paleoclimate network techniques.

Our work extends previous estimates to the terrestrial realm and to longer timescales. The results provide new insight on the climate variability differences between glacial and interglacial states, and on the mismatch between climate simulations and proxy data.
Metakaolin geopolymers applied in the conservation of tile facades: a Portuguese case study
Authors: Rocha Fernando , Moutinho Sara , Costa Cristiana , Andrejkovičová Slavka , Mariz Luis , Sequeira Cristina , Terroso Denise , Velosa Ana
Published: March 2020

The possibility of using geopolymers to fill gaps/lacunae in glazed ceramic tiles (azulejos) has been studied. Since the 15th century, glazed ceramic tiles are characteristic elements of the Portuguese architectural heritage and their use as external rendering elements has made them prone to degradation. On the other hand, civil construction is a sector with a high consumption of natural resources and CO2 emissions. In order to respond a necessary increase of sustainability in conservation/restoration processes, it is important to create/use sustainable repair materials that also ensure compatibility and durability of interventions. Geopolymers were studied as a potential sustainable and compatible repair material. Two commercial metakaolins ARGICAL-M 1200S and ARGICAL-M 1000 were used as precursors in geopolymer pastes and tested. The purpose of this research was to assess the potential of geopolymers in the restoration of the glazed ceramic tiles, both in the filling of gaps and the bonding of ceramic fragments. The physical, chemical and mineralogical analyses of these materials were performed. Additionally, in order to evaluate possible use in conservation interventions, tile lacunae filling, glazing reintegration and bonding of ceramic fragments were studied. Several tests were performed in order to analyse the compatibility and durability of the designed geopolymers and the ceramic/geopolymer system. The results suggest that the geopolymers had a better performance in the bonding of ceramic fragments and can have potential to be applied in the conservation and restoration of tile facades. Thus, as a general conclusion, it was possible to develop sustainable materials to apply in conservation of buildings facades.
Impact of glacial meltwater on biogeochemical cycling in coastal and shelf waters off South West Greenland: Insights from ship-board and glider observations
Authors: Hendry Katharine , Briggs Nathan , Opher Jacob , Brearley J. Alexander , Meredith Michael , Leng Melanie , Woodward E. Malcolm , Henson Stephanie
Published: March 2020

The high-latitude regions are experiencing some of the most rapid environmental changes observed anywhere on Earth, especially in recent years. The Greenland Ice Sheet, for example, is experiencing significant mass loss largely through surface melting, but also via ice discharge at glacier fronts. As well as changing freshwater budgets and ocean stratification and mixing, there has been increasing focus on the role of glaciers and ice sheets in supplying particulate and dissolved organic material and inorganic nutrients to marine systems. Here, we explore how a combination of ship-board and high-resolution ocean glider observations in shelf waters off SW Greenland inform on how these nutrients reach the coastal oceans and, eventually, mix off the shelf and into the open ocean. We find that the proportion of meltwater calculated using salinity and oxygen isotope mass balance agrees well with estimates from glider sensors. These meltwaters contain low dissolved macronutrients, but are characterised by high particulate and high dissolved organic content. Bio-optic sensors on the gliders reveal strong meltwater signals in fluorescing dissolved organic matter (FDOM), and a detectable signal in optical backscatter; these signals can be now observed extending further out into the open ocean in compiled biogeochemical (BGC) argo float data. The mixing of both dissolved and particulate macronutrients and organic matter off the shelf is likely driven by advection in geostrophic currents, tidal and buoyancy forcing, and is also impacted by storm events via wind-driven changes in mixed layer depth and resuspension.
Role of dextral strike slip faulting in the distribution of Aegean extension since Miocene times inferred from receiver function analysis
Authors: Faucher Agathe , Tiberi Christel , Gueydan Frédéric , Gesret Alexandrine
Published: March 2020

Aegean plate is marked since Eocene by widespread NE-SW extension induced by the African slab roll-back. In Miocene times, E-W shortening created by the westward Anatolian extrusion overlays the extension, with the formation of Miocene dextral strike slip faults in addition to normal faults. We propose to quantify the role of large dextral strike slip faults in accommodating Aegean extension, using receiver functions to image Moho geometry.

Aegean extension is particularly evidenced by a topographic difference between the emerged continental Greece and the submerged Cyclades. In this study we characterize the associated Moho geometry with a particular focus on the transition between these two domains. From a geological point of view, the transition between continental Greece and the Cyclades is marked by two dextral strike slip faults: the Pelagonian fault (onshore) and the South Evvia fault (offshore). Our objective is also to show a potential Moho signature of these strike slip faults.  We processed receiver functions (RF) from the MEDUSA stations located in Attic and Evvia.

Our results show that the Moho is deeper beneath continental Greece (~27km) than beneath the Cyclades (~25km). A detailed azimuthal study of RF distribution shows a flat Moho underneath Continental Greece. The crustal thickness is also almost constant inside the Cyclades, as already suggested by previous studies. However, the transition between the Cyclades and Continental Greece is not continuous. These two crustal blocks are separated by the Pelagonian and the South Evvia strike slip faults in a narrow transition zone (~75km). In this zone (South Evvia/Attica), dip and strike of the Moho vary and suggest a crustal signature of the strike slip structures observed at the surface. These strike slip faults therefore accommodate in a narrow zone the inferred variations in crustal thicknesses between the Cyclades and Continental Greece.

Our data show that differences in topography between Continental Greece and the Cyclades are isostatically compensated, reflecting various amount of crustal thinning larger in the Cyclades than in Continental Greece. Inside these two crustal blocks, we imaged a flat Moho, suggesting a wide rift extension process associated with the formation of numerous Miocene and Plio-Quaternary basins.  The dextral strike slip faults at the edges of the continental blocks (Continental Greece and Cyclades) accommodated the inferred variations in the amount of crustal thinning, suggesting that they act as continental transfer zones at crustal-scale during Miocene Aegean Extension.
The CDGP Repository for Geothermal Data
Authors: Turlure Mathieu , Schaming Marc , Fremand Alice , Grunberg Marc , Schmittbuhl Jean
Published: March 2020

The CDGP Repository for Geothermal Data

The Data Center for Deep Geothermal Energy (CDGP – Centre de Données de Géothermie Profonde, https://cdgp.u-strasbg.fr) was launched in 2016 by the LabEx G-EAU-THERMIE PROFONDE (http://labex-geothermie.unistra.fr) to preserve, archive and distribute data acquired on geothermal sites in Alsace. Since the beginning of the project, specific procedures are followed to respect international requirements for data management. In particular, FAIR recommendations are used to distribute Findable, Accessible, Interoperable and Reusable data.

Data currently available on the CDGP mainly consist of seismological and hydraulic data acquired at the Soultz-sous-Forêts geothermal plant pilot project. Data on the website are gathered in episodes. Episodes 1994, 1995, 1996, and 2010 from Soultz-sous-Forêts have been recently added to the episodes already available on the CDGP (1988, 1991, 1993, 2000, 2003, 2004 and 2005). All data are described with metadata and interoperability is promoted with use of open or community-shared data formats: SEED, csv, pdf, etc. Episodes have DOIs.

To secure Intellectual Property Rights (IPR) set by data providers that partly come from Industry, an Authentication, Authorization and Accounting Infrastructure (AAAI) grants data access depending to distribution rules and user’s affiliation (i.e. academic, industrial, …).

The CDGP is also a local node for the European Plate Observing System (EPOS) Anthropogenic Hazards platform (https://tcs.ah-epos.eu). The platform provides an environment and facilities (data, services, software) for research onto anthropogenic hazards, especially related to the exploration and exploitation of geo-resources. Some episodes from Soultz-sous-Forêts are already available and the missing-ones will be soon on the platform.

The next step for the CDGP is first to complete data from Soultz-sous-Forêts. Some data are still missing and must be recovered from the industrial partners. Then, data from the other geothermal sites in Alsace (Rittershoffen, Illkirch, Vendenheim) need to be collected in order to be distributed. Finally, with other French data centers, we are on track to apply the CoreTrustSeal certification (ANR Cedre).

The preservation of data can be very challenging and time-consuming. We had to deal with obsolete tapes and formats, even incomplete data. Old data are frequently not well documented and the identification of owner is sometimes difficult. However, the hard work to retrieve, collect old geothermal data and make them FAIR is necessary for new analysis and the valorization of these patrimonial data. The re-use of data (e.g. Cauchie et al, 2020) demonstrates the importance of the CDGP.
Analysis of tidal sea-ice movement using a drifting ice beacon array in the Barents Sea
Authors: Vasulkar Amey , Kaleschke Lars , Verlaan Martin , Slobbe Cornelis
Published: March 2020

In an experiment to validate an ice forecast and route optimization system, an array of 15 ice drift beacons/buoys were deployed between Edgeøya and Kong Karls Land in the east of Svalbard to measure the sea ice movement. These beacons recorded data at a sampling frequency of 15 minutes in the duration from March 2014 to May 2014 with different start and end dates based on their life. The particularly short time step captures the small scale effect of tides on the drifting ice. In this region of the Barents Sea, the frequency of the inertial motion is very close to the M2 tidal frequency. Hence, it is not possible to extract the tidal motion from the time series data of the buoys by using a Fourier analysis. It is also likely that these effects will interact. Instead, we develop a physics-based free drift ice model that can simulate the drift at all tidal and other frequencies.

The model is forced by winds obtained from the ERA5 Reanalysis dataset of ECMWF and ocean currents obtained from the Global Ocean Analysis product of CMEMS. Due to the effect of tides, the model is also forced by the tides obtained from the Global Tide and Surge Model (GTSM v3.0) which is built upon Delft3D-FM unstructured mesh code. This free drift model is validated against 8 of the 15 beacon trajectories. The model along with the observed data can be then be used to obtain insights on the relationship between the sea ice velocities and the tides. This will be particularly useful to obtain the effect of ice drift on tides in tidal models.

The model uncertainty is mainly due to oceanic and atmospheric drag coefficients, Cdw and Cda, respectively, and the sea ice thickness, hi. This study also focuses on optimizing the ratio of drag coefficients (Cdw/Cda) for the different beacon trajectories while varying the ice thickness between 0.1 m - 1.5 m and the ice-air drag coefficient between (0.5-2.5)x10-3. This ratio facilitates the evaluation of the frictional drag between the ice-water interface and thus, helps in determining the effect of ice on tides in tidal models.